The Insects Living in the Pods of Broom Othamnus

THE INSECTS LIVING IN THE PODS OF BROOM

C OTHAMNUS SCOPARIUS) AND THE RELATIONSHIPS BETarmiN THEM

J.R. PARNELL, B.Sc. A.R.C.S.

A thesis submitted for the Degree of Doctor of Philosophy in the University of London.

March. 1962. Imperial College of Science and Technology, Field Station,. Silwood Park, Sunninghill, Ascot, Berkshire. ABSTRACT. The fauna within pods of Sarothamnus scoparius (L.) Wimmer is examined and attempts are made to evaluate the relationships between the 23 insect species which were found at Silwood Park. The primary habitat of these species (i.e. the pod ) is investigated in all its stages of development. An area of old (i.e. 12 to 15 years ) bushes ("Old Broom") is compared with an artificial plantation of bushes each approximately four years old (Tow Broom").' Preliminary studies showed that the insect fauna could be divided into three almost independent complexes. The first is the complex of insects having their immature stages within broom seeds. These include the two host beetles Anion fuscirostre Fab. and Bruchidius ester Marsham together with their internal and external hymenopterous parasites and hyper-parasites. The second complex is that occurring in the broom pod cavity. This includes three species of Oecidomyidae, of which pantarinia pulchripes Kief. and Olinodiplosis sarothamni Kief. have been recorded. previously from broom. Thesececidomyids also have their own set of internal and external parasites. The third complex is that occurring within galls. on broom. pods, formed. by the cecidomyidAsph.ondylia sarothamni H.Loew. Several species of hymenopterous parasites attack the single sarothamni larva in each gall. The larvae of the inquiline eecidomyid Trotteria,sarothamni Kief. were also found in galls. The population estimations of Anion and Bruchidius larvae and their parasites, obtained from broom pod samplest are compared in the two broom areas in 1960 and 1961. TABLE OP CON.TENTS Page. SECTION I. A. Introduction. .... 1 B. Preliminary Studies of the Broom Plant. .... 3 SECTION II. - The complex of Insects Associated. with the Broom Seed. .... 31 A. Bruchidius ater Marsham. .... 32 B. koion fuscirostre Pab. •••• 117 C. Hymenopterous parasites occurring in the Broom Seed. 0... 155 SECTION I/I. p- .The complex of Insects associated with the Broom pod cavity...... ' 199 A. 'Introduction. 40••• 201 B. Host species. .... 203 'C. Parasitic species on Contarinia Dulchripes Kieffer larvae. .... 223 D. Parasitic species on Clinodiplosis earothsrn,i Kieffer larvae. .... 237 E. Parasitic species on Le todiplosis sp. larvae. 4,410 r . 238 P. Incidental insect species which overwinter in the, curled. broom pod valves. *O.. 239 SECTION IV. ... The comillex of insects associated with galls on broom pods *OM* 240 A. Introduction. 242 B. Gall forming species. 4,4kooe'- 244 C. Inquiline species in the gall. 255 D. Parasitic species in the gall of Asphondylia sarothamni H. Loew. .... 263 E. Hyper-parasitic species on Aprostocetus brevicornis (Panzer). 'v... 285 P. 'Comparative numbers of the different insect species found in pod galls of Asphondylia sarothamni. ' ...Ili 290 ,SECTION V. - Population estimations obtained from pod samples 41104O- i 295 A. Sampling Method. 40400i 295 B. "Old. Broom" area. .... 296 C. "New Broom" plantation. .... 312

SECTION VI. Discussion. .0 • • • 323 SIIMMArys iilligo 334 Acknowledgments. itorrew 337 References. 4... 338 Appendix Tables...... 350

The subsections are given in detail on flysheets preceeding the separate sections. SECTION I A. Introduction. B. Preliminary Studies of the Broom Plant. 1. The Areas Studied. , 2. Growth and Development of Broom in 1960 and 1961. 3. Pod production in the "New" and "Old Broom" areas. 4. Lengths of pods in the "New" and "Old Broom" areas. 5. Number of seed rudiments per pod. 6. NUmber of Mature seeds per pod in the absence of insect attack i.e. Total Potential Yield. 7 Estimation of the total numbers of pods produced in the "Old" and "New Broom" areas in 1960 and 1961. A. Introduction. Common Broom (Sarothamnus scoparius (L.).Wimmer) has a very varied and interesting insect fauna, the different species inhabiting a wide variety of parts of the plant. • Rolibal (1949) reviews many of these species and quotes many earlier references concerning their biology and distribution. More recently Richards and Waloff (1958 and 1961) have studied the biology and population dynamics of Phytodeeta olivacea (Forst.) on broom at Silwood Park, Berks., and they are at present engaged on a study of the Miridae occurring on broom. A series of investigations on other insect species living on .broom have also been made by Dempster (1960), T.R. Smith (1958) B.D. Smith, (1957) and White (1958). This investigation is concerned with the insects which have some or all of their immature stages within the seed pod of broom. The fauna within this limited ecological habitat is found to differ somewhat on broom bushes of different ages. In this study a comparison is made between the insects found in an area of very old bushes (i.e.. 12 to 15 years) and those found in an artificial plantation of young broom bushes, each approximately 4 years old. Preliminary studies showed that the fauna of some 23 insect species living in the pods on both old and young bushes, could be divided into three almost independent complexes. The habitat (i.e. the broom pod) of the three complexes 2.

of species is compared in the two broom areas studied. The immature stages of the majority of the 23 insect species are described and their life histories are included,. The first is the.complel Of insects which have their immature stages within broom seeds. These include the two host beetles-Bruchidius,ater Marsham and. Apion fuscirostrePab. together with their internal and external ,hymenopterous . parasites and hyperparisites. Some of these parasites only occur in pods on either the old or the young broom bushes. The second complex is that occurring inHthe broom pod cavity. This includes three species of Cecidomyidae of which Contarinia pulcka,es Kieffer and Clinodiplosis sarothamni Kieffer,have been recorded previously from broom. These cecidomyids also have their own set'of.internal and external hymenopterous parasites. The third complex is,that,occurring within galls on broom podso• formed by the cecidomyid Asphondylia sarothamni H. Loew. ( = Asphondylia,mayeri Liebel).- Several species of parasitio hymenoptera attack the'single Asphondylia larva in each gall. The larvae of Trotteria sarothamni, Kieffer are also found, living sometimes as inguilines with the Asphondylia larvae and

-sOmetimes,on their own in the pod gall. Some studies of the population dynathics of Apion and. Bruchidiusaults on broom are made using,various sampling methods and these are included where,they'are relevant. Finally an analysis is made of.the pod samples taken throughout 1960 and 1961 in both broom areas. Prom these cc results an attempt is made to a ipess the degree of association between the, different insect species including both the parasitic and the non parasitic relationships.

B. Preliminary Studies of the Broom Plant. 1. The Areas Studied. Broom, Sarothamnus seonarius (L.) Wimmer,, is widely distributed over the 230 acres of the Imperial College Field Station, Sunninghill, Berks., and, this is a preliminary investigation of the plant, since the broom pods form the habitat of many stages in the life, histories of the complex of insects which were studied. The studies have been concentrated on two main areas of broom at the Field Station. The first, is a very old, natural growth of bushes, many of which are now dying of old.age and which originally were spread over an area of approximately two acres. The second area, is a large' plantation of two acres, in which over 1,600 seedlings were planted out in 24 hoursin March, 1957. The average height of these bushes is now 6 ft., and some of the larger ones are up to 10 ft. high. The two areas will be referred to as the "Old Broom" and "New Broom" respectively. 4.

2. Growth and Development of Broom in 1960 and 1961. In 1960 the first growth occurred in early February when a few bushes formed delicate leaves. These were killed off towards the end of the month by frost and it was not until the first week in March that foliage once again began to develop.. The brilliant yellow flowers appeared by the second week in. March and steadily increased in numbers through April reaching a peak around 10 May. Small green rudimentary pods, 15 millimeters long then began to develop where the flower petals fell away. These grew rapidly, doubling their length in 8 days and reaching a mayimum length of 50 to 60 millimeters by the end of May. By the second week in June the last flowers disappeared from the bushes. Only one plant in the "Old Broom" still retained a few buds. Seeds in the growing pods were now swelling out, enlarging the pods but remaining green and soft. Having swollen to their greatest capacity whilst still green and soft, the seeds then became very hard and dry, changing from green to yellowish brown as they "matured". The pod valves also dried out at this time, turning from green to black. Finally the pods dehisced with a sharp "crack", flinging out the seeds to distances up to 4 feet.

The graphs of pod development in 1960, (Fig. 1 Graphs A and B) show that the pods in the two areas developed at the 5

same rate. The change in the pods from green to black, which occurred throughout July, was very rapid as is depicted in the graphs A and B, (Fig. 1). The pods began to dehisce by the second week in July and continued to do so for the next two and a half months. By this time over 80% of them had dehisced in both areas. The remaining pods opened gradually between October and December, these late pods being the smallest and containing very few or no seeds By the 1 September a few 'bushes in the "New Broom" were flowering for the second time. Edwever, none flowered in the

"Old Broom". New pods appeared by 10 September and a sample taken on 27 September showed that the second crop was very small, forming only 3,4% of the first one. These pods remained green throughout the winter of 1960-61. When 100 were examined on the 14 February 1961 it was found that all of the seeds had turned orange brown and were degenerating as a result of fungal infections. By Mnrch, 1961 these pods had shrivelled and dropped off without yielding a single mature seed. In 1961 the first foliage and flowers once again appeared in March, the bushes coming into full bloom a week earlier than in 1960 around 2 Bay. This was due to the warm weather experienced in the early part of 1961. 6..

In this early season the pods were well formed by the second week in May. However, the severe frosts of 25°F. 24°P: and 24°F. In the nights of 27,28 and 29 May had a disastrous effect on pods of all sizes in the "New Broom",'causing over half of them to blacken and shrivel up. To assess the total damage, a series of systematic cuttings were taken from every 35th tree in the "New Broom" plantation. Three cuttings, one from:the top middle and bottom of .aach of 50 bushes were taken and frosted and unfrosted pods were counted in each region. (Table 1) Table 1 Estimation of frost damage to '"New Broom", pods in May, 1961.

Sample region on bush TOP MIDDLE BOTTOM TOTAL 1;

Weight' of sample in grams 687 576 540 — Unfrosted pods . 1141 586 395 2122 38.09 Frosted pods 916 1359 1174 3449.. 61.91 Total 5571 100.00

Table 1 shows that pods nearer to the ground were affected more than those higher up. The overall loss was 61.91% of the total in the area. The "Old Broom" area is surrounded by large oak and beech trees and thus is more sheltered than the "New Broom". However even in this sheltered area it was evident that all pods below a height of 2 ft., from the ground had been killed by frost. Each bush showed a vertical gradation ranging from unharmed pods at the top to frosted pods on the lower branches. To estimate the percentage of frosted pods a similar sample was taken to that in the "New Broom" and the results are set out in Table 2. Table 2 Estimation of frost damage to "Old Broom" pods in May* 1961.

Sample region on bush TOP MIDDLE BOTTOM TOTAL

Weight of sample in grams 603 547 537 Unfrosted pods 1803 1399 758 . 3960 93.40 Frosted pods 6 39 235 280 6.60 4240 100.00

Table 2 dhows that although some pods were killed by frost* they only amounted to 6.6% of the total crop* Thus relatively nearly 10 times as many pods were affected, in the more exposed, "New

Broom" plantation than in the sheltered, "Old Broom" area... ' The development of the surviving pods in 1961 is shown in Fig. 2., (Graphs A and B) and when these are compared with those v, for 1960, (i.e. Fig. 1. Graphs A and B), it can be seen that there is very little difference between all the 4 graphs. The peaks of the graphs for black pods in 1961 are about one week earlier than those in 1960 and the graphs of dehisced pods also show that comparable percentages of pods opened about one week earlier in 1961 than in 1960 in both areas' In both years, however, the dehiscence of pods in the /00 8., U) A w 04 1.-w N 80 m 0

1.... 60 4 0m 0m LL, 40 0 w 0 1- 5 20 0M mW 1 / 0 JUNE AUGUST SEPTEMBER • • Green pods o o Block pods >c—_x Dehisced pods /00 --- Blackening pods N W B i-< o 8 0 N n 0

6 41-- to0 0m 40 0 W 4 Z 20 W 0 M Wm 0 JUNE JULY AUGUST SEPTEMBER Fig. 1. Development of broom pods throughout 1960. A. In the "Old Broom" area. B. In the "New Broom" plantation. A

0 I- BO-,

> 60- 4 8 0 a. U.

0 4 z 20. U

JUNE JULY AUGUST SEPTEMBER •—• Green pods 0-0 Black pods X-->c Dehisced pods 100 Blackening pods tn 0

80 11) 0 ac

1.-60 4

0 0 a. IA. 4 0 0 F- taz 20 U

JUNE JULY AUGUST SEPTEMBER Fig. 2. Development of broom pods throughout 1961. A. In the "Old Broom" area. B. In the "New Broom" plantation. 10.

"New BrooM" lagged behind that in the "Old Broom" by approximately 5 days, the reason for this probably being due to slightly higher day temperatures in the sheltered "Old Broom" area. In the second week of August in 1961 a few flowers again appeared in the "New Broom", these being a fortnight earlier than in the previous year. As in 1960 nevi pods were formed but once again, no seeds matured before the onset of the winter months. 3, Pod Production in the "Nee and "Old Broom" areas In June 'and July, 1960' an estimate of the number of pods in a unit weight of broom was made in' both the "New" and the "Old Broom" areas. Small sprigs of broom were cut from the top, middle and bottom of every 35th bush in the "New Broom" plantation and the complete sample was weighed. The number of pods it contained was then counted. Similar pieces of broom were cut from bushes spread all over the "Old Broom" areas, including a few from the regenerating growth,. Again the samples were weighed and the pods counted. The results are shown in Table 3. Table 3 Comparison of the Pod Production. per unit weight of Broom in the "New" and "Old Broom" areas in 1960, Weight of No, of Pods No, of pods in Sample in in sample equal weights grams of Broom New Broom 5428 3312 100 Old Broom 5933 2992 82.65

Thus in equal weights of broom, the younger bushes in the "New 11.

Broom" plantation produced 100 pods whereas the older bushes in the "Old Broom" only produced 62.65 pods. This comparison could not be repeated in 1961, as many more pods were killed off by the relay frosts in the "New Broom" areas 4, Lengths of pods in the "New" and "Old Broom" areas The lengths of the pods in each of the weekly samples, (see later), taken throughout 1960 and 1961 and also on two occasions in 1959, were recorded), The measurement represents the distance between the tip of the pod and the joint connecting it with the stem. It was made in millimeters by laying each pod flat upon an ordinary wooden ruler. . Once all of the pods had been measured they ere grouped into sets, the difference in lengths in each set not exceeding . 5 millimeters. These sets start with small pods ranging between 21 - 25 m.m. up to the largest pods ranging between 61 - 65 mai. The numbers of pods occurring in each set in both "New" and "Old Broom" areas in all of the 3 years studied* are set out as histograms (Fig. 3). For the purposes of drawing these histograms each set is indicated by its average length.' That is the average 21+25 of the 21 - 25 m.m.'set is -2 = 23 m.m. that of the 26 - 30 m.m. set being 28 m.m. and so on. The histograms show that the "New" and "Old Broom" bushes produce podsv'the lengths of which are diStributed approximately equally around their mean. (i.e. show normal distribution). 12.

These means are indicated on the histograms and a statistical comparison of 'difference of means between "New" and "Old Broom" in 1959 shows no significant difference, = 1.096 n = 1845). However the.mean length' of the "New Broom" pods is'slightly greater than that'of the "Old Brode'ones.' in 1960 this tend icy of the "New Broom" to produce'larger pods was increased and the two means were significantly different, (t . 10.189 n'= 4631) In 1961 the means were again Significantly different, (t = 3.273 n =3383). It is also interesting to note that there was no significant difference:in the mean lengths of pods on "Old Broom" throughout the three years 1959-61 whereas these lengths altered significantly on the "New.Broom" bushes,in the successive years. ("Old Broom" 1959-60 t = 0.919 n = 2848, 1960-61 t = 1.257 n = 3789), ("New Broom 1959-60 t = 8,026'n = 3628, 1960-61 t = 5.250 n = 4225). The small numbers of pods shown in the histograms (101g.,3) as being under 20 mem, long werenot used in the above calculations as their' length was not measured. Also these small pods do not usually produce any seeds and are thus relatively unim- portant to this study. 5. Number of seed rudiments per pod. In each of the samples taken in 1959, the number of developing seeds and the number of unfertilized seed rudiments 13.

400- A

mean 40-50sinn. mean 38-24rom 3

mean 39.20mm.

200- MOW

a. IOO- 3

o 2023211313e4M33SS sonsenseemosess sommiuma.ossmo a. LL

400-

3 3 mean 38.16mm. Z 300- mean 3788 Milt mean 3840mm.

IM•

111

soninssnadsense aowemweftosses aonanummown AVERAGE LENGTH OF THE PODS IN EACH SET IN MILLIMETERS (i e average of the pod set 21- 25nnn. is 23mm. and 26-30mm. is 28mm. etc.)

Fig. 3. Lengths of pods from samples in the two broom areas. A. "New Broom" plantation 1959. B. "New Broom" plantation 1960. C. "New Broom" plantation 1961. D. "Old Broom" area 1959. E. "Old Broom" area 1960. F. "Old Broom" area 1961. 14.

were recorded against each pod length. :They were also recorded in 1960 in two sets. of samples in the "New BroOm"and:in four Sets of samples in the "Old. Broom". When the. numbers of, develOping and rudimentary seeds per pod. were added together. the total initial seed rudiment number was obtained. Table 4'shoWsthe.results obtained in 1959' and it can be seen that in both the "New" and the "Old Broom", the largest number of pods had 17 seed rudiments. There is however, i range from 11 to 23 seed rudiments in all the pods in both areas. • . The means of the numbers'of -seed rudiments per pod in' both' the "New" and the "Old Broom" were found to be significantly different by a'test of, the difference of means (t= 5.68 n 7 1851). The reason for this can be seen in Table 4 when the figures of the "New Broom" are compared with' 'the figures of the "Old Broom".' They show that there are more pods eontainin 11':- 14 seeds in the "Old Broom" area, approximately equal numbers containing 15 18 seeds in both areas and a' greater number of pods containing 18- 23 seed rudiments in the flHew-Broom" area. As has been shown before, the mean lengths of the pods in both areas are not significantly different:and thus it follows. that the younger broom plants produce more pods with a larger number of seed rudiments than do 'the older bushes. In 1960 the same picture can be seen when the numbers of 15.

Table 4* Frequency of need rudiments in pods•collected in the "New" and "Old- Broom" areas in 1959. Number of pods. Nutber of pods Old Broom Number of New Broom Old Broom corrected to Seed Rudiments 4 Samples 3 Samples New Broom figures.

11 21 20 28.8 12 11 14 20,2 13 36 39 56.2 14 68 72 103.8 15 176 131 188.9 ,1.16 225 162 233.6 17 265 185 266.8 18 127 78 112.5 19 92 43 62.0 20 48 9 13.0 21 16 4 5.8 22 .7 1 1.4 23 1 Total 1093 758 1093 Mean No. Seeds per pod. 16.50 15.98 15.98 16"

Table Se Frequency, of seed rudiments in pods collected in the "New" and the "Old Broom" areas in 1960. Number of Number of pods'. Number of pods. New Broom Seed rudiments New Broom Old Broom corrected to 2 Samples, 4 Samples Old Broom figures'

. 3 11 4 32 12 5 32 10 13 20 76 40 14 45 16/ 90 15 98 289 196 16 131 380 262 17 357 421 714 18 99 190 198 19 57 89 114 20 26 24 52 21 6 9 12 22 — 1 25 2 Total 850 1700 1700 Mean No.. Seeds per pod" 16'49 16'06 1649 17

seeds in the pods are compared in samples taken in the two areas. The totals for these samples are set out in Table 5, Once again the mean number of seed rudiments in the "New Broom" pods is significantly greater than that in the "Old. Broom" pods (t 8*67 n 2550)4; These two means, however, compare very favourably with those of 1959 in the two areas. (i.e. 16.50 seed rudiments per pod in "New Broom" 1959 and 15.98 in "Old Broom" 1959). It must also be remembered however that in 1960 the larger .number of seed rudiments per pod in the "New Broom" is also related to the significantly greater average length of the pods. The division in 1960 is a sharp one, the "Old Broom" having more pods with up to-16 seed rudiments and the "New Broom" having a much greater number of pods with 17 or more. seed rudiments. However, even in 1960 in both sets of broom bushes the greatest numbers of pods contained 17 seed rudiments, No comparison of the number of seed rudiments per pod was made in 1961 as a much higher percentage of the pods was killed by frost in the "New Broom" than in the "Old Broom". 6* Number of "Mature" seeds per .pod in the absence of insect attack i.e. Total Potential Yield, The numbers of seeds that had matured, together with those that would have matured had they not been infested by insects, were counted in 4 "New Broom" pod samples and 3 "Old Broom" pod samples in 1959. With the pods grouped into "sets" 18*

Table 6, The Number of Mature seedsocciming in pods of Different lengths in the "New Broom" 1959* Range of pod , No. Pods in each No. Seeds in each Average No. of lengths in mm. set. 4 samples. set. 4 samples Seeds per pod.

20 21-25 17 28 1.6 26-30 111 393 3.5 31-35 269 1375 5.1 56-40 299 2080 6.9 41-45, 252 2257 8.9 46-50 94 1035 11.0 51-55 41 520 12.7 56-60 8 118 14.7 61-65

Table 7 The Number of Mature seeds occ'ming in pods of Different lengths in the "Old Broom" 1959. Range of pod No, Pods in each No. Seeds in each. Average No, of length in mm. set. 3 samples set. 3 samples seeds per pod

20 4* - 0, 21-25 23 20 0.9 26v30 71 201 2.8 31-35 156 709 4.5 36-40 250 1511. 6.0 41-45 174 1347 7.7 46-50 58 670' , 9.8 51-55 9 111. 12.3 56-60 3* 25 8.3, 61-65 - - (s These figures not used in calculations owing to the smallness of the sample) 19. according to their lengths see p. 12) the total number of seeds in each set could be evaluated. These nutbers are shown in Tables 6 and 7 together with the calculated average numbers in each pod set. Tables 4 and 7 show that in a large number of pods the umber of mature seeds varies directly with the pod length. gures 4 and 6 were constructed by plotting the average of each range of, pod lengths against the average, nutber of seeds per pod in each length range. Regression equations were computed for each of the two sets of data and the calculated regression lined are shown on the graphs. In 1959 (Pig. 4) the regression coefficients for these lines were compared and were not found to be significantly different (P>0.10). The variencea of the lines however were significantly different at the P = 0.05 level using the ,T" test with 6 x 6 degrees of freedom. Thus the "New- Broom", pods produce significantly more mature seeds per pod length than do the "Old Broom" ones, but the rate of increase of the number of seeds relative to the incresee in pod length is the same in both areas. This fact follows on the proceeding conclusions that "New Broom" produces more seed rudiments than does "Old Broom". The same results were obtained in 1960, 1.0 the coati- to were not significantly different (P =:w0.10) but in this of data (Pig nee between the variances only 20,

NEW BROOM y. 0.3706x-6.9542 Ij12 3 OLD BROOM 2 y. 0-3687x —7-6963 -110 5

W W

0 6 at o New Broom •Old Broom

I0 20 30 40 50 60 LENGTH OF POD IN MILLIMETRES.

Fig. 4. Computed regression lines comparing the number of seeds produced per pod length in the two broom areas in 1959. 21.

gI2

NEW BROOM y a 0.3170x-4.9866

OLD BROOM I y = 0.3023x —5.7323 e 0

0 6 cc o New Broom O • Old Broom z4

10 20 30 40 50 60 LENGTH OF POD IN MILLIMETRES.

Fig. 5. Computed regression lines comparing the number of seeds produced per pod length in the two broom areas in 1960. Table 8 The Number of Mature seeds occurring in pods of Different lengths in the "New Broom" 19600 Range of pod No, pods in each No. seeds in each Average No. of lengths in set. 3 samples, set.,3 samples, seeds per pod r, m.

20 2 1 0,5 21-25 17 45 2.6 26-30 97 310 3,2 31-35 175 889 5.1 3640 313 2198 700 - 41.45 319 2964 9.3 4650 217 2343 10.8 5155 103 1283 12.5 56?-60 25 317 . 12.7 61-65 7 102 14.6

Table 9 The number of Mature seeds °coming in pods of ' Different lengths in the "Old Broom" 1960. Range of pod No. pods in each No. seeds in each Average No. of lengths in set. 3 samples. set. 3 samples seeds per pod m.m.

20 10 2 0.2* 21-25 38 51 1.3 26-30 .120 323 2.7 31-35 238 990 4.2 36-40 361 1975 5.5 41-45 285 2132 7.5 46-50 156 1315 8,4 51-55 51 556 10.9 56-60 14 167 11.9 61-65 2 26 13.0 (* Not. used in calculations owing to the unknown length of the pods) 23.,

approached significance. The data was computed from the totals of samples from each area, and is shown in Tables 8 and 9. 7. Estimation of the Total numbers of pods produced in the "Old" and "New Broom" areas in 1960 and 1961. Old Broom 1960 To estimate the total number of pods produced in the "Old Broom" area in 1960 the bushes were divided up into small arbitrary units called, "armfuls". :An "armful" consisted of that amount of broom which could easily be taken under one arm and shaken over a 1 m. square beating tray. It was found that, after a little practice the number of "armfuls" of broom in each bush could be estimated visually with a fair degree of accuracy. The total number of armfuls in the area on 10 April, 1960 was found by inspection to be 860. Other estimates for this area, for previous years are given by Richards and Waloff (1961) and they show that since 1955 the number of armfuls in the area have decreased steadily as many of the older bushes died. In the second week in 'Pine, 1960, ten "armfuls" were cut, from bushes scattered all over the area. These were brOught into the laboratory and, the total number of pods on each armful was counted and recorded in Table 10. At this time the flowering period was over and most of the pods were beginning to develop. Table 10 Estimation of the ,total nuniber of pods-per "armful" produced in the "Old Broom" area in 1960. Date No. pods per Date No. pods pei. armful _ armful

8/6/60 204 9/6/60 371 8/6/60 364 9/6/60 317 8/6/60 234 10 6/60 294 8/6/60 410 10/6/60 315 9/6/60 209 10/6/60 . 275

Total number of pods = 2992 x.2 = Estimated number in whole area = 2992 10 254,320 Calculated Fiducial limits (P;= 0.05Y = 37,718 Thus the table 10 shows that, once the average number of pods per armful is known, the total crop of podd can be deduced by simple multiplication. Also as the variance for 10 samples is known, the fiducial limits for it= 0.05 can be calculated and are shown in the table. In this experiment the fiducidl limits are only 1:14,870 of the total number showing that the pod bearing capacity of the broom bushes is fairly constant for a given amount of broom. Old Broom 1961 In 1961 the "Old Broom" area was once again divided into. Ifarmfuls". This year it was found by inspection that there were now 900 "armfuls", as the growth rate of smaller bushes was now exceeding the death rate of the older ones, On 20 June, 1961 ten armfuls"' were again chosen from all over the area but this time, so as not to deplete the amount of broom, they were 25,

not cut. Also the pods on these chosen "armfuls" mere counted in situ and the nuMbers obtained are shown in Table Ur, Table 11 Estimation of the total number of pods per armful produced in the "Old Broom" area in 1961.

Date No. pods per Date No., pods per armful armful

20.6.60 401 21.6.60 178 20.6.60 313 21.6.60 297 20.6,60 518 21.6.60 426 20.6.60 206 21.6.60 374 20.6.60 239 21.6.60 402

Total number of pods =3354, Estimated number in the whole area = 3354 x-375900 = 301,860 pods. Calculated fiducial limits P. 0.05 = ± 60,138 pods + (19..9n The figures in Table 11 do not include the 6.6% of pods that were killed by the May frosts (see p. 6 ). Thus it is evident that in 1961. the "Old Broom" bushes produced slightly more pods than in 1960, this being mainly due to the rapid. growth of young bushes. The fiducial limits for 1961 however are

±19.9;' of the total crop estimation showing that the variation of pod production from bush to bush was greater in 1961 than in 1960. New Broom 1960 To estimate the number of pods produced in the "New Broom" plantation in 1960 a different Method to that used in the "Old Broom" was utilised. Numbers of pods present on a series of 26.

known weights of broom cuttings taken from all over the plantation were counted and recorded in Table 12. Table 12 The Number of pods occuring in various weights of green broom taken from all over, the "New Broom" 1960 Date Weight in grams. No. pods

1.6.60 438,5 438 22.6,60 354,9 166 29.6.60 405.5 199 7.7.60 479.0 311 11.7,60 649,0 329 19.7,60 742.0 430 omonomo.nes Total 3068.9 1873 4••••••10•0•••••••••••

A series of large sampled were taken by Professor0.W. Richards, Dr. N. Waloff and Dr. J.P. Dempster to determine the total weight of sampleable material per broom bush and I am endebted to them for the use of their data in this calculation. They calculated that the average weight of green wood capable of bearing pods, plus the weight of the pods, was 4265.28 grams. per bush. The total number of bushes was kaawn to be 1609 and thus the total weight of pods Plus green wood of 1959 and 1960 was 6,862, 835.52 grams. The total number of pods is therefore calculated as follows:- 1873 6,862, 835.52 x -5-0-68a9 or 4,188,501 pods The fiducial limits at the level of P = 0.05 as calculated from Table 12 were ± 1,094,622.2 pods, this being ±26.1 per cent of the total crop. This shows that the variation of the numbers 27

of pods per bush was large in the "New•Broom" in 1960, compared with that in the Old Broom". New Broom 1961 Similar• counts of the nUmber.of pods were'made throughout July and August in 1961.. This year. however 48 quarter bushes • were .removed frot all over the plantation by Professor . 04., Richards, Dm-N.•Waloffand Dr. J.P. Dempster* Each quarter bUsh was divided up. into 1958 wood, 1959 wood and 1960 and 1961 greeno.ped,bearingwood, and the weights in grams of each of thebe was recorded. I counted the number of developing pods on 36 of these quarter bushes and the results are set out in Table 13* As it is known that there were 1605 bushes in the plantation the total number of pods is calculated as follows:-

64699 x 4 x 1605 x 7791 or 1,389,395 pods 36 x 54089 Calculated fiducial limits for P = 0.05 = ±596,546 pods 1442.9%) The total weight of pods plus green wood of 1960 and 1961 is given 34089 x-4 x 1605 36 6,079,205 grams. Thus in 1961 the May frosts (see p. 6 ) reduced the nutber of pods produced in the "New Broom" to approximately one third of the number produced in 1960. Also the large variation of ±42 shows that the frost damage did not affect all of 28.

Table 13 The Number of pods on 36 quarter bushes taken from all over the "New Broom" plantation in 1961. Weight in grams. Number of pods Weight in grams. Number of per quarter bush per quarter bush Pods.

371.5 3 1202.0 160 1645.0 40 ' '1201.5 448 1039o5 75 467.0 28 2096.0 549 944.0 612 105.5. 1 762.5 105 722.0 •8 425.0 13 1674.0 406 858.00 606.0 301 926.0 1519 1341.5 15 238,0 5 1.381.0 3 711.0 28 •300.0 2 855.5 24 1325.5 1198 900.0 132 458.0 68 912.5 656. 1771.0 150 1106.0 404 711.0 21 751.0 568 1221.5 769 849.5 153 783.5 12 1360.5 13 1138.6 69 898.0 233'

Total weight of 36 quarter bushes - 34,089.0 grams. Total number of pods on 36 quarter bushes = 7791 29.

the bushes alike. This can also be seen from Table 13 where the range of pods occuring on a quarter bush varied between 1 and 1198. The smaller number of pods produced in 1961 also accounts for the smaller weight of "pods plus green wood", produced in 1961 as compared with 1960. If the numbers of pods produced in each year in both areas are compared it can be seen that in 1960 the "New Broom" produced 16.5 times more pods than the "Old Broom". In 1961 however, the "New Broom" produced only 4.6 times more pods than the "Old Broom",

To sum up, this section (i.e. Section I) shows that the broom pod, when viewed as a potential habitat for the immature stages of an insect, is a very unstable and temporary one due to its seasonal occurrence. Also, in successive years as the broom bushes grow old there is:— (a) a reduction in the -number of pods produced (b) a reduction in the .size of the pods produced and (c) a reduction in the number of seeds per pod produced.. Thus, the "broom pod habitat", is also only a temporary one over successive years, as well as within each year, Finally when the bushes die this habitat may completely disappear from an area, as regeneration of younger busheS has been seen to be very slow. 30,

All these factors will affect the size of successive populations of all of the insects that are connected with the pod and the ability to disperse and find younger broom plants will therefore be a major factor in the survival of these species, 31*

SECTION II The Colrlex of Insects Associated with the Broom Seed. Bruchidius ater. 1. Adults. a. Synonymy. b. Populations in the Old and New Broom areas in 1960 and 1961. c Emergence from Hibernation and Pre-oviposition activity. d. Separation of the Sexes.of B. ater adults. e. Seasonal changes in the Reproductive Systems, f. Oviposition. g. Fecundity. h. Weights of Adults throughout the year. 1. Overwintering. Eggs. a. Morphology. b. Development. c. Mortality factors in the field. 3. Larval and Pupal Instars. a. Morphology. b, Life histories within the pod. c, Number of Larval Instars. do Progression in Growth. ' e. Duration of Larval and pupal instars within the pod. f. Mortality factors affecting the larval and pupal stages within the pod. - 32,

Bruchidius ater. Adults a. Synonymy The name, Bruchidius 'Etter, by Which the broom beetle is referred to in this text was obtained from Mr. B. Southgate of Pest Infestation Laboratories, Slough, Bucks. The synonymy of this beetle has been somewhat muddled in the past and full explanation's of the reasons for designating this name to the broom Bruchid are given in Southgate(1962)(in. press). The generic name, "Bruchidius" used here was erected in 1905 by Schilsky-using Bruchas quinqueguttatus Oliver as a type species. The specific name "ater" was given to the. broom Bruchid by Marsham118021 The original specimens named by Marsham are now in the Stephens collection at the British Museum (Natural History), and they have been examined by Mr. B. Southgate.

Population in the "Old" and "Mew Broom" areas in 1960 and 1961. The fluctuations in the size of the population of Bruchidius ater adults upon the broom plants in the Old Broom :area were assessed by regular sampling throughout 1960 and 1961. Each sample consisted of the total number of beellee collected when 40 "armfuls" (see p. 23) of broom were beaten over a collecting tray. These "armfuls" were selected as systematieall as possible, (Milne 1959), from different bushes over the whole extent of the area. 33.

The,Bruchids were assumed to be spread throughout the area in all of the samples except the firat one taken on. 5,May, 1960. Here it was'estimated by inspection that only 20% of the bushes were yet in full bloom, twenty "armfuls" of the flowering broom were systematically sampled and 47 Bruchid adults were collected. When. a further 20 "armfuls" of non flowering bushes were sampled only 'a single adult was Obtained. Thus if there are 860 "armfuls"' in the whole area, then 20 of ..this total (i.e.'172'"armfuls") contained 47/20 Bruchids per, armfUl and the remaining 80% (i.e. 688 "armfuls"). contained, 3/20 Bruchids per armful* , The total,population is .47 172 1 688 ) or 438.6 thus given by k 20 x7r.) .(515 3y-57. adults. 'When the next samples were taken the majprity'of the bushes were in flower and a more even distribution of beetles throughout the area was assumed. Graph A, (Pig. 6) was cohStrUcted from the results of these-samples. The total estimates of the population are, included on the graph, as calculated numbers, corresponding to the dates of sampling. The greatest numbers of adults occurred around the -26 May. After this date the population decreased rapidly and disappeared completely by 28 June., This decrease was, not entirely caused by mortality, but by a dispersal resulting from the decrease in the food: supply (i.e. of broom pollen.) This movement of beetles was also seen at this time in the New Broom plantation. The population of beetlesin the Old Broom-in 1960'failed 31.

100+

1692 A OLD BROOM 1960 B0- 0--0 both sexes 0-0 males Omp.m•11.••• females 60+ 1692 calculated total population.

III 440+ 3 4n

200

2 43 O 0 • U ▪ OLD BROOM 1961 w ecv, o—o both sexes •—e male* rs - 1395 --- females ▪g 60s. 2070 calculated total population. 4C ur 0 C40'• sa O

20-

45 0 APRIL JULY AUGUST SEPTEMBER

Fig. 6. Population fluctuations of Bruchidius ater adults in the "Old Broom" area. A. In 1960 using the "armful" sampling methods B. In 1961 using the "armful" sampling method. to establish an "infestation", of any size in the broom pods since 98% of the eggs failed to hatch. No new generation, apart from one beetle caught on 31 August' 1960, was detected in the Old Broom in August — September, 1960, although sampling was continued throughout these months. In 1961 similar samples were taken in the Old Broom. In this year the total number of "armfuls" in the area increased to 900 (see p. ) Graph B (Flg. 6) shows once again a build up in early May of a population of similar size to that in -1960. It reached a peak slightly. earlier than in 1964 i.e. in the second week in May, (1961 broom.development also 1 week earlier) Throughout June the population dispersed and no further .trace was recorded after 18 July. On 15 May, 1961, when the "armful" sampling method indicated that Bruchids were abundant on the broom bushes, an extra experiment was included as a check on this estimate. Ninety two Bruchids were caught on 15 May by the "armful", method and 88 were marked on the left elytron with a small spot of light blue, "Britfixl colour dope applied by means of a small. pin. These beetles were then released in 5 groups all over the Old Broom area, each group being placed on the top of an emergence tub (see p. 42). On 17 May the top of each tub was examined to ascertain whether all of the released beetles had dispersed. No beetles were found on the tubs and so a 40 36..

"armful" sample was taken, systematically, throughout the area. The number of B.ater adults caught was 83 and this represented L900 a total population of 83 or 1868 (to the nearest whole nuMber), by the "armful" method of estimation. These were however 3 marked beetles in this sample and thus the population, using a Lincoln Index (Lincoln, 1930) method is estimated as 83 x 88 p 3 or 2435* Bailey (1952) modified the Lincoln formula and gives, a(n+1) P r+1 where a is the number of animals marked and released, n is the number caught in the second sample and r, is the number of animals recaptured. This formula has a variance where:- a (n+1)(n-r) "514-4-6"""' (r+1) (r+2) By this method the population p is calculated as 4 p 88(84) or 1848 with a variance of , 88x88x84x80 • 4-4x5 - or 650,496 Thus both the armful method and the Bailey's modified Lincoln Index method give fairly consistant estimates, while the unmodified Lincoln Index gives a rathei, higher estimate. However, it must be remembered that the variance of Bailey's method is so large, as the recapture figure is small that, according to Macleod (1958), the value of the estimate is somewhat reduced. However, Macleod (1958) uses this method with small recapture figures, in his estimates of the population of " Callinhora erythrocephala 37k

The origins of the populations of B.ater adults in 1960. and 1961 are discussed on p. 311 It is also interesting to note that the sex ratios in both 1960 and 1961 were consist- ently 1 male to 2 females. This is shown in graphs A and B (Fig. 6) by the broken lines beneath the main line of the population trend,. To calculate these linesIthe number of males and females were counted in each sample throughout the 2 years.

The estimates of,the_populetion fluctuations of B.ater adults in the New Broem.were,made in 1960 and 1961 by Professor 0.W. Richards, Dr. N 'Waal' and Dr. J.P. Dempster whilst they were sampling the Mirid,populations. As it was unwise to have too many people sampling the Same bushes I used their figures only for, 1960, but sampled myself in 1961 so as to see Whether there was any resemblance between the results Obtained by the 2 different sampling techniques. Graphs A-and B (Fig. 7) are compiled from professor O.W. Richards figures, obtained from the number of Bruchids caught. in each of a regular series of samples, each composed of 80 Separate sub-samples using a carbon dioxide sampler (Dempster, 1961). On 19 May, 1960 however only 33 samples were taken and a simple multiplication to estimate the catch of 80 samples was used to calculate the point on the graph. The average number of carbon dioxide samples per: bush was'calculated in 1960 to be 106.4 and the totalI4Utber of bushes was known to 38,

be 1609. Thus by simple multiplication the total population of Bruchids could be estimated. These numbers, corrected to the nearest whole nuMber'are insetted at each point on graph, A (Fig. 7). In 1961 the number of CO2 samples per bush was 120 and the number of bushes was 1605, so once again on graph B (Fig. 7) total population numbers are inserted. 'In 1960 the greatest number of adults occurred on 19 May, slightly earlier than in the Old Broom in the same year. After this the adults became localised around the bushes remaining' in flower. On 19 June, over; 500 adults were beaten from a quarter of the only bush still in flower, whereas few beetles could be found elsewhere. At this time numerous adults, were observed feeding on the lcusito lanatus growin., beneath the broom bushes, whereas on 29 June, 1960 many Bruchids were collected, from Yarrow (Achillea millefolium Linn.) flowers growing in the lanes between the, broom bushes. As. Holcus lanatus had by now finished flowering, the Bruchids had moved onto Achillea millefolium in search of food, i.e. pollen. Throughout July the Bruchids collected . on the Achillea millefolium and when it rained they sheltered under the cover. of the tightly packed flower heads. A. millefolium does not finish flowering until' late August and some adults were found on dying plants as late as 2 September, 1960.

By this time however, the new generation of adults had 39.

already emerged and had begun to disperse over the plantation. The first Bruchid to emerge in the laboratory ,did so on 27'July4 1960 and the first beetle of,the new generation in , the field was obtained in the sample taken on 12 August, 1960. Graph A (Fig 7) shows, that this emerging population was larger than the parental one., In 1961 the CO2 samples show similar population fluctuation, but this year the numbers of adults are almost. double those found in 1960. In these samples the numbers of males . and females were not counted.: Graph C (Fig. 7) is compiled from the results of a separate sampling technique which I used in 1961. Fifty quarter bushes were chosen systematically over the whole plantation and these were beaten onto a 1 metre square beating tray. This constituted a sample. The total number' of beetles and the, numbers of males and females in each sample, are plotted against time on graph C (Fig. 7). This graph thus represents the same.population as that shown by graph B (Fig. 7). The total number of bushes was 1605 and the total population'nutbers are once more included on graph C (Fig. 7). As in the Old Broom the sex ratio here is also 1 male:2 females. The differences between graphs B and C (Fig. 3) are totally due to the differences between the sampling techniques. It can be seen that although the maximum population numbers, estimated by each method came to approximately 65,000 the

40.

