NIGERIAN JOURNAL OF ENTOMOLOGY (2000) 17:59-67

Distribution of the Emperor Caterpillar, forda (: ) on Sheanut Tree Canopy at Dorin, Nigeria.

M. 0 ODEYEMI and J.O FASORANTI* Department of Biological Sciences University of Ilorin P.M.B 1515 Ilorin, Nigeria.

* Corresponding author,

(Accepted 06 November, 2000)

ABSTRACT

The distribution of larval instars of on the sheanut trees, Vittelaria paradoxa was studied in the permanent site of the University of Ilorin, Early instars were evenly distributed within the tree crowns. The downward movement of later stages was first preceded by a slight upward migration to 'the tree top. Majority (90 %) of the penultimate larva instars live in the lower crown area on their way to pupate in the soil. High mortality factors due to predatory ant Oecophylla will not make the rearing of this economically feasible in the natural setting of Ilorin area. The paper suggests the adoption of artificial diet for the mass production of C. forda larvae.

INTRODUCTION Throughout Nigeria and in the West African Sub-Region, Sheanut trees, Yittelaria paradoxa (Sapotaceae) are attacked by the emperor moth caterpillar, Cirina forda. In the Northern Zaire, Erythropheum africana is also reported as another food plant of the insect (Ande, 1991). In Nigeria, V. paradoxa probably originated somewhere between Jebba and Ilorin, but had since spread to the Nupe speaking areas of northern Nigeria and to Abeokuta in the South (Hutchinson and Daiziel, 1963 .; Keay et al., 1964). It is now known that C. forda distribution and abundance are highly associated with this food plant(Ande,1991). Inhabitants residing where this insect occur have been harvesting, processing and utilizing it as food (Fasoranti and Ajiboye, 1993). C. forda is a popular insect food locally called "monimoni" or "manimani". Although early investigations of C. fordo. provided detailed accounts of its biology, phenology and utilization (Ande, 1991; Ande and Fasoranti, 1997), little information exists on the distribution of immature stages within trees. Our objectives are to investigate the within tree distribution of all the instars of C. 60 Distribution of Emperor Moth Caterpillar on Sheatnut forda aDd to find out the effects of some mortality factors on their population.

MATERIALS AND METHODS Egg clusters of C. 10rOO were collected during oviposition period near Bida in June 1996. Four: suitable V paradoxa plants were selected as rearing materials for C. forda and are located at the University of the Ilorin main Campus. Two weeks prior to larval introduction, grasses and other weeds immediately surrounding the trees were removed to aid observation. About 160 neonate larvae hatched in the laboratory were introduced on each of the four trees distributed uniformly at all levels of the tree crown. The feeding and migration pattern as from those first instar stage were closely monitored. Tree heights (crown) were stratified arbitrarily into lower, middle and upper representing 1.2-2.3m; 2.3-3.4m; 3.4-4.5m respectively. All records of larvae found on each height were kept for all the four plants and the results were pulled. A high power binocular (model 445-25110) 7 x 35 wide angle was used to survey initial population movement of the larvae on the plant. The mean percent distribution on the four plants was calculated. In addition, within tree, larval distribution record was taken by climbing each tree and observing 20 at random in each crown height on daily basis from June 28 - August 13, 1996. Each larva was examined during the observation and classified into instars using head capsule size (Ande and Fasoranti, 1995) A two way ANOVA was used to investigate whether there existed a significant difference between position (lower, middle, upper) with respect to the instars. Daily record of mortality was kept and all predatory factors noted. A partial life table analysis of C. forda larvae on the tree plant was obtained and constructed.

RESULTS C. forda has six larval instars in Nigeria. The relative abundance of each instar and vertical distribution are represented in Figs. 1-6. Between June and July, first and second instars were most prevalent, with the insects preferring the upper and mid sections of the tree foliage to the lower leaves (Fig. 1). During the next one week, larvae were distributed evenly all over the tree top (Fig. 2). From this point however we began to notice a difference in the dispersal of the insect. For example, between July 17·to July 24, though the 3rd instar occurred almost evenly all over the trees, the 4thand 5thinstars seem to prefer the mid sections of the foliage (fig. 3). We also observed that after this stage, an upward migration of the larvae was noticed in the 5thand jthinstars (fig. 4). Beyond this stage, there was a sudden movement of mature larvae downwards and finally, virtually all (90%) of the 6th instar larvae were found at the lower part of the trees (figs. 5 and 6). M.O. ODEYEMI and J.O. FASORANTI 61 FIGURE 1