30- A NEW BROOM 1960

o—o both sexes 20-

S. 3 36 32 00

MPLE 151260 10- 17,120 SA

- 42 0 0 0 A IN., 6 95 13 NEW BROOM 1961

o—o both sexes

4q92 8 62'595 calculated total

MM. population

10- 21668

37 W I- NEW BROOM 1961 m400- 48,278 o—o both sexes .._—• males X 0 •---- females 2 9,01 8 66,137 calculated total 200.* population

5,778 899

APRIL MAY JUNE JULY AUGUST SEPTEMBER

Fig. 7. Population fluctuations of Bruchidius ater adults in the "New Broom" plantation. A. In 1960 using a carbon dioxide sampling method. B. In 1961 using a carbon dioxide sampling method. 04 In 1961 using a beating method. 41.

difference between the two peak, estimates is 2 weeks. The CO2 Amethod only.samples a total of two thirds of a bush, each time, whereas,the quarter bush method is equivalent to 12.5 bushes. It .can only be concluded that neither of these, methods is entirely suitablefor dealing with a population which emerges from hibernation and becomes ,Localised on flowering ,bushes and then'disperses when 611 bushes are in flower and finally, become localised once again on the bushes remaining in flower, as well as :on the surrounding flowering ,gratises and Yarrow plants. 'The size and the complexity of a sample which would give consistent results of the size of this population would be so vast that it would be obviously impracticable for one person to undertake it alone. The densities of Bruchid adults compared to-the total numbers of pods (i,e, the oviposition sites) produced in each area, are strikingly different in the two areas in 1960. nd 1961. In 1960 the New Broom produced 16.5 times more pods than the Old Broom (see .p. 29 ) when the maximum population of beetles in the Old Broom in May, 1960 is divided into the similar estimate of the Bruchids in the New Broom (i,e, 31,536i- 1892) it is then seen that there were 16.6 times more Bruchids in the "New" than in the "Old Broom", in May, 1960. Thus the numbers of beetles compared with the total number of pods, were 'approximately the same-in the two areas in 1960, i.e. they were 1 to 1. In 1961 however; the New Broom produced only 4,6 timeS more pods than the Old Broom, but the maximum Bruchid popula.- tion was 33,1 greater than that in the Old Broom (i.e. 684374- 2070) The density of Brudhids in the New Broom compared with the total number of nods present was therefore approximately 7 times (i.e, 33.114.6) greater than that in the Old Broom in 1961. This led to a considerable concentration of the beetles on the oviposition sites in the New Broom in 1961.

c. Emergence from Hibernation and Pre-oviposition Activity Bruchidius, ater adults emerge from broom seeds in the autumn and straightway disperse to their overwintering sites. A few adults overwinter on the broom bushes but it is unknown where the majority of the beetles pass the winter months. In 1961, 5 emergence traps consisting of bottomless, circular metal tubs were placed on the litter amongst the bushes in the "Old Broom", area, These tubs had a small hole in the top into which a 3 x 1" glass tube could be fitted. Thirty six similar tubs were placed in the, "New Broom" plantation by Dr. Walloffe Insects emerging from the soil below the tub are attracted to the only available light source coming from the 3 x 1" tube. The insects crawl or fly through a "non return" cone and are trapped in the glass tube, where they can be collected when required. 43 ,

Throughout.the thole of the Bruchid emergence period in March and'April, 1961 however,no beetles were ever recorded from these, traps in, either area, Thus it seems certain that either the beetles disperse so widely that there were not enough, traps to record their emergence or, as is more likelyi they do not overwinter,Ixithelitter, The. first_records of emerging adults were obtained, in areas, in 1960 and 1961 in March, when a. few Bruchid.adults. were beaten from the gorse bushes. There are many gorse bushes scattered amongst the broom in the "Old Broom" area, but, in the "pew'Broot" plantation, there are only'tvfew gorse bushes scattered around its northern:edges, At this time the gorse is in full flower and it has been shown (see p.45) that the early emerging adults are attracted to the yellow colour of the flowers. Towards the end of April when broom comes into flower and gorse flowers die off, the Bruchids, whilst they are still lmmature,disappear from gorse and fly across to the broom bushes once again being attracted to the yellow flower's. It is surmised that many more adults emerge from hibernation at this time as the population on broom is much larger than it ever is on gorse. To prove that the yellow colour of the flowers attracted emerging adults,. an experiment ,using water traps of different .colours was set up in May, 1960. The traps consisted of a set 4 - • of 12 metal.baking tins each 12 inches long, 6 inches wide. and 3 inches deep which were supported in the "Old Broom" area on separate, wooden stakes. These stakes were driven. into, ground until they projected po inches and then the tins 'were placed on a support on top of them. The 12 traps were distributed throughout the "Old Broom" area and were placed at least 5 feet fr.= the nearest broom plant. .Four of the tins.were painted inside with .yellow "Oh My", glossy aeroplane dope. Another 4 were painted white and the remaining 4 light green,. The positions of the.traps,were labelled A.B.C. .-- L. The tins were then half filled with a solution of 4% formaldehyde to which was added a very small amount of-"Stergene", This liquid was poured into, the traps, very carefully to prevent a froth forming on thersurface. The formaldehydp preserves insects caught in the trap and also serves to discourage birds from removing specimens. The "Stergene", lowers the.surface tension of the liquid thus causing insects to sink into it. Throughout the experiment the liquid was changed every 8 days and topped up as required every second day, R;cords of the number of BrUchid adults caught, were taken every second day as near to midday as possible, After each record, each tray was moved on one position, that is, the tray at A was moved to Band so on. This movement eliminates the chance of. any one tray of a certain colour being in a faVOurable 'or 45. unfavourable position throughout the experiment, The experiment lasted 24 days and thus 12 changes were made between the first and last readings each tray making a complete circuit of the area., Table 8 shows the total catches of Bruchids throughout the experiment in each of the 3 coloured traps and it can be seen that Bruchids of both sexes are definitely attracted to. yellow whilst white seems to repel them in some way. .Fourteen of the total of 49 beetles were also caught in the light green trays. Table 14 Numbers of Bruchidius ater adults caught in water Traps in the "Old Broom" area in 1960. Colour of the trays

Position White Yellow Green Totalcaught Bruchids

A 0 4 1 5 B 0 3 1 4 C 0 3 2 5 D 0 0 0 0 E 0 2 0 2 P 0 6 1 7 G 0 6 .5 11 H 0 2 1 3 I , 0 6 0 6 3 0 0 1 3 K 0 0 2 2 L .0 3 0 3

Total number of beetles caught 0 35 14 49 Number of male beetles caught — 18 8 26 Number of female beetles caught — 17 '6 23

When the results of the water trap experiment are set out as in Table 9 to show the number trapped every second day 46.

regardless of the colour of the traps_it can be seen that the maximum number of Bruchids caught was betWeen 25 and'29 May, 19601. This is correlated with the maximum population numbers

'which occurred around these dates. (see p.,33 and graph A Fig. 6),

'Table 15 Numbers of Bruchidius ,a ter adults trapped in all of the water trays of all: colours. Date Males Females Total Date Males remales.Totai

12-14.5.60 4 4 8 29-31.5.60 1 4 5 14-16.5.60 . 1 0 1 31- 2.6.60 1 0 3. 16-18.5.60 2 1 3 2- 4.6.60 0 1 1 21.23,5.60 0 3 • 3 4. 6.6.60 1 1 , 2 23-25.5.60 2 2 4 6- 8.6.60 0 1 1 25-27.5.60 5 2 7 8-10.6.60 - 2 0 2 27-29.5.60 7 4 11 TOTAL 26 23 49

The beetles fell into the traps throughout the whole period of the experiment in a 26:23 sex ratio this being statistically equal to a 1:1 catch. However, the sex ratio in the field samples was 1,:2g (see graph A Fig. 6 and p. 3g ) Thus the male.Bruchids are twice as active as the females at this time, probably as they copulate more than once and actively fly around, searching for females. reeding and cleaning. Forty Bruchid adults were collected from another broom area on the. Field Station on 25 May, 1960. These were enclosed in a 24 inch long piece of 1 inch diameter glass tubing, which .47,

had a cork in one end and a piece of muslin tied over the other end. They were given only a small pad of cotton wool, soaked in water and left for 3 days. After this time the pad was replaced. by 10 broom flowers which had pollen loaded stamens and dbservations on feeding were made with the aid of a binocular microscope. Upon discovering a flower the Bruchid walked nervously over the petals vibrating its maxillary palpi over the surface. The antennae were held forwards in all position and also touched the surface at regular intervala. When pollen loaded stamens,were located, feeding began immediately, masses of clotted:pollen grains being forced between the mandibles by the maxillary and labial palpi. At times the beetle; stopped feeding and commenced to clean off the grains adhering to its legs and body. The antennae were cleaned also by being pushed across the maxillary'palpi by the forelegs. Periodically the hindlegs were swept down over the elytra clearing away any pollen grains adhering to them. One adult was dissected immediately after it had fed and crushed pollen grains were discovered in its gut showing that the pollen shell is ingested as well as its contents. Numerous further observations in the field in both broom areas were made and Bruchids were seen to be engaged in similar feeding and cleaning movements within the flowers on the bushes. Copulation Copulation in 13.2, ater was observed for the first time in the laboratory on 6 June, 1960 but must have occurred in the field much earlier, as fertilized females were caught on 20 May, 1960. The male approached the posterior end of the female and began to stroke her elytra with its antennae. After a few seconds the female responded by stroking her hind legs over her elytra and lifting up her abdomen. The male then mounted her and took up a position on her back. Copulation proceeded for 2 minutes 45 seconds. Further observation showed that a second stance was also possible. The male sometimes sits right back on its hindlegs 'assuming an almost upside down position directly behind the female. Copulation here proceeded for 3 mins. 45 secs. and 4 mins. 30 secain the two instances that were observed. 49.

d. Separation of the sexes of B. ater adults. The sexes of B ater adults can be separated by the shape of the tergite and sternite of their last visible abdominal segment (i.e. segment 7) (see Fig, SA and B). In the male when the posterior end of the abdomen is viewed ventrally, the tergite of segment 7 is seen to fold around the posterior end of the abdomen, a part of it thus being visible from below. The sternite of this segment is indented posteriorly to accommodate the tergite and when the aedeagus is extruded between these selerites during copulation,, it is directed anteroventrally. The corresponding tergite of the abdomen of the female is barely visible from_the ventral aspect.and sternite 7 is not indented posteriorly. Thus when the ovipositor is extruded between these oclerites for oviposition it is'directed postero- ventrally. A more detailed description of the external features of the adult is given by Hoffmann (1945). lie illustrates the external features of Bruchus emarginatus and the abdomen of Acanthosce- lides obsoletus but makes no mention of any differences in the structure of the terminal abdominal region between the sexes of these species.

e Seasonal changes in the Reproductive System. Structure of the Male The testes are bi-follicular and appear as globular yellow- 50..

A a Abdominal Terglte 7 Abdominal Tergite 7

314- abdominal sternite 3ril• abdominal sternite

1 0.6mm

D Abdominal Sternlte 7 Abdominal Tergite 8 (pygidium)

Elytron

Fig. 8. Ventral views of the abdomens of 7,, A. Female Bruchidius ater, B, Male Bruchidius ater, C. Female Allioh fuscirostre.D, Male Apion fuscirostre. 51.

A key to the abbreviations used in Figure 9.

acc.g.1 First type of accessory gland. acc.g.2 Second type of accessory gland. acc.g.3 Third type of accessory gland. b.c. Bursa copulatrix, b.g. Bursal gland. b.sp. Bursal spines. cut ovd. Cut end of right oviduct. cut v.d. CIA end of left vas deferens, e.cl. Egg calyx. eg. Egg. ej.d. Ejaculatory duct, ovd. Oviduct. ovr Ovary. r. Rectum. s. Spermatheca. s.aec.g. Spermathecal accessory gland. tsf. Terminal filament. t.foll,. Testicular follicle. v. Vagina. v.d. Vas deferens. Smen

t. foil. acc.

acc.g. i

acc.g

acc.g./. tfta acc.g.3. C. cut vd acc.g.2

Fig, 9., Reproductive systems of Bruchidius ater adults. A. Immature female. B. Mature female. C. Immature male. D. Mature male. 53v

ish-white bodieta measuring'0.54 mm., when,they'are,mature, (Fig. 9D, t. The paired vasa deferentia (Fig. 9D, v.dv), are very short, but each one 'is slightly swollen at the junctio with its fellow at the top of the ejaculatory duct (Fig. 9D, ej.d.). These regions may represent the vesiculae seminalis, but Hoffmann (1946) does not record them'in his generalised drawing of the male reproductive system of the Bruchidae., Arising from the distalends of the vasa deferentia, between the testicular follicles, there are 5 sac-like accessor, glands of 3 types. Two of these glands (Fig. 9D, acc.g1), reach the length of 0.8 mm. when fully mature and are granular greyish-white. The gland which originates at the point of fusion of the two follicular ducts is a simple sac, whereas the other one is a Y shaped sac arising from:the vas deferens just below the point of fusion of the follicular ducts. Two other smaller sac-like accessory glands, (Fig. 9D, accwg.2), arise in this region of the vas deferens and these are thick, floccUlar, white and only 0.4 mmv long. The remaining gland (Fig. 9D, acc.g.3) is only 0#3,mm., long and is a Completely colourless vesicle. Further study of the structure of each of these glands would be required before their functions could be' assessed,' The ejaculatory duct, (Fig. 9D, ej.d) is a simple tube which leads to the aedeagus and its associated structures. These structures in Bruchidius fasciatus (= B. ater) are 54*.

illustrated by Hoffmann (1945) (his figs, 216-9) and hence are not re-described here. Development of the Male Ten males were dissected each week throughout the season in. 196Q and it was found that the reproductive systems of the overwintering beetles remain immature, (Pig. 90.), the testes and the associated accessory glands being approximately one third of the size which they attain later, on maturation. As soon as feeding commences in, late April, the gonads gradually enlarge and reach, their full size and maturity in the, middle of May. They remain in the mature condition until the middle of June, after which they slowly regress to their original size. Specimens with regressed reproductive organs were recorded on 16 August, 1960. In these beetles only the 2 largest accessory glands had not returned to their original size. Structure of the Female Each ovary is composed of 7 acrotrophic ovarioles (Fig. 913, ov-) in which the basal developing eggs are clearly visible in • the mature females, At the distal end of each ovariole there. is a short terminal filament (Fig, 9B, t.f). The ovarioles all open into an egg calyx where 4-5 eggs can be stored before oviposition. (Fig. 913, e.c. and e.g.), The paired oviducts (Fig. 913, ovd),fuse posteriorly to form .the vagina, (Fit. 9B,v,) from which arises the sac-like bursa copulatrix. The bursa copulatrix (Fig. 913, b.c.) lies-dorsally 56,

to the oviducts and bears on its dorsal wall a sclerotised rod armed with.6 large, posteriorly directed spines and 4 small spines (Fig 9B, bi.sp) which protrude into the lumen of the bursa. Also there are 2 globular gland like swellings in the distal wall of the bursa. These are completely membranous but are covered in a multitude of tracheal tubes full of air which appear silvery in freshly dissected specimens. The function of these structures is obscure but the sclerotised spines may well aid in locking the male and female together during copulation. No other references to similar structures in other Bruchid species could be found* The spermatheca, is a brown, well sclerotised hook-shaped structure which is blunt at one end and tapers to a point at the other (Fig. 9B,$). From the blunt end of the spermatheca, a tube connects it with the bursa copulatrix in the region where the latter enters the vagina. Also arising from the blunt end of the spermatheca is an accessory gland, (Fig 9B„ s.acc.g), which is a 2.2 mm. long thread like structure slightly swollen at the tip. The tergite and sternite of, the last abdominal segment form a sclerotispd, tube like ovipositor which surrounds the genital opening and telescopes into the penultimate segment. Only the sternite of the penultimate segment.is scierotised and this plate is elongated anteriorly into a midventral spine onto which muscles are attached. Thus the ovipositor in this 56.

species can be extruded up to a distance of 1 mm, during oviposition. Development of the Female, The development of the gonads in the female was observed in a regular series of dissections throughout 1960 and was the same in both the "Old" and the "New Broom" areas.. Figv 9A shows the immature condition of overwintered females (5 May, 1960) just after they had commenced feeding. Herethp ovarioles were only 0.4-0.5 ram, long and had no differentiated eggs.- The bursa copulatrix was also very small. By the 13 May the first eggs had developed to full size and the total length of the ovarioles was - 1.3 mm, The bursa had enlarged,-but as is shown in Table 16 all of the females were still unfertilised, Table. I§ State of, the internal reproductive organs of female B. ater in May, 1960w Date Collected No. -of No. No.., with Average from. females fertilised mature' fat body dissected ovaries (arbitrary indices of) 0-5

5,5,60 Broom 10 0 0 3.4 13.5.60 Broom 15 0 10 2.6 20.5.60 Broom 10 2 9 1.3. 27.5.60 Broom 10 10 10 0.2

By the 20 May, 1960 nine out of ten females examined were fully mature and ripe eggs were found in the egg calyces of eight of them. However only 2 females were fertilised at this 57,

time. A preparation of the spermatheca mounted temporarily in insect Ringer Solution clearly showed the presence or absence of masses of thread like spermatozoa within the chitinous container. All of the females had eggs in the egg calyces and had been fertilised by 27 May when the population in the."Old Broom" area was at its peak (see p.33 ). In some individuals, even at this stage however there was very little. sperm present. In Table 17 the, ageing of the female reproductive system was measured by noting the diminishing number of females with ripe eggs in the Icalyces. The beetles collected from broom on 1 August and 16 August in Table 17 are the new emerging generation whereas, all of the others are the parental generation. Table 17 State of the internal reproductive organs of female B. ater after May, 1960. Date Collected No. of No. with No. with Average fat from females 'eggs in no eggs body dissected, calyces in calyees arbitrary indices of 0-5

27,5,60 Broom 10 10 0 0.2 17,6.60 Broom 10 9 1 1.0 29.6,60 Yarrow ' 10 8 2 3.0 14.7,60 Yarrow 10 3 7 342 29,7,60 Yarrow 10 1 9 3.0 1.800 Broom 10 0 10 5,0 16.8.60 Yarrow 10 0 10 3A4 16,8.60 Broom 10 0 10 4.9

The number of female Bruchids with eggs in the egg calyces fell off steadily down to zero in the sample from Yarrow

(Achillea millefolium)on 16 August, 1960. On this date there 58.

was little difference between the state of the ovaries of the Old. 'females and those of the new emerging generation. No sperm could be detected.in the parental generation. Only the slightly larger size of the egg calyx and the smaller size of fat body served, to distinguish the parent generation from the emerging one. . The condition of the fat body throughout 'the season is. given in Tables 16 and 17. The arbitrary values assigned to . • the fat body were similar to those used by Waloff and Richards (1958) in the broom beetle Phytodecta olivacea. In B. ater: 5, denoted a fat body completely filling'the body cavity; 4 large; 3 medium; 2 small; and I, traces of fat globules. The value ; • 0 was also used when no fat body could be detected. Tables 16 and 17 show that the fat body is used up when the ovaries mature in the spring and that it increases in volume again when the ovaries regress. ,. Newly emerged beetles have a fat body value very close to' 5. Thus, assuming that' the 1960 parental'generation also had. this value when they emerged from broom seeds in 1959, it can be seen that 30 to 40 percent of the reserves were used up in hibernation as the beetles emerged in the spring of 1960 with fat bodies to which average values of 3 to 3.5 were assigned.

f. Oviposition. At Silwood Park B ater lays its eggs on the outside of the 59.

very young green pods of broom (Sarothamnus scollarius), Steffan-(1946), however, records Spartiamlunceum, Genista andreana and Cytisus sessifolium as the'alternative host plants of this beetle in Europe (i.e. his BruChidius fasciatas) I have also heard from Mr. B. Southgate that he succeeded in making this species oviposit on LaburnuM pods (Laburnum anagyroides) at Slough, Bucks.,' but was unable to rear theM to the' adult stage, although thefirst.instar larvae.entered the pods. The first records of oviposition on broom pods in both 1960 and 1961 were in the second week of May in the two broom areas. However it has been shown that very few temales were fertilised. before SO May, 1960 and thus 19 May was' used as the date for the true beginning of oviposition in 1960 (see Table 16), It was suspected that the majority of the first eggs which were laid each season were infertile. Many of these eggs were enclosed in muslin bags tied over the pods on which they had been laid. It was noted that, by the end of May only 5 out of a total of 71 eggs so enclosed, had developed at all. The rest of the eggs had peeled off the pods and had shrivelled up. By the 27 May, 1960 all the eggs were assumed to be fertile as may be surmised from the dissections (see Table 16) of fema— les on that day. All of the females obtained on 27 May were assumed to be fertilised and several experiments were carried out using the eggs obtained from some of them. 60.,

Three tubes were set up, each containing 15 females and a pad of cotton wool soaked in dilute sugar solution* These were left for 3 days to ascertain whether the insects would oviposit in the absence of any plant material* After 3 days no eggs had been laid in any of the tubes* Two young Broom pods were then placed in the first tube, two Gorse pods into the second, and two Laburnum pods into the third, Immediately, the Bruchids in the first tube with the Broom pods became extremely agitated' and ran about over the surfaces of the pods in search of suitable oviposition sites. This action was not observed in either of the 'other two tubes and no eggs were laid* This indicates that the Broom pods have a definate effect on the female Bruchids which may be olfactory, tactile, or visual, or a combination of these stimuli. In the field, eggs are mostly laid around the edges of the pod where the female can get a firm grip before ovipositing* There seems to be no positioning of the eggs relative to the seeds inside, whatsoever* No eggs could be found on any other parts of the plant although leaves, stems and flowers were searched, Having taken up a firm position, the female extrudes her ovipositor and moves it over the surface of the pod in a circu— lar motion. A small droplet of liquid is smeared onto the pod surface by this movement and then after a pause of a few seconds, an egg is deposited into the central part of the liquid. This 63..

dries very quickly cementing the egg to the surface of the pod. The female then either walks away or begins to lay a second egg next to the previous one. In a series of Observa- tions on 3 days from 12 to 3 p.m. when the, oviposition rate was highest, the maximum number of eggs ever seen, laid one after another was 5. The oviposition period thus started at approximately the same time in both areas but terminated earlier in the "Old Broom" in both years. This was not caused by any difference in the development of the ovaries of the females in the two areas, but by the disappearance of the adult population from the "Old Broom" by the end of June. At this time in the "New Broom" plantation the majority of females, (now feeding on the Achillea millefolium) were still mature and capable of flying to the broom bushes and ovipositing. Fifteen females laid 16 eggs between 28 June and 1 July, 1960 and, although these were th'A last eggs recorded in the laboratory, oviposition probably continued in the field for at least a week after this. In 1961 the Bruchids emerged earlier than in 1960 due to a very warm spring. The. oviposition period was thus brought forward by 10-12 days' in both the "New" and "Old Broom" areas. Three in every eight female Bruchids were fertilised on 5 May and by 15 May all of the females in both areas were mated. However, oviposition finished in both areas on similar dates to those in 1960. Fecundity. Old Broom, 1960 The ideal 'theoretical method of estimating the average fecundity-of a wild populationis first to estimate the number of eggs laid and then to divide this number by the total number :of -fetales than had laid them. However numerous errors can'. creep into these calculations depending on the behaviour of the females during the ovipOsition period. In B. ester the calculation of the total number of eggs laid was relatively easy, as the females oviposit only on brOot pods. The calculation of the total number of females. that laid these eggs was however, much less accurate, as the 'rate of immigration and emigration of Bruchide in this area (i.e. Old Broom) was unknown. The total number of eggs laid in the area was determined from a sample of 430 pods collected systematically from most of the bushes in the region. These pods were examined for Bruchid eggs:(even the empty chorions where larvae had emerged were included) and 391 eggs were found on 113 of these pods. The sample was taken on 25 June, 1960 when all oviposition had finished as.far as could be ascertained. Thus as the total number of pods in the area was known to be 254,320 (see p. 44) then the total number of eggs laid on these pods was 254,320 x.A92 or 231,254 (to the nearest Whole 430 number) 64,

The adult Bruchids however are highly mobile insects and are seen to fly epontaneously during bright sunshine. This behaviour is further accentuated by results of catches in the water traps (see. p. 46 ). Thus the daily population in the "Old Broom" shown in graph A, Fig, 6, does not necessarily represent the total number of beetles which visited the area. If the largest number of females recorded (i.e. 1247) is divided into the total number of eggs laid the average fecundity is estimated as 185 eggs per female. The accuracy of this estimate is of course doubtful and is no more than an approxi- mation. The maximum number of females recorded in the field occurred seven days after the date on which oviposition first started (i.e. 19 May, see p. 5,9 ). If, during these 7 days the immigration and emigration of Bruchids in the "Old Broom" area was very large then, many more females may have oviposited for short periods in the arca than the maximum number recorded by the samples. In this case the previous fecundity estimation would be too high. On the other hand if the majority of immigrants remained in the area until the peak population numbers were attained, after which further immigration was greatly reduced and emigration and mortality greatly increased due to, food shortage, then the total number of female beetles remaining in the area throughout the whole of the oviposition period, (i.e. approximately one month), would be smaller than the peak number recorded by sampling. Here the above fecundity estimation would be too low for females remaining in the area throughout the ovinosition period. From observations in the field I am more in favour of the latter argument as the attraction to yellow colour (see p. 35) and observations of flikht activity in the field suggest that the majority of immigrants remain until the food supply is depleted. Also, beetles marked with paint on 15 Liay, 1960 (see p. 45) were often recaptured in the area throughout the following 4 weeks. Richards and Valoff (1954) used a method involving the compution of a regression equation for the logarithm of the successive population estimations on known days after the peak of numbers. This method was applied to grasshoppers and the regression line was extended back to the beginning; of the egg hatching period to obtain the logarithmic value of the estimated total initial population« It was assumed in this method, that, after all hatching had finished, mortality was stable. A similar regression equation was computed here for the logarithm of the successive population estimations of female beetles after the peak of numbers. The regression line was produced back to 19 Lay when oviposition started (see p.59 ) and an initial population estimation of 3190 females was obtained. In this case the dispersal and mortality of beetles was assumed to be steady instead of the mortality alone as in the 66.

grasshopper experiment. Actual mortality due to senescence of Bruchid adults in the field was thought te begin about the middle of June and to increase steadily in the following months. Mortality due to • predation was thought to be small as the only probable enemies in the field were mice, birds and, to a lesser extent, spiders. The average fecundity of 3190. females. would be 72.5 eggs per female that is, less. than half of the previous fecundity estimate. Thus the application of these methods to field populations of Bruchids give widely differing results both of which are unreliable, the probable average egg number lying between 72.5 and 135. New Broom 1960 In the "New Broom" plantation in 1960 a sample of 1000 pods were collected from all over the area on 30 June, 1960 and, amongst these pods, 330 bore a total of 1180 eggs. Thus, as the total number of pods,in the plantation was estimated to be 4,188,365 (see p. 25 ) the total number of eggs laid was lc-1180 therefore 4,188,365 1000 or 4,942,271. The highest total 'population of B. ater in the "New Broom" occurred on 19 May when 31,536 adults were present. The sex ratio is assumed to be 1 male :'2 females for the purposes of this esiiMation. Thus if 21,024 females were present in the area the estimated fecundity is 235 eggs. per female. As the peak of numbers occurred on the day on which ovip- 67f.

osition began, the Richards and Waloff (1954) method, when applied here gives a smaller estimate than that actually observed on the 19 May. Both Broom areas 1961. Similar calcUlations would'have been made in both of the areas in 1961, but as mate frosts.killed so many of the young pods bearing Bruchid eggs, it was impossible to do 1304 , Laboratory Experiments 1961. On 1 May, 1961, twenty six, ,3 x 1" tubes labelled A, B, C Z, were set up, each containing 2 green broom pods, 4 broom flowers laden with pollen and one pair of B. ater adults.- The tubes were closed with a piece of muslin and kept at outdoor temperatures, shielded only from direct.sunlight and rainfall. The flowers were replaced every 2 days and the pods were replaced every 6 days. All eggs laid on the pods and.some laid , on. the muslin were counted and removed every 6 days. The results of this experiment were not consistent, the total,nutbers of,eggs laid varying between 1 and 35 per female with an average ,of 9.5. These numbers are far too low when compared with those calculated in the field, and it was concluded that the beetles needed other, more suitable conditions before they would oviposit freely within a confined space.

h. Wei hts of adults throughout 1960 and 1961.

lath week, after the sexes were determined (see p,4;9' ) 68,

J 960 2. a---S females •----• males y — adults collects d from 2 yarrow.

MS.

IGRA MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. MILL .___. females ---- males

1•

I . g . . JAN FEB. MARCH APRIL . MAY JUNE JULY AUG. SE PT. *L Less than 10 beetles weighed to obtain average value,

Fig. 10. Average weight of Bruchidius ater adults. A. In 1960. B. In 1961. 69.

th , etles ·re e 1e1 ed on an. Oertlin one an ReI s- o-m tic balanc . T e total nu ber 0 m l ee ere 1 ei , hed to ether a ~ were t he total ,n be of f m l e • he balance d tecte differ e cas of 0 . 2 milli rams.

The vera e 1e1 ht of each se s lotted on the r ph

( i ',. 10) an n the 3 casas 7her less th n 10 adu ts vere used to obtain t hi s avera e the pOints on the graphs are

a ed lit h n asteri k . At all other ti e s t he numbers of b e tles u ad ranged b teen 10 and vOO . he prin op ation. Fi.:;. 1 shows that in vt ay and June , 1960 hen the beetle

re matur~e , the avera. e yei hts ere b ut 2 milli runs in b oth s xes. To.ards th end of June , the beetles collected

...... -- ...... had lost we ht c nsi derabl y . Throu h o~t J y and A ' st th1 deere sa contin ad and the e t jority of beetle d1ed out n t e folIo ing win er month • ei hts and acti i to; of t he emor _ opul tion.

he fir t eetles to e er e r om seeds i n early mat are th l arge tad hcavie t . Upon e er~ence th e adult i d i- ately be . an to disp rae , 1 aV'ng te broom co pl e tely. ss- tv ly sma l er and li ht e i ndi uals continue to e erg t hrou out u at and the b inni of ept emb r a d dispersal d i n thio time . Ad It b eetl s rere e aten :from 23 Au t to 5 eptember t 1960 fr m and cer gro i ng 150 y de a ay from one orner of t e broom plantati n . These trees, 70.

specially the Am', had lar7; colonies of Poyllids on them and the 71ruchids probably tended to cotrxer!;ate here to feed on the Pe7llid sugar secretions. The reason for the sudden apparent weight increase in October is caused either by the death of the smaller bceties, or by the return of some of the larg3r ones, The former is likely as no small beetles more found to eme rj,k. from hibernation in 1961* The weight of the beetles overwintering on the broom bushes tended to fall off slightly from November, 1960 to ::arch, 19G1 CM the reserves in the body were used up (Gee p. 58 Ac soon an the broom flowered once again, feedin b and the weights of both sexes rose once ailin to 2 milligrams as the b etleo mtured. The weight© in 1.461 follow exactly the same trends as in 1960,

Overwinterirr;. e exact locstion of the overwintoring sites has already been discussed (see p 42 ), but in the sinter of 1900.61 two :;xperim ente were made to try and calculnte the percentage mor+ality of the hibernating ix oties. urin, July and early August, 1960, 275 of the 1;ruchids which emerged in 1959 we:#e collected from the plants of trkehillEIR growing in between the ",taw Broom" bushes. These beetles wore nlaced into three 7 pound jars, each containing 71.

a 2 inch layer of a mixture of damp peat; bark chippings and sand, A pad of cotton wool soaked in very dilute sugar solution was also placed in each jar and then the bottles were covered with muslin and placed at outdoor temperatures in an outhouse. The cotton wool pad was moistened once a week until the end of October when nothing more was added to the jars until they were examined in the following spring. Three similar jars were set up containing 230 (i.e. 141 females and 89 males) Brucbids which had been collected from pods in August and September, 1960. These beetles were treated in exactly the same way as the others and re-examined on 17 April, 1961. Table 18 shows that the beetles overwintering for a second time suffer an almost total mortality, i.e. they only rarely survive 'for more than one year. Bruchids overwintering for , the first time however, only showed an average of 35.4% mortality* This mortality is also shown to affect both sexes alike so that the emerging beetles are approximately in the same sex ratio as the ones which had entered hibernation (i.e. 1 male : 2 females). 72,

Table 18. Overwintering mortality in B= ater adults. Collected Examined Year Date Plant No. Date No. d Total emer- (Months) dead alive aorta- l'iorta- ged lity lity

7-8 1959 1960 Yarrow 275 24.4.61 270 5 98.2 98.2 t 141 females t49 92 34.8 1960 8-9 Broom 17.4.61 35.4 1960 89 males 32 ' 57 36.0 75.

A.2. Eggs.

a, Morphology. . The egg of .p.z ater is elongate and oval in shape with rounded ends. The chorion is smooth with no apparent sculpture. It is also extremely tough and rigid even retaining its shape as a transparent. empty husk after the larva has emerged, The colour of the newly laid egg is straw yellow. The average length of ten .eggs was 0.54 mm, ranging between 0.48 and 0.57 mm. the width was 0.28 Tim, ranging between 0.26 and 0.30 mm, Steffan (1946) records the egg size of this species, Which he calls I3ruchidius fasciatus as being about 0.6 mm. long and 0.25 mm. wide and thus there is a fair agreement between the two sets of measurements.

b. Development. A short description of egg development is given by Steffan (1946) and I have studied it further in a:series of experiments undertaken in 1960 to determine the rates of incubation at different temperatures. Eggs were Obtained from large sets of fertilised females collected from an unused broom area. These females were induced, to oviposit on young green pods within 3 x 1" tubes at outdoor temperatures in the fourth week in May, 1960. The pods were removed every day and thus the age of the eggs laid on them was known to the nearest 24 hours. A large batch of eggs laid on 27 May, 1960 was divided into 3 parts and each part was placed,in a 7 lb. jar. These 3 jars were then covered with muslin and placed at 3 different temperatures for incubation (see Table 19). Table 19 'Incubation rates of B, ater eggs at different temperatures. Incubation period Position Mean R.H. Total No, Devel-• Max. Mean. Min. Tempo No.-of Bevel- oped eggs oped %

Outdoors (Shaded) 60.00F 143 75 52,4 24 21.5 19. Laboratory 63.69? 46, 21 46.7 16. '15 14 Constant Temp. Room 86.1°P 67.5% 60 20 33.3 6 5.5 5

The temperatures in each experiment were recorded by thermographs and, in the Constant Temperature room there was also a relative humidity indicator. It can be seen from the table that the incubation period decreased and the egg mortality increased with increasing temperature. Also the mortality was very high even at shaded outdoor temperatures (i.e. 47.6%) and it was wondered whether the drying up.of the pods on .which the eggs were developing was increasing the mortality. It was noticed that, of the 47.6% mortality, 2147% of the total- number of, eggs did not develop and subsequently turned opaque and dark yellow. A few 75 i

of these shrivelled up but the majority remained in this condition for over a year after which, they were dissected and found to be desiccated. It has already been shown (see p. 5'g' that sterile eggs shrivelled under field conditions, and thus it was presUmed that the majority of these yellow eggs were not sterile. The rest.of the 25.95 (i.e. 47.6 -,.21.7) of eggs which failed to develop became deformed in some way during development, As the egg chorion is transparent, the development of the sternal pods and head sclerotisations of the larva within the egg -could'be- observed . (see Steffan (1946)) and it was these sclerotisations that were seen to become deformed and twisted ,during development thus causing the death, of the'etbryo. At first it was thought that this high percentage of deformity was due 'to some humidity factor in 'the experiment.

c. Mortality factors in the field. On 9 June,'1960, 374 eggs were collected in the "Old Broom" from. a large sample of pods which was taken systematically all over the area. Random numbers from Fischer and Yates (1953) were used to find random twigs on the bushes and then the nearest pods to these twigs were picked. Table 20 was constructed from the Observations on these eggs. These eggs were left at outdoor• shaded temperatures in 76,

Table 20. B. ater Egg development and mortality in the "Old Broom" 1960. Sucked ])ate Total Devel. Deformed,Parapi- Total Part- Yellow Normal eggs eggs tiled sally .

9/6/60 374 9 0 9 13 21 97 225 29/6/60 374 15 191 9 . 13 , 21 125 - Percen- tages 100 4.0 51,1 2,4 3,5 5.6 33.4'

3 x 1" tubes covered with muslin. Each tube contained a single pod bearing 1 to 10 eggs. Twenty days later, on 29 June, 1960 the eggs were examined once again and it was found that only 15 larvae had emerged. This represented a 4% hatch, the other 96% of the eggs having either failed to develop, or having become deformed during development, or they were parasitised or sucked. Estimations of these mortalities are given. in Table 20 * "Numbers of eggs totally or partially sucked remaine-- unaltered as further predation was excluded by the nature of the experiment. Under field conditions the percentage of sucked eggs would most probably have risen higher than the 9.1% (i.e. 3.5 + 5.6) shown in the experiment. The number of eggs which turned dark yellow in the field is here shown to be 33.4%, this being much higher than the figure obtained in the laboratory experiment. Also the number of deformed eggs was much greater than in the laboratory experiment and the reasons for this are not readily explicable except that the conditions of the experiment produced this as an 77,

artefact.. However the very high egg mortality indicated by the exper- merit is supported by the pod sample records taken in July and. August, when very few Bruchid larvae were found in the seeds and, the remains of deformed egEm were noted on many of the pods (see p.311 ). Also no new adult generation was observed in September; 1960 (see p.,35 ). .A "New Broom" sample, similar to that in the "Old Broom" was taken and 309 eggs were collected on 16 June, 1960. They were treated in exactly the same way and their development is shown in Table 21. Table 21 B. ater egg development and mortality in the "New Broom" 1960. Sucked Date Total Devel, Deformed Parasi- Total Part- Yellow Normal eggs eggs tised ially

16/q/60 309 29 0 0 4 - 41 235 6/7/60 309 128 .106 0 4 - 71 - Percen- tages 100 41.4 34.3 - 1.3 - 23.0

In the "New Broom" a:greater percentage of the larvae hatched, but still the greatest mortality was due to eggs becom- ing deformed or turning dark yellOW. But. , as this experiment was kept in exactly the same conditions as the one in the "Old Broom", it shoWs that larvae- can survive and develop completely under these conditions. Thus the heavy losses due to deformity 78.

during development in the "Old Broom" are not totally due to the nature of the experiment but to some other factor which cannot be readily demonstrated. Mortality of eggs due to predators was seen to be lower in the"Bew Broom", and, experiments (see below) in 1961 showed that the density of predators in, the "New Broom" was much less than in the "Old Broom". Parasitisin of Brachia eggs by a Trichogramma ap, was found only in the "Old Broom" in 1960 and 1961. Nine of the eggs collected in the "Old Broom" on 9 June, 1960 (see Table 20) subsequently turned black. One adult Trichogramma sp. emerged from each of these eggs and the biology of this species is discussed later (see p. 177) In 1961, similar experiments were set up early in May to investigate further the incidence of deformed and dark yellow eggs on living pods in the field. However the later frosts damaged the experiments to such en extent that they had to be abandoned. From the records of pod samples however (see p. 311) it was evident that similar mortalities occurred in 1961 as in 1960 9.e. very large in the "Old Broom" and small in the "New Broom". However, a series of experiments were made to find the egg predators. To do this the most common insect species and one species of mites occurring on broom were enclosed in separate plastic cages together with broom pods bearing numbers of

79.. fertile Bruchid eggs as shown in Table 22, Table 22. Predation of L.4 ater eggs by various insect species commonly occurring on Broom. Nos. of insect species used 57 12 12 20 20 Bruchid. Anystis Anthocoris Anthocoris Psyllids irids eggs aili ssrothamrni nemoralis ,Arytaina OrthotylusAi Psylla sp. :.eterocord- .12422 Bps Asciodema sp.

.11a. of eggs'intro= duced on, 25.5.61 57 37 - 51 38 Bggs totally or part-' tally sucked on 30.5.61.42 1 2 Percentage of eggs sucked 73.7 5.0. 5.3

Five days later on 30 May these cages were re-examined and each of the ater eggs was investigated, under a binocular ,microscope for signs of predation. It was found that the mite Anystis agilis vas responsible for the destruction of the largest percentage of B. at eggs. These eggs, when placed in with the mites, were at various developmental stages. It was seen that the predators were capable of sucking the eggs completely dry irrespective of the stage of development reached by the embryo. . Some fully developed larvae were observed, to have been sucked just before they were to emerge and only the cuticle of the dead larva was left 80., within the chorion of the egg. The other insect species that were used did not attack the eggs to any extent (see Table 22), Actual population estimations of Allystis agilis were not determined in the field. However, it, was noted from observations of the samples that the number of mites, per'broom:bush'in the "Old Broom" area was much greater than in the "New Broom" area. This factor thus accounts for some of the extra egg mortality in the "Old Broom" area. a

A.3. Larval and pupal instars.

a. Morphology. First instar, It has been ,found that in the great majority of Bruchidae the first instar larva differs in certain morphological pecula- Pities from the subsequent stages (Daviault 1928, Hoffmann. 1945). This phenomenon is often known as hypermetamorphosis and it has been:found to occur also in 1. ater. The complete morphology of the first instar of B, ater has been described in great detail by Steffan (1946)(Bruchidius fasciatus). He also includes a drawing of a newly emerged larva. To compare with this I have made a drawing of a fully fed first instar larva, which was dissected from a broom seed. (Fig. 11A and B). As no salient differences were discovered, no further description was made. It is interesting however to note that Steffan (1946) describes this larva as having both common characters with other Bruchidius species and additional sclerotisations which are unique. The characters found in most first instar Bruchidae include the dorsal prothoracic plate, (Fig 11C and 11A pt.p) and the backwardly directed conical spine, (Fig.. 11A c.$) which is situated above the spiracle of the. first abdominal segment, Kunhi Kannan (1923) gives a review of the functions and the 82.

A key to the abbreviations used in Figures 11,12,13 and 14.

a.s. Antennal socket. a.st. Antennal seta. b. s. Basal segment. ed. Cardo. cl.s., Coronal suture. cly, Clypeus. cips. Conicalspine.: cx. "Coxae". ec. Epicranium.. ep, Epistoma. ePP. Epipleuron. ep.s. Epistomal suture. h.c. Head capsule. hat. Hypostoma. hyp. Hypopleuron. 1, Leg. lbm. Labrum. lig. Ligula. lm. Labium. ip. "Labial plate". me Maas md. Mandible. oc. °callus. occ.f. Occipital foramen. pep. Pre -apipleuron. Pf. Palpifer. plp, Maxillary palp. psc, Prescutum. ps.ep. Post -epipleuron. pt.p. Prothoracie plate. OM. Scutoscutellum. spr. Spiracle. at. Stipes. stn. Sternite. st,p, Sternal pads. st.s. Sternal spines.' t.b. Tentorial bar. vma. Ventral mandibular articulation.

c.s 85 .

pt.p

0.5mm 1 c

0.05mm Fig,. 11. Brachidius ater (Marsham) A. First instar larva, lateral view. B, First instar larva ventral view, Q. Prothoracic plate, dorsal view,

A 84

'PP

I- 1.0mm

Fig. 12. Bruchillius ater (Marsham) A. Fourth instar larva; lateral view: B. Pupa, ventral view. 85

Fig. 13. Bruciaius ester ( Marsham) A. Head capsule of fourth instar larva, dorsal view. B. Head capsule of fourth instar larVal ventral view. G. Left antenna of fourth instar larva. 86 .

O•Imm

Olmm Fig. 14. Bruchidius ater (Marsham) A. Labium and left maxilla of fourth instar larva, ventral view. B. Labrum and clypeus of fourth instar larva, dorml view. 67., diversity of structure of the prothoracic plate while a further reldew of more recent literature on this subject was made by *Hafez and. Osman (1956), The function of the conical spine has also aroused some curiosity, Zachex (1930) believes that it is used for leverage during hatching but Mukerji (1938) states that it is used to rupture the, egg sac. The additional sclerotisations as far as is known characteristic of this species include all of the sternal pads (Fig 11B st,p), the "coxae", (Fig. 11B cx.) and all of the thoracic pleural sclerotisations (see Fig, 11A and B). These extra structures are probably used in conjunction with the long spines on the body to form an anchoring mechanism whilst the larval mandibles carve out a tunnel in the pod tissue. The ventral, backwardly directed rows of chitinous-, lanceolate, spines (Fig. 1)3 st.$) between the sternal sciero- tisations might also be used to move the excavated material away from the mandibles and deposit it behind the larva thus blocking the tunnel. The setation of this larva seems to be similar to that described by Hafez and Osman, (1956) in Bruchidius trifolii (Uotsch). At the first moult this larva undergoes ermetamorphosis and loses the following characteristic structures:- the prothoracic plate, the conical spine on the first abdominal segment, the macro and microchaetae, all of the sclerotised 88„

areas all over the body and finally the brown pigmentation of the head capsule. The 3 pairs of thoracic legs which are well formed in the first instar are retained in the following instars but are developed to a lesser extent and are not used for movement. Second, Third and. Fourth Instars. As the morphology of the second, third and fourth instars was found to be very similar, only the fourth instar was described but mention is made where slight differences occur between the instare. The fourth instar larva of. B ater (Fig. 12A) is whitish, havinr,f a crescent shapedIA'at, fleshy body. The head is deeply retracted into the thorax and only the mouthparts and antennae protrude in the 'centre of the anterior end of the prothoracic segment. A comparative study of the morphology of related Bruchidae (Mylabridae) is given by Baying (1927). The head capsule (Fig. 13A and 13) is composed of transparent chitinous material which is scierotised only in the regions surrounding the mouthparts. It is orientated so that the mouthparts are anterior and the vertex of the head is posterior to the longitudinal body axis of the larva. The head is oval in shape being somewhat attenuated posteriorly. The corona]. suture (Fig. 13A els) runs down the mid-dorsal line dividing the epicranium (Fig. 13A ec.) into 2 halves., There are no distinct frontal sutures and thus no definite 89

limits between the epicranium and the frons. A. crescentic bar, the epistoma (Fig, 13A ep.) is situated anterior to the frontal area and bears laterally the antennal sockets. It is the only fully sclerotised part of the front of the head. Four pairs of setae and a pair of sensory pores are situated on the frontal area and a further 3 pairs of setae are situated on the epistoma. A black pigmented ocellus (Fig, 13A oc.) and a small spine are situated just beyond the outer edge of the antennal sockets (Fig. 13A aws.). Some variation in the .00sition and numbers of the setae was' observed and Fig, 13A represents the arrangement most commonly found. The clypeus (Fig. 13A and 1413, cly.) is situated anterior to the epistoma and is divided from it by the epistomal suture (Fig. 13A and 1413 eps.). It is membranous apart from 2 lightly sclerotised, triangular regions in the 2 posterior corners, Each of these bears one setae and one sensory pore. The labrum (Fig. 13A and 143 lbm.) is divided off anteriorly to the clypeus by a membranous junction. It is transversely oval in shape being composed posteriorly of a thinly sclerotised transverse plate which bears a pair of long .setae and, slightly closer to the mid line, a pair of sensory pores. Anteriorly the labrum bears a largo number of stiff in amongst which are 7 long setae. These setae are arranged in 2 rows, a terminal ror of 4 setae and a posterior second row of 3 setae. The labrum in the second and third larval instars is 90:

similar but has very few or no spines, distally. The occipital region of the head is not sclerotistd and no distinct sutures are visible. The occipital foramen (Fig. 1313 occ.f) is large, being limited anteriorly by the tentorial, bridge. (Pig. 1313 t.b.). This bridge connects the two Poster- ior ends of the hypostomas The anterior part of each hypostomal sclerite is lightly scierotised and forms the socket for the articulation of the ventral condyle of the mandible (Fig. 1313 vma). The antennae (Fig. ).3C) of the fourth instar larva are composed of a large basal sclerotised segment (Fig. 1313 la's) set on the apex of a conical membrane. The segment bears at its tip a fringe of spines surrounding a much thinner conical, papilla-like, segment, There are also 2 smaller papillae pres.. ent in the membrane on top of the basal segment. In the secOnd and third instars there is an extra papilla-like projection in the membrane at the base of the basal segment. Also, the basal segment does not possess a fringe of spines at its apex. Apart from these structures the antennae are identical in the 2nd, 3rd and 4th instar larvae. The structure of the larval mouthparts in many species of Bruchidae has been discussed by many authors,: for instance by Roving (1927), Hoffmann (1946) , Hafez and Osman (1956) and others. The variation of these structures has been used as a major character in the determination of the taxonomic affinities 91.

of the Bruchidae. The epipharynx of l3ruchidius ater is membranous and carries 2 pairs of crotchet-like spines anteriorly. Epipharyngeal lamellae are present as 2 chitinous rods which diverge anteriorly on either side of the mid line, This structure is common to most Bruchidae. The mandibles are typical of those found in the Bruchidae in general. They are nearly triangular in outline with a bluntly pointed, heavily sclerotised, apical tooth and, a groove running along the inner surface of the grinding edge. They articulate with the head through the lateral and ventral condyles. The lateral condyle works against an emargination on the epistoma whilst the ventral condyle articulates on the hypostoma. Woll developed, large adductor and smaller abductor muscle attachments are present in their normal positions. There are 2 long bristles and 2 sensory pores on the upper surface of each mandible. The maxilla consists of a cardo (Fig. 14A cd), stipes (Fig. 14A st), palpifer (Fig. 14A. pf), one segmented palpus (Fig. 14A pip) and a mala (Fig, 14A m), The cardo is a diagonal, elongate, oval scierotised plate which is devoid of any setae, It is drawn out to a point posteriorly to articulate with the base of the head capsule. The stipes is composed of a basal sclerotised strip devoid of setae and a distal larger membranous area bearing 3 setae ventrally and one large seta laterally. The shape 92.

of the stipes is traperzoidal. The palpifer is a well sclerotised strip which almost encircles the distal end of the maxilla. It bears 3 setae and a sensory pore on its ventral surface. The galea and ldcinia are fused to form the mala. This is a projecting, lobe like meMbranous region bearing several small setae ventrally and a distal tomblike structure composed of 6 curved flattened spines arising from the dorsal surface. The maxillary palp is one segmented and well sclerotised, bearing at its apex a pit, in which many sensory spines are located. A sensory pore and several spines are also situated laterally around the base of the palpus. The labium (Fig. 14A 1m) a very poorly represented but according to Boving •(1927) it is; "the most characteristic formation of the 1.7ylabridae", (i.e. Bruchidae). It is composed of a large posterior membranous area which bears 5 pairs of large setae and which is contiguous with the maxillary area laterally and the cervical membrane posteriorly. Bearing (1927)' gives an illustration of a sclerotised submental plate in this region in Pachymerus and Spermophagus species. He also shows, however, that it is vestigial or entirely lacking in other Bruchidae. Hafez and Osman (1956) record the presence of thiS plate in the second instar only in Bruchidtus trifolii. No trace of this sclerite was found in any, of the instars of at ater. 93'

The anterior, very weakly sclerotised, shield shaped sclerite is known as the "labial plate" (Fig. 14A 1p.). It is composed of the fusion of the mental and premental sclerites and it carries a pair of small bristles. A° other labial structures are present. The ligula (Fig, 14A lig) is the membranous area between the indistinct tips of the anterior arms of the labial plate, It is slightly incised in the mid line and is provided with a pair of long bristles which have a pair of sensory pores at their bases. The hypopharynx is membranous and is supported on either side by a chitinised hypopharyngeal rod. The thoracic segments of the fourth instar larva are completely membranous aad they increase both in width and diameter from front to back, The tergal area of the prothorax is undivided, but the mesa and meta-thoracic terga are transversely divided into 2 equal parts. These are referred to as the prescutum anteriorly (Pig. 12A pee) and the .scutoscutellum posteriorly (Fig, l2A scs). Laterally the pleura are subdivided into an anterior, triangular pre-epipleuron (Fig. 12A pep) and a posterior poste. pipleuron (Fig. 12A ps.ep) by a V shaped prolongation of the alar area, The hypopleuron bears a pair of rudimentary conical, membranous legs ventro-laterally on each thoracic segment, The sternitee are undivided but bear many bristles especially around 94.

the, bases of the legs. Very small setae are also distributed sparsely all over the thoracic and abdominal segments. Their positions however varied ine every larva that was examined and thus none are included in the generalised drawing of the larva (Fig. 12A) There is only one pair of spiracles on the thorax and these open laterally in the mesothoracic pre-epipleuron, The abdomen, which is curved and completely membranous consists of 10 segments. The first 8 segments are identical having a tergum divided transversely similarly to the two posterior thoracic segments. Laterally the pleura are divided into a dorsal epipleuron (Fig. 12A epp) and a ventral hypopleuron (Fig, 12A hyp), The sterna (Fig. 12A stn) are wrinkled transversely but are undivided.

The 9th abdominal y ".r^ is small and the 10th bears the terminal anus. Eight pairs of simple circular spiracles (Fig. 12A. sp) are present laterally in small depressions on the alar areas of the first 8 abdominal segments. The Prepupa. J'ust before pupation the 4th instar larva undergoes a change of shape and enters the resting prepupal stage. The head capsule now protrudes from the thorax and assumes a vertical position relative to the body axis, so that the mouthparts are now erected ventrally. Also the once wrinkled thoracic and abdominal 95.

sternites are expanded so that the body axis is now straight instead of curved. The pupa (Fig. 123). In ventral view (Fig. 123) the pupa is of the typical aoleopterouS exerate type. The head, with its prominent.eyes, is inclined ventrally below the prothorax.' The mouthparts lie •between the cozae of the fore and mid legs. The antennae pass laterally; behind the forelegs and' lie on the elytra. The fore'- legs and midlegs are folded back on themselves and the tarsi are directed posteriorly on either side of the mid line. The femora and part of the tibia 'of the hind legs are folded under the hindwings but the tarsi lie bn.the sternites on either side of the mid line. The first 6 abdominal sternites are visible and the pupa 'is terminated, posteriorly by a pygidium like seventh sternite which-bears 2 small, posteriorly pointing, curved spines. These probably serve as an anchoring structure for the pupal case to aid in the emergence of the adult as they are not present on the latter. Laterally the spiracles of abdominal segments 2-6 are visible andodorsally, a large triangular prothorax, the curved elytra, 6 equal tergites,and'a seventh triangular pygidium are the major features. 96.-

b„ Life Histories within the pod. The development of the first instar larva' within the egg is discussed by Steffan (1946) and he Shows that the larva develops upsidedown with res eet to the pod surface. The larva then rotates through 1800 and elaborate mechanisms, (Kunkd Kannan 1923) Including the prothoracic plate and the egg chorion enable it to get a firm grip, whilst the mandibles chew a hole in the underside of the, egg where it is in contact with the pod. Once through the chorion, the larva bores straight into the soft green tissues of the pod and searches for a seed. There is no free living larval stage In this species. In the process of. boring into the pod the material excavated by the larva is left behind in the form of greyish-white powder, which almost fills the egg chorion, It was originally thought in Bruchus oundrimaculatus Mikerji 1953), that this substance was frass, but cafes and Osman (1956) have shown that in Bruchidius trifolii, this powder is not eaten by the larva. It is simply the residue from ceecavation which is pushed along the grooves on the inner sides of the mandibles and which is left behind, as the larva moves forward. Thus as the 2.1 ater'larva enters the broom pod it blocks up the tunnel behind it and also has the added protection of the egg chorion over the entrance to the tunnel. 17hen the larva reaches the pod cavity it commences to move around in search of a soft green seed. The larva does not 97. necessarily bore directly into the nearest seed as, in several casesp.a.single larva was found inhabiting a seed up to 4 centimetersaway from its point of entry into the pod cavity. in these cases up to 3 unoccupied seeds had been passed by before an entrance had been made. The larva normally enters a broom seed through the micropore. It bores into the seed and commences to feed on the part of the embryonic cotyledons directly,below,the entrance hole. However, if by chance a larva happens to bore through the pod wall directly onto a seed it rill bore through the testa and enter the seed cavity from the bide. This happens very rarely and only 4. instances were recorded from a total of 280 seeds examined in the New Broom in 1960. The first instar stage is primarily a locomotory one and it was observed that once it reached a seed and bored into it very little feeding,occurred and the larva soon moulted to the second instar, The second, third and fourth maters are the feeding stages and by the time the fourth instar is fully grown the seed embryo has been completely devoured. Thus . the seed. testa now surrounds a hollow cavity in which is occupied by a single fully grown larva together with an accumulation of white frass and 3 larval exuviae. The larva is always orientated so that its anterior end points away from the seed caruncle and diagonally towards the distal tip of the pod. In this position the larva enters the 98,,

resting or prepupal stage and finally moults to a pupa. The pupa assumes a similar position as the last' instar •-larva. Vey few pupae were found with the anterior end inclined towards the opposite end of the pod (i.e. the end joined to the bush). Do pupae were found to be "upsidedown" - that is with the anterior end just below the seed oaruncle. . After a brief, pupal period the adult beetle hatches and immediately begins te'gnaw a neat circular incision in, the seed coat, As in many Bruchid species, the last instar, larya gnaws half way through the testa marking out the hole through which the adult can emerge. Thus when the adult has finished gnawing' through the testa it pushes off the disc shaped trap door and pulls itself through the hole into the pod cavity. It was noted that adult beetles could not gnaw their way out of the pod4 Instead they remain in the cavity until they are released automatically when the pod dehisces. Thus throughout its larval life inside the pod, the Bruchid does not leave the seed, which provides enough food for the complete development of one larva only. Occasionally, however, when 'the seed is very small, :the larva devours all of the seed embryo before reaching the, prepupal stage. Four instances where this occurred were found in the 9604 pods sampled and examined in 1960. In these cases 2 of the larvae had. bored out of their original seeds into the" neighbouring ones where development had been completed. In the other 2 instances there were 99.

no other seeds close to the infested ones, Here the larvae had bored out into the pod cavity and died from starvation.

c. The Humber of Larval Instars. To find the number of larval instars of Bruchidtas ester a total of 126 larvae were dissected from pods in 19590 These larvae were preserved in 70 -; alcohol. Measurements were made of the only 2 heavily sclerotised regions of the larvae, These were the epistoma and the mandibles, The distance between the centres of the antenna' sockets across the epistoma, and the length of the right mandible from the centre of the grinding surface to the outer edge between the 2 articulations were measured in each larva. Measurements were made using one side of a Charles Perry binocular microscope fitted with a micrometer eyepiece which, by chance read 1 graduation to 1/100 mm. When the two measurements were plotted against one another on a scatter diagram they fell into 4 distinct groups represent- ing 4 distinct larval instars. (see Pig. 16A). All the larvae falling into the lowest group were observed to be of the hypermetamorphic let instar type. The other 3 instars were similar to each other morphologically and their head capsules are shown in fig. 15A, B and C, Similar measurements were also made of the mouthparte Of. 5 prepupae. They were all found to fall into the 4 instar group proving that this is the last instar. 10.0.

d. Progression in Growth. Dyer (1890) was the first to postulate a law of geometrical progression for the growth of selerotised parts of the insect body:* He used the head widths of Lepidopterous larvae and showed that the measurements of each successive instar bear a constant ratio to one another, this ratio being 1.4* Przibram and Megusar, (according to the review given by Duarte (1938)) extended this principle by showing that, in .Sphodromantis bieculata'the exuvitie and bodies doubled their weight between each moult. They concluded that the nutber of body cells doubled at each moult and so correspondingly, the body size. increased by the cube root of 2, (or 1426)i There is however no proof for this, Ratios higher than 1.26 obtained for the nymphs of Schisto- cerca pyegaria and. Locusta migratoria migratorioides were attributed to extra "latent", cell divisions taking place between successive modlts, by Bodenheimer (1927), and Duarte (1938). However, as has been pointed out by Richards (1949) in many insects, in constant conditions the increase is propor- ,tional not only to the instar but to its actual duraction. The growth ratios of the antennal width and the length of the right mandible of Be ater larvae were calculated and the results are shown in Tables 23 and 24. 101.

Table 23, Calculated Mean values. and growth ratio s of the distance between the centres of the antennal sockets of 3ruchidius ater larvae, (measurements in

Stage Number of Minimum :.aximum Mean .S.D. Growth Individuals Value Value Ratio Measured.

1 e3r- .0,070 0.030 0,075 0:0029 2 21 0,120 0.137 0.129 0,0041 1,70 3 40 0.165 0.210 0.196 0.0092 .1.53 4 40 0.240 0.280 0.268 0.0098 1.36 Mean growth from 1st to 4th instar 1.53

Table 24 Calculated mean values and growth ratios of the length of the right mandible of 3ruchidius ater , larvae. (measurements in millimeters) Stage Humber of Minimum Maximum Mean S.D. Growth, individuals Valte Value Ratio

1 25 0.035 0.050 0.044 0,0046 2 21 0.055 0,070 0.033 0.0051 1,43 3 40 0.095 0.115 0.105 0.0060 1.66 4 40 0.140 0.155 0.145 0.0051 1.39 .1...1.1=0“••• Mean growth from 1st to 4th instar 1.49

Although there is some variation in individual values the mean growth ratios of both the measurements are similar to eachother and close to the value originally obtained by Dyar. According to the l'rzibramt s and Bodenheimert s theories llowever, there must be some "latent" divisions occurring within instars in 'both of the regions that were measured. The standard deviation (S.D.) for each set of measurements 102. .

calculated from the formula :- - - where 'x equals the value of each measurement, i equals the mean and. N equals the number of measurements made. The standard deviation in both sets of measurements increas es with successive instars but falls off in instar 4 in the mandible length. When the means of the linear measurements were plotted against their corresponding instars they showed typical expon- ential growth curves (Pig. 16B). When their logarithmic values were plotted against the instar, the points were such that straight regression lines could be calculated for them (Fig. 16C) These lines show that Dyars law of geometric progression tends to hold true for Bruchidius ater larvae. When the means of the linear measurements were plotted against the mean accumulated days of the duration of each instar (see Table 26) there was greater scattering of points than when these measurements were plotted against their corresponding instars (see Fig. 16D) Richards (1949) however used this method to show that Dyars rule only applied when all of the instars were of the same duration. He also showed that, when regression coefficients were computed for these points a better fit was obtained when the first instar measurements were omitted. When this was done in 13. ater larvae (Fig. 16D) this was 103.

found to be the weial ea 44 whol,e Dyars .4.)plies- an the differences between th durntions of each inotar aftor the fi3ot, mrc found to amalle 104.,

e. The duration of larval instars within the pod, The larvae of B. ater complete their development concealed inside the broom 'seed, i.e. in a medium into which they cannot be replaced. The approximate duration of each larval instar was determined by the examination of samples of pods. A series of different larvae, all of known age (i.e. days after oviposition) were removed from the seeds at various times throughout their development. The first appearance of an instar and the first appearance of the following one gives the minimum duration at the prevail- ing temperatures, while the first and last records in time of each larval, stage represents the period of time in which this instar occurred in the field. The temperatwes in the field were recorded in a Stephenson screen. Richards (1947) used this method with Calandra granaria (L) larvae and he estimated the average instar length at different temperatures and humidities, by inspection. To obtain B. ater eggs of known age, small plastic contain- ers measuring 7.5 cm. x 4.2 cm. x 2.0 cm., with sliding lids and muslin covered ventilation holes, were used as oviposition cages. Twenty of these cages were each used to enclose 5 at ater females on a living broom pod still attached to a broom bush in the "Old Broom" area. A notch, cut in the centre of one end of each cage accommodated the broom stem. 105.

The pods,used in this experiment had previously been enclosed in muslin bees to prevent any extraneous oviDosition by wild 3. ater or Anion fuscirostre Fab. females, Twenty pods were used on each of 5 dates in 1960 (i.e. 1, 3, 5 and 6 June) and in each instance the female l3ruchids wore enclosed on the pods from midday until 5 p.m. The cages were then removed and the number of ens laid. on the pods was recorded. Where too many eggs had been laid on.a single pod, some were scraped, off with a razor blade until only 20 remained. "Iach pod was then enclosed in a separate muslin bag and carefully labelled. Thus, a total of 100 pods were inoculated with up to 20 3ruchid eggs each, the age of each egg being known to the nearest five hours. From daily observations, the first Lnstar larvae bored into the pods between the sixteenth and the eighteenth days after oviposition. Thus, the mean length of egg development was 17 ,days, The developmental temperatures and humidities were assumed to be the same within all of the pods. Dissections of the seeds in these pods were made at internals throughout the season and the numbers of each larval instar in each pod were recorded. As the oviposition date of the eggs was known it was Possible to record the age of these larvae in terms of "days

106.

after oviposition".. Thus, one table could be constructed using the results of all the dissections (see Table 25). Dissections of 70 pods were used to construct Table 25, and, of this number, 20 'nods= contained. no larvae. Table 25. Dissection of 70 Broom pods containing Bruchidius ater larvae of various known ages in terms of "days after oviposition". The mean length of egg development was 17 days. Temperatures :lax.27 floans.15Min. 4°C. Days after No. pods Larvae oviposition dissected 1- II 'III IV P.P. P.

21 5 7 - S: * 25 3 •7 2 26 3 2 5 — * 29 3 - 3 6 30 2 3 1 31 3 '2 10 3 35 1 3. 36 2 1 1 7 8 37 1 40 1 6 41 1 2 1 42 1 6.010 41. 4 2 43 1 AAA 100 9 2 46 2 8 47 1 AMA 1 52 1 1 1 53 4 011 1 14 AA/ MAA. - 62 1 — 2 1 66 1 MIA ••• 1 67 4 ONO 4•11k - - - 7 70 8 elea NMI 1 2 3 No. of pods with no larvae 20 TO TAE, 70 22' 23 35 31 5 31 P.P. = prepupae. P. = pupae.

The data in Table 25 was found to be insufficient to 'frarrent 107. a closer analysis using methods such as those suggested by Eastham and Segrove (1947) (on Calandra 1;:ranaria Linn. larvae) and Howe (1952) (on Calandra oryzae (L.) larvae).. The records of the first and last appearance of each larval instar are summarized in Table 26 using data derived from Tables 25 and 27. Here the fourth instar and prepupal phases are added together. The length of the prepupal stage was known to be one to two days from observations on larvae in the laboratory. • Table.26. First and last records of each developmental stage of Bruchidius ater in terms of "days after ovipositicif Data derived from dissections of broom pods. 1".nstar First Record Last Record Duration (in days) (in "days after oviposition") ?lax.* Iean. Min.** •

1 171L 36 19 13.5 8 2 25 37 12 8.0 4 3 29 43 14 10.5 7 4 36 70 34 25.5 17 Pupa 53. 101+ 48 32.5 17 Adult 70 101+ - - - - mean hatching day. + = day numbers derived from Table 27, * = Duration of stage in the field = Last minus first record. ** = L!inimum instar duration = e.g. First record (instar 2) minus first record (instar 1).

Table 26 shows that it probably takes the first instar larva between 8 and 19 days to get from the egg to the broom seed and there, to change into a second instar. Thus the length of life of the first instar larva depends to a certain extent on the length of time it takes to locate and bore into 108.

a broom seed since (as has been mentioned, on p. 97 ) the first instar larva only spends a short time in the seed before it moults into the second instar. This factor obviously adds large discrepancies to the rest of the observations on the mean durations of the second, third and fourth larval instars. The first record of a second instar larva was on the 25th day after oviposition (i.e. 8 days after the thean hatching day). Thus the minimum duration of the first instar larva was 8 days, By a similar argument the minimum durations of the second, third and fourth instars (including the prepupa) and the pupal period are 4, 7, 17 and 17 days respectively (see Table 26). The mean durations and the total durations of each stage shown in Table 26 are, as already stated, unreliable due to the discrepancies caused by the "period of searching" in the first instar stage. The remaining 30 pods not used for dissection, were left to dehisce within their muslin ,bags. The seeds were, collected and kept separately at outdoor temperatures in the insectary. Daily records of adult emergence from these seeds were kept and they are shown in terms of "days after oviposition" in Table 27. It can be seen (Table 27) that the variation of the develoDmental period from oviposition to adult emergence was 31 days (i.e. from day 70 to day 101). The variation in all of the 109«

stage's omittin.the "period of searching" (i.e. 19 minus a 11 days) in the first instar stage, is therefore approximately -20 days (ie, 31 minus 11 days). Table 27. The variation in time of Bruchidius ater adult emergence from the seeds of 30 broom pods, in terms of "days after oviposition". Average temperature Max .27 Mean 15 Min.' 4Pc• Days after No, beetles Days after No. beetles oviposition, emerging. oviposition, emerging.

70 . '5 87 3 • 72 ' . 1 88 1 , 79 . 4 89 1 80 6 91 2 81. 1 •92 . 1 82 3 96' 1 83 5 - 97 1 84 12 101 2 85 5 86 3 TOTAT, '31 days ' 57 adults

f. Mortality factors affecting the larval stages within the pod. First instar mortality during the "tunneling" period. The fact that B. ater females lay their eggs with no relation to the position of the seeds inside the pod does, to some extent, affect the survival of the first instar larvae hatching from the eggs. The failure of a first instar larva to reach a seed is partly due to chance (i.e. due to the original position of the egg) and partly due to the way in which the larva tunnels into 110,

the pod. Some larvae tunnel straight into the pod cavity from wherever they are placed on the surface of the pod. Once inside the pod cavity the larvae usually find a seed and, as has been shown, may take up to 19 days to do so. Other larvae tunnel for some distance in the mesophyll layer between the outer and inner epidermal layers of the pod valve. These tunnels have been observed to run in all directions in the pod valve, even directly away from the seeds. It seems therefore that larvae are not attracted to the seeds whilst they are tunneling into the pod. Many tunnels up to 1 cm, long were seen to end blindly, having a dead larva at their furthest tip. Thus, if the larva travels too far in the mesophyll, it is unable, or does not have the strength to cut through the tough lower epidermal layer and enter the pod cavity. Other, more unfortunate larvae hatch and tunnel into the pod in a position where the 2 pod valves touch one another. Here there is no pod cavity and no seeds and these larvae usually make several attempts to cut into the lower epidermal layer and finally die of starvation. First instar mortality due to competition for a seed. From observation it is known that one normal broom seed only contains enough food for the complete development of one Bruchid from first instar larva to adult. In 1960 an artificial crowding experiment was made to see what would happen should more than one first instar larva attack a seed. To do this, 20 female Bruchids were enclosed in each of 5 plastic oviposition cages on 5 separate pods in the "Old Broom" area. The cages were left from 12 to 3 p.m. on 4 June, 1960, and then they were removed and the number of eggs laid on each pod was counted. Each pod was given a letter from A to E and 48, 64, 72, 51 and 55 eggs were laid on pods A,B,C,D and E respectively. On 29 June, pods A and B wore nicked and dissected. Pod A contained 6 seeds and each one of these had been attacked by more than one Bruchid larva. However, when each seed was carefully dissected it was found that only one larva had survived. This larva, presumably the first one to enter the seed through the micropore was now feeding on the cotyledons. There :ere also 4 deed shrivelled larvae in the passage by which the first larva had gained access to the seed. Two of these had burrowed a little -ay into the tissue of the caruncle before death, but the others had died in the tunnel. All of the other seeds in pod. A showed a similar condition, as did the 10 seeds in pod B. Thus the first larva to enter a seed excludes all later larvae from getting to the cotyledons and thus from feeding. No seeds were found where a second larva had entered from the side of the seed as well as the first one in the normal manner. B

I 0- 25mm I

Fig. 15. Bruchidius ater.,Head capsule of larvae, anterior view. A. Second instar., B.. Third instar.. C._ Fourth instar., 113..

According to Hafez and Osman (1,956), then more than one larva of Bruchidius trifolii enters a borseem seed they all feed and.grow to a certain size and then all except:one of them dies. . Skaife (1926) shows'that,this can happen even, when the larvae are separated by the whole diameter of a seed and he dramatically states. "It seems as though they recognise, by some mysterious means, or other the presence of one another in the seed and all except one unaccountably' favoured individual stop feeding and die". In this statement Skaife refers to the larvae of Bruchus piserum, Pods C, D and Evere dissected on 3 August, .1.e._60 days after 'oviposition and either one pupa or one fourth instar larva was found in each seed. Once again some remains of first instar larvae could be' seenin the entrance passage of some of the seeds, NO seed was ever found with 2 living larvae in it. Intensive. competition such.as was experienced in 'this experiment was never met with under field conditions. In the "New Broom" area in 1961, however, when many pods were killed by the late frosts (see p. 6 ), the large population of I3ruchids in that area now had only under a. half of the original number of pods on which they could oviposit. The number of eggs on these pods rose to as many as 25 in some instances and 15 to 20 eggs per pod were quite common. Many dead first instar larvae in Seed entrance passages were found when these field pods were examined. (see also p.317 ) 114.

This in3icated that under certain conditions of overcrowding competition for seeds can cause mortality of first instar larva under natural conditions. In 1961 this was caused not only by the reduction of the oviposition sites, but also by the increase in the population of adults (see p.39 ). Mortality due to insufficient food supplies in some broom seeds. It hae already been shown (see p.98 ) that if a larva burrows into a seed which does not contain sufficient food for it to complete development it can move to a neighbouring seed, if one exists. This situation is however so rarely found (i.e. 4 instances in 9604 pods in 1960) that mortality due to this factor is very small. Mortality due to the "maturation" of some broom seeds, Several dead second and third instar larvae were found inside seeds which had "Matured" (i.e. the seeds had become very hard). No explanation of their death could be found except that the seed embryo was no longer available as a food for the larva once the seed had "matured". In all these pods the first instar larva must have reached and bored into the seed very late in the season, just before the seed was about to harden. Under normal conditions the seed and the embryo both remain soft and green up to the stage when the Bruchid larva is in its fourth instar. By this time there is no seed embryo left and the seed never hardens.

A 0 025 0 a X2 E E E E C Y antenna C 02. C C O .5• 15

▪••• •• 15 V

C • II • • • • V • • • • • V e I

0 0 C •Y 5 CB 5 o 4 8 12 I 6E Length of mandible in mm.x100 I II III IN STARS C .c C ° 25

0C y =0-183s +0.720 y= 0.7478s+ 3.0661 C 0 antenna

C antenna 0 C a 15 0 151.0 E mandible 0

E mandible y=0.178x +0.460 y=0•440Ix+0.6045 0 0.5 10 20 30 40 INSTARS Accumulated days of mean larval duration.

Fig. 16. Bruchidius ater (Marsham) A.. Scatter diagram showing the number of larval instars. B. Growth of mandibles and rntennae in successive larval instars. C. Computed regression lines illustrating Dyars law. D. Computed regression lines using the Richards (1949) method. 116.;

:ol-tality due to parasitism. Another cause of mortality of the mature larvae (and to some extent the pupae) of B. ater is parasitism. Two parasites are involved (i.e. Habrocytus sequestor (Walker), Triaspis sp. nr. obscurellus (Tees)) and the percentage mortality caused by them is given in Section V , The larval morphology and life histories of these parasites are described in the last part of this section. 117.

Section IIB Anion fuscirostre Fab, 1. Adults. a. Synonymy. b. Populations in the "Old" and "New Broom" areas in 1960 and. 1961. c. Pre-oviposition activity. (i Feeding. (ii Attraction to colour. (iii Copulation. d, Separation of the sexes of Apion fuscirostre adults e. Seasonal changes in the Reproductive System. Structure of the male, Development of the male reproductive system. Structure of the female. Development of the female reproductive system. f. Oviposition. g. Fecundity. h. Weights of adults throughout 1961 in the "New Broom" plantation. i. Longevity and Overwintering. 2. Eggs. a. Morphology. b. Development, c. Mortality factors in the field. 3. Larval and Pupal Instars, a. rorphology. b. iiife history within the pod. c. 3Tumber of larval instars. d. Mortality factors affecting the larval stages. (i) First instar mortality during the "seed finding" period. (ii) First instar mortality due to "competition" fir a seed, (iii) Mortality due to insufficient food supplies in some broom seeds. (iv) Mortality due to parasitism. Apion fuscirostre. 1. Adults. a. Synonymy. The name Apion'fuscirostre was first•given to the small greyish weevil which is restricted to broom by Pabricius (1775) Hoffmann (1958) reviews the synonymy of this species,but.ohly records it on'Sarothamnus. Roubal (1949) reviews a 1ist of 25- 30 references, all of which are species lists showing that At tuscirostreis distributed all over Europe and even in Algeria. In'some of these references'Bruchid us fasciatus (= B. ater) is also listed from broom. b.- Populations in the "Old" and "Hew Broom" areas in 1960 and 1961. The numbers Of Apion adults caught in regular,"40. armful" '•samples'in'the "Old Broom" area•in'1960 and 1961 are connected. by solid lines on graphs A and .13. (Fig. 17) The total popUlation- nUtbers are inserted on these graphs these numbers being estimated from a total area of 860 "armfuls" up to the middle of June, 1960, 850 "armfuls" from the middle • of June to the end of December, 1960 and 900 "armfuls" though- out 1961 (see p. 23 ). • The beetles were never found on any plants except_broom throughout the whole sampling period. A small number of beetles were present on broot threughaut - the' winter months but, in the spring there is an influx of adults causing.a sharp population increase. It was suspected•that

A LOD

502 •—• Old Broom 753 • o--o New Broom z 95,1 calculated total population i ...... ir2 4 0 ..... %... m 12446 -...... "0i 1 0 .i 0g l 2S I 0-; p APR MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. z 0 551 577411( le g im 240- i i I inIC I _i 1 ' r -1 if 1 i Sao- 1 I 3595/ / . i 3. I z I g20. ./ I r / 8 -,, .1 339 ‘. o- \ . . 12 042 / 1264 la O *R. i rlk 611 t , z V JAN ' FEB MAR I APR ' MAY JULY • AUG SEPT

Fig. 17. Population fluctuations of Apion fuscirostre adults in the two broom areas. A. In 1960. B. In 1961. 1200

these extra beetles had ovcrwintered in the litter or very low down on the broom bushes. No ,beetles were ever found however, in the emergence tubs (see p. 42 ) in the "Old Broom" area in 1961 In the last week in May, 1960 the population of Apion adults reached its peak number,but this was small compared with the numbers of B. ater in the area at this time. Throughout June and July, after oviposition,the size of the population decreased rapidly due to adult mortality. How- ever there was a slight overlap between the spring and autumn generations. The peak of the autumn generation emerging from the pods occurred towards the end of August, 1960. During September the majority of these beetles disappeared from the parts of the bushes that were regularly sampled, presumably moving down to their overwintering positions. In 1961 the beetles were active earlier than in 1960 and the largest numbers were recorded in the second week in May. This vas mainly due to the warmer weather and the resulting early growth of the broom plants (see p.7 ). However the mortality of Apion adults also occurred earlier in 1961. As can be seen in graph B, (Fig. 17) very few adults remained in the "Old Broom" area in the third week in June, 1961 whereas a large proportion of the 1960 population were still alive at a similar date in 1960. The emerging autumn population began in 121.

July and only attained half of the size of the 1960 population. In the "New Broom" plantation, no sampling was made until August, 1960 when the highest number of the emerging autumn population was estimated to be 5278 by the "50 x * bush" sampling method (see p. 39 ). The results of similar samples taken at the end of 1960 and throughout 1961 are connected by broken lines in graphs A and 13 (Fig. 17). Once again the total population estimations are included as there was a total of 1609 bushes in the plantation in 1960 and 1605 bushes in 1961, The figures obtained by the carbon dioxide sampling method used by Professor O.W. Richards, -Dr. N. Waloff and Dr. J.?. Dempster previous to August, 1930 could not be used as the size of these samples was not large enough to give consistent estimates of populations of less than 5000 insects« In graph B, (Fig. 17) the populations in the two areas can be compared in 1961. It can be seen that, although there is a much, greater population in the "New Broom" (which is a larger area) the fluctuations are similar in the two regions. Buddeberg (1884) gives' a short account of the life history of A. fuscirostre in Germany and he notes similar population fluctuations. He records a large number of beetles on broom in spring just before and during the flowering season and then again in the autumn, The sex ratio of the beetles sampled throughout 1960 and 122'

1961 was very variable (see Appendix table i ) mainly due to the very small numbers of adults in each sample. However when the total number of beetles cantured in each area are summed, as in Table 23 it can be seen that, over the total sampling period of 1960-61 the beetles were caught in a 1:1 ratio in both areas. Table 23. Numbers of adult Anion fuscirostre sampled in the "Old" and "New Broom" areas in 1960-61, and a determination of the sex ratio by the x2 test. 'Old Broom New Broom Total No. of Total No. of Total No. of Total No. of males caught, females caught, males caught. females caught. 259 249 247 279 1 i I 1 1 0.197 1.946 X2 value for expected 1:1 ratio.

P <0.05 -<0.05

c. Pre-oviposition activity. (i) Feeding. Feeding was first recorded in the "Old Broom" area on 30 March, 1960 when a female beetle was observed attacking a delicate young broom leaf. The mandibles at the tip of the rostrum were first used to tear a hole in the upper epidermis of the centre of the leaf. The rostrum was then forced into the mesophyll layers and true feeding began. Feeding proceeded for 16 minutes during which time the beetle walked around the hole

123.

inserting its rostrum as far as possible into the mesophyll layers. Eventually the rostrum pierced the lower epidermis thus making a hole through the leaf. At this stage the beetle .ceased feeding. Further observations were also made at later dates on beetles feeding on young green stems, leaves and pods of broom. (ii) Attraction to colour. The water traps, that were setup in 1960 (see p. 43 ) also recorded the activity and attraction to colour of Apion adults. The results are set out in Tables 29 and 30. Table 29. NuMbers.-of Apion fuscirostre-adults caught in water traps in the "Old Broom" area in 1960. Colour of traps Position White Yellow Green Total adults captured .

A. 0 1 0 B 0 1 0 1 .0 0 1. 0.. 1 D , o 1 o . 1. E 0 2 0 2 F 0 2 0 2 G.' 0 3 0 a 1 0 . 0 0 0 I 0 3 0 .. 3 J 0 3 0 3 K 0 4 0 4 L 0 2 0 2. Total beetles caught -- 23 . - 23 0.1....W• ••••••••••• Male beetles caught .... 20 - 20 Female beetles caught - .3 - , 3

,11•0..1•110.11•••••••111 Table 29 'shows that A. fusciros re adults were attracted

to the yellow vrnps own more than 24 &tat aduita. ilowever thq. grcat majority of tho Puocircrtm adults that fell into those trapn yore males. "then the remits arc rc,arraned as in Table 30 they silow that the male beetles were activc; early in. 4 lowr,ver aftr 27 Ltay only 3 females veva caureat. Thus tho *amen aCtivoly fly about saarchtnc: rap and copalating with- fcmalo Ixletles in the early part or J. Females do not fly until the end of May. i.e. after ovipositio • J.Ahle 7.1uMbrs o.A. lion .fuoc roctVo adults to npped in all or the ti tor trarz of all colours. Date Males Vomalos Total Date "ales .cmsle:c Total

12.14.540 2o.31.5.60 14-16.6.60 16-15.6.60 4.6.60 4 G.6.60 23025.5.60 6- 34.60 85.27.6.60 3.10.6.60 27-29.5.60 TYJAL

(iii) Copalation• Ccrulation first.obncrved in the field in the cv?.cond tired: in 1030. rtilined females wore recorded no in able 31 The male follow s the female about and thus suddealy mounts her gripping her ps °thorax with his ferelc Copula ion was ObscrAmd to proceed for 4-5 =lutes. !jaidwyn,ZavieS (1928 recordc coAlation in pion, ita 125.

on Ulex taking place 30-42 days before oviposition, but, in A. fuscirostre oviposition begins directly after copulation.

It is interesting to note that copulation in A fuscirostre occurrs up to 20 days before it does in B. ater. d.. Separation of the sexes of Anion fuseirostre Adults. The sexes of Apion adults can be separated by an examination of the abdominal sternites. In the male, when the posterior end of the abdomen is viewed from below the tergite of segment 8 is visible posterior to sternite 7 (see Fig. 8D). Thus when the aedeagus is extruded between these sclerites during copulation it is directed antero-ventrally, It is interesting to note, that in a ater the arrangement of sclerites is very similar but here tergite 8 is incorporated in the, genitalia, In the female the eighth tergite of the abdomen is not visible from below and sternite 7 is triangular (Fig, 80) e. Seasonal changes in the Reproductive System. (i) Structure of the male. Each testis is composed of 2 testicular follicles (Fig. 180 t.foll) each of which is very small being only 0.11 mm, in diameter when immature and 0.2 mm. in diameter when mature. Both follicles open directly into a swollen vesicula seminalis (Fig. 180 v,s.) Posterior to the vesicula seminalis, arising from the vas deferens are 2 blindly ending accessory glands, one being much 128.

longer than the other. (Pig. 130 acc.g). The vas deferens (Fig. 18C v.d.) fuses with its fellow at the toy of the ejaculatory duct (Pig. 18C ej,d.). The H. ejaculatory duct is a short tube leading posteriorly to the transfer apparatus (Pig. 180 tr.ap.) it was called by Maldwyn Davies (1928) in Apion ulicis. This apparatus was described for Rhynchophora by Sharp (1913) and a more recent review of the terminology of beetle genitalia is given by Lindroth (1957), lost of the terms used here are, those proposed by Lindroth (1957) except where otherwise stated.. The largest curved sclerotised tube is the penis (Fig. 180 pe) and it encloses the terminal portion of the ejaculatory duct and the internal sac. Anteriorly the penis is divided into 2 sclerotised rods referred to as temones (Fig. 180 tem) by Sharp (1918). The ostium (Pig. 18C os) or posterior'opening is situated at the posterior tip of the penis and it is this region that is inserted into the vagina of the female during copulation. Ventral to the penis is the spiculum gastrale (Fig. 180 s.g) which is a simple rod attached to the genital tube by muscles. The sclerotised region surrounding the penis is the basal piece (Fig. 13C bp.t) of the tegmen. The basal piece is elongated anteriorly, ventral to the penis, as a single apophysis or tegminel strut (Fig. 130 ti.) of Sharp (1918). Dorsal to 127.

A key to the abbreviations used in Figure 18

acC.g4 Accessory gland. b.c. Bursa copulatrix. bp.t. Basal piece of the tegmen. cp.t. Cap piece of the tegmen. cut ovd, Cut end of left oviduct. cut v.d. Cut end of right vas defersns. e.cl. Egg calyx* eg, Egg ej.d. Ejaculatory duct. ml. Muscles. °cc. Oocytes. os. Ostiums ovd. Oviduct• OVI1 • Ovary. Pe. Penis. B. Spermatheca. s.acc.g0 Spermathecal accessory gland. s.g,- Spiculum gastrale. spic., Spiculum ventrale tem. Temones. t.f. Terminal filament, Testicular follicle. trsap. Transfer apparatus. tss. Tegminal strut. .v. Vagina. Vas deferens, .v.s. Vesicula seminalis. Fig. 18. Reproductive systems of Apion fuscirostre adults. A. Immature female. B. Mature female (ovary only) C. Immature male. D. Mature male. 129.

the penis the tegmen is 'referred to as the cap-piece (Fig. 18C cp.t.) , by Sharp .(1918) and the fused parameres by Lindroth (1957) In& fuecirostre all of these sclerites are well developed and all,other membranous regions are similar to those described by Lindroth-(1957). Similar sclerotised structures are illustrated by Melts .(1941) on Apion dampyi and by.Servadei (1940) on Apion apricans. (ii) Development of the male reproductive system. From regular dissections throughout the year it was found that the reproductive systems of overwintering beetles remained immature until feeding was resumed in the spring. The gonads then began to enlarge reaching maturity in the first week in May in 1960. (see Fig. 18D). The testicular follicles enlarged as described above and the large accessory glands increased in length from 0.43 mm: to 1.00 mm. After copulation the beetles began to die, off and no regression of the reproductive systems could be detected. (iii) Structure of the female. The structure of the female reproductive organs of Anion fuscirostre is very similar to that described in Apion ulicis by Maldwyn Davies (1928), Each ovary is composed of 2 acrotrophic ovarioles (see Imms, revised Richards and Davies 1957). Each ovariole is terminated anteriorly by a short terminal filament (Fig. 18A t.f.). Posteriorly, each ovariole is swollen into an egg calyx where it joins with its fellow. (Fig. 18A e.c1). The paired oviducts (Fig. 18A ovd) fuse posteriorly to form the vagina (Fig. 18A. v) from which the bursa copulatrix arises, dorsally, The spermatheca is strongly sclerotised and is curved in shape, very similar to that of B. ater. It is connected to the vagina by a short tube and bears a small globular accessory gland on its widest end. A sclerotised spiculum ventrale, 0.8 mm, in length (Fig. laA epic) is situated ventral to the vagina. According to Lindroth (1957) this spiculum is present in beetles which have an ovipositor and it serves as an attachment for the ovipositor muscles, In& fuscirostre the ovipositor is composed of the membranous sternite of segment 8 together with the genital segment. (Segment 9). (iv) Development of the female reproductive system. The immature condition of the gonads of the overwintering female is shown in'Fig. 18A. When feeding began in the spring of 1960 the gonads enlarged. The ovarioles increased from 0.9 mm. to over 2 0 mm. in length and developing eggs were readily visible in their:`- lower regions, in early May. By 12 May, 1960 up to 2 mature eggs were present in each of the four egg calyces and all of the females had been fertilised (see Table 31) The female gonads remained in this condit on for the 131.

Table 31. State of the internal reproductive organs of female Anion fuscirostre in 1960. Date Year that No. of NO. No. with Average fat females : females fertilised mature. body emerged dissected ovaries' (arbitrary from pods indices of 0-

11.5,60 1959 10 0 0. 3.4 25.4.60 1959 .10 0 0 :.3.1. 6.5.60 1959 10 2 6 2,0 12.5.60 1959 10 .10. 10 . 1.2 24.5.60 1959 6 6 6 0.7 17.6.60 . 1959 7 7 7 , 0.8 1.9.60 1960 10 0 '0 4.9

following month, throughout the oviposition peried. Females were observed to be dying whilst still fully mature and no subsecuent regression of the gonads was detected.

The fat body value of A. fuscirostre females is also shown in Table 31 using the same arbitrary units already used. for B. aterfemales. (see p,58 ) Table 31 shows that the emerging generation in the autumn have a large fat reserve w-rlich is partially used up in overwintering. Beetles emerging in the spring have a fat body value of 3.4 (range 3-4) and this slowly decreases as the beetle matures,- This decrease continues after maturity and thereds little fat body present when the beetle dies in June-July. f. Oviposition. Apion fuscirostre lays its eggs next to the seeds inside the young green broom pods. Frequent observations .of oviposition in the field were made in the last 2 weeks of May, 1960. When about to oviposit, the female beetle ran all over the pod until it located one of the humps in the pod surface caused by the seedsvithin the pod, It then bored a hole with its rostrum beside one of these humps. This boring sometimes took several hours. Maldwyn Davies (1926) records up to 5 hours for Anion ulicis females boring into gorse (Ulex europaipus.) nods and similar times were recorded. by myself for A. fuscirostre. Having completed the hole the female turned around and inserted its ovipositor into it. A single egg was then laid next to the seed in the cavity of the broom pod. The ovipositor was then retracted and the female walked away. It was found however that the oviposition. hole was plugged with a colourless fluid which quickly dried hard. An oviposition hole could thus be distinguished from a feeding hole because the latter was not plugged by this transparent material. No eggs were ever laid within broom pods when beetles were kept in captivity in 3" x 1" tubes. The beetles fed on the pod tissues but laid their eggs all over the glass ar the tabes. even when only one female was kept in each of 20 tubes exactly the same thing occurred. In 1960 the first egg was discovered on 14 May in a small pod sample in the "Old Broom" area. Buddeburg (1884) first records finding, A. fuscirostre eggs in broom pods on 25 May, 1883 in Germany. 133.

On 25 May, 1960 a small sample of 32 pods from the "Old Broom" area, were dissected. Twenty A. fuscirostre eggs were found in a total of 15 of the 32 pods.; In 1961-oviposition began earlier than in 1960 due to the higher temperatures. The first ApiOn eggs were found in pods from both areas. on 9 May, 1961. Oviposition ended and the females died off throughout June in both areas during 1960 and 1961 (see p. 120'and graphs A and B Fig. 17). Thus the length of the oviposition period was the same in both,areas in 1960 and 1961, but, in 1961 it started and finished earlier than in 1960. g. Fecundity. As shown on p. 132 female beetles could not be induced to: oviposit properly under experimental conditions and thus all of the fecundity experiments were rendered-void. Also the small numbers of beetles caught in the field samples and the large fluctuation of the sex-ratio.of these beetles made calculations, similar to those made for B. ater adults, impossible. h. Weights of adults throughout 1961 in the "New Broom" plantation. As the samples in the "New Broom" in 1961 yielded the largest numbers of Anion adults the average weights of these are used to construct Table 32. The same balance was used as described for .13A ater (see p.69 ) .134.

Table 32 The average weights of male and female Anion fuscirostre throughout 1961 (in' milligrams) Females Males Date Year the To. Average No. Average beetles weighed weight weighed weight emerged. (:a gm) (mgm)

30.1.61' 1959 12 1.43 3 1.32 18.4.61 1959 12 1.52 16 1.44 27.4.61 1959 24 '1.73 10 1.50 5.5.61 1959 161.81 21 1.62 12.5,61 1959 10 '1.97 33'. - 1,60 25.5.61 1959 1 1.80 9 1.54 22.6.61 1959 6 1.70 3' 1.50 19,7.61 1959+60 2 1,71 4 1,56 3.8.61 196(Y .3, 1.84 5 1.55 549,61 1960 25 2.05 20 1.56 5.10.61 1960 28' 1.94 32 1,50

Table 32 shows that female beetles are always heavier than males. Also the weights of both sexes rise considerably during the oviposition period but decreases again when the beetles die off throughout June. The weight of newly emerging beetles in August and September is high due to the vast reserves of fat in the body cavity. These reserves are partially used up in overwintering and account for the low weights of the beetles coming out of hibernation. 1. Longevity and Overwintering. Fifty one beetles which emerged from hibernation in the spring of 1961 were kept in muslin bags tied over branches of broom bushes in the "Old Broom" area. The beetles were origina— lly collected from an unused area of broom on Chobam common on 10 May, 1961. Throughout the year the bags were inspected 1351 for dead beetles. It was found that every beetle had died by 5 SepteMber, 1961 and thus it was assumed that Apion does not live for a second year. An experiment was set up in September, 1960 to determine the overwintering mortality of A. fuscirostre. Thirty eight males and 43 females which had been collected from "New Broom" pods were placed in a 7 lb, jar similar to those used for the B. ater experiments (see p. 71 ). On 10 March, 1961 the beetles were re-examined, Only 7 males and 6 females had died. This represented a 18,4% male mortality and a 14.0% female mortality. These figures are lower than those Obtained from the B. ater adults under the same conditions (see p.72 ),

B2. Eggs. a. Morphology. The egg of A. fuscirostre was first deberibed by Buddeburg (1884) as being white with traces of yellow, 2 mm. long and twice as long as broad. I can only add that the chorien is unsculptured and that measurements of 10 eggs obtained directly from female beetles were 0.67 mm. (range 0,62-0.71 mm.) long and 0.26 mm. (range 0.23-0.28 mm.) wide. As the egg develops however, it becomes more round in shape measuring approximately 0.55 mm. lair; and 0,40 mm. wide. This change in shape of the developing egg was also recorded 136.

in Apion ulieis by Maidwyn Davies (1928). b. Development. Normally the egg ofAst fuscirootre develops within the cavity of the broom pod and, as described above, becomes round in shape as development proceeds. The body segments of the first instar larva develop first within the egg chorion and finally, just before eclosion the sclerotised head capsule becomes visible. The larva then proceeds to chewits way out of the egg chorion and into the pod cavity. To test if the eggs laid by females in captivity on the glass of 3" x 1" tubes (see p. 132 ) could develop they were placed at outdoor temperatures on living broom pods. Within 3 days all of these eggs had completely shrivelled up. When first instar larvae were nlaced on the outsides of pods at outdoor temperatures they made no attempt to bore into the pods and died within'a few hours. Thus eggs must be laid within the pod tissues if they are to develop and first instar larvae are incapable of boring into pods. A large series of experiments were set up in May, 1960 to determine the incubation period of Anion eggs. The eggs were , obtained in the same way as above and they were kept in small plastic boxes, on damp filter paper, in a saturated atmosphere, o o at outdoor temperatures (max. 65 I? min, 43 F mean 55°F) The 137.

main problem was the growth of moulds in the boxes and the filter papers were changed every 2 days to prevent this. Even so, only 5 out of 77 eggs developed successfully. After 20 days the head capsule of the developing larvae became visible and these eggs hatched 22-25 days after they had been laid. This is slightly longer than the incubation period (i.e. 17 days) of It ater eggs but is similar to that of Apion ulicis eggs as shown by Maldwyn Davies (1928). c. Mortality factors in the field. The broom seed, beside which the adult beetle oviposits, is often damaged by the action of the mandibles of the female boring into the pod. Eggs were often discovered. beside degenerating seeds and in 9 instances in the "Old Broom" in 1960, fungal infection had destroyed both the seed and the egg. Full details of mortality in the egg stage and calculations of the percentage of eggs failing to develop are given on p. 303.

1$3. Larval and Pupal Instars. a. Morphology. The taxonomic characters of A. fuscirostre larvae have already been described and included in a Key to Rhynchophora larvae by Van Emden (1938). A more complete description is given here of the cruciform and' apodaus third or last instar 138. larva which is morphologically similar t.o the proceeding 2 instars. , The three instars differ however in colour,.. the first instar is white, the second cream and the third, orange, Al]. morphological descriptions except for pupal structure were made from microscope slides. All figures were drawn using the,squared eyepiece, The orthognathous head capsule is well sclerotised (Fig. 19A Band C), The coronal epicranial) suture is well developed (Fig, 19A cl.s,) as are the frontal sutures (Fig. l9A ec.$) which meet the articulating membrane of the mandibles outside the antennal sockets. A single ocellus is situated in .the membrane of each of the frontal sutures just above the leVel of the antennae (Fig. 19A oc). The antennae, which are enclosed in the triangular frons (Fig. 19A f) consist of a single bristleless, notched segment (Fig, 12D. segm. 1) set on a basal metbrane. There are 2 sensory pores and 2 sensory cones set in the basal membrane lateral to the antennal segment (see Fig. 19D), The posterior region of the head consists of a large occipital foramen (Fig. 19B occ.f): bordered ventrally by a well formed tentorial bar (Fig. 19B 'bob), The hypostomal areas are well Sclerotised (Fig. 19B het) and bear articulatory points for the cardines of the maxillae and the condyles of. the 139,

mandibles (see Pig. 1913), The setation of the head capsule is shown in Figs. 19A, B and C and it can be seen that there are long setae, short setae and sensory pores scattered on the frons, epicraniui and hypostoma. The epistoma (Fig. 19A ep.) Is a dark brown, highly stierotised region between the antennae and it is divided, from the clypeum: ventrally by the epistomal suture (Fig. 19A ep,s0 The clypeus '(Pig. 20B cly) is scierotised laterally, but , is almost completely divided medianly by the labrum, On each of the 2 clypeal sclerotisations there is one short seta and one sensory pore. The labrum (Fig. 20B lbm) is bluntly rounded ventrally ' and pointed in the mid line dorsally between the clypeal sclerotisationseit bears one pair of long bristles and is divided from the clypeus by a membranous junction. The epipharynx (Pig. 21A) bears several pairs of large flattened bristles which were named by Van Emden (1938) according to their position relative to the epipharyngeal rods (Pig. 21A eph r). The epipharyngeal rods are solerotised arms and their size varies greatly in different specimens. There are 2 pairs of antero-lateral setae (Fig. 21A ant.lat.$) on the ventral margin outside the tips of the rods, '2 pairs of antero-median setae (P17. 21A antomed.$) on the same margin, between the rods and one pair of epipharyngeal spines (Pig. 2IA eph.$) between 140.

the rods. There are also several sensory pores and a pair of small hairs between the rods (see Fig. 21A). The 2 mandibles are similar in shape having 2 terminal, sharp, pointed teeth and an inner blunt tooth. On the anterior surface there are also 2 setae and 2 sensory pores (see Fig, 21B The condyle (Fig. 21B end) is well formed and articulates with the hypotoma posteriorly (see Fig. 19B). The anterior articulation on the epistoma is shown in Fig. 19C. Large adductor muscles and smaller abductor muscles are well formed in this larva. The maxillae (Fig. 20A) are well developed consisting of a cardo (Fig. 20A cd) which articulates with the hypostana, a stipes (Fig. 20A st) which is fused with an inner lobe or mala (Fig. 20A m) and a 2 segmented palpus (Fig. 20A plp). Arising from the dorsal surface of the mala are 4 long setae which all point towards the mid line, On the ventral surface of the mala there is a terminal seta and several sensory pores. Setae of various sizes also occur on the stipes and on the maxillary palp as shown in Pig. 20A. The terms used to describe the labium are those used originally by Boving and Craighead (1931) and also by Van Emden (1938). However the latter author dislikes the use ae the term "prementum" and retains it only to facilitate comparison. The "prementum" in Apion fuscirostre larvae is Y shaped and distinctly eclerotised (Fig. 20A pm). It bears a single sensory: 141.

A key to abbreviations used. in. Figures 19.20,21. and 22.

abd. Attachment of abductor muscle on the mandible. add, Attachment of adductor muscle on the mandible, ant.med.s. Antero-median setae, ant.lat.s. Antero-lateral setae. as. Antennal socket. ed. . Cardo. ass. Coronal suture, Clypeus. end. Condyle of mandible, ec. Epicranium. ec,s. Frontal suture. ep. Epistoma. eph.r. Epipharyngeal rods. eph.s. Epipharyngeal spines. epp. Epipleuron. eps, Epistomal suture. f. Frons. hat. Hypostoma. hyp. Hypopleuron. ibm. Labrum. lig. Ligula. l•plp. Labial paip. m. Mala. rad. Mandible. mn + smn. Mentum plus submentum. oc. Ocellus. occ.f. Occipital foramen. pip. Maxillary: palp. pm. Prementum. psc. Prescutum. sea. Scutosautellum. segm.1 First antennal segment. spy. Spiracle. at. Stipes. stn, Sternite. t.b. Tentorial bar. vma Ventral mandibular articulation.

ep eps 0.25mm cly I bm and

• 0.025mm •

i 0.25mm Fig. 19. Apion fuscirostre Fab. A. Head capsule of third instar larva, anterior view. B. Head capsule of third instar larva, posterior view. C. Head capsule of third instar larva, lateral view. D. Left antenna of third instar larva. cd

0 -05 mm

O.05 mm i Fig. 20. Apion, fuscirostre Fab. A. Labium and left maxilla of third instar posterior view. B, Labium and clypeus of third instar larva anterior view. 0.025mm

Fig. 21. Apion fuscirostre Fab.. A. Epipharynx of third instar larva. B. Right mandible of third instar larva: 0.5mm

o_• r

Fig. 22. Anion fuscirostre Fab. A. Third instar larva, lateral view: Be Pupa, ventral view: 146. pore on each arm of the Y. In the membrane between the tips of the premental arms are the one-segmented labial palpi together with one pair of setae and a pair of sensory pores* The setae are closer together than the palpi. (Fig. 20k 1.plp). The mentum and submentum are membranous (Pig. 20A mn+ smn) and bear 2 pairs of medium and one pair of long setae. The ligula (Pig. 20A lig) 'is membranous and bears one pair of short setae. It is continued into the oval cavity as the membranous hypopharynx which is supported laterally by hypopharynge al br ac one. The robust, fleshy curved body (Fig. 22A) consists of 3 thoracic and 10 abdominal segments. Each thoracic segment bears ventro-laterally a pair of pedal lobes which are unseg- mented. They have an apparent segmentation however due to the blocks of muscle which can be seen through the transparent cuticle. On the tergal region of the prothorax there is a poorly sclerotised region surrounded by 6 pairs short setae. The significance of this plate and its affinities, if any, to the prothoracic plate of B. ester larvae is too wide a subject to be discussed here. All of the other segments with the exception of the last 2 have 2 tergal folds (Van Emden 1938) and in this respect the A4, fuscirostre larvae are similar to B. ester larvae. The abdominal segments of Apion larvae are clearly divided 147. into sternal (Fig. 22A stn) hypopleural 22A hyp) and,,to a lesser extent epipleural (Fig* 22A epp),regions0 No divisions are apparent however in,the ninth and tenth abdominal segments and the anus is situated ventrally between these segments. This is normal for all.Curculionidae according to Iran Emden (1938)4,.. Spiracles. are present between the prothoracic and mesothoracic segments and on the-anterior region of the epipleura of the first 7 abdominal segments* The thoracic spiracles, are bicameral ,(Fig* 23A) and the abdominal spiracles are unicameral (Fig, 23B). Short setae are arranged on the bodyHsegmentsas shown in Fig* 22A and,the body cuticle is covered with minute cuticular spines,(Fig* 23B). When the third instar larva enters the prepupal stage the body Is,straightened out and the head capsule protrudes from the prothorax much more distinctly. This is the non feeding phase just before pupation. The pupal structure is described by Buddeburg (1884) and. Fig. 22B is included here as a visual guide to the identification of this stage within the broom pod. b. Life history within the pod* The first instar larva hatches from the egg into the pod cavity and immediately begins to search ,for a seed. Usually it enters the seed against which the egg has been laid, but, CHD25nmm Fig. 23, Anion fuscirostre Fab. Third instar larva. A. Bicameral mesothoracic spiracle. B. Unicameral abdominal spiracle and cuticular spines. 149.

if this seed has not developed, the larva wanders around in the pod cavity searching for another seed. The seed is penetrated through the micropore (Fig. 2415) in a manner similar to that by B. ater larvae. Once inside the seed, the larva begins. to feed on the cotyledons (Fig. 24A), It soon moults to a second instar and feeding continues. Finally the third instar is reached and when this larva finishes feeding in the first week in July, very little seed etbryo is left at the bottom of the seed coat. The larva now begins to devour the seed coat in the region around the micropore. It continues to do this until it has devoured all of the upper half of the testa on the side of the seed nearest to the tip of the pod (Fig. 24C). If the next seed towards the tip of the pod is closely applied to the seed containing the larva, then the larva will chew up part of the testa and cotyledons of the former seed (Fig. 24C), Having thus formed this large'pupation cavity the larva then cements the edges of its own seed testa to the inner walls of the pod valves. Faecal pellets are removed from the anus and chewed up by the larval mouth parts (the body is curved and these 2 regions are close together). The mixture of salivary fluid and faeces is used as the cement,which is brownish in colour. In the regions where there is no testa the larva builds up a "cement" wall between the 2 pod valves. This also happens micropore

radiclele mbryo cotyledons

'cement wall' of mature Apion fuscirostre Apion fuscirostre larva prepupa

uneaten seed embryo and frass Pod valve

Fig. 24. A. Diagram showing the structure of the broom seed - lateral view. B. Dorsal view. C. Diagram showing Apion fuscirostre larvae constructing pupation cavities in broom seeds. 151.

when larvae occupy 2 neighbouring. seeds, One. larva cuts through into the cavity of the next ono nearer the tip of the pod and then blocks off- this hole with: a "cement" wall. Thus each larva finally finishes up, in a cell which is completely sealed off from the pod cavity. The larva then becemes a prepupa and finally pupates within the cell by the third week of July. Similar cell formation has been npted in Apion ulicis larvae by Maldwyn Davies (1920, but here, as all.of the seeds are usually devoured 'cells are constructed haphazardly in the 'gorse pod. Adult fuscirostre beetles hatch:from the pupal sheath within the cell or'cocoon and. then wait for the pod to dehisce before they are liberated. In dampish weather pods were observed to open partially, the valves being held together by the "cement" cell. Adult beetles were then seen to chew around the "cement" walls until the pod was able to dehisce finally. This mechanism (i.e. cocoon formation) may thus prevent soft white pupae from being flung out by the early dehiscence of a pod. In some cases however, when the weather is very hot and dry, the enormous force with which a pod dehisces is more than enough to split open the "cement" cocoons, thus liberating whatever they contain. 152.

c. Number of larval instars* Measurement of the distance between the centres of the ,antennal sockets, and the, length of the head capsule from the top of the epicranium to the epistomal duture, , of a range. of A.L fuscirostre larvaeldivides , them into 3 distinct non over-; lapping instars (see,Table 33). All measurements were made, by the same means as those. described in the section on 2s. ater 2arvae. ,(see,p. .99 ). Table 33i Separation of the instars of Apion, fuscirostre larvae by measurement of the distance between the antennae and the length of the head capsule. (in millimetersx 1000) 'A* : B* No. Max, Mean Mini' Range lax,-lean Min. Range larvae

Instar I 25 95 90 85 10 150 139 120 30 Instar II 25 175 164 'pp- H25 290 261.240 50 Instar III 25 280 256 240 40 470 407 370 100 * A. Distance between antennae. B. Length Of head capsule,

Ten of the first instar larvae which were measured were . hatched from eggs in the laboratory. Of those measured as third instars 7 subsequently pupated, thus showing that this stage is the last instar. When larvae which had just moulted were obtained from pod Samples the distances between the antennae of the exuvium and of the newly moulted larva were measured. In 3 specimens the measurements showed a first instar'exuvium and a second instar larva and in 5 specimens, a second instar exuvium and a third 153*

instar larva. - Thus there is no possibility-of there being more than one instar between the first and the last larval etages4n fuscirostre. di Mortality .factors affecting -the larval , stages*, (1) First instar mortality` during the '"seed finding" period.. As has already been described eggs of,..6. ;2. fuscirostre are laid on seeds -that sometimes not develop (see p. 137 , .), Thus the first instar larva has to search.for' a nearby seed .and a small percentage Of these larvae'TaiI to find'it‘ .Calculations:ofAhiS mortality_ are shown on p. 303. As the dead larvae soon shrivel .up.within the pod cavity they were seldom detected .in the pod samples. However, as shown on p.'303' an'estimate.of this mortality was made by finding the difference between the number of eggslaid and .the numbers of larvae inseeds." This estimation of mortality howevery also includes all of the eggs that either failed to develop or Were attacked. by moulds. (ii). First instar mortality due to "competition" for a seed. The incidence of Anion larvae in the pods from both broom areas in 1960 and 1961 was too low for "competition for seeds" to be an important mortality factor. However, as only 154.

one adult can develop from each broom seed this factor becomes more important as the population increases. As shown on p. 39 the population of B. ater larvae in pods in the "New Brood'1961 was very large. However, as Apion adults began to oviposit before at ater (see p. 133 ) the first Apion larvae to emerge had, "first choice" of the broom seeds. The later emerging larvae probably had to "compete for seeds" with, ater larvae but no positive evidence of this was found* (iii) Mortality due to insufficient food supply in some broom seeds. No actual mortality due to the above cause was observed although very small pupae were found in small seeds and large pupae were found in large seeds. (iv) Mortality due to parasitism. Mortality due to parasitism of last instar and pupal stages is high in A. fuscirostre (see section V ). The main parasite is Habrocytus sequester (Walker) but, the larvae of Eupelmus urozonus Dalman and Torymus sp. nr. mieropterus (Walker) were occasionally found parasitising A. fuscirostre larvae. The larval morphology and life histories of these parasites are described in the last part of this section.

Section HO,- Hymenopterous parasites occurring in'the broom seed. - 1. Introduction.to the'study of the immature stage's of hymenopterOUs. parasites including materials, ,and methods. 2. Hymenopterous parasite Of both BruchidiUs.ida-and— ApiOn: fuscirostre larvae. . a. Habrocytus sequester (Walker). 11. Synonymy and host records. (ii Morphology of the immature, stages. (iii Life history. _ . (iv . Number of larval instare and length of developmental period.' 3. Hymenopterous parasites of B. aternly. a. Triaspis Bps nib. obscurellus (Nees). (ii Morphology of the immature stages. (ii Life history.. b. Trichogramma sp. (9 Problems of identification. (ii Notes on the life history and adult behaviour. 4. Hyperparasitee of Habrocytue sequester.. a. Mesopolobus mediterraneus (Mayr). (i Identification of species and host records. (ii MorpholOgy of the immature stages.. • . (iii Life History. . . . (iv Mortality factors affecting the larval instars. b.Aprostocetus tibialie (Kurdjumov). (i Synonymy. (ii Morphology of the immature stages. (iii Life history. . • 5. Occasional Hyperparasites of Habrocytus seouester. a. Eupelmus urozonus Delman. (i Identification and host records. (ii Morphology of the immature stages. iii Life history. Torymus sp, nri micropterus (Nalker). (i Problems of identification. (ii Notes on the morphology of the immature stages. (iii Notes on the life history. 156.

SECTION IIC. Hymenopterous parasites. 1ib Introduction to the study of the immature stages of hymenopterous parasites including materials and meththds. In all of the following descriptions of the head capsules of the immature stages of parasitic hymenoptera in this and later sections, the terminology used is that of Short (1952) who in turn followed Snodgrass (see Short (1952) for individual references) with some modifications. Short (1952) also gives a full summary of the, equivalent terms used by Beirne (1941) and Vance and Smith (1933) to facilitate comparison* All larval head capsules in this thesis are drawn as flattened objects and thus are morphologically inaccurate since the head is hemispherical. This arrangement is of use in distinguishing the larvae however, since all of the parts can be shown in one diagram. When certain parts, i.e. epistoma, pleurostoma, are said to be present or absent in this thesis, this means that they are sclerotised or unsclerotised (Wigglesworth 1948). Only the larval head capsules of Habrocytus seouestor (Walker) and Triasris sp. nr. obacurellus Nees are labelled (Pigs. 25D and Pig, 26 C). All other drawings of head capsules are based on the same plan as that adopted for H. seouester. Eggs and first instar larvae were mounted on slides directly into Hoyers solution to which lignin pink had been added as a stain. Mature larvae were opened by a mid ventral 157.

incision, gently boiled in 5% potassium hydroxide solution and mounted as above. In a few instances however the larval cuticle was stained in chlorazol black before mounting* All drawings were made with the aid of a squared.eyepiece and on squared paper. Pupae were drawn from living or preserved specimens by the above method. Eggs and larvae were reared in. the laboratory in 3" x 2" x 1" blocks of plaster of paris in which holes, .e diameter and e deep had been drilled in the top 3" x 2" side* Larvae of the parasites were placed separately in these holes together with their host larva and then a microscope slide was placed over the top to prevent escape. Each block was kept damp by spraying it with water every few days and regular observations and records were made of each parasite* Overwintering larvae were kept in these plaster of paris blocks in an outhouse at outdoor temperatures. Overwintering adults were kept in 2" x i" tubes in the same outhouse, Observations on copulation and oviposition in the field were made whenever possible and these data together with those obtained from the breeding experiments and from the pod samples (see p. 295 ) were used in interpreting the life history of each parasite. 156.

2.. Hymenopterous parasite of both Bruchidius ater and Anion fuscirostre larvae. a. Habrocytus seouester (Walker). (1) Synonymy and host records* Dr. M.W. de V. Graham identified this.species from material which Y hadtklecifrom.,host larvae of B: ater and A. fuscirostre in broom pods and Anion ulicis in gorse pods. The species was originally described as Pteromalus seouester Walker (see Kloet and Hincks 1945). The subsequent removal of this species to the genus Habrocytus was made by Graham (personal communication) when he identified some material for Dr. Steffan at the Paris Museum. The name Spintherus lekuminum Ratzeburg, may also refer to this species, but the type specimens have been lost and the description is somewhat vague. Otherreferences that could possibly refer to this species are those of Maldwyn Davies (1928) (here mis -spelt as Splintherus legaminum Ratz) and of Goureau (1847) (named wrongly as Semiotus anionia Nob). In both of these references the host was Anion. uncle in gorse pods. (ii) Morphology of the immature stages. The egg is rounded at the posterior pole and drawn out to a blunt point at the anterior pole. The average length of

6 eggs was Q.62 mm. (range 0.60 - 0.64 mm.) and Width 0.24 mm. (range 0.21 0.25 mm.). The chorion is smooth ventrally but. the dorsal surface of the egg (Fig. 25A) is covered with minute 159.

'cuticular. spines. There are no spines on either of the poles. The first instar larva consists of a head and 13 body segments. -The bead capsuIe-is a chitinous dorsal plate bearing the 'antennae at the ends of grooVes -which appear to be ,frontal sutures (Pig. 250. Ventrally the head capsule is membranous and 3 pairs of setae surround'the oral: cavity. The mouthparts are similar to those' described below: in the mature larva. (Fig25C). A ring of small cuticular spines encircles the anterior region of each of the body segments. In 'segments 20 4, 5 and 6 laterally on the PosteriOr edge of these spiny areas there are small spiracles. If the body be divided into 3 thoradic and 10 abdominal segments then these Spiracles are on the :Inesothoracic and first 3 abdominal segments. In the Xdddle of each segMent except the first and the last there is one pair of snail dorsal setae, andLone pair of lateral setae. One pair of ventral setae are present on the thoracic segments only. 'Dorsally the prOthoraxbears only one pair of setae and these are much larger than and more lateral to'the other. dorsal segmental setae. The last (13th) body. segment is bilobed and devoid of any setae. The size of a newly emerged first instar larva is- similar to that of the egg. The maturelarVa is similarly segmented to the 'first instar, 3.60 •

A key to the abbreviations used in Figures. 25 and 26.

app. Anterior p eurostoma3. process. cd. Cardo• epst Epi stoma. het. ostoma. lbs. Labial selerite. 1plp. Labial palp rudim rad. Mandible. mplp. Maxillary palp (Braconid). mxp. Maxillary palp rudiment (Pteromalid). plst. Pleurostoma. ppp. Posterior pleuros omal proces prib. Pre-labium. pt. Posteriok, tentorial pit. sp. Silk press. seq. Stipitai solerite. tb. Tentorial bar., a

0.25mm

0.3mm

Fig. 25. Habrocytus sequester (Walker) A.- Egg. B. First instar larva, dorsal view: C. First instar larva ventral view. D. Cephalic skeleton of last instar larva. E. Antenna of last instar larva. F. Pupa ventral view.- G. Pupa lateral view. 162.

but the head capsule is not chitinised dorsally, Also the cuticle is smooth, except for the aamesetal pattern as in the first instar. There are however 3 extra pairs of setae on the .13th, segment and a large ventral pair of Setae on the 12th. When fully grown, the larva is approximately 3 rims long and 1 mm, wide and poseSses. 9 pairs of:spiracles on the second to the tenth body segments. The antennae are short and squat being less than 2.5 times as longHas wide. (Fig. 25E). This:character is important in distinguishing between the larvae of H. sequester and Mesopolobus ap. nr.mediterraneua (Mayr). 'The mouthparts are well formed (Fig, 250- with all of the main structures present as thickened ridges. The pleurostoma (Pig, 20 'plst) 'encircles the lateral margins _of the mandibles and is elongated on either side into anterior and potterior pleurostomal processes (Fig, 25D app and ppp). The mandibles are heavily sclerotised and the two tips overlap each other in the mid line. (Pig. 25D md). A posterior mandibular condyle articulates with the posterior pleurostomal process whilst the anterior lateral.margin of each mandible butts against the anterior pleurostomal process. The epistoma (Fig. 25D epat) joins the 2 anterior pleurostomal processes anterior to the mandibles. . The hypostoma,(Fig. 25D hst) is short and runs from the posterior pleurostomal process to the 'region of the posterior 163.

tentorial pit (Pig.' 25D pt). The two posterior tentorial pits are joined 'by the internal invagination or tentorial bar (Pig. 25D tb). Several papillae are present en the larval .membrane above, the mandibles and 3 pairs of short setae and 4 pairs of papillae are present on the maxillary• and labial membranes below the mandiblet$ (see Fig. 25D). The 2 larger pairs of papillae on the latter membranes are often referred to as the vestiges of the labial and maxillary palpi (Short•1952). 'The 3'pairs'of large setae surroundinOhe mouthparts are well deVeloped4 as theyare410he firSt'instaraarva, The pupa is approximately 3 mm, long and 1.3:mm. wide' (Pigs. 25 P'and G). Only the features'which distinguish this pupa,from'other hymenopterous species within the broom pod.' are discussed here. The forelegs (Fig. 2511.can be seen to project posteriorly as far as the tips of the, wings. Also the head of this pupa is large and almost as wide as the maximum' width of the, pupa.. In side• view (Fig. 25G) the pupa is hunchbacked and the head, is pushed forwards by the excessive curvature of the thoracic terga. ,(iii) Life History. At Silwood Park Habrocytus was found to be an ectoparasite in its larval stages on the mature larvae and pupae of Anion ulicis in gorse (ilex) pods and of A. fuscirostre and Bruchidius ater in, broom pods. 164.

This parasite has 2 generations on gorse but only-one on broom. This may be related to the fact that the gorse pods are produeed over a longer period during the year than the broom pods. Also At ulicis has a very much longer oviposition period, i.e.• from May to August, as was recorded at Harpenden by Maldwyn Davies (1928), Thus there is an abundance of last instarAt'ulicis larvae in gorse pods from the second week in JUne onwards throughout the summer. A.fuscirostre and ater only have a short oviposition period and thus, the mature larvae are only present in large numbers in the broom pods throughout. July. Gorse pods from bushes in the "Old Broom" area were examined at intervals throughout 1961 and observations on them together with those.on, broom pods elucidated the life history of Habrocytus. Habrocytus overwinters in the adult stago and could be beaten from its overwintering site on gorse and on broom bushes throughout the winter of 1960-61.' The adults become active in June and the females begin to oviposit in the gorse pods. First abservations of this oviposition were made on 19 Junee, but an examination of gorse pods on this date revealed eggs and small larvae of Habrocytus on A. ulicis larvae. On 23 June all stages of Habrocytus from the egg-,to,the mature larva were present in gorse pods and on 3, July the first pupa was found. 165,

On 6 July, round boles,,cut by emerging adults'in the, sides of gorse pods were observed in,the "Old Broom" area. and several male Habrocytus -emerged. from pods brought into the laboratory on,this•date„ On 7 July female Habrocyt4s :began, to.emerge.from gorse. pods in the laboratory. and the males copulated with the females as soon as they emerged. The, method of 'courtship and copulation was very. similar to that described'by Barrass (1960) in Mormoniella•vitripennis Walk. 'The male f011owed the, female • and eventually jumped. on her back and stood in the courtship . position. (Barrass 1960. fig, 1) with his .head above and. between the femalOs erect antennae. ..kseries, of head and antennal movements followed until the:female lifted her abdomen, the male .then backed and. copulation proceeded (Barrass 1960 see fig, 5)... Some post-copulatory .courtship occurred before, the males dismounted after copulation (Barrass 1960). From 7 July. onwards more adult Habrocytus,emerged from , gorse pods and on 10 JUly the first Habrocytus egg was recorded in the broom pod samples in the 701d .Broom", area. On•13 July the first egg was recorded from samples` in the "New Brpoi" plantation, Adult insects continued to emerge from gorse pods throughout this period of time and new eggs were also found on ;.0.1.- ulicis. larvae in the gorse pods, Oviposition on broom pods, was observed in the field.on 166.

21 July 1961. .The female ran over the pod tapping it with her antennae until by some unknown means she located an. As fuscirostre, or 21 ater larva or pupa, in the seeds below. She then drilled through the pod valve with her ovipositor. A feeding tube was sometimes construoted, similar to that described by Fulton (1933) and reviewed by. Clausen (1940). The female then proceeded to feed. on the exuding host larval juiceS before inserting an egg into the seed. cavity. A pod was opened directly after •oviposition- had been observed and a single egg of Hdbrocytus was found adhering to the thorax of a paralysed third instar A. fuscirostre larva. The broken feeding tube was also observed. Feeding, does not always occur however and some females were observed to oviposit directly onto the host larva having first stung and paralysed. it. When a young parasite larva was placed on a healthy non paralysed .41„ fuscirostre larva in the laboratory the host larva was seen to wriggle violently until it was in a position where it could bite and. kill the parasite larva with its mandibles. Thusin the field, the stinging of the host larva by the adult parasite eliminates the chance of the parasite larva being killed in the above manner. A second egg was often laid by a second female Habrocytus into a seed already containing a parasite egg or first instar 167.,

larvEL In these eases the first instar larVa usually 'devoured the new egg'before it could hatch and-thuS one larva and 2 eggshells were found on some host larvae. (see p.305 ). In some cases however 2 healthy larvae were found on one host but presumably one larva eventually killed and fed on the other as 2 pUpad were never found together in the same host cavitY. By 24 July, 1961 (see p. 306 ) many Habrocytus-eggs and larvae were found in the broom pod samPles an&the first pupa was' recorded. in the "New Broom" 'on 31 July and in the "Old Broom" on 3 August. 'During this time adults of Habrocytus were still emerging from gorse pods. Superparasitism was recorded in broom pods at this time, when a new egg was laid into the host cavity after the adult Habrocytus had stung and paralysed a mature larva of its own species. The superparasitic larva devoured the paralysed larva (the remains of the primary host were by this time desiccated and shrivelled up) and pupated. beside it. The size of the pupa was however somewhat smaller than normal, as less food was available to the superparatitic larva. In many cases of superparasitism, however (see p. 331 )* the adult Habrocytus had paralysed a small or medium sized larva of its own species, leaving the emerging superparasitic larva with insufficient food on which to complete development. These larvae died. before pupation and thus nothing emerged from these seed cavities. 168,

Similar mortality occurred when,,in the:few cases that ,could :be identified, small,superparasitie, larvae were paralysed and a third egg-was laid into the cavity., ,By 8 August;, 1961 new adults of Habrocytus began to . emerge fromthe broom nods in both areas. Second generation adults were also now emerging from gorse pods. Emergence was effected by the adult cutting a neat round hole with its mandibles through the side of one of the pod valves and then squeezing through it. This emergence in the field continued throughout August and -September, when large numbers of adults could be caught on the broom bushes in the "Old Broom" area. However these second generation adults did ,not mature but. dispersed to overwintering sites. until the following year* (iv) Number of,larval instars and length of developmental period. .The number of larval instars of pteromalidae varies from 2 to 5 .according to Clausen (1940). Measurements of different parts of. a large number of H. sequester larvae' indicated that there were 5 instars. The first instar is easily distinguishable by its head capsule and. spiracular arrangement. (see p. 159 ) but, the last 4 instars could not be separated completely as the ranges of each measurement overlapped from instar to instar. This was not really surprising as the range of size of 169.

pupae and adults was very. great depending on the food supply available to the larva. No positive proof can thus be given here regarding these 5 instars and'no distinction was made between the larVae in the pod samples (see p. 306 ). The developmental period was completely followed through on only 1 specimen.- A single egg, which was observed to be laid on 21'July, 1960 at 3.45 p.m., was placed on a paralysed A. fuscirostre larva in'a plaster of patis cell (see p. 157 ) in the .laboratory, It hatched on 23 July and began to feed on the host larva. Pupation occurred on 2 August and an adult female emerg6d on 13 August.' Temperatures throughout this period were mean, 15.3 max. 22.8 min. 10.0°C. Thus at the above temperatures the incubation period of the .egg was 1.5 - 2 days, the larva developed in 10 days, and the adult emerged after a pupal period of 11 days, The average length of the developmental period of 6 male pupae in the laboratory at 17°C was 8.7 days (range 7 - 9 days) whereas this period for 8 female pupae lasted 9.6 days (range' 8 - 11 days). Thus on the average the female takes one day longer to develop than the male. This difference has been shown in several other Pteromalidae (see Clausen 1940) and it explains why male insects are the first to emerge in the gorse pod samples (see p. 165 ). 170#

Hymenopterous parasites of B. ater only. a. Triaspis sp. nr. dbscurellus (Nees.) This species was examined by Dr. R.D. Eady at the British Museum (Natural History) but the taxonomy of this extensive group of Braconidae is in a very neglected state. A definite specific name could not therefore be given to this insect. However the species is near to Triaspis obscurellus (Nees) and will here be referred to as Triaspis sp. nr. dbscurellus. (i) Morphology of the immature stages. The egg of this species is unknown. The first instar larva is "mandibulate" (Clausen 1940), having a fairly distinctly segmented body and a large head capsule.(Fig. 26A). The sclerotised mandibles are falcate and the tips overlap in the median line. The antennae are reduced to small tubercles on the front of the head. The body cuticle is smooth and no spiracles are visible. The one larva that was measured was 0.17 mm. long and 0.06 mm. wide (across the head capsule). Intermediate instars are of the "vesiculate" type (Clausen 1940) having the proctodeum evaginated into a spherical external swelling. The mouthparta of these larvae are reduced to a pair of weakly sclerotised mandibles of similar size to those in the first instar. The body cuticle is smooth and no spiracles could be seen. This type of larva is common in many endoparasitic Braconidae according to Clausen 171,

(1940). The last instar larva has,a,distinct head capsule and a complete set of mouthparts and spiracles., (Fig. 26B). The mouthparts (Fig. 260) are similar to those of Triaspis Vallipes (Nees)' described and illustrated by Short (1952)* The nomenclature, here is after Short (1952)* The pleurostoma and its anterior and posterior processes (Fig. 260 plat, app'and ppp) and the bypostoma (Fig. 260 list) are lightly selerotised and the hypostomal spur is absent. The mandibles (Fig. 260 md) have teeth on their anterior edges and their tips cross in the median line. They articulate on the anterior and:posterior pleurostomal processes.

(The epistoma,is incomplete and the clypeus and ldbrum are membranous bearing one pair of setae and 2 pairs of sensory pores. The maxillae are represented by an oval, weakly sclerotisel plate or eardo (Fig. :D60 ad). which articulates with the posterior tip of the hypostoma. The atipes is reduced to a stipital,sclerite (Fig. 26C! ssq) along the posterior edge of the maxilla. The rest of the maxilla is membranous except for the maxillary palp which is represented by a.flat disc. The labium, according to Short (1952) is composed .of 2 membranous regions. The prelabium'(Fig.,260 prib) is the anterior region and it is divided from the postlabium by a marginal sclerotisation called the labial sclerite (Fig. 260113) 0.05mm , 0:7mm

0- emm

Fig. 26. Triaspis sp. nr. obscurellus (Nees). A.-First instar larva, ventral view. B. Last instar larva, lateral view. C. Cephalic skeleton of last instar larva. D. Antenna-and E. Spiracle of last instar larva. F. Pupa, lateral view. G. Pupa, ventral view. 3.73,

The vestiges of labial palpi are situated on the prelabium as :flat ,discs._ Between these paipip but below the''Ourface' of the labium, the'silk press, (Fig. 260 sp) which ia'a thickening of the wall of the median silk duct, can be seen, A U shaped structure.' The silk duct opens anteriorly to the 'silk press at a narrow slit between 'the anterior-tips of the. labial sclerite. 'tentorium (Fig. 260 tb) is. present in this. species: lbe antennae '(Fig. 261?) are disc 'shaped and bear 2 small sensory pores in their central region. The body is divided into 3 thoracic and 10 abdominal" segments. 'It is shaped like a comma and abdominal segments 5 and 6 are the widest, the rest of the body tapering towards either end. Cuticular spines are present in the areas shown on Pig. 26B and several setae are interspersed amongst these spines. A few setae, but no spines are found on the ventral surfaces of all of the body segments and all intersegmental regions have smooth cuticle. - Spiraoles (Fig. 26E) with an atrium and closing apparatus are present laterally and anteriorly on'themesothoracie and first' 8abdominal segments. They are not directly surrounded by cuticular spines. The'puPa is very characteristic. The main distinguishing features are the antenna' Sheaths which-extend posteriorly beyond the ends of the wing pads and mid-leg sheaths. Also the 174,

pupa is enclosed in`a silken cocoon within a broom seed, and. it is approximately 2,6 mm, long and, 1.0 mm, wide, (ii) Life History, The egg of Triassis sp nr obscurellus is inserted. into the developing egg of B• ater. Thus the oviposition of this parasite is coincident with that of 131 Ater ,end, in 1960, it began In.,the third and fourth weeks gin May. Oviposition was observed' in the laboratory when a female Triaspis was enclosed in a 3" x 1" tube containing a broom pod. on which several ater eggs had, been laid,. The female located an egg 'with its long antennae and then arched. up its abdomen bringing the long' ovipositor next to .the .BA ater egg* The tip of the ovipositor was then pushed under an edge of the n.ater egg adhering to the pod. surface*, ,The female then laid en egg up through the surface of the host egg adhering to the _broom pod and:promptly withdrew her ovipositor and flew off, The time taken for the whole operation was less than SO seconds. No trace of this parasitism was' thus' visible from above and the B, KUL. egg was not exposed to desiccation as the puncture made in oviposition was adjacent to the broom pod surface once again, after the female Triaspis had. withdrawn her ovipositor. The female Triassis was observed to oviposit in 1.3.1 eggs in all stages of development, but she was never seen to 175,

lay in already parasitised eggs.

The B. ater larva develops "upsidedown° (see` p. 73 and the egg of Triaspis is laid just below its dorsal surface. The parasite larva develops completely in this position with its anterior end directed towards the posterior end of the host larva. First instar parasite larvae were dissected from .121, ater eggs on the broom pods and also from apparently normal first instar B. ater larvae in the broom seeds. Thus,this parasite does not interfere with the normal development of the host larva in any way that can be observed externally. "Vesiculate" parasitic larvae were dissected from second and third instar host larvae in broom seeds and mature Triaspis larvae were found in mature B. ater larvae, The mature Triasoia larva kills the B. ater larva at this stage and emerges head first from the anal region of its. host. The cuticle and head capsule are all that remain of the host and these soon shrivel up, leaving the Triasiie larva in the cavity of the broom seed eaten out by the host. Parasite larvae were Observed emerging from their hosts in the "New Broom" plantation from 17 July onwards in 1960 and, slightly earlier, from 10 July onwards in 1961. The Triaspis larva then spins a silken cocoon within the broom seed cavity. in the ldboratory the construction of these cocoons in artificial cells was completed in 1 - 2 days. 176.

Soon after the cocoon was finished, the larvae pupated. and male adult insects began to emerge. about 9 days later, on. 29 July, 1960. Females did not begin to emerge until, a week after the males as their pupal period lasted up to 16,- 17.. days. Once emerged, the adults chew a small hole in the testa of the broom seed and escape into the, pod cavity. . This hole is 0.6 to 0.9 mm., in diameter and can be distinguished from an. emergence hole of a B .ater adult which is 142 to 2.0 mm, in diameter. Once in the broom pod cavity, the adults chew a second hole through one of the pod valves and escape.., However, if the pod has already partially or totally dehisced, the adult escapes directly froth the seed., The first adults to emerge in the "New Broom" plantation in 1960 were not seen until 4 August whereas adults were escaping from pods a week earlier i.e. on 28 July in 1961. Emergence continued throughout August in both years until all of the adults had escaped. This parasite was not recorded in the "Old Broom" area in either 1960 or, 1961. This was correlated with the fact that very few P.A. at larvae were found in, the "Old Broom" area in these years. It is most unlikely that this parasite overwinters in the. adult stage. Adults-emerging from, the."New Broom" plantation 377.

in August 1960 survived for only' three weeks when fed on. honey ,and sugar water. in.3" x 1" tubes. These Braconids. prdbably parasitise another,, unknown host, -Waich has an overwintering egg stage. .. This host presumably develops. early in the following year so that Iriaspis adults.emerge in. May, ready to oviposit in ant Ater eggs once again. Investigations on insects with overwintering eggs on, broom produced no results in 1961 and -the second-host if any, of this parasite, is still unknown. b. Triehogramm (i), Problems of Identification. The taxonomy of. the genus Trichogramma is extremely: complex as shown by Quednau (1961). The number. of potential hosts is very high and it. is not possible to identify Trichogramma species by reference to them. General criteria used by Quednau -(1961), for distinguishing Tricholvamma- species. include:- 1. Colour and pigmentation of the females at a constant temperature of 30°C. 2. Number of days and hours required for the completion of a full life-cycle at 30°C. - 3,' Length and nutber.of hairs.on the male antennae, length of bristles on the margin of the fore-wing, length of 'ovipositor, arrangement of the hairs on the disc of-the - fore- wing. 178.

4.' Geographical' distribution." Ecotypes.are.disinguished'by Quednau (1961) by even more obscure criteria, Viz:- -Pl.. Changes in the rhythm. of Parasitisation. 2. ',Formation of adaptation into certain' hobts. or• refusal:to sting certain hostS4 3. •°ccUrence,of.uniparental forts."

:Very few adult parasites .were obtained in this Study, these beingloredat'laboratoryteMlieratures which were not constant and, seldom of,30°C. Thus, identification& using the above critoriai-was impossible. (ii) 'Notes on the life hiStorYand:adult behaviour. Trichoaramma sp. is a parasite- of the 'eggs of Is ,ter,a The first discovery 'of.this-parasite was on' 12 June, 1960. whon one,of the , eggs in thefield•sample.taken in,the "Old'BrooM". on 9 Junes 1960 (see Table20) was seente have,tUrned,blacia In the following few days 8 more eggs. in this sample turfed ' black. Four.Trichogramma adults emerged from separate lit tea,ter' eggs on 23-3-line and two more emerged on 24 June '1960. 'These' adAts'vere all fenales'and they fed readily on'a small pie6e of raisin in - a 3" x 1"'tnbe. No males were'ever seen' and it was presuMed'that the femaleti were parthenogenetic 'By 24 June, 1960 however the adult B.-ater.population 179.

had disappeared. from the "Old Broom" (see Fig. 6A) and, 15 females were obtained from the Yarrow plants growing between the rows in the "New Broom" plantation. These produced. 7 eggs on 29 June 1960. These eggs were placed. in a 3" x 1" tube with one of the parasites. When the adult discovered. an egg, it probed all over it with the antennae for 45 seconds. It then placed the tip of its abdomen against the host egg and, after 30 seconds, managed to pierce the chorion by a series of pulsatory movements and. oviDosited within the egg Oviposition within the second., third, fourth and. fifth host eggs took, 4 minutes, 6 minutes, 5 minutes and. 7 minutes respectively. The parasite thus took longer to lay each consecutive egg. The adult could distinguish between parasitised. and. non parasitised eggs by the antenna' probing and it was never seen to oviposit in the same egg for a second time. The two Trichogramma adults which emerged on. 24 June were isolated in a 3" x 3." tube with a piece of raisin. One adult died, within a few days but the other surviied'until 13 July (i.e. 19 days). The parasitised. eggs were kept but, after several days they collapsed. and. shrivelled. up.. Thus no second. generation was bred. out and no other hosts of this parasite could. be 180..

found, Trichonramma sp was not recorded in the "New Broom" plantation in either 1960 or 1961 and only 2 females emerged

in the laboratory from samples of DA, ater eggs taken in the "Old Broom" in June and July, 1961.

4, HYperparasites of Habrocytus sequester

a. MesopolobUs mediterraneus '(ME0, 1)• (i) Identification of 'species and host records. Dr* R.R. AskeW has compared my specimens with some of the true Mesonolobus'thediterraneus specimens determined by 1Fan Rosen. Morphological differendeS are very slight and Dr. Askew regards my specimens as true mediterraneus species. However Dr.V4IN, de V. Graham only regards my specimens as Mesonolobus3p..nr, mediterraneus (Mayr) . The true species of mediterraneus-was originally described by Mayr (1903) ad Eutelus mediterraneus but Van Rosen (1958) recently revised this species renaming'it Mes000lobus mediterraneus.(Mayr).. M, tediterraneus is distributed all over:Europe and Sweden according to Van Rosen (1958) who gives a host list' including several species of Diptera (Cecidomyidae),-Lepidop- tera and Hymenoptera, He also states that this species has .been reared as a hyperparasite on the parasites of lepidopterous larvae. (ii) Morphology of the immature stages. The egg is oval at the ante; for end but is drawn out to a point posteriorly (Pig. 27A). The chorion is covered with minute spines except at the two poles. The average length of 5 eggs=0.47 mm. (range 0.45 to 0.50 mm.) and the average maximum width was 0.19 mm. (range 0.18 to 0.20 mm.) The first instar larva Pig. 278 and C) is very similar to, but smaller than the first instar larva of HabrqcYtus seoue4er. It consists of a head capsule and 13 body segments, the last one being bifid. The head capsule is longer than that of the Habrocsrtus larva and is shaped differently being almost hemispherical in dorsal view (Fig. 27B). The body segments are covered with cuticular! spines in all except the intersegmental regions and, in this respect, the Mesopolobus larva differs from that of Habroaytus. Dorsal and lateral rows of setae are much more pronounced than in Habrocytas larvae. The setae lie within the bands of cuticular spines. Lateral setae could only be distinguished on the first 8 body segments. On the first 3 body segments the lateral setae are raised on papillae. Ventral setae were found only on the third body segment (see Fig. 270). The spiracular arrangement is similar to that of Habrocytus first instar larvae but in Mesopolobus the spiracles are situated amongst the cuticular spines and not posterior to A

►0.25mm ;

► 0.3mm

0- I mm , 002 mm ►

0-5mm

Fig. 27. Yesonolobus mediterraneus. (Mayr). A. Egg. B. First instar larva, dorsal view. C. First instar larva, ventral view. D. Cephalic skeleton of last instar larva. E. Antenna of last instar larva. F. Pupa, ventral view. G. Pupa, lateral view. 183.

them as in Hdbroctus larvae. The mature larva is almost identical with that of Habrocytus and only a microscopical investigation of the larval antennae can distinguish between the two species. In the Mesopolobus larva the antenna (Fig. 27E) is more than 3.5 times as long as it is wide, whereas the larval antenna of Habrocytus (Fig. 25E) is less than 2.5 times as long as

wide, (see p. 162 ) When the mouthparts of Habrocytus mature larvae (Fig. 25D) are compared with those of Mesopolobus mature larvae (Fig. 27D) it can be seen that the principle difference between them is in the arrangement of setae and sensory pores on the ldbrum, labium and maxilla. The distribution of these pores and setae on the Mesopolobus larval mouthparts is however open to some doubt as the few slides that were made from the relatively scarce larva , were, unfortunately, very poor. The pupa of Mesopolobus (Fig. 27F and 4) is easily distinguishable from that of Habrocytue by the following features viz:- The foreleg sheaths do not reach posteriorly as far as the tips of the wing pads; the head is small compared with the rest of the pupa; the pupa is upright (not hunchbacked) when viewed laterally and the thoracic terga are well below the level of the top of the head. (iii) Life history. The larvae of Mesopolobus are hyperparasites on the 186.

larval and pupal stages of Habrocytus within the broom pod. MesonolOus does not occur in very large nudbers (see p. 306 ) but was recorded from both broom areas in 1960 and 1961. It is similar to its host in that it has two generations in gorse pods•and only one in. broom pods (see ps164 ) Mesonoldbus overwinters in the adult stage and it can be beaten from its overwintering site on gorse and. on broom bushes together with its hbst (see p. 164) throughout the winter months. 'The adults however, do not become active until. after the Habrocytus females have oviposited in the gorse pods(see p.164) Mesopolobus adults oviposit from the end of June onwards, on the mature Habrocytus larvae having first stung and paralysed them. 'A new generation of Meso-plcibus adults begins to emerge towards the end Of'July ready to oviposit on the Habrocytus larvae now developing in both gorbe and 'broom pods. Eggs laid on paralysed Habrocytus.larvae in broom pods were first recorded in the "Old Broom"' area on 27 July, 1960. Egg laying continued until 17 August 1960 by which time all of the Habrocytus larvae had pupated. However pupae that were not too far developed were suitable hosts and Mes000lobus larvae hatched and began to develops Mesonolobus pupae'appeared in the broom pods in the middle of August, 1960 and adults began to emerge by cutting 185.

through the side of one of the pod valves (similar to Habrocytus see p. 168 ) towards the end of. August. These adults dispersed to overwintering sites until the following year. The life' history of this species in the "Old Broom" area in 1961 was similar to that in 1960 except that in 1961 it began 7 to 14 days earlier. In the "New Broom" plantation the incidence of parasitism of Bruchidius Mai and Aoion fuscirostre larvae by HabrocYtAs WAS los and consequently so was the incidence of hyperparasi— tism by Mesopolobus (see p. 316 ). However the period during which ?Iesopolobus occurred in the pods was similar to that in the "Old Broom" area in 19604and 1961.' On 14 September„ 1960 a male pupa of Mes000ldbus was discovered within the cocoon of TriasDis sp. nr. obscurellus (see p. 170 ) together with the shrivelled remains of, the Triaspis larva. Thus Mesopolobus can also develop as a hyperparasite on triatlois sp nr obscurellus in the field. No'direct evidence was found to suggest that Mes000ldbus can develop, directly, on. A. fuscirostre or ater larvae and, it was presumed that they could not do so. (iv) Mortality factors affecting the larval instars. The greatest mortality affecting the larvae of Mes000ldbus was caused by starvation. This mortality occurred when the 186,

adult oviposited into a broom, seed containing a larva of Habrocytus which, was too small to provide sufficient food on which the MesaT)lobus larva could complete development. Similar mortality was caused by superparasitism in Habrocytus (see p. 306 ) Also, the dehiscence of broom pods was greatest during August in both broom areas,in 1960 and 1961 (see Figs, and 2), Thus, many Mesopolobus larvae were thrawn out of the pods and separated from their hosts before' hey completed their development. This mortality only affected larvae where the original host of the primary parasite (i.e. Habrocytus) was an Apion fuscirostre larva which had chewed up part of the testa of the seed. Where the original host was Bruchidius ater larva the testa was still intact and the Mesopolobus larva could, complete its development within the broom seed on the ground. Some pods. ,only dehisce partly however, leaving the Mesopolobus larva still within the seed but exposed to the atmosphere. (Once again this mortality only affects larvae in cells originally constructed by Apion larvae). These exposed Mesopolobus larvael if they are not fully developed, either die as a result of desiccation due to exposure w:aaamsuilt of the drying up of,, or the growth of mould upon, the host's remains. The larvae are also exposed to predators such as Anthocorip sarothamni Douglas and. Scott (1 record)and Lestodiplosis op. (3. record see p 306 ) 187.

b. Aprostoeetus tibialis. (Kurdjumov). (i) Synonymy. This species was identified by Dr. M.W. de Vs Graham at the Hope Department of Entomology, Oxford. 'It was originally given the name Genlocerus tibialis by Kurdjumov (1913) who synonymised it with vinulae Thorns. but not G. vinulae of Ratzeburg. However the name tibialis is already preoccupied in the genus Aprostocetus according to Dr. Graham and he states that Dr. Domenichini in Milan will rename my species in due course. (ii) MorPhologY of the immature stages. As this hyperendoparasitie species is rather rare, the eggs and young larval stages still remain undescribed. The mature larva consists of a head and 13 body segments. The mouthparts are somewhat reduced (Fig. 28A). The mandibles are fairly well sclerotised and can be seen in unstained specimens. The ridges surrounding them however are not clearly visible unless the specimen is stained with chiorazol black. This staining technique shows that a chitinised pleurostoma with well developed anterior processes is present. The epistoma is less well defined and the two posterior pleurostomal processes are fused together in the mid line posterior to the mandibles. Two pairs of papillae are present and distinct on the maxillo-labial membrane. These probably represent the

C 0.05mm

0.8mm

04mm •

Fig. 28. Aprostocetus tibialis (Kurdjumov). A. Mouthparts of the last instar larva. B. First abdominal spiracle and C. Second abdominal spiracle of the last instar larva. D. Pupa, lateral view. E. Pupa, ventral view. F. Aprostocetus sp. nr. aethiops pupa, lateral view. G. Pupa, ventral view. 189.

maxillary and labial palpi. The cuticle of the body segments is smooth and there are 9 pairs of spiracles situated laterally on the second to the tenth segments (i.e. on the meso-,and meta-thoracic and first seven abdominal segments). The spiracles on body segment 4 (i.e. the first abdominal segment) (Fig. 283) are approximately only one third of the diameter of the other spiracles (Fig. 28C). The pupa (Pig. 28D and E) is most readily distinguished by its position within the broom pod. (see p.190 ). It can also be distinguished from the pupa of Aprostocetus sp. nr. aethiops (Zetterstedt) (Pig. 28P and G) by the shape or its head capsule. In A.. tibialis the eyes are set into the head whereas in& spa nr. aethiops they protrude. Also when the adult cuticle becomes pigmented the colour can be seen through the pupal sheath-,to be a metallic green in A. tibialis whereas it is black in A. sp# nr. aethiops (see p# 225 ). (iii) 'Life history. Aprostocetus tibialis is a hyper-endoparasite of the larvae and pupae of the primary parasite of Anion fuscirostre, i.e. of Hdbrocytus seauester. Aprostocetus was very rare in both broom areas in 1960. and 1961. Only a few specimens were found in broom pods and none were seen in gorse pods. This, hyper-parasite was first discovered by observations on non developing Hdbrocytus pupae in August, 1960. The 1901

contents of these pupae seemed to be coagulating into a central mass within the pupal case. When one 'of these pupae was split open this central mass was found to be a single mature ADrostocetus larva. Several other pupae were dissected and the anterior end•of each Aprostocetus larva was found to be facing towards the posterior end of each ' host pupa. Mature Aprostocetus larvae were also found in two Habrocytus last instar larval skins. Also, several smaller larval maters of Aorostocetus were dissected from preserved larvae and pupae of HabrocYtus which had been collected in - the "Old Broom" pod samples'in the first two weeks Of August, 1960, It could thus only be presumed (and no further proof was found in 1961) that the 'Aprostocetus adults oviposited at the end of truly and in early August directly into the elate larval stages and possibly into the pupae 'of HabrocYtus. The larvae of Aprostocetus developed within the Habrocytus larvae or pupae eventually killing their hosts and devouring all of their internal organs. It was found that if these hyPerparasites were kept in the laboratory the larvae soon pupated within the host cuticle. Adults of Aorostocetus emerged from the posterior region of the host cuticle in the second week of September in 1960. All attempts to keep them alive throughout the winter months failed. 191.

Several Habrocytus pupal cases, from which Anrostocetus adults had. emerged, were found. in "Old Broom" pods on 13 September, 1960* 'Thus it seems that a few of the' earliest ADrostocetus larvae do mature each year and pupate and. emerge as adultd. These presumably die without ovipositing and are therefore wasted. However, five Anrostocetus larvae in five separate Habrocytus pupae, kept at outdoor temperatures, did not pupate* They overwintered as fully grown larvae and pupated in the ,last week of May, 1961. Adults emerged between, l9 and 25 June, 1961 and they were fed, on sugar water. All 5 adults were females and no males were seen, or bred out. These females lived for ,2 to 3 weeks only and did not oviposit although they were offered gorse pods containing last instar larvae and pupae of Habrocytus. Although no evidence could, be found in the small, 1961 samples of gorse pods, it was assumed by analogy with Mesonolobus, that the adults of korostocetus which emerged in. June, hyper-parasitised Habrocytus larvae and pupae in gorse pods. These produced a second generation of adults in late July which oviposited in the Habrocytus larvae and pupae in the broom pods. This generation again overwintered in the, last instar stage and, began the cycle once more in 1962. In the "New Broom" plantation, Anrostocetus was very rare and. only one larva was found inside a Habrocytus pupa in 192,

August, 1961. No othsr, specimens were found in any of the samples in either 1960 or 1961.

5, Odeasional Hyperparasites of ,Hdbrocytasseduester., a. Eupelmus urozonus Daman. (i) Identification and host 'recordsw This species ,was identified by Dr. M.W. de V. .Graham and Dr. R.D.Eady. it has however.been recorded from numerous hosts including Dipteral, Hymenoptera*, Lepidoptera and Coleoptera, many of which have been reviewed by Nikofskaya (1952) and • Askew (1961)w Askew (personal communication) states that this may possibly bean as yet unidentified group of sibling species. These groups are not uncommon in Chalcidoidea, a typical example being that of the Eurytoma rosae:group, recently, investigated by Claridge and Askew (1960). (ii) Morphology of the immature stages.. Illustrations and a brief description of the immature stagesof Eupelmus urozonus are given by Askew (1961) and the morphology of this larva is very similar,to that of Eupelmella vesicularis Retzius larvae illustrated by Morris (1938)w The egg (Fig. 29A) is oval, being 0.53 m.m. long and G.24 mm, Tide in the one specimen that was measured. At the anterior pole there is a long thin fluid filled process approtimately 0.48 mm. long. This process is 0,02 mm. wide. At the posterior 193* pole there is a short process which is used for anchoring the egg against a substrate. The chorion is unpigmented and unsculptured. The first inetar larva (Fig. 29B) is similar to that illustrated by Askew (1961) except that he has accidentally omitted (Askew, personal communication) a small pair of setae situated dorsally on the head capsule between the "frontal" sutures. The mouthparts and ventral setal arrangement are similar to those described in Eupelmella vesicularis by Morris (1938) The spiracular arrangement is not mentioned by Morris (1938) or by Askew (1961), but I have examined the material collected by the latter and find that his specimens are similar to mine. The spiracles are borne on the mesothoracic and first three abdominal segments only and each opening is - surrounded by several small sharp cuticular spines. (see Fig. 29B). The mature larva (Fig. 29C) is. composed of a head and thirteen body segments. The head bears a pair of antennae and four pairs of long setae as described by Askew (1961). However it also bears two pairs of short setae situated on the frons just above the fronto-clypeal junction. Dr. Askew does.not describe these setae but I have a personal communicattai from him that at least one pair of these setae are present on his larvae. Fig. 29. Eupelmus urozonus Dalman. A. Egg. B. First instar larva, dorsal. C. Last instar larva, lateral. D. Mouthparts of the last instar larva. E. Pupa, ventral view. F. Pupa lateral view. 195.

The mouthparts (Fig. 29D) are similar to those described by orris (1938) the most striking feature being the strongly sclerotised, toothed clypeus, below which the membranous labrum bears four pairs of sensory papillae. The mandibles are sturdy and simple and all the accompanying sclerites are fairly distinct. The setation of the body segments is complex. There are 18 setae situated in pairs all around the prothoracic segment, 14 setae in seven pairs around the mesothoracic segment and 10 setae in five pairs situated around the motathoracic segment. The first five dbdominal segments bear 2 pairs of setae each, the dorsal pair being shorter than the ventral pair. Abdominal segments 6 - 9 each bear an extra pair of short setae making a total of three pairs on each segment (see Fig. 290). The terminal segment is bilobed and the three pairs of setae are very reduced. The pupa (Fig. 29E and F) is easily distinguished by the very large tibial spine sheaths on the mid legs situated between the wing pads. The female pupa has a short ovipositor sheath which curves up dorsally. (iii) Life history. Eupelmus was found only very occasionally hyperparasitis- ing the mature larvae of Hdbrocytus in the pods of the "Old Broom" area only. This species was not recorded from gorse pods. Askew (1961) describes how the female of Eupelmus 196.

spins a tiny web across the egg after. oviposition. These webs covering Eupelmus eggs were discovered attached to' the walls of the original Alpion pupation chambers which now' contained mature Habrocytus-larvae, in pods collected in the "Old Broom" area on 4 and 10 August,'1960. EupelmUs larvae were reared in the laboratory and produced adults in the first two•weeks of September, 1960. However 'at this time two Euoelmus-larvae were found in the field. These' , larvae were kept at outdoor temperatures throughout the winter months and' they pupated in April, 1961 and new female adults emerged on 7 May, and 19 June, 1961.`. Askew (1961) records oVerwintering'larvae of Eupelmua in the' galls formed by eleven different Cynipids on oak. These larvae produced adults in June of the following year. These first generation adults oviposited in spring galls of three Cynipid species on oak and prOduced'a second generation of adults in July and August. Thus it is probably this second generation of adUlts emerging from oak galls in August that occasionally oviposits in the broom pods at this time. , Smith (1958) also records that these adults attacked the contents of the galleries of Scolytids at this time of year in the "Old Broom" area. He reared out adults of Eupelmus in May of the following year but states that eggs and larvae were not seen in the galleries again until the following August. 197.

b. Torymus sp. nr micropterus (Walker). (i)Problems of identification. This species was identified as far as possible by Dr. R.D. Eady at the British Museum (Natural History). However,slight differences between my specimens and the types of Torymus micropterus (Walker), (see Eady, 1953) were found. Until the biology of these closely related insects is investigated further, it is impossible to say whether or not they are distinct species or simply spring and summer forms of the same species. (ii)Notes on the morphology of the immature stages. This insect was rarely found and thus the morphology of the larvae was not studied. All larvae that were found were bred out as adults. The eggs, larvae and pupae do however resemble those of Torymus sp. nr. microstigma (Walker) found in the gall (see p.285). These descriptions must therefore suffice for Torymus sp. nr. micropterus immature stages until further work is done on this subject. (iii)Notes on the life history. Various larvae were found feeding on Hdbrocytus larvae and pupae within the broom pods in the "Old Broom" area in 1960. Mature larvae overwintered and produced adults in the early spring months. Four larvae, kept in the laboratory at a temperature of 15°0. were forced to pupate and emerge as adults in November, 1960. These adults were pinned. 198.

Thus this species still has a very incompletely known life history and it is, probable that, similarly to Eupelmus, it only occasionally breeds in the broom (see p. 195 ). Torymus sp. nr. micropterus was not recorded in the pods formed in the "New Broom" plantation in either 1960 or 1961. Neither was it recorded in the "Old Broom" in 1961. . 199,

SECTION III. The complex of Insects associated with the Broom pod cavity.

A Introduction. B. Host species. 1. Contarinia pulchripes Kieffer. a, Synonymy and literature review. b, Morphology of the immature stages. (i The egg. (ii The first instar larva,, The second instar larva, (iv The third instar larva. (v Pupa. C. Life history. 2. Clinodiplosis sarothamni Kieffer. a. Identification of species. b. Morphology of the immature stages. (i The egg. (ii The first instar larva* (iii The second instar larva. (iv The third instar larva. c. Life history. 3. Lestodiplosis sp. a. Problems of Identification. b. Morphology of the immature stages. (i) The egg. (ii) The larval instars. c. Life history. C. Parasitic species on Contarinia pulchripes larvae. 1. Aprostocetus sp. nr. aethiops (Zetterstedt). a. Problems of Identification, b. Morphology of the immature stages. The egg. - The first instar larva. The last instar larva. The pupa. 200.

•c. Life history. 2. Systasis encyrtoides Walker. a. Identification of species and previous host records, b. Morphology of the immature stages. (1 The egg, • (ii The first instar larva. (iii The last instar larva. (iv The pupa. c. Life history. 3. Inostemma lycon Walker a. Identification of species. b. Life history. 4. Torymus ap. nr. Elataplign4, a. Notes on the life cycle. D. Parasitic species on Clinodiplosis sarothamni larvae. 1. Platygaster sp. a. Notes on identification of species. b. Life history.. 2. Lestodiplosis- sp. E. Parasitic, species on Lestodiplosis sp. larvae, 1. APhanogmus venustus Parr. a. Identification of species. b. Notes on the life history.' F. Incidental insect species which overwinter in the curled broom pod valves.' 201.

Section III. The complex of Insects associated with the Broom pod cavity.

A. Introduction. The larvae of three species of Cecidomyidae occur in the cavities of Broom pods-at Silwood Park. Although they all occupy the same ecologiCal niche the larvae have different feeding habits. CCntarinia pulchApes Kieffer larvae are phytophagOUs, Clinodiplosis sarothamni Kieffer larvae are fungus feeders and Lestodipiosis sp. larvae are predatory, jmainlY on Clinodiplosis larvae. Such occurrences of several genera of Cecidomyidae have previously been recorded by Milne (1960) who found 10 different species in clover heads, including species from the genera mentioned above. Otter (1938) also records a complex of spedies of the genera, Lestodiplosis, Clinodiplosis and Dasyneura in knapweed (Centaurea)-flowers. Barnes (1948) records Clinodiplosis pisicola Barnes larvae in pea pods infested with Contarinia piss Winn. and he also states that the larvae of Lestodiplosis sp. are quite frequently found amongst the flowers and seeds of ornamental plants together with Clinodiplosis larvae. Nutberous records of parasites of cecidomyid larvae are given by Barnes (1946, 1946a, 1948, 1948a, 1949 and 1951). These parasites include representatives from all of the 202.

genera found in this study. The actual species found in this study however do not occur in Barnes's references. 203.

B. Host species. 1. Contarinia pulchripes Kieffer. a. Synonymy and literature review. This species was originally described by Kieffer (1890) as pi-olosis pulcbrives from adults bred frou(gregariOus larvae found in broom pods. 'Kieffer (1900-p261) rdferred to this species as Contarinia pulchripes and noted its oviposition behaviour. In his key to the cecidomyids of broom plants. Kieffer (1901) again referred to this -species as Contarinia pulchripes and noted that it also occurred in the pods. of 'Genista pilosa More recently Docters van Leeuwen (1957) also recorded this species from broom pods but not from pilosa.: b. Morphology of the immature stages. (i) The Egg. (Fig. 30A). The egg is smooth and oval, being,0.54 lam. long and 0.1 mm. wide. There is a small tail at the posterior pole by which the egg is attached to the substrate.

(ii) The first instar larva. (Fig. 30B) When fully grown this larva measures 0.7 mm. long and 0.17 mm. wide. It consists of a head, supernumerary segment and 12 body segments.the cuticle being smooth and transparent., The respiratory system is metapneustic and the single pair of spiracles point backwards and are positioned.oh the dorsum of the eighth abdominal segment. 204.

The head capsule is htlYselerotised and a pair of lateral spinet are present on the supernumerary segment. There are four pairs of terMinal,papillae on the dorsal surfade of the ninth abdominal segment and the'slit'shaped anus is on the venter of this tegment: :Other minute papillae oecur, on the body surface as haft been detcribed by Condrashoff (1961)'in Contarinia nseUdotsUgae'Condr.' larVae, (iii) The second' instir larva'(Fig, 50E). This larva is 1.2 1.6 mm.' long and 0.3 0.4 mm.'wide .(.0 measurements). It is white and the cuticle is.smooth, The head capsule is weakly sclerotised and the respiratory.: system is peripneustic. Spiracles are:.presenton the dorsuM of the prothorax, laterally on the first 7 abdominal segments and dorsally, but facing posteriorly and. slightly inwards on the eighth abdominal segment. The anus is in a similar position teTthat of the first. instar and Other dermal papillae,are similar to those described by Condrashoff (1961). The papillae on the last abdominal segment (see Fig. 30G) are better developed than in the first instar (see Fig. 30F). (iv) The third instar larva .(Pig. 50D). This larva is 2.95 mm, long and 0,71 mm. wide (range 2.8'A. to 3,2 mm., and 0.56 to 0.90 mm. : 6 measurements) and its colour varies from white tolight cream, The body is slightly flattened and tapers towards the anterior end. The posterior'

A B

0.5mm

D E

O•Smm 1 0-25mm 0-5mm

Si H

0.25mM Fig. 30. Contarinia Dulchripes Kieffer. A. Eggs. B. First instar larva. C. Last instar larva, ventral view of anterior segments. D. Last instar larva, outline. E. Second instar larva. P. Posterior segments of first instar larva. G. Second instar larva and H. Third instar larva, composite view. 206.

end is blunt. The description or the external morphology of the third instar larva of Contarinia pseudotsugae by Condrashoff (1961) corresponds to that of C. DuldiaiDes, except that the latter has much larger papillae on the ninth abdominal segment. (Pig. 30H). The sternal spatula, situated on the venter of. the prothoracic segment is indistinctly eclerotisedin young larae. The bilobed anterior, regions become deeply sclerotised however, and the spatulate unscleroticed posterior region becomes recognisfble in the older larva (Fig. 30C). (v) The Pupa. No data, but probably similar to that described by Condrashoff (1961), c. Life history. The adult fly ovlposits into the cavities of young green broom pods in the first three weeks.in June. Oviposition was Observed on several occasions in the "Old Broom" area on 12 June, 1961. In each instance the female settled on a pod and probed the surface with its antennae. The antennae were curled up at the tips so that only the middle region of the flagellum came in contact with the pod surface. When the female located a hole in the pod surface, where a plant sucking insect had previously fed (e.g. ADion fuscirostre), she curved her 207,

abdomen down and inserted the tip of it into the hole. She stayed in this position for 64 seconds and then flew off. The pod was examined in the laboratory and 157 eggs were discovered in one large cluster just below the hole, Females were never observed to bore directly into the pod and it was assumed that this cecid always utilises a previously formed hole in the pod valve, for oviposition. Kieffer (1900) also observed at vulchrines females ovipositing on broom pods in June and he came to the same conclusions. Speyer (1921) found this was also true in Dasyneu.ra brassicae Winn. where the adult flies oviposited through puncture holes made by weevils (Ceuthorrh.vnehn4 assimilis Payk. and allied species). No significant connection was found between the numbers of pods containing both Apion fuscirostre larvae and Contarinia rulchripes larvae in the "Old Broom" area in 1960 (see p. 310). The eggs, in batches of up to 200 (average 30) are suspended by their posterior- tails and they hang inside the pod cavity. The first instar larvae emerge from the anterior ends of the eggs, directly into the pod cavity and on 22 June, 1960 many of these larvae were seen in the "Old Broom" pods. The larvae spread throughout the entire pod cavity and feed on the surface cells of both the seeds and the pod valves. 208.

The interiors of infected pods thus become brown as these surface cells begin to break down. Towards the end of June, 1960 and in early July, 1961 second instar larvae appeared in the pods. On 26 June, 1960 infected pods in the "Old Broom" area did not show any external discolouration or deformities. However by holding an infected pod up to the sun and looking through it, the outline of the seeds was seen to be- indistinct and irregular whereas it was distinct in the uninfected pods, By the first week in July, 1950 most pods in both broom areas contained third instar larvae. These larvae were capable of jumping as is typical of Contarinia larvae (see Barnes 1954). The interior of infected pods, including the seeds, was by this time deteriorating into a brown mass of rotting plant material. Full sized third instar larvae were found on 7 July, 1960 in the "Old Broom" pods and these larvae were placed in 3" x 1" tubes containing a mixture of sterilised peat and sand. The larvae immediately began to burrow into the mixture using the sternal spatula, as described by Milne (1961). Ten tubes containing up to 50 larvae each were placed at outdoor temperatures from July, 1960 onwards. By 11 July, 1960 infected pods could be recognised in the field as their outer coats were wrinkled and covered with. small, 209.

yellowish brown, closely set protuberances (originally described by Kieffer 1890). As the wrinkles, dried up, cracks appeared all over the pod surfaces. The mature larvae leave the pods through these cracks, thus escaping before the pod valves completely dry up. On 29 June, 1960 twelve infected pods were covered individually with small muslin bags. It was found that, by 20 July, 1960, larvae had emerged from all of the enclosed pods and were trapped by the muslin bags. All of the larvae that had not yet desiccated were placed into 3" x 1" tubes. After all of the larvae leave a pod, it drys up completely and all its interior becomes covered with fungi. Very few seeds "mature" in Contarinia infected pods .and these pods seldom dehisce. Several of the larvae which burrowed into the soil in the 3" x 1" tubes were examined through the glass and were seen to have excavated a pupal chamber in the soil and then to have spun a silken cocoon around themselves. This insect overwintered in the prepupal stage lying in the cocoon in a U shaped position as has been described by Hedlin (1961) in Contarinia oregonensie Foote. Pupation occurred in May, 1961 and, before emergence of the adult each pupa wriggled through the cocoon and up to the surface of the soil. The adult then emerged from the pupal skin. 210.

In 1961 adults emerged from the 3" x 1" tubes between 26 May and 15 Jun% Adults also occurred' at this time in the emergence tubs in the "Old Broom" area and ovippsition was' observed in the field as has been described above (p.206 ), In 1961 all the immature stages occurred aboUt one week later,than in 1960 in the "Old ,Bropeiarea,'Also there were very few pods infected compared with 1960. This' may have been due either to the dry conditions in 1961 which reduced the'nutber of adults.. and also delayed their emergence, or to the late frosts which affected:the.Pupae* The percentage of pods infected by.COntarinia was very low in both broom areas and Tables 34 and 35 show these percentages in 1960 , and 1961* These figures were calculated from weekly pod samples (see Section V). Table 34, The number of pods containing Contarinia pulchnipes larvae in the "New Broom" plantation in 1960 and 61. New Broom 1960, New Broom 1961. of Date No. pods Contarinia 51 Date No, pods Contarinia IQ examined infested examined infested pods. pods.

12 June 425 - - 8 June 425 1 0.2 19 June 425 1 04.2 15 June 425 11 0.2 4 July 425 1 0,2 22 June 425 4' 0.9 11 July 425 5 1.2 29 June 425 2 0,5 18 July 425 1 0.2 6 July 425 9 2,1 24 July 425 . - 13 July 425 6 1.4 31 July 425 2 ' 0.5 20 July 425 5 1.2 8 Aug, 368 1* 0,3 31 July 328 5* 1.5 15 Aug* 315 - '- 9 Aug. 258 2* 0.8 211".

Table 35 The number of pods containing ContariniapulebtalPes larvie in the "Old Brooth" area in 1960'and old Broom, 1960 Old Broom 1961. Date Tio. pods Contarinia Date No. pods Contarinia examined infested examined infested pods pods..

8 June 425 8 1.9 12 June 425 15 June 425 20 4.7 20 June 425 2 0.5 22 June 425 26 6.1 26 June 425 5 1.2' 29 June 425 22 5.2 3 July 425 3 0.7' 6 July 425 19 4.5 10 July 425 12 2.8 13 July 425 21' 5.0 12 July 395 3 20 July 425 20 4.7. 24 July 350. 6 1.7 27 July 425 12 '2.8 3 Aug. 120 2* 3 Aug. 385 12* 3.1 8 Aug. 104 2* 2.0, 10 Aug. 331 17 Aug, 349 1(g: 2.2 ,Larvae emerged from the pods.,

2. Clinodiploais sarothamni Kieffer' a. Identificatioh of species. Adult specimens bred from broom. pods in 1961 were identified by Dr. -N., lajveldt. Kieffer (1902) originally described' this spedies from adults bred from the pods of both broom and of - Genista tinctoria L. - b. '71,orphology of the immature stages. (i) The egg. The egg is oval, measuring 0.42 mm. in length (range 0.38. to 0.44mm. ; 10 measurements) and 0.12 .mm.- in tidtlijrange' 0010 to 0.16 mm. : 10 measurements). The chorion'is smooth and unpigmented and.when-the'egg is newly laid it is transparent. 212.

As the larva develops inside it, it becomes reddish. (ii) The first instar larva.

These larvae range in size from the dimensions of the egg to approxidately 067 mm. in length and 0,2 mM. in width when fully grown. The larvae are creamish yellow, but are easily distinguished by an oval red area in the two segments just posterior to the mid point of the body*. Each larva is composed of a head capsulp, supernumerary segment, pro-, mesa- and meta-thorax and nine abdominal segments. This arrangement is typical of all the other, larvae so far described in this group of Diptera. The respiratory systemic metapneustic, the single pair of spiracles being similarly placed to those in the Contarinia puldbaApes larva. ' However, each body segment of the Clinodiplosis larva (except the supernumerary segment) bears several pairs of setae. The setal pattern is the same in each instar and is thus described in the third instar only (see below). The cuticle is raised in many minute papillae dorsally and there are three to six transverse rows of ventral spines on each body segment, except on the first one and on the last two. Also, there are two "friction pads" on the venter of the last abdominal segment, but, on the eighth segment there are a median and two lateral pads. The morphology of all of the head structures is similar to 43.

that described by Otter (1938) in Clinodiplosis cilicrus Kieffer larvae. (iii) The second instar larva. This larva is yellowish orange and is approximately 1.2 mm. long and 0.3 mm. wide when it is fully grown. It is very similar to the last instar larva except that it is smaller, it has no sternal spatula, but it has a spiny cuticle, Also the tubercle based setae on the ninth abdominal segment are less well developed. (Fig. 31D), (iv) The third instar larva. (Fig. 3113). These larvae are bright orange and are approximately 2 mm. long and 0.45 mm. wide when they are almost fully grown. The morphology of these larvae is similar to that of Clinodiplosis cilicrus larvae (described by Otter 1938). Only the main distinguishing features are discussed in this thesis. The setal pattern on all of the body segments, except on the last two and on the supernumerary segment, consists of three pairs of dorsal setae of which one pair are usually smaller than the others, and two pairs of lateral setae (see the diagrammatic plan Fig. 320). On the eighth abdominal segment there is a dorsal pair of setae between the spiracles and two pairs of lateral setae (Fig. 310). The ninth abdominal segment bears a pair of long postero- lateral setae and two pairs of short terminal, blunt, thick 0.5mm

D E

O•Imm Fig. 31, Clinodiplosis sarothamni Kieffer. A. Last instar larva, ventral view of anterior segments. B. Last instar larva. C. Last instar larva, dorsal view of posterior segments (ventral anus dotted in) D. Posterior segments of instar II. E. Posterior of instar I, dorsal view. 215.

setae set on tubercles. There is also a small pair of setae on the dorsum of this segment. The increase in the development of the setae on the ninth segment with each instar forms 'a good character for the identification of the instars (Figs. 31C, )3 and E). The sternal spatula (Fig. 31A) is present in this larva as a sclerotised bilobed structure in the middle of the venter of the prothorax. The stem is only apparent in fully grown larvae. The cuticle is reticulated.into numerous papillae dorsally. All other dermal structures are similar to those described by Otter (1938) on Clinodiplosis cilicrus larvae. Small papillae, arranged in away described by Condrashoff (1961) in Contarinia pseudotsugae larvae, were noted on the ClinodiDlosis larvae, but no detailed account of their distribution is given here as they are not taxonomically importax Kieffer (1902) also gives details of the papillae on sarothamr larvae* The respiratory system is peripneustic and the arrangement and number of the spiracles is similar to that described in the Contarinia DulcheiDes second instar larva. c• Life history. In 1960 adult flies oviposited in broom pods in late July and early August. Oviposition was not observed in the field. It is probable however, that the females lay their eggs into the pod cavity through cracks which develop on the sides of the 216.

black, dry pod valves at this time. (see p.209 ). Eggs were found in "Old Broom" pods in July and in early August, 1960 and they occurred singly, usually in the upper half of the pod near to the seed caruncles which now had a growth of mould on them. First instar larvae were most common in the pods in the first week of August, second instar larvae were' most common in the second week and third instar larvae were most common in' the third week in August 1960. Larvae were alWays found near to, or feeding on the moulds growing on the seed caruncles and they only occurred in low numbers in each pod. Although seven larvae were recorded in a pod in. August, 1960 usually only one or two larvae were found in each pod. The numbers of pods in which these larva occurred were impossible to estimate accurately as, throughout August so many pods dehisced and presumably ejected the immature larvae onto the soil. However, up to one third of the pods which remained on the bushes of both broom areas at the end of August, 1960, contained one or more of these larvae. When fully grown, the third instar larvae leave the pods and drop to the soil. They burrow into the soil and overwinter in the prepupal stage without forming a cocoon (see Kieffer 1902 1 In August, 1960 eighty larvae were put into five 3" x 1" 217.

•tubes cOntaining a mixture'of sterilised peatand,sand, These larvae were kept at outdoor temperatures throughout the

. following winter months, • Adult flies emerged from these tubes in the last ,week of June.and,in the first two weeks ofA'uly, 1961 and oviposition began in the broompods once again.: The larval instars occurred in the pods in both broom areas on the same dates in 1961 as in 1960, but since the pods dehisced.'earlier in 1961 than In 1960 (see p. 7 ) there were

fewer larvae in the second year. . - • Larvae, very similar to those found In, broom pods were , also seen in UleX europaeuspods in July, 1961. No adult, flies were bred outt but it seems likely that this. species also breeds in the Ulex pods at the same time as in the broom pods,

3. Lestodiolosis sp,' a. Problems of Identification, The species belonging to this genus.are, very difficult,to, separate morphologically, Felt, RUbsaament Barnes and. Kieffer do not give any information, concerning a Lestodiolosis species occurring in broom and Dr, 17..1113veldt comeiderb:thatthis,is probably a new species. However,, until an extensive revision: , of this genus is made which will include,both, mOrphological and biological data, it will remain unknown whether the 218.

already existing Lestodiplosis species are valid or whether some of them are synonymous* b. Morphology of the immature stages. (i) The egg. The egg is oval and is 0.4 mm, long and 0.12 mm, wide (1 measurement) The chorion is smooth and unpigmented and the egg is transparent when newly laid. (ii) The larval instars. Otter (1938) gives a detailed description of the first and last instar larvae of Lestodiplosis miki Barnes. These larvae according to this author are morphologically almost. identical with those of Lestodiplosis alvei Barnes (see Otter 1934), The larvae of Lestodiplosis species studied here were found to be 'similar to those described by Otter (1934, 1938). Only the important distinguishing characters between the Lestodiplosis larvae and other cecidomyid larvae occurring in broom pods are discussed here. The chaetotaxy of these Lestodiolosis larvae (Fig. 32A) is similar to that of the Clinodiplosis larvae except that there is an extra pair of ventral setae on the first seven abdominal segments and three extra pairs of ventral setae on the thoracic segments (Fig* 52D), The arrangement of setae on the eighth Abdominal segment is identical with that of Clinodirlosis. The ninth segment however bears two pairs of long terminal setae and, one pair of long dorsal setae (Fig. 32B). 13

C anterior anterior

0 7 t

1I? mid dorsal posterior mid ventral mid dorsal posterior mid ntra I

anterior anterior

0 1 T mid dorsal mid ventral mid dorsal mid ventral Fig. 32. A. Dorsal view of last instar larva of LestodiploSiB sp. B. Lateral view of last instar larva of Lestodiplosis sp. Setation patterns on the first abdominal segment of:— C. Clinodinlosis sarothamni. D. Lestodinlosis sp. E. Asnhondylia sarothamni. F. Trotteria sarothamni, 220*,

The slit shaped anus is also situated dorsally on the ninth abdominal segment as in all Lestodiplosis larvae so far described (Fig. 32A). Another feature common to all LestodiT)losis larvae is the presence of two ventral pseudopods on each of the mesa-# and meta-thoracic segments and three ventral pseudopods on the first seven abdominal. segments. (Pig, 32B). Also all Lestodiplosis larvae are blood red in colour. The first instar larva is easily distinguished by its metapneustic respiratory system but, as there is no sternal spatula in the third instar larva, measurements must be made to distinguish it from the second instar larva. The length of the dorsal setae on the ninth abdominal segment is a good distinguishing character and this is included, with several other measurements in Table, 36. Table 36. Body measurements of Lestodiplosis larvae. (10 measurements of each in millimeters x 1000) Instar I Instar II Instar III Max. Mean Min. Max, Mean Min. Max. Mean Min, Length of body 800 650 500 1600 1170 900 2700 2100 1800 Width of body 220 150 120 390 260 190 600 490 390 Length of head 51 50 48 85 82 80 137 127 119. Width of head 30 28 24 48 42 39 72 65 62 Length of antenna 24 26 28 36 35 34 47 44 42 Length of dorsal setae on abd, seg. 9 29 25 '23 48 42 37 72 68 . 64

a. Life history Eggs. were laid singly into the cavities of broom pods in 221.

the "Old Broom" area at the end of July and:throughout August, 1960. Oviposition was not observed but ii was presumed that the females utilised cracks in the sides of the pods through which they layed their eggs. First instar larvae were most common in the pods in the third week of August, 1960, second instar larvae were most common in the last week of August and third instar larvae were most common in the first week of September. The majority of Lestodiplosis larvae thus occur in the pods approximately two weeks after the Clinodiplosis larvae. Lestodiplosis larvae are predatory in all instars, mainly on Clinodiplosis larvae which are mostly all in the third instar stage by the time the first instar Lestodiplosis larvae begin to hatch, (i.e. in the third week in August). The majority of Lestodiplosis larvae were found in pods which also contained Clinodiplosis larvae,but, in a few cases the latter species was absent. Lestodiplosis larvae were also found feeding on various hymenopterous larvae and pupae in the Apion pupation cavities in several pods from the "Old Broom" area in 1960. It seems therefore, as suggested by Milne (1960) Otter (1934) and Barnes (1930, 1933) that Lestodiplosis larvae are polyphagaus, Only one or seldom two larvae were found in each broom pod since the larvae were extremely active and also cannibalisti Larvae occurred in both broom areas in. both 1960 and 1961. 222.

The number of pods containing these larvae was slightly lower than the number of pods with Olinodiulosis -larvae iu each year. In the third week in August, 1960 several of the earliest fully grown larvae were placed in 3" x 1" tubes containing a sterilised peat and sand mixture. They burrowed. into the soil and. pupated without forming cocoons. The tubes were kept in the 'laboratory and adult flies emerged in September, 1960 If this emergence also occurred in the field (and no trace of it could be found) the adults would probably have been wasted. In September, 1960 more fully grown larvae were put into 3" x 1" tubes and. left at outdoor temperatures. These larvae entered. the soil and overwintered in the prepupal phase without forming cocoons. In the field, larvae were:..found in both the undehisced pods and. in the curled up pod valves of dehisced, pods throughout September and, quite commonly in October. Some larvae overwinter in these pod. valves, a few of which remain hanging on the bushes until the following spring. The majority of larvae however, overwinter in or on the soil. In the tubes containing the overwintering larvae, adult midges emerged in 1961 at the end. of June and throughout July, S. when once again eggs were found in the, broom pod samples. 223.

Parasitic species on Contarinia pulchli)es larvae. 1. Aprostocetus sp. nr. aethiops (Zetterstedt). a. Problems of Identification. This species was identified as far as possible by Dr. W.W. de V. Graham and Dr. R.R. Askew. Askew (1961a) records Aprostocetus (= Tetrastichus) aethiops as a parasite in oak galls of various types but, he states that my specimens differ from his in several ways. b. Morphology of the immature stages. (1) The egg. The egg of Aprostocetus sp. nr. aethiops is approximately 0.5 mm. long and 0.15 mm. wide. Posteriorly, the smooth unpigmented chorion is bluntly rounded but anteriorly, the cephalic pole is narrow and somewhat drawn out (Fig. 33B). (ii) The first instar larva. The larvae of both Aprostocetus en. nr. ,aethiops, and of Systasis encyrtoides Walker occur together in broom pods and the following description of the former species is mainly intended to distinguish it from the latter. The first instar larva of Aprostocetus sp. nr. aethiops, is 0.78 mm. long and 0.26 mm. wide when fully grown. It consists of a head and 13 body segments the last of which is bifid (Pig. 33A). The maximum width of the larva can be measured across any of the thoracic or first three abdominal segments, all of which 324.

are the same size..• The rest of the abdominal segments taper posteriorly. The mouthparts are well sclerotised. The pleurostoma has 'a membranous junction at its mid point but both the anterior pleurostomal processes and the epistoma are.distinct (Fig. 33C). The heavily sclerotised tips of the mandibles are simple and overlap in th mid line. Posteriorly the mandibles articulate on:the fused ,poSterior pleurostomal processes. The hypostema is reduced to a small knob opposite the posterior mandibular'articulation and there is no tentorium in this larva. Two pairs of small papillae occur on the membranous,. ldbrum and there are also two pairs of large papillae, probably the'remains of the labial and maxillary palpi, together with one pair of small papillae on the membrane posterior to the mandibles. The head capsule is moderately sclerotised dorsally and bears the antennae and one pair of small setae (Pig. 33A). In the intersegmental regions of the body there-are two or three rows of minute cuticular spines, but the cuticle in each segmental region is smooth. The thoracic segments each bear one pair.ofdorsal, lateral and ventral small setae in the middle of each segmental. region. The first nine abdominal segments each have only one pair of small dorsal setae. No setae could be detected on the last abdominal segment. 225.

Spiracles are situated in the clear segmental regions of the mesothorax and in the first three abdominal segments. The spiracles connect interiorly with two longitudinal, lateral, tracheal trunks which are joined by transverse trunks in the prothoracic and in the eighth abdominal segments. (iii) The last instar larva. When fully grown this larva is 3.0 mm. long and 1.0 mm. wide (Fig. 33E), and has the normal number of body segments. The mouthparts (Fig. 33F) are similar to those of the first instar and have only a few extra papillae on the labial membrane. There are nine pairs of spiracles situated laterally on the meso-and metathorax and along the first seven abdominal segments. The distance between the atrium and the closing apparatus of these spiracles is much shorter than that of the spiracles of Systasis encyrtoides. Walker. (Compare Figs. 33D and 34A). No setae could be distinguished on the Aprostocetus larva but pronounced dorsal intersegmental ridges were very apparent. (iv) The pupa. The pupa (Fig. 28P and G) is approximately 2.4 mm. long and 0.8 mm. wide. Its distinguishing feature is the pronounced protrusion of the eyes. (see p. 189 ). c. Life History.. The period of oviposition lasted from 26 June to 30 July 0-25mm

i 0.02mm

1 0-25mm

0 0 1.0mm 0.05mm Fig. 33. Aprostocetus sp. nr. aethiops (Zetterstedt). A. First instar larva. B. Egg. 0. First instar mouthparts. D, First abdominal spiracle of last instar larva. E. Last instar larva, lateral. F. Mouthparts of last instar larva, ventral. 227.

in the "Old Broom" area in 1960. Oviposition was not observed but single eggs were found in pods containing Contarinia larvae throughout, this time. Very few eggs were found in- pods'where there were no.Contarinia larvae and it was presumed that the Aprostocetus adults either probed' into the .peds.tofind the host larvae or could detect them by some other means. The' majority of eggs.were found from 14.to 21July. First instar larvae occurred in the pods from 28 June ,until' 4 August, 1960. These. larvae were ectoparasitic on Contarinia larvaeand, to complete their.developmentleach' parasite' sucked from eight to ten cecid larvae completely. They also murdered any other larvae that they came. across including those of their own species. For this reason only one or two larvae of the parasite survived in the same pod. The first larvae to, mature, pupated in the, pods, in the last few days of July, 1960. In the laboratory one first instar larva collected on 5 July was fed on Contarinia larvae, pupated on 18 July and emerged on 29'july. There were many pupae in the pods in-the "Old Broom" area in the first week of August, 1960 and adult emergence in the. field was first observed on 3 August., Having emerged from its pupal case the adult Aprostocetus had cut a hole in the side of the pod and thus escaped. Further recordS of larvae, pupae and emerged adults were found in the pods throughout August, 1960 and 30 females were 228.

bred out in the laboratory. No males were found and it was presUmed that the females were parthenogenetic. All attempts te:keep the females alive in the winter failed and thus what happens to those in the field remains unknown. Most of the adults had emerged in the field by the first week in September but three larvae, found in pods on 15 September,' were put into a 3" x 1" tube containing steril ised soil and kept at outdoor temperatures. Adults emerged from this tube on 24, 26 and 29 May, 1961 i.e. a month,earlier than in 1960. This was probably due to the warmer average temperatures. In the "Old Broom" in 1961 there were fewer pods containing Contarinia larvae than in 1960 and only four larvae and one pupa of Aprostocetus were found throughout the whole period of sampling. The larvae occurred in pod samples on 10 July, z,; 17 July and 8 August and the pupa alscOdurred on 8 August. Aprostocetus was not recorded ei all in the New Broom plantation in 1960 when there were very few pods with Contarinia (See Table 34 ). HoweV•r, in 1961 there were more infected pods and two larvae and vie pupa of Aprostocetus were found in samples taken on 17- July and on 9 August. Thus this species is probtely polyphagaus, breeding mainly on some other unknown httit and only occasionally 229.

parasitising the relatively small populations of Contarinia larvae in the two broom areas.

2, Systasis encyrtoides Walker. a. Identification of species andprevious,host records. Adult insects bred from pods in 1961 were identified by' Dr. m,vir. de V. Graham at the Hope Department of Entomology, Oxford. The occurrence of this species in broom pods is recorded by Hoffmann (1958 p 1559), who states that it actively parasitises Apion fuscirostre larvae in France. He also' states (p 1562) that Anion-compactum Desbr, larvae in the pods of Genistai piloss are parasitised by SYstasis encYrtoides,_ These records were probably obtained from Systasis adults bred from pods where the hosts were assumed to be the beetle

:larvae. No Systasis larvae were ever found parasitising' Apion fuscirostre larvae, in broom pods at Silwood Park. b. Morphology of the immature stages.. (i)The egg. This egg is the same shape but much larger than that of Aorostocetue (see=Fig. 35B). It is approximately 0.72 mm.long and 0.2 mm. wide (1 measurement). (ii)The first instar larva. This, larva is of the normal "hymenopteriform", shape (Clausen 1940) having a head and 13. body segments. 230.

The spiradular arrangement and internal tracheal system are exactly the same as those of the corresponding larva of AprostocetUs. HoweVer, the'SYstadis larva differs from that of 'toprostoeetus in many ways. When fully grown the Systasis first instar larva'is approximately 0#78 mm. long and 0.29 mm. wide. It is widest in the region of the second and of the third abdominal segments and it tapers both anteriorly and posteriorly. The mouthparts are Well developed (Fig.'3a) and all of the sclerotised'strUctUres present in Aprostocetus larvae are also.present here. HOwe'Ver, the hypostoma of the Systasis larva is well deVeloped and a large U shaped tentorium is present. The pleurostoma is not divided and the mandibles are'hook shaped, their tips overlapping in the mid-line.' No .papillae could be distinguished on either the labral or the labial membranes, but there is a pair of stiff setae, on the epistoma. The cuticle in the intersegmental regions of the body is quite smooth, but many irregularly spaced cuticular spines cover each segmental region. The thoracic segMents each bear very small pairs of dorsal, lateral and ventral setae. 'The ventral setae are missing on the abdominal segments and the lateral setae occur only on the first six. Dorsal setae are present'on all 231. abdominal segments except the last one which is covered with cuticular spines only. All the setae are situated in the centre of the segmental region of each body segment, i.e. amongst the cuticular spines. The spiracles are also situated amongst these spines. (iii)The last instar larva. The fully grown larva is white and rotund, measuring 2.7 mm. in length and 2.0 mm. at its widest point, i.e. across abdominal segments two and three. The mouthparts are similar to those of the first instar except that the mandibles are not hooked and many papillae and setae are present on the labial membrane (see Pig.341)). The setation of this larva is also similar to that of the first install, each seta being very small. The last abdominal segment however bears a pair of short ventral setae and two pairs of terminal setae (Fig. 340). There are very few cuticular spines on the body segments except in the ventral intersegmental regions of this larva. (iv) The pupa. The pupa of ,Systasis, is similar to, but smaller than that of Habrocytus. Only fourteen pupae were obtained and no complete description was made. The pupae are easily distinguished in the field however, since they are enclosed in a silken cocoon in the broom pod cavity. c. Life history. In 1960, oviposition first occurred in the pods of the 0-05mm 0.05 mm $

c D ti

0.05mm I 0.1mm Fig. 34. Systasis encyrtoides Walker. A. First abdominal spiracle of last inatar larva. B. Mouthparts of the first instar larva. C. Last abdominal segment of last instar larva, ventral view. D. Mouthparts of the last instar larva, ventral view. 233.

"Old Broom" area in the first week of July. Only very few groups of eggs were found and the length of the oviposition period is unknawn. Eggs were found in groups' of four to six in the pods containing Contarinia larvae. The emerging first instar larvae fed ectoparasitically on the Contarinia larvae, each parasite killing each host with which it came into contact, similarly to the'Aprostoceus larva (see p.227 ). However, up to five fully grown Systasis larvae were found in the same pod in the second week in July so that cannibalism amongst these larvae does not appear to be as great as it is in the Aprostocetus larvae (see p,227 ). This suggests that the rotund shape of these larvae reduces their mobility to a greater extent than the stream- lining of the Aprostocetus larvae. The full grown Systasis° larvae spin silken cocoons around themselves within the pods at the end of July and in the first week in. August. As the Contarinia larvae had previously reduced the pod contents to a rotting mass, these pods did not usually dehisce and the SYetasis larvae over— wintered within them, on the bushes. Fourteen of these larvae in cocoons were collected on 8 August, 1960 and they were kept in a 3" x 1" tube at outdoor temperatures until the last week in April, 1961, when they all pupated. Some of these pupae were brought into the laboratory 236.

at this time and adults emerged. in the second week of May in 1961. In the field however, adults did not emerge until the end of May. This emergence was probably earlier than that in 1960, as was the emergence of Anrostocetus adults. In 1961 in the Old Broom" area only eleven Systasis larvae were found in the:pod. samples. Whereas in 1960 no Systasis larvae were , recorded in the "New Broom" plantation, , in 1961 five larvae were found in one pod together with, many Contarinia larvae on 20 July.

3. Inostemma ly con Walker. . a. Identification of species. This species 'was identified .by. Dr. G.E.J. Nixon at the British Museum (Natural .Iiistory)., Barnes (1946, 1946a, 1948, 1949, 1951) records many species of Inostemma as endoparasites of several cecidomyid genera including Contarinia, but he does not refer to Inostemma lycon.. Marchal (1907) describes the 'morphology of 'the immature stages of Inostemma oiricola Kieff in the larvae of Dipiosis (= Contarinia) pirivora Riley. b. Life history. Adult females emerged from 23 May to 7 June, 1961 from the soil' in the 3" x 1" tubes into which pontarinta larvae had been placed in July, 1960. No males were. seen. 235.

Females were also found in the emergence tUbs in, the "Old Broom" area (see p. 42 ) in the first week of June in 1961. When pods, in. the "Old Broom" area were observed closely in June, 1961, these females were often seen to be probing them systematically with flickering antennae, Oviposition was not observed, but it was presumed, by reference to the life cycles of related species (see Imms 1957) that the adults oviposited within the eggs of Contarinia puldwiDes within the broom pod, cavity at this time. These eggs hatched normally and the parasitised larvae developed and overwintered in cocoons in the soil. The parasitic larvae killed their hosts in May, 1961 and pupated within them. One adult female parasite emerged from the skin of each larval host. Each parasite then chewed through the cocoon made by the host and crawled up to the soil surface, emerging on the dates given. At this time Contarinia adults were also emerging and ovipositing in the broom pods so that the life cycles of both the host and the parasite were repeated once again.

4. Torymus sp. nr. micropterus. a. Notes on the life cycle. Two larvae of this species (see also p. 197 ) were found feeding ectoparasitically on Contarinia larvae in pods 236.,

from the "Old Broom" area in the second week of July, 1960* These were bred out in the laboratory and the adults (one male, and one female) emerged on 29 July. Also, from one pupa, found in a pod on 24 July, 1960 an adult male emerged on 5 August. These adults were 'of the same species as those bred out from Habrocytus host larvae (see p. 197 )4, This species is thus polyphagous but its life cycle is still 'incompletely known. In 1961 no Torymid larvae were found feeding on Contarinia larvae in either broom area. 237.

Parasitic species on Clinodiplosis sarothamni larvae. I. Platyaaster sp. a. Notes on identification of species, Although specimens were sent to both the British Museum (Natural History) and to thelHope Department of Entomology, Oxford* no identification has yet been made. Life history, Platyaaster adults emerged it 'the end of June and in the first two weeks of July, 1961 from the soil in the 3" x 1"' tubes into which Clinodinlosis earothammi larvae had been placed "in August, 1960 (see p.216 )• Oviposition was not observed but these females (no males were ever seen) probably lay their eggs into the eggs of' Clinodinlosi,s in the broom pods at this time. Parasitised eggs hatch and the Clinodiplosis larvae develop. normally and overwinter in the soil. The parasitic larvae kill their hosts in June and pupate within them. Platyaaster females emerged at the same time as the Clinodiplosis'adults and the life cyCles were repeated once again in 1961. Thus Platyaaster sp. and Inostemmalycoll have very similar life cyclesi both parasites being closely associated with their hosts and emerging simultaneously with them.

Lestodi,plosis sp. As already stated the predacious Lestodinlosila larvae 236.

feed mainly on the Clinodiplosis larvae in the broom pods. The life history of Lestodiplosis sp. is discussed on p.220.

E. Parasitic species'= Lestodiplosis sp. larvae. 1. Aphanocmus venustus Parr. a. Identification of species. The female of this species was first described by Parr (1960) 'and he identified my specimens.. There are no host records. b. Notes on the life history. Three Aphanogmus venustus females emerged on 17 September 1960 from the soil in the 31t x 1" tubes into which the earliest fully grown Lestodiplosis-sp. larvae had been placed in the third week of August, 1960. The endoparasitic Aphanogmus larvae had killed their host larvae and pupated within them.. It was from these host larval skins that the adults had emerged. Whether or not these adults emerge in the field at this time is unknown. No Aphanogmus emerged when the Lestodiplosis adults emerged in June and July, 1961 but most probably in the field this parasite has a life cycle similar to that of Inostemma and Platygaster. 239.

F Incidental insect species which overwinter in the curled broom, pod valves.

Once the pods have dehisced in August and Septetber each year, many of the curled pod valves remain attached to the bushes until the following year. These pod valves are utilised as overwintering sites by many species of insects including Anthocoris sarothamni Doug. and Scott, Anthoeoris nemoralis (Fab4 (Hemiptera Heteroptera), Forficula auricu3.aria L. (Dermaptera), Entomobrya nivalis (L.) (ColleMbola), several species of Psocidae and also several species of mites. (Acarina). 2400

Section IV The complex of insects associated with galls on broom pods. A. Introduction. B. Gall forming species. 1. Asphondylia sarothamni H Loew (= Asphondylia mayeri Liebel). a. Synonymy and literature review. b. Morphology of the immature stages. The egg. First instar larva. Second instar larva. Last instar larva. The pupa. c. Life history.- 0: Inquiline species in the gall. 1. Trotteria sarothamni Kieffer. a,Synonymy and literature review. b,Morphology of the immature stages. The egg. First instar larva. Second instar larva. Last instar larva. c. Life history. Parasitic species in the gall of Asphondylia sarothamni. 1. Aprostocetus brevicornis (Panzer). a. Identification of species and host records, b. Morphology of the immature stages. (i) The egg. (ii First instar larva. (iii Second instar larva. (iv Last instar larva. (v The pupa. c. Life history. Pseudocatolaccus thoracicus (Walker), a. Identification of species and host records. 241.

b. Morphology of the immature stages. (i The egg. (ii First instar (iii Last instar larva. (iv The pupa. c. Notes on the life history. 3. Eurytoma dentate Mayr. a.'Identification of species and host records. b. Morphology of the immature stages. The egg, First instar larva. Last instar The pUpa.' c. Notes on the life history. E. Hyperparasitic species on Aprostocetus brevicornis (Panzer). 1. Torymus sp. nr. microstigma (Walker). a. Problems of identification, b. Morphology of the immature stages. (i The egg. (ii First instar larva. (iii LaSt instar larva. (iv The pupa. c. Notes on the life history. F. Comparative numbers of the different insect species Pound. in pod czalls Ia s ar amnith on b oom._ a. Numbers of pod galls found in each broom area in 1960 and 1961.. b. Numbers of insect species found in .galls in the two broom areas in 1960 and 1961. 212.

Section IV The complex of insects associated with galls on broom'pods. A. Introduction. The gall midge_Asphondylia sarothamni H. Loew oviposits in the very young pods of broom. The eggs hatch and the.. larvae develop in an oval swelling or gall wilich forms on both valves, of the infected podS. The size of these swellings- varies considerably, but in general they are approximately 5 mm. long, 2,5- mm. wide. and 2.5 mm,.broad. A group of parasites, a hyperparasite and an inquiline are associated with this gall. There are three hymenopterou6 species parasitic on sarothamni viz: Aprostocetus (= Tetrastichus) brevicornis Panz. Pseudocatolaccus thoracicus(Walker) and-Eurytoma dentata Mayr. The hymenopteran Torymus sp. nr. microstigma (walker) is a'hyperparasite. Of Aprostocetus (= Tetrastichus) brevicornis and the inquiline found in the galls is the cecidomyid Trotteria sarothamni'(Kieffer). Parker and Thompson (1928) record Asphondylia sarothamni H. Loew from bud galls of Calycotome ,spinosa Link (le genet epineux) in France. They give an account of the biology of four hymenopterous parasites of .A.,2 sarothamni and Parker (1924) describes and illustrates their larval stages. The parasites are referred to as, Oxymorpha (= Tetrastichus = Hyperteles) intermedia Thom., Pseudocatalaccus asphondyliae 243.

Masi (generic name mis-spelt), Eurytoma dentata Mayr and Callimome (= Torymus) sp. nro rhYllyeae Ruschka, The possible synonymy of'theed species with those found in the present study is discussed as each insect is described in the following section. The hymenopterous genera mentioned above are Characterist- ically found in galls of many different Asphonqylia species according to Mikorskaya (1952). The genus Trotteria has only a few species. All of these, however, are always associated with spedies from other eeeidomyid genera (Barnes 1954a). B. Gall forming species. 1. Asphondylia sarothamni H. Loew (= Asphondylia mayeri Liebel). . a, Synonymy and literature review. The gall midge Asphondylia sarothamni was.original1y described by H, Loewy (1850 - not consulted.in original) from specimens bred out of bud-galls of broom. Thirty nine years later Liebel (1889) described' Asphondylia mayeri, from pod-galls of broom. He. distinguished between A. sarothamni mayeri adults by differences in. the morphology of the last abdominal segments of their pupae. Kieffer (1892) showed differences in the larvae of these midges and retained the two names in his key to galls on Sarothamnus scoparius in 1901, In this key he also included flower-galls formed by A. mayeri on broom. Docters van Lepuwen (1953) recorded mayeri in pod-galls of Cytisus albus Lk. and sarothamni in bud-galls of both Cytisus albus and a. praecox Bean. However, Docters van Leeuwen (1954) shored that A. sarothamni adults, bred from broom bud-galls in May, oviposited in the ovaries of broom flowers and produced a second generation in pod-galls in June and July. He could not obtain any. adults from the pod galls owing to heavy parasitism, and thus could not complete his studies of the life cycle. He did, however, propose that the name A.. mayeri be synonymous with the older name A. sarothamni and he used this 244%

synonymy in his book (Doctors van Leeuwen 1957). Stelte“1957) independently, studied the morphology of .the adults, larvae and pupae from both pod- and bud-galls and came'to the conclusion that they were identical. The differences originally separating these two species were no more than individual variations the range of which was similar in both types of gall. Once again A..t sarothamni'was proposed as the true name for this species. Vollert (1958) verified this synonymy conclusively, by conducting extensive breeding experiments with these insects .In May,- 1955, he enclosed a broom bush in a muslin bag and liberated A. sarothamni Midges'inside it. Pod-galls developed in the summer of 1955 and, in the followingspring, bud galls formed on the bush. Pour, months later in May and June, 1956 there were over 300 pod galls on the bush thus proving that this midge has an, alternation of generations..- Parker and Thompson (1928) record A. sarothamni from bud galls found in March and April on Calycotome :spinosa in the region of Hyeres in Prance. They also mentioned that, after these galls disappeared, new galls formed on the developing pods. From these pods, midges, which were identified AS Asphondylia calycotomae Kieffer, were bred out. This is probably another instance of an alternation of generations,these two species being synonymous. Another. factor which also points to this conclusiOn is the occurrence 246.

of the same parasites on both bud- and pod-galls. This was also found in the present study. b. Morphology.of the, immature stages. (i) The egg. .The egg,is 0.44 mm, long and 0.13 mm, wide (2 measurements) It,is widest at the posterior, pole and somewhat tapering anteriorly.(Fig. 35A),, 'The chorion is smooth,and unpigmented and the .- egg is transparent when newly laid.:Jt.becomes white however as the larva develops inside it, (ii) First instar larva., The first instar larva- is white and is :composed of a fairly well sclerotised head capsule .and_15 well defined body segments. It. varies in, size between that of:the egg and is 1.6 mm. long and 4.4 mm. wide:whentuily grown measUrements) It is unlike all other first instar ceeidomyid larvae found in the broom pod since it posesses a„pair of ventrally directed, sclerotised, thick, setae (Fig..350) on the ninth abdominal segment.- Also there is a.0 shaped sclerite situated ventrally -on:the eighth abdominal segment, which bears two small posteriorly direeted.spines (Fig.35C).. Moreover no spiracles could be found.on any segments. No other, dermal structures could be seen_except a pair of small lateral spines on the supernumerary segment and a minute pair of lateral papillae on the prothorax (Fig. 35B). 24,7

(iii)Second instar larva. This larva is similar to the last instar except that it does not have a sternal spatula and the cuticle is smooth. Only one larva was mounted and this wee 1.6 mm. long and 0.5 mm. wide. (iv)Last instar larva. This larva measures.approxiMately 3.mm. in' length and 0.9 ram. in width when newly moulted. It is approximately 4,5 mm. long and 1.3, mm. wide when fully grown however., This bright orange larva is deeply segmented and tapers posteriorly,. -The head ,capsule is mell developed but is very small and somewhat retracted into the supernumerary segment (Fig. 36A), The cuticle As covered in minute pustules (see Fig. 35D inset) and it bears small setae in a regular pattern as shown in Figs. 35D and E. Kieffer (1900) first noted that the papillae of Anohondylia.larvae bore small hairs, unlike the larvae of other cecidomyid genera. These papillae were named by Kieffer (1900) according to their positions on the larva. However,, the positions, of these papillae seem to,be 'fairly stereotyped throughout the genus Asohondylia and the. papillae on A. sarothamni, are in similar positions to those found by Kieffer (1900) on A. ounica March. larvae. Ventrally there are lobes on the thoracic segments and to a lesser extent on the abdominal segments also. Lobes are also 'apparent dorsally on the thoracic, segments and their function 0.2Smm j

0.0Mm 2

O•Smm

Pig. 35. Asphondylia sarothamni H. Loew. A. Egg. B. First instar larva, ventral view, C.Posterior segments of instar I, ventral view. D. Anterior segments of instar III, ventral view (with inset of cuticular pustules) E. Last (III) instar larva - dorsal view showing setation. 249.

is obscure unless4heyheIpthe:larva to.rollaround within the gall, ,There are no sets of the lOcomatory,ventral pads or spines, on larva. .Ninepairs. :Of-spiracles are present on .theprothetax and first eight:dbdotinai segments0jFig.:35E) The 'Sterna spatula, which is heavily splerotiSedonly in fully grown ldrvde4 isdividedinto,fOurteeth,anteriorlY. 'The, .outer. teeth:are larger:than-thelinneronest this- being-typicalH -ot -the genus AsnhOnavli6-(see 4effer: 1900), The stem is'long and, posteriorly/ '.theHsterhaI:"Spatula:widens where itmerges with the intersegMentalHfol4s:between the'pro,!.andmeso'-thoracic segthants. The ninth dbdominal segment is partially diiirided and bears the anus ventrally, NO setae could be found on this segMent and thecUticle is. quite smooth. (v) The pupa, The structure of .this pupa is discussed by .Stelter (1957). It is 3.5 to 4.5 mm..long and ,yellowish orange when newly moulted. but it gradually darkens to a chocolate brown as it - hardens, The most characteristic feature of this pupa is the two sclerotised teeth on the top of'the ,head.(Pig, 3632- arrowed). c. .Life history* .The life history of this.midge has already been described to some extent.,in the literature review (p. /14) and:only a brief resume is-given:here. 250.

Young green pods in the "Old. Broom" area were carefully searched for signs of gall development in May,.1960 when the adult midges were ovipositing.'. Voller.t (1958) showed that this midge was able to insert eggs into plant, tissue using its long, pointed ovipositor. Kieffer (1892) describes this ovipositor ,as being typical of 'the genus: Asehondxlia It. was found that different 'types of -galls developed in the' field, depending on the degree of, growth. of the pod when the egg was inserted into it. -Flower galls ,were formed when the female midges oviposited into flowers almost before they had opened. Stunted pods, .containing no seeds and consisting only of the ,globular gall swellings,. were formed when the midges oviposited after the flower petals had. dropped-but before .the pod..had begun to elongate. Finally, when a female midge oviposited in, a pod after it had begun to elongate, an oval gall was formed at the base (of the pod. The rest of, the pod developed normally, and produced seeds. This last type was' by far the most common variety that occurred at Silwood, Park. A white mycelium of 'an unidentified fungus was found growing on the inner walls of every gall that was opened (Fig. 36.k and B). This mycelium is also present .in the bud. galls of A. sarothsrint on broom according to Docters van Leeuwen (1954). Docters van Leeuwen (1957) reviews the fiterature on'fungi growing in galls of cecidomyids and he includes a description Fig. 36. Asphondylia sarothamni H. Loew. A. Last instar larva in a gall, June, 1960. B.Pupa in a gall, June, 1960. (Note also the white fungal mycelium in each gall) 23

of the structure of the mycelium He .also quotes a tropical example of Asphondylie. burearia • which lays its ..eggs deep .

into the tissues of Simplocos: faeciculata;, With each egg a few spores of a certain fungus are . always found.. These spores ,germinate. when the eggs hatch and the ceoidorayid..larvaebrowse on the fungal-mycelium. , This may- happen in.Ati earothamni galls*. but more work will have to be done before this can be proved•. The different. stages of At sarotharani were foUnd to occur in the broom pods in,both broom areas on similar .dates in both 1960 and 1961. Thus •the follovrIng summary refers. to both broom areas and both 'years. except: where otherwise stated.

Adult midges were found in the field in • the second week of May. Only one egg was laid. into each•pod. usually into the cavity near to the Joint with the stem. Eggs were also found in pods where small galls were already developing in the third week of May and small solitary larvae were found in fully developed galls in. the last week of May :and the first week of •June. These larvae were presumably, feeding on the, white• fungal mycelium which had by-now completely covered the inside walls of the gall. Solitary, bright .orange• last instar larvae were common in galls in the second • week of June (Pig. • 36A) and • pupae (Pig. 36B) were frequently found in the third..week of June« The, first adult emerged in the laboratory . on .19 June, 1960 254.

after a 12 day pupal period. The majority of adults emerged in the field in the fourth week of June and in the first two weeks, of July. The latest adult that was recorded was bred out on'22 July from a pupa found on 20 July, 1961. The emergence of the adults is briefly referred to by Liebel (1889). Detailed observations showed however, that, just before emergence, the pupa wriggles violently inside the gall; the two sclerotised teeth at the anterior end of the pupa cut a hole through the side of the gall. The pupa wriggles through this hole until the head , and thorax are protruding from the gall. The adult then emerges, leaving the pupal case wedged in the hole. The rest of the life history is described by Vollert (19581 He shore that these emerging adults oviposit in July into the growing points of the rudimentary 'buds in the leaf axils of broom. When these buds begin to grow in the following February and March, the eggs hatch and the infected buds form bud galls from which, adult midges emerge in the first two weeks of May. The numbers of AsphondYlis, adults that emerged from pod galls and the numbers of parasites and inquilines that attacked these galls in the two broom areas in 1960 and 1961 discussed on page 293 and shown in Table 39. 255,

Inouiline species; in the gall. 1.: Trotteria sarothamni: Kieffer.. a. Synonymy, and literature reyiew.

'This midge, was originally described:by.Kieffer.(1890) as Lasiontera sdrothatni:but, ten years later Kieffer (1900) divided: up the genus. Lasiontera:and renamed this species as Choristeneura_sarotheimni.. In his key to the galls of Sarothamnad•(Kieffer 1901) he explained that the zenus Choristoneura was preoccupied in the Tortricidae (Lepidontera), and so he erected a new genus which he called'Trottepia. .Trotteria sarothamni larvae have been recorded from pod and flower galls of Asnhondylia sarothRinni on broom by Kieffer (1890,. 1901). Barnes:(1954a) reviews the. habits'of this genus of .midges and shows that they are all inquiline, found only in galls formed by other cecidomyids. b. Morphology of the immature stages. (1). The egg. The egg is oval and measures 0.25 mm. in length and 0.12 mm. in width (2 measurements),, • The chorionis smooth and the egg is,yellowish;wben newly-laid. (Fig. 37A). (ii) 'First instar larva. •, This 37BYhas a well developed head capsule and 13 body segments. When fully grown it is 256.

approximately 0.5mm 'long (range 0.38 to 0.39 mm•,.. MeasUreMental and 0.12 pm. wide -(4 measurements). The cuticle is smooth and 'no4ermal structures could be Seen.on'any of the body segments-except-the:1E64 two. The eighth'abdominal-iegment bears one pair of dorso-lateral One pair of dorSal setae and .one:Pair of lateral setae. The ninth abdoMinalHaegment bears the'ventral'anas and four pairs of terminal setae. (iii) Second indtar'larvae. jihen fullY-grown. this lirtra 3.s 1.2 mm. long (range_ 1.0 to '1.4 mm.: 5 measurements) and 0.33 mm.: widelrange 0.3 to 0.4 mm. :5 measurements). It. is light yel1011iorange. iind the head capsule. is distinct `andwell sclerotiseds The respiratory system is vetapneastic and there are nine pairs of spiracles situated torsally and',vosteriorly on:the: prothorak, dorso-laterally on the first seven abdominal- segments and 'dorsally and posteriorly on the-eighth abdotinal:segtent (Fig. 370(r No'citherdermal structures could be found except the setae on abdoMinal segments 8'and 9 which hive' already been described in the.first instar larva. Last'instar larva. This larva'is approximately 2.6 tm. longArange 2.4 to 2.9- 'Mm. i1, 6'measurements).and 0.8 Mt wide (range,0.7 to 0.9 mm 5 measurements). It is hyalineAn appearance ankis'light. orange except for mid-dorsal and lateral, white fat 'bodies. , 0-25mm ,

O.25 mm ,

0.25mm

0.5mm F

0.25(nm I Fig. 37. Trotteria sarothamni Kieffer. A. Egg. B. First instar larva. C. Second instar larva. D. Third (last) instar larva, dorsal view. E. Anterior segments of last instar larva, ventral view. F. Posterior segments of last instar larva ventral view. 253,'

The head capsule is sclerotised and very well developed (Fig. 38B) This larva is quite distinct from the preceeding ones as it bears a regular pattern of setae (Fig. 32F) on the last two thoracic and the first seven dbdominal segments. There are, three pairs of dorsal, setae situated towards the posterior edge of each segment, two pairs of lateral setae situated towards the anterior edge of each segment and one ventral pair of setae situated in the middle of each segment. (Fig. 32F and 37D). On the prothorax there are six pairs of setae situated anteriorly all around the segment. The supernumerary segment has no setae. The eighth abdominal segment bears the dorsal and lateral pairs of setae as described in the first instar larva, but it alio has two pairs of small ventral setae in the last instar larva (Fig. 37F). The ninth abdominal segment bears four pairs of long terminal setae and a slit shaped ventral anus. (Fig. 37F). The cuticle is reticulated and ventral pads of Cuticular spines are situated on each thoracic and abdominal segment (Pig. 37E and F). Condrashoff (1961) describes the arrangement of papillae on the cuticle of Contarinia pseudotsugae larvae. Tr9tteria larvae also have a similar set of papillae, but some of them 259.

are enlarged. to form the.setap as describedabove.. The remainder,' however, (Figs. 37E and F) are in similar positions to those found: on theContarinia•.pseudotsugae larvae. The sternal,apatula,is very ;well developed: and-the: two anterior lobes are, pointed and highly: splerotisedOlg. 37E).• c. Life.history, The different,stages of:this -loidgewere,found .on similar dates, in both brpom,areas in, 196,2 and. 1961, .Thus the dates,in the following ,section ,refer 'to :both :broom areas .and:both years. • Groups of 6 to 8 small yellow eggs were, found inserted into the ,cavities of: the galls , of Asphondylia sarothamni in the second and third weeks . of: Arne. When, the. Trotteria, midge, oviposits,.it does not paralyse the Asphondylia third instar larva or pupa that already occupies the gall.. The-survival of. the Asphondylia-depends•to a, great extent on the stage. that, it. has reached when the Trotteria larvae hatch,, If these larvae hatch before the Asphondylia larva is fully grown, the latter usually dies., _ Probably the, continuous movement of. the 6,to 8 active Trotteria larvae, irritates the Asphondylia larva and prevents it from either feeding or, pupating.. If,,,howeverv the. gall forming midge,. has reached the prepupal or pupal stage when the Trotteria larvae hatch, the adult of Asphondirlia,emerges quite normally. In these instances thelrotteria larvae,,are.cramped and their development is delayed until the:AmphondYlia adult has emerged. 260.

It was found that the number of galls containing Trotteria larvae and•the' remains of a dead Asphondylia larva • was far greater than the number of galls containing Trotteria larvae and a living As2hondxlia pupa (see p. 294 ). In the third and fourth. weeks of June the. orange and white Trotteria larvae (Fig. 38B) were found in tunnels in the white fungal mycelium, which completely filled the gall after the Aslahondylia larva.died, These Trotteria larvae presumably feed on the mycelium and this may explain why this species is an inguiline. Presumably the adult Asphondylia.has,some means of carrying the fungal spores (see p. 252 ) whereas the Trotteria adult does not. Fully fed last instar Trotteria larvae pierce&holes in ,the sides of the galls and emerged from them at the.end of June and in the first three weeks of July. -As'.the cellular structure of the side walls of each gall had already been partially broken down by the fungal mycelium, the.larvae could easily pierce these emergence holes with their mouthparts. Many of these emerging larvae were trapped in polythene bags tied over infected pods in the "Old Broom" area in 1960. Thirty four larvae were placed on damp sterile soil'in a 3" x 1" tube on 30 June, 1960; many more larvae were put into similar tubes•throughout July. On 4 July, 1960'the larvae in the first tube mentioned. above were observed to have burrowed into the soil and spun Fig. 38. A. Pupa of Pseuclocatolaccus thoracicus (Walker) in a gall. B. Trotteria sarothamni last instar larvae in a gall (note excessive growth of the fungal mycelium) 262,,

cocoonti• around, themselver3.' .Prom these cocoons, adult midges emerged three weeks, later, between'-25' and.• 1960. •••Kieffer (1890) bred' out' two, female midges, in July and": based his description of -. the 'species' on these. What •happens to these---midges and. how many 'emerge, in the, field at unknoWn.' '''There are no, AiDhendylia:• galls left and. Trotterid--"sarothamni,,has not,been recorded ''-from • any _other 'hosts so that :presumably ,theSe. emerging, adults.' are .wasted. The rest of the larvae which Were put,- onto. soil 13i. .1960, overwintered as prepupae in:cocoons and emerged, as adults between- 1 and 15 June, •1961. These adultd oviposited in pod galls once-again, Thus, to sum •up Trotteria sarothamni breeds in: the .pod galls of .the second. generation of Asphondxlia'sarothamni in June, but not in the bud galls ,of • the first generation of Asphond.vlia: An'llarch and ,April.- This is correlated 'with the fact that, no Trotteria larvae have •ever been' recorded from -budgalls on broom. The approximate ,numbers of Trotteria larvae occurring in. the two broom areas are discussed on page 293 and Table 39.. 233.

D. Parasitic species in the gall of Ashonli mr4. 1. Aprostocetus brevicornis (Panzer). a. Identification of species and host records. This species was identified by Dr M.W.de V. Graham at the Hope Department of Entomology, Oxford; Graham (1961) disausses at length the synonymy of this species. Host records of this species are many and varied. Thompson (1954) lists several Cecidomyidae and also Bruchoshagus anus, Boh. and Burytoma onobrychidis Nikorskaya (Hym. Eurytomidae); Marchal (1900) records Aprostocetus (= Tetrastichus) brevicornis as an internal parasite of a Cecidomyia speciee (Dipt. Cecidomyidae). However, this description of the larval stages differs so much from the one given below, that this is probably a different species. Speyer (1923) also records Tetrastichus brevicornis Thompson as a parasite of Dasyneura brassicae Winn. (Diet. Cecidomyidae), but whether this species is synonymous with Aprostocetus (= Tetrastichus) brevicornis (Panzer) is unknown« Parker and Thompson (1928) describe Oxymorpha (= Tetra- etichus) imterniedia Thome. (now called Hvperteles) as a parasite of the larvae in the bud galls of AsphondYlia sarothamni and in the pod galls of Asphondylia calycotomae Kieffer on Calycotome spinosa Link in Prance. This parasite was named by Dr. Luigi Masi, but the description that Parker and Thompson (1928) give of the 264..

adult, does not agree with that of the true species of I intermedia. In the genus HmDerteles there should be four. funicle segments in-the antennae (according to Graham : personal communication), but the description shows only three segments, as in Anrostocetus brevicornis.,The rest of the description also corresponds with A brevioornis but the larval instars, which are described by Parker (1924),.show minor differences to those of& brevleornis. Thus, it is most probable that the species described by Parker and Thompson (1928) 'is either the same as, or closely related to, ha brevipornis• b. Morphology of the immature stages. (i) The egg. The egg is more sharply pointed at the posterior than at the anterior pole. It is 0.40 mm. long (range 0.38 to 0.42 mm. : 6 measurements) and 0.15 mm. wide (range 0.14 to 0.15 ram. : 6 measurements) and is slightly arched. The chorion is smooth and unpigmented and the egg is white when newly laid (Pige 39A). Parker and Thompson (1928) record the egg .of Iii intermedia as being 0.7 mm. in length. (ii) First instar larva. This larva is 0.45 mm. long (range 0.42 to 0.54 mm 12 measurements) and 0,14 mm„ wide (range 0.12 to 0.25 mm. : 12 measurements) when fully grown (Fig. 393). The head capsule is rounded anteriorly and the mouthparts are similar to those 265.

described in .the last instar larva. There are 13 body segments, the last one being somewhat bifid posteriorly. No dermal structures and no spiracles could: be seen on this larva. Parker (1924) makes no' mention_'. of a similar larva in al. intermedia. He does however, record a first luster larva similar to the second instarlarva of A. brevicornia which is described below. (iii)Second instar larva. This larva has four pairs of spiracles situated on the mesothoracic and the first three abdominal segments. It is variable in size ranging between 0.6 and 1.5 mm. in length and 0.2 and 0.5 mm. in width. All of the other dermal structures are similar to those described in the last instar larva. (iv)Last instar larva. There are more than three larval instars in A. brevicornis but, the exact number was not determined as there was insufficient material. The whitish, last instar larva is 2.0 to 3.0 mm long and 0.5 to 0.7 mm. wide. It tapers to a point posteriorly and is widest in the meso- and meta-thoracic region. It is composed of the normal 13 body' segments :the last of which is very small. The head capsule bears the prominent antennae and the mouthparts, although small, are distinct and similar to those described in the other Aprostocetus species (Figs'. 28A

0.25mrri, , 0.25mm

C D

$ 0.5mm , 0.05mm

$ 0.8mm I Fig. 39. Aprostocetus brevicornis (Panzer) A. Egg. B. First instar larva, dorsal. C. Last instar larval skin, lateral view. D. Mouthparts of last instar larva. E. Pupa, lateral view. F. Pupa ventral view. 267. •

33C and 33D). The shape and external appearance 'of this larva is similar to that of O. intermedia described and illustrated by Parker (1924 : figs. 165 and 166) and Clausen (1940 : fig. 64B). Figure 39C in this thesis is a drawing of the larval skin after it has been boiled in potassium hydroxide and stained in chlorazol black. This stain shows up extra thickenings in the cuticle, which are not evident in unstained specimens. The first eleven body segments of this larva are covered dorsally and ventrally with small papillae. Laterally, the papillae enclose a rectangular area of smooth cuticle. Around the edges of these "smooth areas" the papillae are thickened and are much closer together than they are elsewhere (Fig. 390. On the thoracic segments only one pair of ventral setae amongst the papillae and one pair of dOrso-lateral setae in the "smooth areas" could be seen. On the abdominal segments, only the latter pair could be seen. There are nine pairs of spiracles situated laterally in the middle of the "smooth areas" on the last two thoracic and first seven abdominal segments. Parker (1924) found more setae on the larva of O. intermedia but apart from this the larvae of the two species are similar. (v) The pupa. The outline of the dorsum of this pupa is steeply curved (Fig. 39E), Also the eyes do not protrude from the head 268.

capsule .(Fig..39F These characters, together with the slightly smaller size.of the pupa (althOughythis varies considerably) and its position in the gall of Asphondylia, distinguish it from the pupae of Aprostocetus, ,sp. nr.aethiops and A. tibialis. c.' Life history. Eight to ten eggs were found in the cavities of the galls of Asphondylia,:sarothamni throughout June in both 1960 and 1961 in both broom areas. As the oviposition period was. so long, new adults,emerge&whilst*others were still ovipositing. Thus no definite dates of the occurrence of particular larval or pupal stages in the galls could be given and there was no fixed number of generations. OViposition was observed in the "Old Broom" area on 15 June, 1960. The female probed a pod. with her antennae and, .having found a'gall, inserted her ovipositor into it, stung and paralysed the occupant. and laid nine eggs on its body. Other observations proved that these Aprostocetus brevicorni:s adults always paralyse the occupant of the gall before, ovipositing. Eight to ten. A.-brevicornis larvae were commonly found in pod galls examined in./Tune in 1960 and 1961. They were all the same age and wriggled violently when touched, exactly as' described by Parker and Thompson (1928), However, Parker and Thompson (1928) state that 269.

intermedia larvae develop completely as ectoparasites of the single Asphondylia larva. This does not happen in the pod galls of Sarothamnus since the tissues of the Asphondylia larVA were soon exhausted by the AprostoCetus larvae. These larvae continued their development by feeding on the fungal mycelium and on the tissues of the broom plant. No evidence of cannibalism was ever found amongst these larvae. In galls where ten or more larvae were present however, there was never enough room for all of them to, develop fully and two or three of the smaller larvae usually died from the effects of overcrowding. Also, in other galls, small, malformed pupae were often found when the overcrowding was intense. The occurrence of galls containing both At brevicornis and Trotteria larvae was quite common in the "Old Broom" area (see p.294 ). When Ai brevicornis adults oviposited into galls containing Trotteria larvae, they usually only paralysed one or two of them, leaving the rest still alive within the gall. When the A. brevicornis larvae hatched they presumably either fed on the paralysed Trotteria larvae or immediately became 'phytophagous. Many galls containing up to four larvae of each species were seen in 1960 but no evidence that the brevicornis larvae either killed or fed on the Trotteria .larvae was found. Fully grown A. brevicornis larliae pupated within the 270.

galls and the first adult insects to emerge were found in the last week of June. Usually the first adult to free itself from the pupal skin cuts a hole through the side of the gall and emerges. The rest of the adults in the gall, however, also use this hole for emergence (see Parker. and Thompson 1928)* Eggs were still being laid into galls at this time (i.e. end of. June) and superparasitism often occurred when adults paralysed and oviposited on larvae of their own species. Adults continued to emerge in the field throughout July and they could be beaten from broom bushes at any time through. out the ensuing winter months. A. brevicornis adults were bred. out in the laboratory in June and July, 1960 and it was noted, that there were more than twice as many females emerging as there were males. Mating behaviour and copulation occurred in July and was similar to that described by Barrass (1960 on Mormontel44 vitrinennis Walk. The males died in the following month but the majority of the females, which were put in an outhouse and. kept at outdoor temperatures survived until the following March and. April, 1961, thus living for nine to ten months* In the field in March and Aspil, 1961 adults of A. brevicornis were found ovipositing in the bud galls of AsphondYlia on broom. prom these bud galls, neW Anrostocetus brevicornis adults emerged throughout May and the life cycle commenced once again in the pod galls. 271.

2. Pseudocatolaccus thoracicus (Walker). a. -Identification of species and host records. Pseudocatolaccus thoracicus was first described by Walker (1836) (see Rloet and Hineks (1945) under Pteromalus thoracicus Walker). Masi (1908) first erected the genus Pseudocatolaccus and described _p_a asphondyliae as a parasite of a species of Asphondylia in lupins. Parker and Thompson (1928) recorded P. asphondyliae from the galls of A. sarothamni and calycotomae on Calycotome spinosa and they describe its biology. Parker (1924) also describes its immature stages. P. asphondyliae may possibly be synonymous with a thoracicus according to Graham (personal communication), b. Morphology of the immature stages. (i) The egg. The egg is 0,5 mm. long and 0.2 mm. wide, this being larger than the egg of Aprostocetus brevicornis. It is elongate oval, being somewhatarched and slightly narrowed at. either end (Fig, 40A). The chorion is smooth and unpigmented and the egg is whitish, similar to that of P. asphondyliae described and illustrated by Parker (1924 : fig. 26). (ii) First instar This larva is similar to that of Habrocytus (see Figs.

2513 and C) except that it does not have any setae on the 272.

eighth, ninth and tenth abdominal segments but, it does have seven pairs of papillae on the labral and labial membranes (Figs. 40B and C). Xt is also similar to the first instar larva of P. asphondyliae described and illustratedby Parker (1924 : figs 119 and 120) and Clausen (1940 : fig. 55B). (iii) Last instar larva. The number of larval instars of P. thoracicus is unknown as .insufficient material was available'for this study, The external morphology and arrangement of setae on the last instar larva of P thoracicus (Fig. 41B) is the same as that of the corresponding larva Of Es. asphondyliae described and illustrated by Parker (1924 : fig. 178 and 231). The mouthparts of the larva of P. thoracicus are shown in Fig. 40E. The mandibles are heavily selerotised and all the surrounding structures are plainly visible when stained in chlorazol black. The two posterior'arms of the tentorium are not joined, as they are in the predeeding instar. The arrangement of papillae and setae on the labral and labial membranes is illustrated in Fig. 40E and the single segmented antenna, which is lightly sclerotised is illustrated in Fig. 40D. (iv) The pupa. There is a large variation in size of the pupae of P. thoracicus but, the illustrated one was 2.7 mm. long and 1.1 min. , 0.25mm ,

0- I mm

g o•emm

Fig. 40. Paeudocatolaecus thoracieus (Walker) A. Egg. B. First instar larva, dorsal view. C. Head of first instar larva, ventral view. D. Antenna and, E. Mouthpartsof last instar larva. F. Pupa, lateral view. G. Pupa, ventral view. 274.

wide. This pupais easily distinguished in lateral view'(Fig. 40F) by the protrudingmauthparts (especially the mandibles) of the developing adult. In ventral view (Fig. 40G) the paUches containing the developing mandibles overlie and obscure the pouches containing the maxillary and ldbial, regions. (These regions are all visible on the pupae of Uesopolobus mediterraneus and Habrocytus sequester : see figs. 25F and G and 27F and G). Also, there are no tibial spines on any of the legs of thoracicus and thUs the pupa has no spine sheaths. • Finally this pupa can be distinguished by its position in the broom pod. Only, one pupa was found at a time and it was always in a gall of A, sarothamni on broom (Pig. 38A). c. Notes on the life history. This parasite occurred infrequently in the pods in both. broom areas in 1960. In 1961, only one record was made, this being in a pod gall in the "Old Broom" area. Single eggs and single, young larvae were seen in pod galls of Asphondylia sarothamni in both broom areas in the fourth week of Juno, 1960. The larvae were feeding ectoparasitically on the prepupae and pupae ofAsphondylia. Whether the hosts were paralysed by the ovipositing adult parasites is unknown. Two larvae were brought into the laboratory on 24 July, 275.

1960. One pupated on 28 June and an adult emerged. on 7 July and the other pupated on 2 July and emerged on 11 July. Both adults mere females and they both had' a 9 day pupal period. In the "New Broom" plantation a large larva (Fig. 41B) was found feeding on an Asphonaylia pupa on 4 July, 1960. On 10 July a male adult, which had just emerged from the pupal sheath, was found, together with the remains of an Asphond.xlia, pupa in a pod gall in the "Old Broom" area. Thus, in 1960,a thoracicus had one generation in the . pod galls of AsphondAia sarothamni on broom and adults emerged from these galls in early July. The rest, of the life cycle is still unknown and no immature stages were found in bud galls of Aaphondylia on broom, in either 1960 or 1961. In 1961, this parasite was not found in the "New Broom" plantation. Also in this year, only one pupa of12.1. thoracicus was recorded in the pod galls in the "Old Broom" area, this being on 10. July.

3. Eurytoma dentate Mayr. a. Identification of species and host records. This species was identified by Dr. Ma, Claridge at the. University College of South Wales and Monmouthshire, Cardiff. Mayr (1878) originally described EurytomaAlentata from. ,276.

adults reared from the unripe pods of Lotus corniculatus L., Medicago falcata L. and Genista tinctoria Le He also states that Brischke reared it from galls of Asphondylia sarothamni in the region around Vienna and from the galls of A. verbasci Vail. in the Tirol, Masi (1908) illustrates an Lt dentata adult and records it as a parasite of Asphondylia sp. in lupins. Also Parker and Thompson (1928) record it as a parasite of A. sarothamni and A. calxcotomae oh Calycotome spinosa in Prance and Parker (1924) describes the morphology of its immature stages. Claridge (personal communication) states that it has also been bred from the galls of A. ulicis Verra]1 on Ulex europaeus and Nikol'skaya (1952) lists three other Asphondylia species as hosts of E. dentata. Perri;re (1950) sums up this species by stating that it is a common parasite of the cecidomyids found in the pods of many Leguminosae (Papilionaceae). b. Morphology of the immature stages. (i) The egg. No eggs of E. dentata were found in this study, but according to Parker (1924 : fig. 7) this egg is similar to that of E. rosae Nees. This egg is .oval and is covered .in short spines except on a short pedicel at one end and on a long one at the other. Claridge and Askew (1960) however revised the rosae group and they have shown that Parker's drawing refers 277.

to the egg of :Et brunniventris Ratz. and not E. rosae. (ii) First instar larva. Parker (1924) describes the morphology of the immature stages of at dentata, but the larvae he illustrates (his figs. 69, 70, 87, 134, 158, 159) are more characteristic of .a Eupelmus species than of Eurytoma. My4escription,of the immature stages of Ea. dentata' differs widely from Parker's, but it is similar to his description of'the larvae ar rosae. The first instar larva of E. dentate is 0.75 mm. long and 0.25 mm, mide (across the meta-thoracid segment.) when fully grown. It consists of a head capsule and 13 body segments, of which the first 12 are Covered in the Segmental region with bands of small cuticular spines. All. intersegmental regions are smooth however (Fig. 420. The head capsule is well sclerotised and bears three dorOal and three ventral pairs-of setae. The mouth-parts are poorly sclerotised except the tips of the mandibles, which are simple and hook shaped. There are three'pairs of papillae on the labral membrane and five pairs on the labial membrane. Also,, the tentorium is complete and U shaped in this larva. The prothorax bears a ventral, brown, sclerotisedregion separated from the head. capsule by a narrow strip of cuticle. In this narrow'strip a pair of lateral and a pair of ventral long setae are found. Ventrally, in the centre of the sclerotised region, there 278.

are two hemispherical pits,of • unknown function, similar to those described by Parker (1924) on the first instar larva. of rosae. Dorsally the prothorax bears one pair of long setae on papillae amongst then cuticular spines. (Pig. 42A). There are three pairs of setae amongst the spines on the meso- and metathoracicsegments but, only two pairs on each of the first nine abdominal segments. The last abdominal segment is devoid of spines and setae and is somewhat bifid posteriorly. Pour pairs of spiracles are present laterally on the mesothoracic and first three abdominal segments* (iii) Last instar larva. The nuniber of larval instars is unknown as little material was found. The last instar larva is 3 to 4 mm, long and 0.8 mm. wide when fully grown (Fig. 41A). The chitinous head capsule bears six pairs of setae and the antennae are as in the first instar larva, but the mouthparts are enlarged and very characteristic. The tips of the mandibles are heavily scierotised and their anterior edges are serrated.• The first tooth is the largest and makes the mandible appear somewhat bicusped. The mandibles articulate normally, the posterior condyles being heavily sclerotised (Pig. 42C). The epistoma is indistinct but the pleurostoma is well Fig. 41. A. Last instar larva of Eurytoma dentata Mayr in a gall (also two dead Trotteria sarothamni larvae) B. Last instar larva of Pseudocatolaccus thoracicus (Walker) in a gall. C

0.7mm

04mm

Fig. 42. Eurytoma dentata Mayr. A, First instar larva, lateral view. B. Last instar larva, lateral view. C. Mouthparts of last instar larva, ventral. D. Pupa, ventral view. E. Pupa, lateral view. 281.

developed and lightly selerotised. The hypostoma is fully developed, but the tentorium is reduced to two small rudiments of the posterior arms. Setae and papillae are scattered on the labial and labral membranes as is shown in Fig. 420. The arrangement of setae on the body segMents is rather peculiar in this larva. The pro-and mesothoracic segments each bear six pairs of setae, the metathorax has four pairs, the first abdominal segment has two pairs and the second. to the ninth abdominal segments each have three pairs (see Fig. 42B). The terminal segment is small and devoid of setae. Dorsal intersegmental tubercles are wellAievelOpedin this larva and they occur between all except the pro- and meso-thoracicand the ninth and tenth abdominal segments. (see Fig. 41A and 42B). (iv) The pupa.. Pupae were found singly in the galls of A...parothamni on broom. They are easily distinguished., as the antennal sheaths extend posteriorly further than the fore-leg sheaths extend but, not as far as the mid-leg sheaths. 'In all the other pupae found in the broom pod (except Triaspis sp. ni. obscurellus) the foreleg sheaths extend posteriorly as far as, or further than the antennal sheaths. In the pupa of Triaspis however the antennal sheaths also 282.

extend beyond the mid leg sheaths (Fig. 26F and 0.). An almost circular head capsule and a constriction in the wing pad region are other less distinct characters of the E dentata pupa. 0. Notes on the life history. This parasite was only occasionally found in the pod galls of sarothamni in the two broom areas in 1960 and it was not recorded at all In 1961 A half grown larva was found feeding ectoparasitioally on a pupa of LA, sarothamni in a pod gall in the "New Broom" plantation on 26 June, 1960 and two others were found in the "Old Broom" area on 27 June. These larvae were reared in the laboratory and they both pupated in the first week of July. One male and one female adult emerged on 10 and 15 July respectively. Other small and fully grown larvae found on the dates shown on Table 39 were preserved for, morphological studies On 25 June, 1960 one larva was found feeding on the pupae of Aprostocetus brevicornis in a gall. This larva was reared and an adult insect emerged on 13 July thus proving that a dentate can develop as a hyperparasite of AA brevicornia. The only other dentate seen, was a pupa, which was found in a bud gall of sarothamni on broom on 31 May, 1961. An adult female emerged from this pupa on 12 June. Thus the life history of this species on broom is still incompletely known. but probably it has one generation in ,the bud gall6 of At sarothamni and. a second. generation in the pod. galls of AL sarothamnia It was never seen in the galls on Ulek euronaeuss Fig. 43. Torymus sp. nr. microstigma (Walker). A. First instar larva, dorsal view. B. Egg. C.Mouthparts of last instar larva, ventral view. D.Last instar, lateral diagrammatic view. E. Female pupa, lateral view. F. Female pupa, ventral view. 266.

Hyperparasitic 'species on Aprostocetus brevicornis-(paner) 1. Torymus sp. nr..microStigMa (Walker). a. 'problems of identification. This species was identified as far as possible .by Dr. R.D. Lady at the British Museum (Natural History). Lady (1958) refers to the true species of microstigma.and discusses its synonymy. Parker and Thompson (1928) describe Callimome (= Torymus) sp. nr. phyllyreae Ruschka in bud gallsof Asphondylia, sarothamni.on Calycotome spinosa in France. Also the larval morphology of this parasite is described by Parker (1924) who also illustrates the egg. This morphological description is similar to that of the larVae found in this study, .but the morphology of the eggs of Torymus sp. nr. microstigmet and Torymus sp. nr. phyll:Oette is different. FOr this reason one can only assume that these two species are not synonymous. b. Morphology of the immature stages. (i) The egg. The egg is oval, but it is somewhat tapered, poSteriorly and. bears a tubercle-like projection anteriorly.. The chorion is covered with small, densly, set,,short spines, except at the two poles, where' it is smooth. (Fig. 45B).. The egg of T. sp. nr. phyllyreae is described by Parker 286«

(1924 : fig. 2) as an elongated ovoid with a smooth chorion. This is obviously different from the egg described above. (ii) First instar larva. The structure of the first instar larva is the same as that of T. sp. nr, phyllyreae described by Parker (1924). Figure 43k is included here to show a dorsal view of this larva, Parker (1924) shows the lateral and ventral views (his figs. 54 and 68). The, larva is characteristic, having a sclerotised head capsule bearing three pairs of dorsal and three pairs of ventral setae, The mouthparts are similar to those described in the last instar larva, except that the mandibles are hook shaped.

There are 13 body segments, all covered with many dhort setae, Small setae occur in rows anteriorly and they increase in size posteriorly in each segment* On each thoracic segment there are three pairs of large bristles raised on tubercles and situated dorsally, laterally and ventrally amongst the small setae. On each of the abdominal segments, except the last two, there are two pairs of these bristles. Two bristles are situated dorsally on all of the segments but the other two are lateral on abdominal segments 1 - 3, ventral on segments 4 - 7 and once again lateral on segment 8. The ninth abdominal segment has only a pair of dorsal 287.

bristles and the tenth segment is somewhat bifid posteriorly and is devoid of bristles. Mid ventrally the first eleven body segments are enlarged into a small lobe. These are most prominant on body segments 4 - 11 and are probably locomotory in function. Four pairs of spiracles are situated laterally on the mesothoracic and on the first three abdominal segments. (iii) Last instar The number of larval instars was not determined as only a few larvae were found. Parker (1924 figs. 170 and 217) illustrates the structure of the second instar larva of T sp. nrs phyllyreae and my description is similar to his. The last instar larva of T. sp. nr. phyllyreae is also illustrated by Parker (1924 : fig. 173). The fully grown, white, last instar larva of a sp. nr. microstigma is 4.5 mm. long and 1.3 mm, wide (across the first abdominal segment), It is cylindrical, but is tapered at both ends and is somewhat curved in outline when viewed laterally. Each of the 13 body segments is covered with many setae of various sizes. Fig. 43D shows the general appearance of this larva in the gall. There are over 30 pairs of setae on the thoracic segments and 20 to 25 pairs on each of the abdominal segments. Dorsally, the intersegmental tubercles are well developed, especially 288

between the first three abdominal segments. leteraliyi spiracles are born.On'themeso'and metathorax and the first seven abdominal segments. The. head. capsule bears many pairs of dorsal setae as described by Parker '(1924.:: fig. 204). The mouthparts (Fig. 43C). are moderately well developed. Only the: tipsof the Mandibles are scierotised and the other regions :only show up clearly when"stained in ehiorazol black. The structure of, these' mouthpart6 is very similar. to that of AprostocetT1 spanr.: aethiobs (Fig. 33F) except that the Torymus larva has a long indistinct .hYpostoma and a fully developed- tenterium.• Also the arrangement of, papillae and setae on the labraIandaabial membranes is slightly different

(see Fig.H43Q), 4 (iv) The pupa. The size of this pupa varies considerably,'that.of-thw, male. being,soMewhatsmaller than that of the female. The female pupa,' which is illustrated (Fig. 43E and F) is 3.2 mm. long and 1.1 mm. wide. The distinguishing character.of this pupa is the presence of. two tibial spine sheathson the hind leg sheaths. No other pupa found in the gall has. these structures. Also, the female pupa has a long ovipositor sheath, which is curved anteriorly in the. mid dorsal line otthe'abdomen. 0. Notes oh the. life: history. 289.

This hyperparasite occurred infrequently in the pod_galls •in 1960 and it was almost non existent in 1961 (see Table 39 Single eggs, laid in galls containing Aprostocetus • brevicornis larvae and pupae, were first found on 22 June, 1960. However, the oviposition period of Torymus is long and an ovipositing.female was observed in the field on 4 July. Having discovered a pod gall, the female inserted her ovipositor into it. On subsequent dissection of the gall it was found that one egg had been. laid amongst several

. AA. brevicornis pupae. Torymus larvae of various sizes were found in galls, feeding ectoparasitically on either A. brevicornis larvae and pupae or Trotteria, larvae in the last week of June and.in the first three weeks-of JUly, 1960., Three pupae ►ere found in pod galls on 6, 8 and 10, July and adults emerged from these on 18x21 and 24 July in the laboratory. Also, in the field, the remains of a pupa were found' on 8 August, 1960. The adult had emerged. from the gallHby*' Cutting.a hole in one wall. Thus, the 'larvae of this species can develop on the immature. stages of either It brevicornis or Trotterig and one gall was found containing a Torymus larva feeding on a 'Ipseudocatolaccus pupa. Parker and Thompson (1920 state that wherever another 290.

species occupies a gall with the voracious first instar Torymus larva, the latter always survives at the expense of the fomer. Although only a few Torymus larvae were found in, thi s study, the above statement always held true. No larva of any species was ever found feeding on a TorYmus larva. The complete life history of this species is still obscure and the fate 'of the adults which emerge in truly and August is unknown. No Torymus larvae were found in the few bud, galls, of. A. sarothamni that were examined in 1961.

F. Comparative numbers of the different,insect species found in pod galls of Asnhondylia sarothamnk on broom. a.' Numbers of pod. galls found in each broom area in 1960 and 1961. The numbers of pod galls of At sarothamni found in the pod samples (see Section V) taken in 1960 and 1961 are shown in Table 37. In 1960, the percentage of pod galls in the "Old Broom" was slightly higher than that in the "New Broom", although in both areas the percentages were low. In 1961, there was a marked reduction in the numbers of galls. This decrease was the same in both areas so that the "Old Broom" area still had a larger percentage of pod galls than the "New Broom" area. The ratio of the percentages in 291.

Table 37. The total numbers and percentages of pod galls found in pod samples in both broom areas in 1960 and 1961. Samples Broom Year Total pods No. with Ratio* used, area Examined galls galled pods

S1-89 'Old' 1960 r 3785 142 3.75 1.76 81-S9 New • . 1960 3658 78 2.13 Z5-S12 .01d 1961 24' 0.80 1,90 86-512 .New 1961' . 2868. ' 12 0.42 Old. Broom 'percentage' of pod galls * Jbatio New BrOoM percentage of pod galls. These samples of pods are discussed in Section V each area was fairly constant in 'both years. Temperature and rainfall averages at Silwood Park in 1960 and 1961 are shown in Table 38. Table 38. Meteorological data recorded in 1960 and 1961 from the station at Silwood. Park, Berks. 1960 1961 Temperature Rainfall Temperature Rainfall in .in MeanMean accumulated Mean Mean accumulated Max. Mins Max. min. Op Op millimeters op OF millimeters

January 43 34 54.5 43 33 78.2 February 45 33 110.8 50 40 135,5 March 50 37 148.9 57 35 143.8 April 57 58 164.6 58 42 205.0 May 64 45 207.2 61 42 225.1 June 70 50 239.7 69 47 261,6 July 67, 52 304.7 .70 50 298.5 August 67 51 378,3 68 50 348.5 September 64. 47 445.7 58 50 427.6 October 56 44 633.9' 59 43 494.4 November 51 39 744,7 48 37 541.4 December 44 34 811.4 43 31 613.0 292..

Table 38 shows that the rainfall was approximately the same in the first nine months of both years. But, whereas in 1960 the rainfall was distribUted.throughout . each month, in 1961, heavy rain fell only on one day in May and one day in June. Thus, although the average rainfall is similar in both years, these months (i.e. May and. June) were actually much drier in 1961 than in 1960.. This may have affected the .emergence of cecidenyids'in 1961. Also, the mean maximum temperatures In February, March and, to some extent, April of 1961, were considerably higher than those of 1960* (The mean maximum temperatures from, January to May, 1960 are the same as the average temperatures • recorded at Kew Gardens from 1921 to 1951). Thus, the exceptionally warm spring of 1961 probably, accelerated the rate of development of the larvae, of A. earothamni in the broom bud gallb• Adults emerged before. .the broom pods had developed and many of them died without ovipositing. Also, in May, 1961, the late frosts destroyed many pods, especially in the "New Broom" plantation (see p. 6 ). This factor also contributed to the decrease of the number of pod galls in 1961. The numbers of A. sarothamni adults emerging from bud galls in 1961 .may also have been indirectly reduced by the removal,' in 1960, of relatively large' numbers of pod galls in sampling. 293.

(b) Numbers of Insect speciesfoUnd in galls in the two broom areas in 1960 and 1961. Between May and August in 1960 and in 1961, Many pod galls were collected from both broom areas, Each gall was opened and the larvae or pupae found. within it Were identified and recorded. ' No population estimates were attempted as the numbers that were obtained were too. small. .The results of these investigations (see Table 39) do, however, give some indication of the proportions of each insect species occurring in the pod galls. In 1960, it was found that Torymus, Pseudocatolacaus and Eurytoma were present in similar, small percentages in both broom areas. Many galls containing Trotteria larvae only and mixed Aprostocetus and Trotteria larvae were found in the "Old Broom" area in 1960; few were found in the "New Broom". There was, however, a higher percentage of Aprostocetus larvae in the galls in the "New Broom". The percentage survival of Asphondylia larvae and pupae was approximately the same in both broom areas in 1960 and the percentages of galls containing mixed Asphondylia and Trotteria larvae were also similar. In 1961, few galls were found in the "New Broom" plantation and the results obtained were thought to be somewhat unreliable (see Table 39). They do show, however,' 294.

Table 39, Numbers and percentages of all of the insect species found in pod galls of Asphondylia sarothamni in the "New" and "Old Broom" areas from May to August in 1960 and 1961. (Numbers of galls include those found in the pod samples (see Section V) and those in individual gall collections) 1960 1961 'Old New Old New Old New Old New Broom Broom Broom Broom Broom Broom Broom Broom rf /0 ' %

Total galls examined ' 259 119 100% 100% 148 17 100% 100% Aaphondylia 64 29 24.7 24.3 10 2 6.8 11.8 Asphondylia & Trotteria 3 2 1.1 1.7 - . - Trotteria 59 '8 22.8 6.7 51 1 34.4 5.9 Trotteria & Aprostocetus 9 1 3.5 0.8 8 1 5.4 5.9 Aprostocetus 93 54 36.0 . 45.4 77 12 52.0 70.5 Tor7imus 19 9 7.3 7.6 1 0.7 . Pseudo- catolaccus 4 2 1.6 ,1.7 1 - _0.7 - Eurytoma 3 9 1.1 7,6 -- -- - Empty galls 5 5 1.9 4.2 - 1 - 5.9 that once again there were more Aprostocetus parasites in the galls in the "New Broom" and more Ttotteria larvae in the "Old Broom". Also, Torymus, Paeudocatolaccus and Eurytoma were rare in both broom areas and the percentage of Asphondylia larvae and pupae which survived was much lower than in 1960. SECTION V. Population estimations obtained from pod samples. A. Sampling Method B. "Old. Broom" area. 1. Anion fuscirostre 1960. a.Population estimations. b.Distribution of Anion in broom pods. c.Frequency of Anion in broom pods. d.Combinations of different insect species occurring in the same pods 2. Apion fuseirostre 1961. 3. Bruchidius allt 1960 and 1961. C. "New Broom" plantation. 1. Anion fuscirostre 1960 and 1961. 2. Bruchidius ater 1960. 3. Bruchidius ater 1961. 4. Distribution of Bruchidius ater on and within the pods. a.Distribution of eggs. b.Frequency of Bruchidius ater larvae in pods. 5* Combinations of different insect species occurring in the'same pods. 295.

Section V. Population estimations obtained from pod samples. A. Sampling method. Samples of 425 broom pods were taken in each broom area once a week throughout the season in 1960 and in 1961. (Not enough samples were obtained in 1959 for any population estimations to be made). In each sample in the "Old Broom" area, five pods were taken from each of 85 bushes, chosen systematically (and treated as random - see Milne 1959) over the whole area. Pods were removed from the top of the first bush, the middle of the second, the bottom of the third, the top of the fourth and so on, in each sample. A hand was thrust into each bush five times at the appropriate level; each time the nearest pod to the thumb was picked. In the "New Broom", the bushes were planted in 24 rows and five pods were "picked" (see above) from every nineteenth bush until a total of 85 bushes had been sampled. This sample covered the whole area of the plantation. In the first sample (S1) bush one, twenty, thirtynine and so on, were sampled; in S2, bush two, twenty one, fourty and so on were sampled. Thus,in all the samples made each yearno bush was sampled twice and several bushes in each nineteen Were not sampled at all. Dehisced pods were counted where they occurred in the samples in both broom areas and in some samples, (see Tables 2960.

40 and 41) towards the end of the seasons more than 425 pods were collected so that the number of undehisced pods was large enough to be analysed. Each pod sample was examined in the laboratory and the numbers of green, blackening, black and dehisced pods was noted. Each pod was measured (see p. 11 ) and then dissected under a binocular microscope. The fauna it contained was identified and the numbers and stages of each insect species were recorded together with the numbers of broom seeds and seed rudiments. From this data the following deductions were made. B. "Old Broom" area. 1. Apion fuscirostre, 1960 (a) Population estimations. The broom pod represents a self contained habitat for the immature stages of the insects which inhabit it. Thus, the numbers of eggs, larvae and pupae of any insect species in regular systematic (= random) pod samples will remain constant, since all mortalities, effects of parasites, hyperparasites etc., will theoretically be detected and recorded in each sample. Also, the number of infected pods will be constant in each sample; this occurrence of constant numbers will only take place however, after the oviposition of the adults has ceased and, provided that the adults oviposit throughout the whole area

2974

Table 4.0 Numbers and stages of the pods in the samples in both broom areas in 1960.

Date. Total. Green. Black Dehisoed Total Average Sample pods. pods. ening pods. pods. pods pod len- number. pods. examined gth(mn).

(a)liew Broom" plantation.

12. 6. 60 425 425 - IMP ••• 425 38.56 Si 19.6.60 425 425 %., I. ... 32 4.7.60 425 338 36 51 - 4 2 41 0:1 (71 53 11.7.60 425 230 38 157 .. 425 41.24 S4 18.7.60 4.36 109 26 290 11 425 40.89 S5 24.7.60 445 42 22 361 20 425 40.78 s6 31.7.60 4.61 20 10 395 36 4.25 40.31 87 8.8.60 4.66 4 7 357 98 368 40.34 58 15.8.60 500 1 6 308 185 315 40.50 S9 23.8.60 850 2 1 377 470 380 39.08 S10 2.9.60 665 - - 212 453 212 38.47 Sit 9.9.60 500 1 - 137 362 138 37.20 S12 17.9.60 500 - iii 389 111 37.01 313 (b) "Old Broom" area. 8.6.60 425 425 - - 425 36.67 Si 15.6.60 425 425 ... - 425 37.55 32 22.6.60 425 425 - . - 425 37.21 33 29.6.60 425 397 26 2 ... 425 38.97. 84- 6.7.60 4425 344 43 38 - 425 39.73 35 13.7.60 425 180 37 208 ... 425 39.99 86 20.7.60 432 57 25 343 7 425 39.43 87 27.7.60 453 4 7 414. 28 4.25 39.4.0 38 3.8.60 4.80 1 8 376 95 385 39.02 89 10.8.60 600 - - 331 269 331 37.97 S10 17.8.60 850 - - 349 501 349 36.94. S11 25.8.60 500 - - 14.9 351 149 36.03 512 1.9.60 900 .. 224 676 224 37.19 313 7.9.60 500 - - 107 393 107 35.34 314 15.9.60 500 - - 85 415 85 36.26 815

298.

Tab3.e 41 Numbers and stages of the pods in the samples in both broom areas in 1961. Date. Total. Green Black- Black Dehisced. Total Average le pods. pods. ening pods. pods. pods pod len- er. pods. examined. gth (nun)*

(a) "New BrocaPplantation.

12.5.61 425 425 AM 40 40 425 29.63 Si 18.5.61 425 425 - . . 425 30.89 S2 . 10 40, 340 66 83 25.5.61 425 425 425 2.6.61 423 423 40 110 425 39.47 34. 00 Oa 8.6.61 423 425 425 400 24 35 10 M. 06 56 13.6,61 425 425 425 00 30 011 06 22.6.61 425 4.25 . '425 41001 37 29.6.61 425 420 5 . . 425 40.73 Se 6.7.61 424 311 28 85 1- 424- 40.67 S9 13.7.61 432 100 25 300 7 425 41.12 310 20.7.61 425 9 . 5 401 10 415 40.28 511 31.7,61 425 71 - 321 97 328 39.47 812 9.8.61 425 258 167- 258 38.82 813 (b) "Old. Broom" area.

15.5.61 4.25 4.25 Y. 60 425 27.42 Si 23.5,61 425 425 - 425 31.56 S2 29.5.61 425 425 . S. 425 34.39 33 5.6.61 425 425 . . 425 37.40 84. 12.6.61 425 425 . . 425 40.99 35 20.6.61 425 425 ... 40.! 425 40,29 s6 26.6.61 423 425 . . 425 40.16 87 3.7.61 425 365 10 50 - 425 40.30 s8 10.7.61 442 153 28 242 19 425 40.33 s9 17.7.61 425 18 10 367 30 395 40.61 810 24.7.61 500 3 3 419 75 425 39.95 311 3.8.61 425 2 118 305 120 38.92 Si 2 8.8.61 4.25 104 321 104 35.95 813 25.5,61 .425 45 380 45 32.74 814. 299*

sampled. The latter is assumed in the following calculations. The basic figures obtained from the examination of the samples (with slight modifications, see below) are direct estimates of the numbers of the different species of insects found in pods collected throughout the area (i.e. of the populations in the area.) No elaborate methods, such as those of Richards and Waloff (1954), for estimating mortality are required. This seemingly ideal habitat for sampling does however present difficulties after the pods begin to dehisce, since the larger ones dehisce earlier than the small ones. The mean lengths of the pods in the "Old Broom" samples (Table 40) show the growth of the pods up to an average length of 39 to 40 mm. in samples S5 and 86. In S7, S8 and S9 the average pod lengths are close to those of S5 and S6, showing that the first pods to dehisce, do so in proportion to their distribution of lengths (see p. 11 ). But, after 89, as larger numbers of pods dehisce, the average pod length decreases showing that the larger pods are opening faster than the smaller ones. Thus, whereas all samples before S9 should contain comparable numbers of Apion, as soon as pod dehiscence becomes inequal,(i.e. in 810 to 815) the numbers of insects in these later samples cannot be directly compared with those in the earlier ones. 300,

To correct this error, the.poda were divided into six groups according to their lengths. The total number of pods ' in each group was found in S1 to 85 (i.e. before dehiscence :began) and the percentage of pods in each group was calculated ,from the totals of these samples (Table 42). As the average pod length decreased (i.e. in 810 to S15) the percentages of pods in the smaller length groups increased and in the.larger length groups they decreased; these pereentageb were re-calculated in each sample and the results obtained in S10 are shown in Table 42. Thus, dbserved numbers of Anion occurring in each pod length group could now be corrected to:those which-would have been present, had pod dehiscence been proportional to the distribUtion of pod lengths. ?or-instance, each number of insects occurring in sample 810, pod length group 3 (see Table 42) was. multiplied by the percentage of pods occurring in group 3 in the SI to St totali (i.e. 47.9) and then divided by the percentage of pods occurring in group 3 in the S10 total (i.e. 54.1). Similar corrections were made in all of the samples after.810.before any analysis was made. As already stated, if one allows for sampling errors, each sample should contain approximately the same number of infected pods and approximately the same number of Anion provided that Anion oviposition has ceased and no pods have dehisced. The first six samples (Table 43) have similar

301.

Table 4.2 Correction of the observed numbers of individuals found in pod simple 810 in. the "Olt Biome area 1960, to what they would hive been had poi dehisoenee been proportional to the distribution of poi lenObs. Groupe et pod lengths. 1 3 4 ' 5 Under 21 2-30 3i -40 41 .50 51 60 oner Total 20 s. me. m4 IOU ma. 61ms. To 31 313 1017 668 94. 2 2125 Si to 35. % Pods. 1.5 14.7 47.9 3144 4.4 0.1 100.0 Total pods in 610. 1 41 179 98 12 331 % Poe& 0.3 12.4 54.1 29.6 3.6 100.0

Total number' surviving has - 1 16 15 2 iss 810. No. parasitised. Anion in MO. 9 49 54 5 • 117 No. deal ads in S10. 13 1 - 37 TOTAL Ads Cornetati12121 fidtares.(Ketimid. shown in text.) Total number survi ving Ads - 1.2 14.2 15.9 2.4 33.7 Parasitised &lap 10.7 43.4 57.3 6.1 117.5 Dead A via% - 3.6 17.7 13.8 1.2 36.3 00IMOTED =AL. Table 43 Numbers of immature stages of Anion fusoirostre found in he pod samples in the "Old Broom" - • . in 1960. Observed numbers. "pod dehiscenoecorreoted numbers. Sample 81 52 83 54. 85 56 S7 88 59 510 311 812 513 314. S15 810 511 S12 513 314. 515 egg. 187 197 103 54. 21 17 10 2 3 OP.

Instar I. , - 22 55 55 30 43 3 ' 6 1 - - OW POW

Instar II. - - 42 53 31 9 6 - - - IOW IMP

instar Ills - 4 15 142 96 49 29 7 - - - OW OW •••

Pre-Pupa. - - . - - 13 26 3 2 - - OOP .111 IOW OW WIP

Pupa. - - - 8 4.0 71 30 • 8 1 ' - - 7.9 '1.1 POO OOP

- - 6. yob MO .. Adult. 4.. 7 26 16 5 18 4 1 25.8 17.4 5.4. 18.1 3.9 1.0 Parasitised. ------5 21 6i 404 117 64. 4.0 -48 21 8 117.5 72.8 40.6 48.2 18.5 8.8 larvae. Dead. larvae. - 7 18 37 56 27 55 27 19 36.3 55.6 28.4 56.6 27.7 19.6

Total Anion. 5 21 68 122 154.120 67 03 48 27 153.8 128.4 69.0104.8 46.2 28.4. mortality.

Total Anion, 187 219 204. 177 494 191 155 179 172 188 1.37 72 121 52 28 187.5 446.9 74.4122.9 50.1 29.4

Total number .106 128 117 107 115 111 101 119 111 110 97 45 80 35 18 os• OW. of pods with c.a A pion. 0 303.

numbers of Anion infected pods and the mean of these was taken as approximating to the true number in a sample of 425 pods. 684 114 pods (k40 fiducial limits ± 6.48) 6 The numbers of Apion of all stages in these six samples were also similar and the mean was taken as the true value. = 11726 195.3 individuals. (5% fiducial limits ±11.70)

Al]. of 'the Samples were corrected, to 114. infected pods including the ."dehiscence corrected" figures in samples 310 to S15 (Table 44). Thus, all of these samples are comparable and the . occurrence of various immature stages of Anion are tabulated. The average numbers of Apion in the 114 infected pods was higher in the earlier samples when many eggs were present. All the eggs which failed to hatch and shrivelled up and the first instar larvae Which:failed to find seeds were not found in the later samples. To calculate this mortality the mean.numbers of Apion in the corrected samples S10 to S15 were found

12226 s2 = 180.0 individuals (5% fiducial limits It 9.30) Thus, in the first samples there were approximately 195.3 individuals and in the later samples only 180.0. /,195.3-180.0 122 Therefore mortality of egg and instar LA 195. 3 7 al Table 44 Numbers of immature stages of Apion fuscirostre corrected_ to a. constant infection of 114. pods per sample. Sample. Si S2 83 S4 25 66 ST S8 S9 810 811 S12 S13 S14. 215

A3g. 201.1 175.4-100.4 57.5 20.8 17.5 11.3 109 30 IVO LaMar I. - 19.6 53.6 58.6 29.8 44.2 3.4. 5.7 1,0 ... - Instar II. 40.9 56.5 30.7 9.2 6.8 -

401.• Instar in. 3.9 16,0 111.0 98.6 55.3 27.8 7.2 - .4 - - Pre-pupa. - - 13.4 29.3 2.9 2.1 - - - Ptpa. - - - - 8.2 45.2 68.0 30.8 8.2 1.3 .. ..

Adults. Ai .7.2 26.7 20.4 13.7 25.8 12.7 6.3

Parasitised 410 5.1 23.7 58.4.106.8 121.8 85,6 102.9. 68.7 60.3 55.7 larvae.

Dead. larvae. rr a. 6.7 18.5 37.6 6'5.3 71.9 80.7 90.2 124, 2

Total Auion MO 5.1 MT 65.1 125.3 159.4. 150.9 174.8 149.4. 150.5 179.9 mortality. Percentage Anion, 2.6 12.1 33.3 64.2 82.3 mortality on 195.3 individuals.

Total _Apion 201.1 195.0 198.8 188.6 192.3 196.2 175.0 171.24.176.7 1924-.3 172.6 188.5 175.2 163.2 186.2 305.

No mortality eras detected in the second instar Apion larvae, Third instar Apion larvae suffered mortality from parasitism, mostly by Hdbrocytus sequester', although the column in Table 44 includes' all of the various parasites that were found. More detailed data on parasites are given in Table 45 and their life histories haVe been described. In Table 44 the column of "dead larvae", refers to those instances where both host and parasite larvae died due either to superparasitism (p.167 :) or.hyperparasitism (P.183 ) or to some other unknown cause. The "total Apion mortality" column (="parasitism" plus "dead larvae") is shown in Table 44 and the percentages of mortality are calculated on 195.3 individuals so that they can be used in conjunction with the egg and instar I mortalities to build up a life table of Apion. Samples 310 to S15 have similar percentages of parasitism and only the mean is given in the table. Parasitism did, not increase after S10, since there were no Apion hosts left. In all of these calculations it is presumed that the individuals thrown out of the dehiscing pods are parasitised to the same extent as those left in the unopened pods. Thus, to sum up, the Apion population suffered:- Mortality of eggs and,instar I. 7,8 per cent Mortality owing to parasitism etc. 82.3 per cent Total mortality in the pod 90.1 per cent 306

Table 45 The numbers of the various parasites and hyper-parasites found on Apion fuscirostre larvae and. pupae in the "Old Broom" samples in 1960. Sample S6 87 88 S9 810 811 S12 813 814 815 ffabrocrbia sequester Eggs, 1 5 16 2 1 IOW larvae. 16 41 71 46 2 1 Pupae. 10 25 21 14. 8 Adult s. 1 6 12 20 MesopolobUs mediterraneus Eggs„ 6: 18: 8 tarete. 20 16 Pupae 4-Adults. 2 Apavatooetus tibialis. 34- 4. Torte sp. nr. mioropterus Eupelmus urozonus. 2 2 • 1 Isestodiplos s sp. *Mr

Anth000ris sarothamni. 1 al• 21 61 104 117 64. 40 48 21

Ftrasites dissected from liabrocytus pupae. 307.

Therefore 9.9 per cent of the eggs laid. into broom pods in 1960 produced adult beetles. The number of Anion larvae and pupae thrown out by the dehiscing pods' Was not investigated. but this mortality is probably low* Few (i.e. 20%) of the pods had dehisced in 89 When the numbers of Anion pupae were already decreasing rapidly as the adults emerged. This source of mortality is much more likely to affect the larvae of the parasites. ' The numbers of ,Apion adults which emerged from pods in 1960 were reduced by everwihtering mortalities (p. 135 ) 'and by dispersal. Fewer'adUlts were:found in the spring of 1961 than in the spring of 1960 (Pig. 17) b. Distribution of Anion in broompods. The total numbers of pods of various lengths, infected with one or more Anion in samples 81 to S5* are shoWn in Table '46(a). The pods are divided into similar sets as in Section I (see Table 6). ARM squared teat, using the expected valueS obtained from the hypothesis that the number of infected pods in each ,set is proportional to the total number of pods in each set* showed a highly significant difference. Thus* the Apion infected pods are not normally distributed* as are the pod lengths (p. 11 ) but are grouped in some way. An inspection of the data shows that greater percentages of the larger pods, are infected.. 308.

Table 4.6 A series of X2 tests showing a significant difference between :- .(a).the distribution of Apion infected pods of various lengths and, the normal distribution of pod lengths in samples Si to 55. (b).the ,:distribution of numbers of Anion. individuals in pods of various lengths and the normal distribution of pod. lengths in samples 81 to 35. (o).the distribution of developing seeds in pods of various lengths and the distribution of won -

Under. 26-30 31-35 36-40 4445 46-50 51-55 Over Total 25mm mm nnn mm mm can mm 56mn (a). Nosoof pods Si to 35. 110 234. 428 589 444. 224. 76 20 2125 No a. infected pods S1 12 29 98 .181 151 75 22 5 573 to s5 infected pods 10.9 12.4 22.9 30.7 34.0 33.5 28.9 25.0 100.0 X2 expected values. 29.7 61.3 115.4. 158.8 119.7 60.4 20.5 5.4 573.0 2 P=x:..001 (b). X- (7)22 g-LZ Nos.of pods Si to 55. 110 234. 428 589 444 224. 76 20 2125 Total no. Apion 9 30 104. .182 180 73 26 6 610 X 2 expected values. 31.6 67.2 122.9 169.0 127.5 64.3 21.8 5.7 610.0 X 2(7) Pr.-.‹.001 C. Total nos. seeds 356 889 2198 2364 2343 1283 4.19 10,4.52 Total no. Apion 39 104 182 180 73 26 .6 6i0 x2 expected values. 20.8 51.9 128.3 173.0 136.7 74.9 24.4 610.0 2 X (6).= jigja P=<=.001 309.

The distribution of numbers of Apion individuals found in"pods in each length group is also significantly different from the normally distributed pod lengths. Again there are. more individuals in the larger pods. (Table 46(b)). The distribution of numbers of developing seeds in pods of various lengths has already been discussed (p. 18 ),and this distribution was also significintly different front the distribution of Anion individuals. (Table 46(c)). Thus to sum up, Anion females avoid the smaller podS; they do not'however lay eggs into the larger, pods in proportion to the numbers of seeds the pods contain. - c ► Frequency ofAnion'in broom pods. The numbers of pods containing different-numbers of-, Anion. individuals in .81..to S6 are shown in Table 47. The -calculated expected values assuming a Poisson distribution are also shown. Table 47. The frequency of different numbers of Anion fuscirostre individuals occurring in broom pods. Number of Apion individuals. 0 1 2 3 4 5 6 Total

Total No. pods S1 to 86. 1866 389 170 80 28 11 6 2550 Expected Poisson Value. 1610.5 740.1 170.1 26.0 3.0 0,3 . 2550 X2(2)= 519.68 P < .001

A Khi squared test showed a highly significant difference 310.

. between the expected and the observed. values. As the , observed number bf,Pods with no Apion and the expected number With one Anion areboth too.high to approximately equal extents, a binomial distribution is indicated. This.grouping.has been Shown above to be more confined to the'larger pods. d. Combinations of different insect species occurring in the same'pods. The total numbers of Anion, Bruchidius, Contarinia and Aanhondylia and the obServed combinations of these species occurring in the same pods, were Obtained, from the "Old Broom" samples, The expected number of occurrences of. each combination were calculated, on a.NU11.Hypothesis and all of these species were founcl to be significantlyAndependant of each other in the pods, The pods infected with 'both. Avion and Contarinia gave the'greatest X2 value, but this was only significant at. the P'=. 0,5 level (see Table 48). The distributions of these two species are connected as has been discussed on 14'207* 2. Anion fuscirostre 1961. Although the total population in the "Old Broom" was slightly smaller in 1961 than in 1960, the numbers of ,Anion infected pods were low* Only 10 to 20 pods were infected in each sample and the variation was so great that no analysis was attempted. (Appendix _T_TT ) Reasons for this low incidence are obscure* The warm dry 311.

Table 48. The combinations of Apion and Contarinia occurring together in pods in the "Old Broom" area in 1960. Sample S1+2 83 S4 S5 86 S7+8 S9+10 Sll to 15

Total nos.pods with Anion (A) 234 117 107 115 111' 220 221 275 Total nos, pods with Contarinia 26 26 '22 19 2/ 32 '22 , 21 Total nos* pods with A.+ C. 12 7 8 8 8 5 5 6 Expected nos, pods w. A + C 7.7 .7.2 5,5 5.1 5.5 8.3 6.8 6.3 Total pods 850 425 425 425 425 850 716 914 X2 (7) = 0.12 (i.e. not significantly different from the Hull Hypothesis, P = 0.5) weather in the first half of May and then the heavy frosts towards the end of the month may have killed early Apiaa eggs 'without damaging many of the pods (p. 7 ). Also these- climatic conditions may have affected the adult beetles in some way, although this was not obvious from the dissections, 3. Bruchidius ater 1960 and 1961. In both years there were approiimately 2000 adult beetles in the "Old Broom" area during the oviposition period. However, the high egg mortality reduced the numbers of larvae to 'a low level. Four to five pods per sample contained larvae in 1960 and 10 to 15 pods in 1961. These population data were small and no analysis was attempted. (Appendix IV ). It is unknown from where the population of adults which emerged 'from hibernation in the "Old Broom" area in1961 originated. Probably this population was composed of a few 312.

beetles which had emerged from "Old Broom" pods in 1960 and of others which had immigrated from other broom areas.

C:, New Broom plantation, 1, Apion fuscirostre 1960 and 1961. Although there were Tightly more Anion adults in the "New Broom" than in the "Old Broom" in 1960, there were also 16,5 times as many pods (P.29 ). The numbers of infected pods per, .sample varied between 17 and 37; these data were insufficient for further analysis, (Appendix III). In 1961, approximately 5,500 beetles were present in the plantation during the oviposition period (Fig. 17). The number of pods however, was greatly reduced by frost and many. Apion eggs were killed. The unknown factors which caused the low incidence of Anion in the "Old Broom" area in 1961 also affected it in the "New Broom". As only 10 to 15 per cent of the pods were infected and the variation in the range of infection of successive samples was great, no detailed analysis was attempted (Appendix III). 2, Bruchidius ater 1960. The numbers of all of the stages of Bruchidius found in pod samples in the "New Broom" plantation in 1960 are shown in Table 49. Once again the larger pods dehisced earlier than the smaller ones after sample S9 (see average pod lengths Table 40) so that the numbers of insects found in samples Table 49. Numbers of immature stages of B fond in the pod samples in the "New Broom* area in 19 Observed numbers. "Pod dehisosnoencorrestei lumber* Vie. Si 32 83 sh. 35 36 37 38 39 310 sii 812 8i3 310 311 812 813 Matta.' I. 14. 54 41 30 9 7 I II. 5 56 47 18 11 1 V III. 72 51 45 27 7 1 1 Instal' IT. - 19 71 88 96 52 33 17 9 9.8 1.2 PromPupa. - 1 1 18 19 19 7 6 3 3.2 1.2

Pupa. IMO - 2 21 34 74 55 40 19 5 20.6 6.2 Adult. 15 44. 27 57 29 28 17 61.9 35.9 32.1 18.4- Parasitised, ; 27 35 85 80 91 111 39 26 22 122.6 42.1 24.6 23.2 lam

Dead larvae. 011. - i6 14 21 31 27 28 10. 10 3 29.7 10.8 9.8 2.6 Total "mobid 3 43 49 106 111 118 139 49 36 25 152.3 520 34.4. 25.8 ins martially. Total 14 59 189 205 2f2 24.3 2 251 209 227 85 64 42 247.8 97.4. 66.5 44.2 Bruohidtms

Total mbar 10 29 115 116 134 129 146 128 116 131 53 32 23 vat of pods with BrnoIddlin; 314.

after this date had to be corrected as described in the previous analysis of Apion fuscirostre (p. 301). After oviposition had finished and all Bruchidius eggs had hatched (i.e. after sample S4), the mean number of infected pods in samples 85, S6 and S7 was calculated. This was taken as approximating to the true number of infected pods per sample. 409 to nearest whole nutbgr) = 136 (5% fiducial limits =,:, 9.88) All samples after S4 were corrected to, 136 infected pods (Table 50), The mortalities of Bruchidius eggs on the outsides of pods and of first insuar larvae during the tunnelling period are not included in the observations within the pods. Thus, as shown in Table 50 the numbers of larvae found in seeds are similar in each of the samples after S4. The true number of larvae in each sample was taken to be the average of samples S5 to 813. = 2319,9 = 257.8 individuals (5% fiducial limits = ± 7.6) Table 50 shows the percentages of Bruchidius larvae and pupae that were parasitised in each sample. Parasitism by the braconid Triaspis sp. nr. obscurellus was recorded when the parasitic larva had killed and emerged from its host larva. However, it must be remembered that this parasite oviposits into the eggs'of Bruchidius. The paiiasitism shown in Table 50 includes all the 315

Table 50. of iseature stages of Brtnkl.Itit Aux corraoted to a oonatext infection of. 136 Polls per u 1a ( last ain• sasWilss only, Mew Broom* 1960. 85 16 87 X38 89 810 811 812 813 Inst." L Instar 18.3 11.6 0.9 Initar 45.7 28.5 6.5 1.1 1.1 Instar IV. 89.3 101.2 /48.4 35.1 19.9 10.2 3.2 Pre.pupe, 18.3 200 17.7 74 7.0 3.2 3.2 Pupa. 21.3 35.8 68.9 58.4 46.9 21.4. 15.9 Adult. 14.0 46.8 31.7 64.3 92.0 1364 108.8 Paraeitiaet 274 36.9 79.2 85.0 106.7 127.3 108.0 1044 1374 lanes. Dee& larvae. 16.2 14.8 19.6 32.9 31.7 30.8 27.7 41.6 15.4 %Pandtisollii.2 14.4 31.0 31.9 43.6 1.145 0.2 YNO 52.5 %Deal. 6.6 5.8 7.7 12.3 12.9 12,0 11.1 14.7 5.9 Total % 17.8 204 38.7 44.2 56.5 61.5 54.3 51.7 58.4 mortality. Total 210.5.6 256.2 255.2 266.7 245.0 2574 250.0 282.6 261.4 Bnkstfitgus. 316.

hymenopterous species that were found. More detailed data on the various parasites are given in Table 51. This table also shows the numbers of larvae that died owing to the early "maturation" of the seeds in which they were enclosed (p. 114 ). Table 51 (a) The numbers of the various parasites found on Bruchidius ater in. the "New Broom" samples in 1960. (b) The numbers of Bruchltdius ater larvae which died owing to various causes (New Broom 1960). Sample 84 85 86 S7 88 89 S10 Sll 812 S13 (a) Triaspio 3 24 30 57 38 54 61 18 15 n Hdbrocytus 3 5 23 30 36 46 17 10 11 Mesoriolobus 5 12 1 4 4 1 (b) Instar I 401. 1- 4 2 - Instar II 4 - 8 1 - Instar III 9 11 9 22 23 24 8 Instar IV 2 3 - 6 4 4 2

Parasitism by Habrocytus WAS low and hyperparaeitism by Mesopolobus was rare. No instances of mortality of all species concerned, resulting from superparasitism or hyperparasitiam were observed. The total percentages of parasitism and of larval mortality of Bruchidius are shown in Table 50. These percentages are calculated from the total estimated numbers of Bruchidius individuals in each sample (not as in Amion). Table 50 shows that just under half of the larvae which had entered the seeds, produced adults. Thus, the Bruchidius adult population emerging from the pods was much larger than the parental population in 1960. Also 317,

the adult population samples showed that twice as many Bruchidius-adults emerged from hibernation in 1961 than in 1960 (Fig. 7A, B and C). 3. Bruchidius ater 1961. Samples of pods taken in 1961 in the ''New,Broom" ,plantation are shown in Table 41. The pods developed earlier in this year (p.7 ), Late frosts in May however, killed a large proportion of the young green pods (p. 6 ) on which many Bruchidius eggs had been laid. Thus, awing to the large population of beetles in the area (Fig 7B and C), the numbers of eggs laid, after the frosts, on each remaining unaffected pod, were greatly increased.. In many instances* much larger numbers of eggs were found On pods than there were seeds within them. Under these conditions in the field, "competition" for seeds by the first instar'larvae cautsed high mortality. Dead first instal:, larvae in the seed entrance tunnels were counted' in samples S60 7, 8 and 9 (Table 52). Table 52 shows the dbserVed numbers of Bruchidius larvae and pupae foUnd in the pod samples and' it also includes the numbers of unhatched eggs found on the outsides of the pods. It can be seen that eggs were laid on more than three quarters of the pods in the plantation (i.e. 330 to 340 pods in every 425), but larvae only developed in half of the pods in the

Table 52. Numbers of immature stages of in ua As found in the pod in. tbs "New Br area "Pod dabisoenoe" Observed numbers. corrected numbers. Si S2 83 84. S5 86 87 88 89 S10 Sii S12 813 812 813 Eggs. 44.0 532 1068 922 14,31 1611 1170 889 828 / / / Instar I. - .. . - 3 65 397 314 - 57 7 Instar .. - - . 2 190 192 18 . . . Instar — PO MP OM NW 011 .. 17 241 76 13 1 . 1.3 - Instar IV. . - - . . . 91 362 301 35 13 34.3 12.7 Pre-pupa. - 4.- . ... - - . - - 6 46 12 4. 13.6 4.3 a* all. 4* 01.11, WO mat. .. - .. 9 -6-‘ ill gl 19492 gl. No.pods 'with eggs. 128 120". 206 196 295 ;28 330 339 34 / / / / Dead instar I duet to "oompetition". - - - 6 127 292 232 --- not reoorded ---

Triasois. ds, 37 72 156 119 Parasitise& Bruohidius Habrocartus. OW 2 15 34 5 200.2 13(x.2 larvae. limeade's!. - 3 4. 2

Dead Bracbidius larvae* *It 20 26 12 4 11.3 4.1 No. pods containing - 24 127 211 230 224 227 168 123 Bruohidius larvae. Total no. "'Tualatin - 7 526 813 814. 537 54.0 394- 281 408.8 298.5 larvae.

319.

plantation (i.e. 210 to 230 pods in 425). In samples S8 and S9 the percentages of larvae which hatched and entered pods, but subsequently died mainly as a result of "competition" were 35.9% and 28.5% respectively. The true number of pods in'which larvae were found in each sample was taken as the mean of samples 89, S10 and 311. 681 227 pods (55 Piducial limits 3.39)

Samples 812 and 313 were first corrected (p. 301 ) since the dehiscence of pods was not proportional to the- distribution of their lengths (Table 41), Then, all of the samples from S9 onwards (i.e. after all larvae had entered seeds) were corrected, to the number of 227 infected pods (Table 53). The percentages of parasitism and other causes of mortality of the Bruchidius larvae in the seeds are shown in Table-53. Individual numbers of each species of parasite are listed in Table 52. Thus, in 1961 the mortality due to parasitism and to causes unknown did not rise much above 50 per cent, this 'being lower than in 1960. However, the death of eggs laid on pods which were subsequently killed by frost and, the death of larvae "competing for seeds, were extra causes of mortality in 1961, which were not incurred in 1960. Thus, in 1961 the total mortality of the immature stages 320.

Table 53. Numbers of immature stages of BruclAdius aUx corrected. to a constant infection of 227 pods per sample ( last five samples only, "New Broom" 1961).

811sPla S9 810 811 Si 2 Si3 'near I. 56.3 7.1 - - .. Inetar 11. 189.5 18.2 - - - Instar III. 237.8 77.0 13.0 1.8 . - Instar IV. 89.8 366.9 301.0 46.3 23.4 Pro-PuPs. 6.1 46.0 18.4 7.9 Pupa. 9.1 64.0 175.5 169.1 Adult. - 24.6 102.6 Parasitise& larvae. 39.5 90.0 270.5 240.3 Dead larvae. 1.0 20.3 26.0 15.3 7.6 % Parasitised 7.3 16.7 49.0 43.6 % Dead.. 0•2 3.7 4.8 2.8 1.4 Total Percentage mortraity. 0.2 11.0 21.3 51.8 45.0 Total Bruahldius•574.4 54442 540.0 552.4 550.9

Table The numbers of Bruchidins satt infected pods of different lengths fount in sample Si in the "New Brow" plantation in 1960. Sets of pod lengths. Under 31 -35 36 -4 41 .45 4.6. 50 Over Total 30 ma. - nab nu acre. 3iram. Total pods in Si. 66 77 103 99 52 28 Infected pods in Si. 6 13 32 37 30 19 137 X2 expected values, 21.3 2448' 33.2 31.9 16.8. 9.0 137.0 xt5r 38.8 p4.00i 521.

of Bruchidius was much higher than in 1960. This is further shown by the small numbers of adult Bruchids that emerged from pods in 1961 (Fig. 7B and C). 4. Distribution of Bruchidius Ater on and within the pods. a. Distribution of eggs. In the earliest sample - Si, in the New Broom plantation in 1960, all Bruchidius oviposition had not finished and the pods were not yet fully grown. It was assumed however, that the lengths of the pods were normally distributed throughout the field and, that the selection of pods on which the Bruohids oviposited was constant throughout the oviposition period. The numbers of .pods of various lengths on which one or more Bruehidius eggs were laid in sample Si are shown in Table 54. A Khi squared test shows that the distribution of infected pods is significantly different 'from the normal distribution of all of the pods in the sample. An inspection of the data shows that there are too many infected large pods and too few infected small ones. Thus, when ovipositing, the female Bruchidius avoids the smaller pods more than the larger ones. (as does the Ation adult). The distribution of the larvae in pods confirms this. As with the Apion larvae in the "Old Broom" area again there is no connection between the distribution of Bruchidius larvae and the numbers of seeds in the pods in the "New Broom" plantation. 322.

b. Frequency of Bruchidius ater larvae in pods Table 55 shows a significant difference between the expected values of a Poisson distribution and the observed numbers of larvae in broom pods. Once again* as with the Anion larvaepthe distribution of Bruchidius larvae is binomial, in other words it is grouped. Table 55. The frequency of different numbers of Bruchidius ater individuals occurring in broom pods in the "New Broom" in 1960. Number of Bruchidius individuals 0 1 2 3 4 5 6 7 8 Total

Total no. pods 83 to S7. 1485 352 164 65 34 15 5 2 2125 Expected Poisson value 1235.1. 670.2 181.8, 5.0 2125 30(3) = 817.9 P •x.00'

5. Combinations of differentinsect species occurring in the same pods 'As the number of pods infected by Contarinia was so small (Table 34) there were few occurrences of this species in pods which were also infected by either Ai:don or Bruchidius. NO analysis was attempted. = the email amount of data. 323.

SECTION VI. DISCUSSION The general factors which influence the stability and cause fluctuations in any insect population, fall into well defined but interdependent groups. These include; the influences of the habitat, the influences of climatic factors, intraspecific factors and the effects of.interspecific factors including parasitism and predation. These factors are classified according to what they do to influence an.animalts chance to survive and reproduce, (similar to the concept of Andrewarthaiand Birch (1954) )4. Throughout the discussion, references to the nature of these factors (i.e. density, ,dependent etc.) have been included. This study, however, only extends over two seasons and it, is not possible to demonstrate the exact influence which each of the above factors plays in determining population levels. A long-term project, extending over a minimum of five years, such as that of Richards and Waloff (1961) on Phytodecta olivacea on, broom, is the only way to attempt to demonstrate these factors. However, in this study, it is possible to show how some of the factors influence the population fluctuations from year to year. The influence of the.habitat is of great importance in this study since. the tuidehisced broom pod is only a temporary 324.

"micro-habitat" which occurs in the field at Stlwood Park. between Lay and September in each year. The exact times of -pod development vary in-each year according -to the influence of climatic factors and it has been Shawn:that in 1961 the pods: developed l0 to 14 days.earlier than.in 1960. It was found that the pod "habitat", could be divided into three almost independant "micro-micro-habitats" in each of which. a, different set of insect species occurred. 'These habitats were; the broom sepd; the pod cavity and the pod gall of Asrehondylia sarothamni. In the preceeding sections of this study the insect .species occurring in each of 'these habitats have been described in detail. The age of the broom bush affects these pod "micro-habitats" in that' smaller,pods with fewer seeds are produced as the bushes. grow older. Thust.the Apion and Bruchidius larvae have a slightly reduced chance of finding a seed in. each consecutive year on' the Same broOm:bush.' . . As broom is a perennial the adult insects do not necessarily need to be highly mobile. Both species of beetles are however, very active in.the adult stage, especially When the_broom is.in. flower. Whether there is any difference in the "food - value" of the seeds produced by older.bushes is unknown and effectt of this factor on beetle larvae were not detected. :However, a small' number of Aston and Bruchidius larvae in both broom areas.died 325.

when the broom seeds which contained them "matured". This factor is further discussed on p. 114. Also, as the Apion adults feed exclusively on the broom plant, it seems possible that the ageing bush may provide a less adequate diet and thus reduce the fecundity of the beetles. The larvae of the three species of Cecidomyidae which occupy the same habitat in the broom pod cavity are probably not affected by the alight decrease in pod length as the broom grows older. The gall of Aaphondylia is a plant growth which develops in response to and around an insect infection. Thus the larva of this species develops within a habitat of its own formation. In this instance the insect has some effect on the habitat instead of the opposite, more usual, occurrence. Another important feature of the influence of the temporary habitat is "pod dehiscence". The immature stages of many of the insect species which live within the pod must therefore develop rapidly, before this occurs. These species include the Apion larva, which cuts out of the seed testa in the third mater and all of, the species which live either as parasites of Apion or as pod cavity dwellers. It has been shown however, that Apion is mostly in late pupal or adult stages when the pods begin to dehisce in large numbers. Many of the hymenopterous larvae which parasitise Apion however, are thrown out of the pods before they have finished 326,

feeding. These larvae presumably die if they are too small to pupate. The numbers of these larvae which died, or pupated on the soil was not investigated quantitatively. By contrast, each Bruchidius larva develops completely and pupates within the tough, intact testa of a broom seed. Thus, even when the pod does dehisce, this species and all of the species which parasitise it are still protected. by the seed testa. It was presumed that the ma jority of the TriasDis and other parasitic larvae of Bruchidius that were thrown onto the ground inside broom seeds, developed and emerged normally. The larvae of Contarinia leave the pod cavities before dehiscence begins, but many young Clinodivlosis and Lestodiplosis larvae are thrown out of dehiscing pods. These larvae may be able to survive on the ground by utilising other food sources, but this is a subject for further research* The insects living in galls are not affected by pod dehiscence since the galls never dehisce with the rest of the pod* In many instances the gall is still green when the rest of the pod is black and dry and partially dehisced. Climatic changes are, most commonly* the major factors which cause large annual changes (i.e. outbreaks etc.) in insect populations. However, since macro-climate is never influenced by the density of any insect population, this factor alone can never "control" (Milne 1957) the fluctuation of that 327.

population. The favourability or unfavourability of this density independent factor does, however, affect the ultimate fluctuations of populations at the lower extinction level (Milne 1957). In both broom areas in 1960, climatic factors were close to the expected averages of the last 30 years and no obvious effects on the insects within broom pods were experienced. In 1961, however, the dry, hot weather in the early spring months and then the sharp frosts at the end of May had both a direct and an indirect effect on these insects. The direct effect of frost was the killing of all of the Apion and Bruchidius eggs laid on pods which were killed. The indirect effect was the reduction of the total number of pods (i.e. the components of the habitat) especially in the "New Broom" area. Also, these frosts and the dry weather at the beginning of 1961 probably affected the pupae and reduced the nudber of Contarinia adults which emerged from the. soil. The warm weather also caused As-phendylia adults to , emerge from broom bud galls before broom pods were formed and thus the emergence of this Cecidomyid was not synchronised with the availability of the habitat. Thus, climatic factors had a major influence in reducing the numbers of Contarinia and Asphondvlia infected pods in 1961.

Climatic factors also influenced the development and 328.

dehiscence of pods but this has already been discussed. Intraspecific competition, usually for food or space, is one of the main upper limit regulating factors in insect populations. That is, it is perfectly density dependent (Milne 1957) although Solomon (1958) does not believe such a condition can exist except at high levels of abstraction. In 1961, intraspecific competition for broom seeds (i.e. directly for space and indirectly for food) between the first instar larvae of Bruchidius was Observed in the "New Broom" plantation. A large population of Bruchidius adults and a small number of broom pods were present in the plantation in this year owing to the effects of two other factors. Firstly, the low percentage of parasitism of Bruchidius larvae in 1960 caused a doubling of the size of the adult population which oviposited in 1961 (compared with that in 1960). Secondly, the late May frosts in 1961 killed 62 per cent of the pods in the plantation. The resulting mortality of the first instar Bruchidius larvae (which either failed to find a seed or died in the entrance tunnel of a seed already occupied by another larva) rose to 35 per cent of the total number of larvae which entered the pods (Table 52). Ullyett (1950) discusses similar intraspecific' competition phenomena in sheep blowfly populations where food and space are in short supply. 329.

No evidence of intraspecific competition was recorded amongst the insects in the broom pod cavity although up to 200 Contarinia larvae were often found together, in one pod. Intraspecific competition for space, owing to excessive overcrowding does,howeverl ocour in the gall amongst Anrostocetas brevicornis larvae, The smaller larvae in these overcrowded galls either die as larvae or as small malformed pupae. The effects of different species on. each other.within broom ,pods caused high mortalities of some of 'the interacting speciest 'especially in the "Old Broom" area. These effects are referred tofby Milne (1957). as being "imperfectly density dependent", by Varley (1953) as being, "delayed density. dependent" and by Solomon (1958) as being "alternately density . related" factors. There is still much disagreement in the literature on population dynamics, as to the exact definitions ,of terms that . have come into popular usage; this is beyond the scope of this thesis. Over 80. per cent of the total number ,of Apion larvae in the "Old'Broom" area in 1960 were killed by ectoparasites. .Various.species, were involved but the main one was Aahroeytus seaaester.. . In the "New. Broom" plantation in 1960 only 40,per cent of the Bruchidtas- larvae were killed by, parasitism, this being mainly by Triaspis and to a lesser extent, by Habrocytus. As' 330. already stated this low level of parasitism caused an. enormous increase in the number of autumn emerging Bruchidius adults compared with the parental population in 1960. In 1961, once again parasitism was low but other factors (see above) increased the total Bruchidius mortality in this year. In 1961, in the "New Broom" plantation, there must have, been some interspecific competition for seeds between Apion and Bruchidius first instar larvae. As Apion eggs began to hatch before Bruchidius:eggs, the first Apion larvae to emerge had "first choice" of the seeds. The later Apion larvae to emerge however must have competed with the already overcrowded Bruchidius larvae although no direct conclusive evidence of this was found. In the pod cavity, each species of Cecidomyid has its own set of parasites. These have some effect on the population regulation of the cecids, but no quantitative study was made of thiS subject. It is of interest that there is little interspecific competition between the three species of Cecidomyidae however, since the larvae have different food requirements. Contarinia larvae feed on the pod tissues; Clinodiplosis larvae feed on the fungus which grows on broom seed caruncles and Lestodiplosis larvae are predatory. In the gall, Asphondylia is only strictly "parasitised" by Pseadocatolaccus and Eupelmus larvae, Aprostocetus larvae 331.

•feed on the Asphondylia larva, the fungal mycelium and on the tissues of the broom pod* .The adult does kill the Asphondylka larva before ovipooiting in the gall however, and thus is more of a.predator,than a parasite. The larvae of the in ulline species Of.Trotteria feed on the fungal mycelium within the gall* However, the Asphondylia larva'isoften irritated and prevented from pupating by these intruders as 'already described (p. 259 ). Hyperparasitist is quite common in'all: f the three complexes of insects found in the broom pod. Unless the hyperparasite oviposits at such.a time when the primary - parasitic larva is fully fed, and contains sufficient food for the hyperparasite to complete its development, the- net result. .of hyperparasitism will be starvation and the death of all species concerned. In many. instances (e.g. Mesopolobus on Habrocytus) this .._ , condition.Was.frequentlyfeUnd* Thus, the, factors regulating the population fluctuations . of an obligatory hyperparasite are even more complex than those. regulating populations of hosts or primary parasites. •Also, where auPerparasitism. Was observed, as in Habrocytus the..same-problems as with hyperparasitism were encountered. Superparasitismin-itself shows a degree. of inefficiency in any insect species since only a.depletion of numbers camvesult

from it. • 332.

Predation is not an important factor in population . regulation within the broom pod since each of the three complexes of insects are separated both from each other and from any external predators. Only the eggs of Bruchidius are deposited on the outside of the pod and mortality of these due to predation by the mite Anystis agilis was high in the "Old Broom" area in both 1960 and 1961. Within the pod, the larvae of Lestodiplosis are the only true predators. These larvae are polyphagdus and have been found sucking the larvae of Clinodiplosis, Amion - anid Habrocytas. Thus, the adaptations of the 23 insect species which have some or 611 their immature stages in or on the broom pod are seen to be many and varied. They all have one common feature in that the overwintering stages are either in the adult, pupal or last instar larval stages. The temporary nature of the habitat excludes all species (except parasites) which overwinter in egg or young larval stages. Several of the species are confined to broom, whereas others are of more general occurrence. The former species (Anion, Bruchidius, Contarinia,) must therefore have adequate ability to survive from year to year on broom alone whereas the other species have a wider choice of habitats. St issurmised that all these species living together 333,

within a temporary ecological niche are able to do so as their life histories are spread in time and also as their requirements for space and for food show a sufficient diversity. To extend the ideas on the constitution and the levels of populations within the broom pods at Silwood Park, it would be essential to examine pods from bushes all over the British Isles and throughout the whole range of distribution of Sarothamnus seonarius, namely from Scandinavia to the Canary Islands. 334.

SUMMARY 1. The fauna .thin, pods of. Sarothamnus scopartus:was examined and attempts were, made to evaluate the, relationships between the 23 insect species which were' found at Silwood Park. 2., The primary habitat of these: species the pod) in all its stages of' development was investigated. This develop-. ment and dehiscence was compared in an area of, young broom bushes ("New Broom") and and area of old bushes 'Old Broom" The older budhes produced fewer pods, smaller pods and less seeds than the young bushes. 3. The 23 insect species.within the pod were divided into three independent complexes. i.e. (A) those connected with the broom seed, (B) the pod cavity and (C) the pod gall of Asphondylia sarothamni. A(i) The larvae of Apion; fusciroatre and Bruchidius ater develop in broom seeds and their biology and morphology is included. The adult population fluctuations in the two broom areas in 1960 and 1961 are described. A(ii) The biology and larval morphology of the parasite Habrocytus sequester (Hymo Pteromalidae) is described. It has a first generation as an ectoparasite of Apion ulicis larvae in gorse seeds and a second generation as an ectoparasite of Apion fuscirostre

and Bruchidius ater larvae in broom seeds. A(iii) A Trichozramma sp. and a braconid Triaspis sp nr. obscurellus oviposit in the eggs of Bruchidius on:the outside of the broom pod. A(iv) Mesonolobus medterraneuil (Hym. Pteromalidae) and Aproatocetus tibJalis (Hym. Eulophidae) are hyperparasites on the immature stages of Habrocytus. The former species is an ectoparasite and the letter is an endoparasite. The biology and morphology of the immature stages is included. A(v) Two other hymenopterous species hyperparasitise Habrocytus larvae. These species also breed elsewhere. B(i) In the pod cavity the eggs and larvae of three species of Cecidomyidae are found. Contarinia pulchripes larvae are phytophagous, Clinodiplosis sarothamni larvae are fungivorous and Lestodiplosis op, larvae are predacious. The biology, life history and larval morphology of these species has been studied. B(ii) Each cecidomyid species has its set of internal and external parasites. The biology of these is closely linked to that of its host. C(i) Asphondylia sarothamni forms a gall at the base of the pod that it attacks. This species passes alternate generations in broom bud galls and in broom pod galls, C(ii) Several ectoparasitic species are found in the gall and notes on their biology and morphology are recorded. 336.

C(iii) An inquiline species, Trattoria sarothamni is often found in the galls and its relationship with Asahondlylia is discussed, C(iv) karostocetus brevicornis larvae occur in galls, but they are phytophagous. The life cycle of this._species 'is unusual since.the adults live for 10 months. Over- -crowding often causes mortality amongst the larvae. The populations of Avian and Bruchidiud larvae in broom pods in 1960 and 1961 are discussed. As the result of high egg Mortality only a few3ruchidius ater were found in the "Old Broom" in both 1960 and 1961. Avion fuscirostre larvae were present in large numbers in the "Old Broom" in 1960 but not in 1961. Reasons for this are thought to be climatic. Bruchidius ater larvae were present in large numbers in the "New'Broom" in 1960. Parasitism eras low and the emerging autumn population was much larger than the parental. one. In 19610 there were many adults in the "New Broom" area. Heavy frosts at the end of May severely decreased the numbers of pods and intraspecific competition for seeds amongst first instar larvae was observed. 5. It is surmised that all these species living together within a'temporary ecological niche are able to do so as their life histories are spread in time and.also as their requirements for space and for food show a sufficient diversity. 337,

ACKNOWLEDWIENTS I wish to express my appreciation to the following persons for assistance which I received while carrying out this project. To Professor O.W. Richards for granting facilities at Silwood Park and for his interest in the hymenoptera that were found in this study. To my supervisor Dr. N. Waloff for her guidance and valuable criticism in the preparation of this manuscript. To Mr. J.W. Siddorn for photographic assistance during the study and for taking the photographs in the thesis. To Dr. R.E. Blackith for statistical advice. To Mr. B. Southgate for identifying the broom bruchid Bruchidius BLUE. To Dr. W. Nijvelt for identifying the cecidomyid . Clinodinlosis sarothamni. To Dr. R.D. Eady, Dr. M.W. de V. Graham, Dr, M.P. Claridge, Dr, R.R. Askew and Mr, N.J. Parr for identifying the various hymenoptera found in this study. To my sister Miss Margaret 3. Parnell for typing the manuscript. And. to my wife Patricia M. .Parnell for her constant help and encouragement. I have been a recipient of a Department of Scientific and Industrial Research Studentship throughout the course of this study; the generosity of this authority is gratefully acknowledged. 338.

REFERENCES 1.Andrewartha, H.G. & The distribution and abundance L.C.Birch, 1954. of animals. University of Chicago Press, Chicago. 2.Askew, R.R. 1961. Eupelmus urozonus Daman ( Hym. Chalcidoidea ) as a parasite in Cynipid Oak galls. Entomologist,94 s /96-201, 3. 1961a. On the Biology of the inhabitants of Oak Galls of Cynipidae (Hym.) in Britain. Trans.Soc.Brit.Ent.,14 : 237- 268, 26 figs. 4.Bailey, N.T.J. 1952, Improvements in the interpret. ation of Recapture Data. J.Anim.Ecol.,21 :420-127. 5.Barnes, H.F. 1930. Gall midges (Cecidomyidae) as enemies of the TingidaerPsyllidae Aleyrodidae and Coccidae. Bull.ent.Res.,21 319-329. 7. 1933. Gail Midges as enemies of Mites. Bull.ent.Res.,24 : 215-228. 8. 1946. Gall Midges of Economic Importance. Gall midges of Root and Vegetable crops. (Vol I ) Crosby Lockwood and Sons London. 9. 1946a, Gall Midges of Economic Importance, (Vol II.) Gail midges of Fodder crops. Crosby Lockwood and Son,London. 10. 1948, Gall Midges of Economic Importance (Vol III.) Gall midges of Fruit. Crosby Lockwood and Son, London. 6. 1948a. Gall Midges of Economic Importance (Vol IV.) Gall midges of Ornamental plants and Shrubs. Crosby Lockwood and Son, London.

3S9.

11.Barnes„H.P. 1949. Gall Midges.of Economic Importance (Vol.V1.) Gall midges of Miscellaneous crops. Crosby Lockwood and Son, London. 12. 1951. Gall Midges of Economic Importance (Vol.V./ . Gall midges of Trees. Crosby Lockwood and. Son, London. .15. 1954. Gall Midges living in White Clover flowerseEntomologist„87: 258-264 14, 1954a. A. neweciessp of Trotteria Kieffer (Cecid.) reared from unopened flower buds of Privet, Ligustrua vulgare L. Ent.Recs,66; 281-283 15., Barrass, R. 1960. The courtship behaviour of Mormoniella vitripennis Walk. (Hym. Pteromalidae ) Behaviour, 15 : 185- 209, 10 figs. 16.Beirne„ B.P. 1941. A consideration of the cephalic structures and spilacles of the final 'initar larvae of the Ichneu- monidae. (Hym.) Trans.Soc.Brit. Ent., 7 : 123-190, 31 figs, 17. Bodenheimer, F.S. 1927. Tiber Aegelmassigkeiten in. dem Wachstum von Insekten I. Das Langenwachetum. Dtsch.ent.Z., 4 : 33-57, 4 figs. 18. Boving, A.G. 1927. On the classification of the Mylabridae larVae ( Col. Myla- bridae ). Procsent.Soc.Wash., 29 : 133 - 142, 1 pl., 1 fig. 19.Boving, A.G, & P.C. Craighead. 1931. An illUstrated synopsis of the principal larval forms of the order Coleoptera. Ent.Amer., (Brooklyn) 11 : 1-351, 125 pls. 20, Buddeberg, Dr. 1884. Beitrage zur Biologie einheiMischar Kaferarten. Jb.nassau.'Ver.Naturk 37 : 70-106. (See p.86.) 21. Claridge, M.P. & R.R.Askew. 1960, Sibling species in the Eur oma rosae group (Hym.„ Eurytomidae Entomophaga„ 5 : 141-153,10figs. 22.Clausen, C.P, 1940. Entomophagous Insects, Me'Graw- Hill Book Co. Inc. New York & Londdn. 23.Condrashoff, S.F. 1961. Description and Morphology of the Immature stages of three closely related species of Contarinia Rond. (Diet. Cecidomyiidae) from galls on. Douglas-fir Needles. Canad.Ent., 93 : 835-851,24figs. 24.Daviault, L. 1928. Sur le developpement post- eMbryonnaire de la bruche du haricot; Acanthoscelides obtectus Say. Suivi de considerations sur la signification phyletique de son dimorphisme larvaire. Ann.Soc.entar.,97: 105-132, 25.Dempster, J.P. 1960. A quantitative study of the predators on the eggs and larvae of the broom beetle Phytodecta olivacea (Forster), using the precipitin test. J'Amim.Ecol,,29: 149-167,4 figs. 26. 1961. A sampler for estimating populations of active insects upon vegetation. 3.Anim.Ecol.,30: 425-427,1 fig. 27. Docters van Nieuwe Gallen van Nederland, Leeuwen, W.M. 1953. derde bijdrage. Ent.Ber.,Amst. 110 257-265. 28. 1954. Generatiewisseling biJ Galmuggen. Ent,Ber.,Amst. /5: 161-162. 29. 1957. Gallenboek,N.Thieme & Co. Zutphen. 30.Duarte, A.J. 1938. Problems of growth of the African migratory locust. Bulls ent Olen. p29:425-456. 341.

31.Dyar, M.G. 1890. The number of moults of Lepidopterous larvae. Psyche,5: 420-422. 32.Reidy, R.D. 1958. A revision of the nomenclature in the European Torymidae (Him" Chalcidoidea) with special reference to the Walker types. Ent.mon•Mag., 94: 257-271. 33.Eastham, L.E.S.& The influence of temperature and F.Segrove. 1947. humidity on instar length in Calandra pasanaria Linn. J.exp•Biol.„ 24:. 79-94, 5 figs. 34.Emden, F.van 1938. On the taxonomy of RhynchoPhora larvae (Coleoptera). Trans.R.ent.Soc.Lond. 87: 1- 37, 108 figs. 35.Fabrictas.I.0. 1775. Systems Entomologiae. Fleneiburgi et Lipsiae, Kortii. 36.Ferriare, C. 1950. Notes sur e les EurYtoina I. Les types de Thompson et de Meter. Mitt.schveiz.ent.Ges., 23: 377- .410, 6 figs. 37.Fisher, R.A. & Statistical Tables for Bioloxicall Faates. 1953.:..icul.alturarjd_Medical R-e-sear.(Fchourth edition) Oliver and BOyd, London. 38. Fulton, B.B. 1933. Notes on Habrocytus cereallae parasite of the Angoumois grain . moth. Ann.ent.Soc.Amer., 26: 536-553. 39.Goureau, M. 1847. Note, pour servir a l'histoire des insectes qui vivent dans les gousses dugenet epineux (Ulex euronaeas). Ann.Soc.entar.III15: 245-253. 40 Graham M.W. de V. 1961. The genus Aprostocetus Westwood, aensu lato (Hym., Eu1ophidae); Notes on the synonymy of European species. Entsmon.Mag., 97: 34-64* • 342.

41, Hafez, M. & Biological studies on Bruchidius P.H.Osman, 1956. trifolii (Motsch) and Bruchidius alfierii Pic, in Egypt. Bull. oc • ent •Egypte , 40: 23/- 277, 37 figs. , 42, He 1961. The Life History and Habits of a Midge, Contarinia oregonen.sis Foote, in Douglas-fir cones. Canad.Ent„ , 932 952-967, 23figs. 43. Hoffmann, 1945. Coleonteres Bruchides et . Anthribiders. Faune de France,. 44: P.Lechevalier,Paris, 184pp.. 382 figs. 44. 1958. Coleonteres Curculionides (Troisieme partie)', Paune de France„.61: P.Lechevalier,Parie, pp 1209-1841, 642 figs. Howe, R.W. 1952. The Biology of the rice weevil, Calandra orvzae (L). s 168 180 , 1fig 46. Imms, A.D. 1957. A General Textbook of Entomology. (Ninth edition entirely revised by 0.W.Richards and R.G.Davies) Methuen and Co. London. 47, Kieffer, J.J. 1890. Die Gallimtoken des Besenginsters • Wien.ent.Ztg., 9: 133-137. 48. , 1892. Beobachtimgen uber Gallmucken and Beschreibung einiger neuer . Arten. - Wien.ent.Ztg., W 212424. 49. , 1900. Cecidomyides d'Europ e et 41Algerie. Ann.Socont.Fr., :69:•18144472. 50. 1901. Synopsis des Zoocecidies d' Europe. Ann.Socontar•, 70: 233-579.

51. 1902. - Description de quelcseeL Cecidomyiea nouvelles41- Marcellia,•1 : (page 117 ). 52. Ic1.oet, G.S. &. A. check list of British Insects. Hincks 1945. T.Buncle & Co., Arbroath. ' 53 :Kunhi Kannan, K. 1923. The function of the prothoracic plate in Mylabrid (Bruchid) larvae ( a study in adaptation). Bull.Dep*Agric.Mysore ent.Ser., '7 :'47pp*, 54. Liebel, R. 1889. Asnhondylia payeri, -Ein neuer Gallenerzeuger 'des ,Pfriemen- strauchee. Ent. Naehr.0.2a s (17) * 265-267. 55. Lincoln,: P.O. 1930. Calculating waterfowl abundance on 'the bias' of banding returns. Circ.U.S.Dep.Agric., No. 118. 56.Lindroth,,C.H * 1957. The principal terms used for male and female genitalia in Coleoptera. Opusc.ent. 0 22 241-256. 57. Loew, H. 1850. Dirrtii•Tieitr., p38. 58. MacIeod,! 1958. The estimation of numbers of mobile insects from low incidence recapture data. Trans.R.ent.Boc.Lon.d., 114 363 - 392. 59.Maldwyn Davies W. 1928. The bionomics of Avian ulicis Forst.(0orse Weevil),with special reference to its role in the control of Ulex euroyaeus in New Zealand. Ann.appl.Biol., 15 : 263-2860 15 figs. 60.Marchal, P. 1900. Notes biologiques sur les Ohalcidiens et Proctotrypides obtenus par vole d'elevage pendant flea annees 1896,1897 et 1898. Ann.Soc.entar.0 69 : 102-112. 61.Marchal, P. 1907. La cecidomyie des poires Diplosis (Contarinia)'pirivora Riley. Anns-Socontar., 76 : 5-27. 62.Marsham, T. 1802. Entomologia Britannica Tomus 1, Coleoptera. Wilke & Taylor London. 547 pp.

63.Masi,L. 1908. Contribuzioni ails conoscenza dei Chalcididi Italiani. Boll.Lab.Zool.,Portici, 3 : 86-149, 45 figs. 64.Mayr, G. 1878. Arten der Chalcidier-Gattung Eurytoma durch Zucht erhalten. Verh.zool.bot•Gesaien., 28 : 297-334. 65. 1903. Hymenopterologische Miszellen Einiges caber Pteromainen Verh.zool.bot•Gesaien., 53 387-397. 66.Melia, A. 1941. Contributo alla conoscenza dell' Anion del Carciofo. Anion (Ceratrion) damryi Desbr. Redia, 27 : 135-165, 18 figs. 67.Milne, A. 1957. Theories of Natural Control of Insect Populations. Cold Spring Harb.SympeQuant. Biol., 22 : 253-271. 68. 1959. The centric systematic area sample treated as a random sample. Biometrics, 15 :(2), 270-297. 69, Milne D.L. 1960. The gall midges (Diet. Cecido- myidae) of clover flower heads. Trans.R.ent•Soc.Lond.. 112 : 73-108, 57 figs. 70. 1961. The function of the sternal spatula in -gall midges. Proc.R.ent.Soc.Lond., (A) 36 : 126-131, 4 figs. 71. Morris, X R S 1938. Euielmella vesicularis Retz. (Chalcidida4)- as a predator of another chalcid Microrlectron fuscirennis Zett. Parasitology, 30 :,20-32 5flgs . 72.Mukerji, D. 1938. Anatomy of the larval stages of the Bruchid beetle Bruchus auadrimaculatus Fabr., and the method of emergence of the larva from the egg-shell. Z.angew.Ent.,Berlin, 25 : 442- 460, 22 figs. 73.Nikoltskaya, M.N. 1952. Chalcids of the fauna of the U.S.S.R. (Chalcidoidea) ( In Russian). Opred.Faune SSSR., LIOSOWN, 44 : 575pp., 592 figs. 74.Otter, G.W. 1934. On the early stages of Lestodiplosis alvei Barnes (Dipt. Cocidomyidae), especially in relation to the larval head capsule. Parasitology, 26 : 582-593. 75. 1938. On the morphology of the larvae of three species of Cecidomyidae from Knapwced(Centaurea) flowers. Trans.R.ent.Soc.Lond., 87 : 39 -68,65 figs. 76.Parker, H.L. 1924. Recherches sur les formes post- embryonnaires des Chalcidiens. Ann.Soc.entar., 93 : 261-379, 285 figs. 77.Parker,,H.L. & Contribution a la biologie des W.R.Thompson. 1928. Chalcidiens entomophages. Ann.Soc.ent.Fr., 97 : 425-465. 78.Parr, M.J. 1960. Three new species of Aphanortmus (Hym. Ceraphrontidae) from Britatn,with a re-description of fumipennis Thoms.,1858. A species new to Britain. Trans.Soc.Brit.Ent., 14 : 115- 130, 17 figs. 79.Quednau, W. 1961. Die problematik der Nomenklatur bei den Triehogramma arten Bntomophaga, 6 : (2), 155-161. SO. Richards, 0.W. 1947. Observations, on grain weevils, Calandra (Col.Curculionidae). I. General biology and oviposition Proc.zool.Soes Loud., 117 : 1- 43, 81. 1949. The relation between measurements of the successive inmtars of insects. Proc.R.ent.Soc.Lond., 24 : 8-10, 4 figs. 82.Richards, O.W. & N.Waloff. 1954. Studies on the biology and population dynamics of British Grasshoppers. Anti-Locust,Bull., : 184pp, 67 figs. 83. 1961. A study of a natural population of Phytodecta olivacea (Forster) (Col. Chrysomeloidea) Philaranss, (B), 224 : 205- 257, 2 figs. 84.Rosen, H. van 1958. Zur Kenntnis der europaisehen Arten des Pteromaliden-Genu0 Uesopolobus Westwood 1833. (Hym. Chaleidae). Opusc.ent., 23 : 203-240,39figs. 85.Roubaler. 1949. Sarothamnus scoparius Wimm,„ au point de vue de la coleopterologie nottament en Boheme. (IN Czech) Acta.ent.Mus.nat.Prag., 24 : 141-157. 86, Schilsky, Jo 1905. Die Kafer Europa' s. Heft 41, Nurnberg, 100pp. 87.Servadei, A. 1940. Contributo all conoscenza deli' ento fauna delle leguminose foraggere I. Redia, 26 : 177-212, 18 figs, 88.Sharp, D. 1918. Studies in. Rhynchophora /V. A preliminary note on the male genitalia. Trans.R.ent.Soc•Lond., 66 209-222, 9 figs.

347.

89.Short.J.R.T. 1952. The morphology of the , head of larval Hymenoptera with special reference to the head of Ichneumonoidea including a classification of the final instar larvae of the Braconidae, Trans.R.ent•Soc•Lond..1K : 27-84, 34 figs. 90.Skaife, S.H. 1926. The bionomics of the Bruchidae. S.Afr.J.Sci., 23 t 575-588. 91.Smith, B.D. 1957. A study of factors affecting the populations of Aphids on Sarothamnus scoparius (L). Univ. London Ph.D. Thesis. 92.Smith, M.R. 1958 The biology of the Scolytid beetles on broom and their hymenopterous parasites. Univ. London Ph.D. Thesis. 93.Solomon, M.B. 1958. Meaning of density-dependence and related terms in, population dynamics. Nature, 181 : 1778-1781. 94. Southgate, B. 19626' The true identity of the broom Bruchid. (not yet in press), 95. Speyer, W. 1921. Beitrage zur Biologie der Kohlschotenmucke (Dasyneura brassicae Winn.) Mitt.Biol.Zent.Anst.Berl.„ 21 t 208-217. 96 1923. Kohlschotenrussler (Ceutorrhynchus assimilis Payk.),Kohlschotenmucke (Dasyneura brassicae Winn.) and ihre Parasiten. Arb.biol.Abt.Anst.Reichsanst, Berlin, 12 : 79-108, 4 figs. 97. Steffan, J.R. 1946. La larve primaire de Bruchidius fasciatus 01. et ses rapports avec quelques larves neonates de Brfthides Bull•Soc.entOr., 51. : 12-16, 7 figs. 98. Stelter, H, 1957. Untersuchungen uber Gallmucken III. Die Artberechtigung von. AePhondylia mayeri Liebel. Arch.Fr.Natur.G. Mecklenburg, 3 152.158, 9 figs. 99, Thompson, W.R. 1954. A catalogue of the parasites and Predators of insect pests. Section 2, part 3. The Commonwealth institute of Biological Control, Ottawa, Ont., Canada. 100 Ullyett, G.C. 1950. Competition for food and allied phenomena in sheep-blowfly populations. Phil.Trans., (B), 231 : 77-174 50 figs. 101. Vance, A.P. & The larval head of parasitic H.D. Smith. 1933. hymenoptera and nomenclature of its part. Ann.ent.Soc•Amer., 26 : 86-94, 3 figs. 102.Verley„ G.C. 1953. Ecological aspects of population regulation. Trans. IXth. Internat. Congr. Ent., 2 210-214. 103.Vollert, I. 1958. Asphondylia sarothamni H.Loew = A. mayeri Liebe'. Naturvissenschaften, Berlin, 45 276. 104.Waloff, N. & Richards 1958. The biology of the Chrysomelid beetle Phytodecta olivacea (Forst) (Col. Chrysomelidig77----- Trans.R.ent•SocsLond., 110 : 99-116, 7 figs. 105. White, T.3. 1958. An ecological study of Syrphidae (Diptera) with an account of their larvae. Univ. London Ph.D. Thesis. 106.Wigglesworth, V.B.1948. The insect cuticle. Biol.Rev., 23 : 408-451,1 fig.

349.

107. Zacher, F. 1930. Untersuehungen zur Morphologie and Biologie der Samenkafer (Bruehidae Lariidae). Beitrage zur Kenntnis der Vortssehadlinge 6. BeitragsArb.Biol.Reichsanst Land-u Forst., (Berlin), 18 : 233-384, 99 figs. '.•-•• ...1. 2.A Vs.& N.• .• 1,) vtvpm:AslrWyIVV;IFipf• • vr rprT, Prr .rrFrPiWPOrrr et': -o,...00,03-• • • • • • • •m.‘mmulkylknvo.m.rr.00... • 0.• • • • • • •" e • • P0.11.0•w\ocom-4,,mmovvivivivivIvl.p. • • 0 0 • • • • • • • • • • • a0 OCNCNCY MCMO Cif Ei1 MON,MMONCAMO1gh010 0 0,47%MMCMT%MMONO CIN M.P10.‘. .b..1.. ..b....bwMCA00000040.00, 00:0000 mk 000

ON 0 co

MI 1,4 1,12 >4.11 got N# t10.710‘44.4440-bW.POI.miNVPRI.PwW...

Nr .Pnddi' MCNVUW02 4,tom.• m%mwe-c441.P...49%m4 tii Bt%nta

MIsit I 1.,.303,,,..1..,4m4itcowcstal 3i t 313 1 1## 110.4t tm„,

8 8 t t t# Ws ;Ili PI try "ca DI 13 3131341,....30„4„.4 '3,2t81:1K“1"1 .16714.0* Si 1 1ll 1111,v1VE •

SU.

A WX . Usb Numbers of A ion fueciroatre and Bruchidiun Mu adults caught in "50 buah"samples in the'Neir Broom" area throughout 1960 and 1961. Date Arlon stre pruchidiue Ara Flea e8- Total Feeilea Malta ,- Total 15.8.60 i7 22 39 30 19 49 3.9.60 20 21 41 32 20 • 52 27.9.60 10 18 28 26 14 40 8.11,60 15 4. 19 2i 17 38 14.12.69 9 8 17 30 17 47 30.1.61 12 3 15 36 16 52 20.2.61 4• 1 5 45 22 67 24.3.61 6 10 16 33 18 51 18.4.61 12 16 28 193 99 292 27.4.6i 10 24 34 210 .166 3S 5.5.61 21 16 37 270 162. 432 12.5.61 33 10 43 353 180 533 18,5.61 10 8 18 266 120 386. 25.5.61. 9 I 10 451 75 226 2.6.64 6 1 7 125 65 190 19.6.61 2 2 4 30 20 50 22.6.61 3 6 930 12 42. 29.6.61. 4 3 T 42 21 63 86.7. 1 2 2 2.5 8 31 19.7.61 4. 2 t 6 1 7 24.7,61 - 1 1 17 11 28 • 3.8.6i 5 3 8 39 24 63 10.8.61 6 4 10 79 31 fio 17.8.61 7 8 45 58 40 98 5.9.61 20 25 45 25 20 45 5.10.61 32 28 60 14. . 14 TOTALS. E2 272 N = EN Eg 352.

APPENDIX III. Numbers of individuals found in the pod samples in trand 19 numbers too small for analysis ).

Samples Si 82 83 S4 85 s6 87 88 89 810 811 212 813 . (a) "Neer Broom" 1960.

Eggs. 25 21 Larvae. 3 12 27 19 31 20 2 Pupae. .. - 10 15 12 Adults. am 11. m* aim 1 4. 12 11 21 2 2 2 Parasites: . •1 - 2 7 16 15 14 16 3 12 8 Deairtipkg. Total A.A1.9_,n. 28 33 29 19 .4.3 4.537 27 27 52 7 .15 10 Total - of-itrated. pods. 22 25 23 17 32 36 28 18 23 37 6 10 9 (b)"Old Broom" 1961• Eggs. 8 22 30 15 18 16 6 Larvae. OW 1 2 13 8 11 6 5 1 Pupae. Me law am MO as II" 24 3 Adults. .. .. - - - - .. » 1 1 9 13 ab 1= 14abzvoytas: - ilia la Ma .1. .. 5 5 5 P Mesoco2pbus. - -- - - .. 1 1 Total Wm: 8 22 30 1.g 18 18 19 8 12 11. 35 19 19 Total infected. pods. p 18 26 12 15 16 17 8 11 8 26 13 12 (o) New Broom" 1961.

Eggs. 18 26 4.1 28 57 58 24 16 4. /4111111141 ••• 2 3 14. 31 56 54. 17 Pups,* . IS Oa 1 21 34 11 Adults. 40 - 0. 1.0 MI Air MO am ma .. 1 47 20, Parasites. art a* 001 ma al ma im. — am 6 10 38 23 Dead Apion, - Mr Me 1 -1 5 Total &I..._.on 18 26 4.1 30 57 61ar.* 38 47- 61- 82 62 96 4.8 Total infected pods. 18 20 36 24 41 4.6 30 32 49 54 48 74. 32

Ps Parasites.

353.

APPANTEEX ITf• Numbers of Bruchidius 8. individuals found in the pod simples in the "Old Broom" area in 1960 and. 1961. (numbers too wall for analysis ). Samples 31 82 83 84, 85 86 87 88 89 810 811 812 813 814. (a)• "Old. Broom" 1960.

Eggs. not recorded. Larvae. .1 1 1 6 5 8 4. 2 3 1 1 - - Pupae. - - w - - 00 1. 011. 1 3 2 - 1 1 00 .0 on 00 00 — M 1 00 Adult s. .00 0. 000 0. 00 - - .0 010 — Oa 010 Parasites. - 4 . 3 - Total Bruohidius - 1 1 1 6 5 8 4- 3 10' 3 1 5

Total infected. pods• 1 1 1 3 4 4 3 3 9 3

(b)• "Old Broom" 1961. Eggs. not recorded. Larvae. . - - -8 4.0. 38 10 15 15 2 Pupae. - . - - - . 1 2 3 1 Adults. - - - . . . . - - 110 2 00 WM .10 00 00 Sim Parasites a - I 3 . Dead Brulhidius - - - . . . . - i. . 1 100 Total Bruchidius - 8 40 38 12 17'. 22 5 Total infected pods, - 4. 25 26 11 11 18 4.

354.

APPENDIX V. Classification of the various insect species occurring within the Broom Pod. A. DIPTERA NEMATOCERA. - CECIDOMYIDAE 1. Contarinia pulchripes Kieffer. 2. .Clinodiplosis sarothamni Kieffer, 3. Asphondylia sarothamni H. Loew. 4. Trotteria sarothamni Kieffer* 5. - Lestediplosis sp. B. COLEOPTERA POLYPHAGA CURCULIONOIDEA APIONIDAE 6. . Apion fuscirostre Pabricius. CHRYSOMELOIDEA 'BRUCHIDAE 7. Bruchidius ater (Marsham). C. HYMENOPTERA APOCRITA ICI NEUMONOIDEA BRACONIDAE 8. Triaspis sp. nr. obscurellus Nees. PROCTOTRUPOIDEA PLATYGASTERIDAE 9. • ,Platygaster sp. 10. Inostemma lycon.Walker. CERAPHRONIDAE 11, Aphanogmus venustus Parr. CHALCIDOIDEA EULOPHIDAE 12. Aprostocetus brevicornis (Panzer). 13. Aprostocetus sp. nr. aethiops (Zetterstedt). 14. Aprostocetus tibialis1Kurdjumov). TRICHOGRAMMATIDAE • 16. Trichogramma sp. , EUPELMIDAE. 16, Eupelmus urozonus (Daman). TORYMIDAE 17, . Torymus sp. nr. microstigma (Walker). 18. Torymus sp. nr. micropterus WalkerL PTEROMALIDAE 19, Habrocytus sequester (Walker). 20. Mesopolobus mediterraneus (Mayr). 21. Pseudocatolaccus thoracicus (Walker). 22. Systasis encyrtoides Walker. EURYTOL!IDAE • 23. Eurytoma dentata Mayr.