40

35

30

2 o ~ 25 III ~ !!1 20 o '" 15

10

2 INSTARS Fig. 1: Percentage Distribution of Larval instar of Cirina forda. 28 June - 9 July

FIGURE 2 4S

40

35

30

~ 25 :iii LOWER I I , ~ '.MIDDLE ~20 ~ DUPPER

15

10

5

0

INSTARS

Fig. 2: Percentage Distribution of Larval Instar of C. forda, 9 - 17 July r I Distribution of Emperor Moth Caterpillar on Sheatnut 62 FIGURE 3 90

80 ...... -...... ·...--...·-..·-----1

70

60

z 0 ...•..__ 48 ..... _48 . :;,;::50 !!! DLOWER iii: .. III MIDDLE ~ 40 c DUPPER ~

30

20

10

INSTARS Fig. 3: Percentage Distribution of Larval instar of Cirina forda, 17-24 July

FIGURE 4

90

82

80

70 ... 60· z 0 550 ..CDa: l·L~~ !!! 40 ~:;; c ;II

30

20

10

0 6

INSTARS

Fig. 4: Percentage Distribution of Larval Instar of C. forda, 24-31 July M.O. ODEYEMI and J.O. FASORANTI 63

FI5>URE 5

iO-LOWER illlMIDDLE :OUPPER

INSTARS

Fig. 5: Percentage Distribution of Larval instar of Cirina forda, 31 July - 7 August

FIGURE 6

100~------~ __~ 90

80

70

60

'SLOWER i ...... - - - ..------.-- ..-.--- ..-----1 • MIDDLE, OUPPER ' 401------j

301·------1

20I----~!

10 1------1

INSTARS

Fig. 6: Percentage Distribution of Larval Instar of C. jorda, 7- 13 August 1 _

64 Distribution of Emperor Moth Caterpillar on Sheatnut

Analysis of variance (ANOVA) iridicates that instar and position have influence on the distribution of Ci-forda larvae on V. paradox plants (Table 1). Table 2 represents observation on the various mortality factor prevailing on 630 larvae that were monitored on the field. Larval loss was due to many factors most important of all these factors is the predation by other insects especially ants. We frequently observed the helpless larvae being killed and carried always by the ant, Oecophylla sp, which is present in large members in Kwara state living in leaf nests on V paradoxa and other trees such as Terminalia catappa. According to Aina (1997), Oecophylla ants constitutes about 80% of total ant population in the main campus of University of Ilorin, Oecophylla alone is responsible for heavy mortality in the first and second instar stages. Other mortality factors include, dispersal hazards, disappearances and death due to spider predation.

Table 1: ANOVA table showing the interactive effect of instar/position on the spatial distribution of C. forda larvae.

Sources of d.f s.s m.s V.r F.pr variation

Instar 5 173.4 34.7 0.09 0.993 position 2 1988.9 994.5 2.71 0.071 Instar/position 10 39139.6 3914.0 10.67 <0.001 Residual 120 44023.2 366.9 Total 137 85325.1 M.O. ODEYEMI and J.O. FASORANTI '::):;

TABLE 2: Partial Life-Table Analysis of Cirina Forda Larvae (Lepidoptera: Saturniidae Within the Period of June-August 1996 e.ge No.Alive Factor No. of dx as a K value

Interva! at the respons ible for mortality of IX

bcgmmng monatnvux during (x) IOOqx) of> (dxf) by (dx)

.une 2~· Instar i 630 143 22.7 0.036 July 9th predation Disappearance II 5.3 0.Q25 Dispersal 9 4.3 0.021 Unknown 5 2.4 0.011 SUB TOTAL 46 22 O.IOS

July()9.17th Instarll 209 Anhropod 21 10 0.048 predation

Disappearance II 5.3 0.025 Dispersal 4.3 0.021 Unknown 2.4 0.011 SUBTOTAL 46 22 O.IOS July 17-24th Instar II 163 Anhropod 4.3 0.026 predation Dispersal II 6.7 0.041 Un1rnown 1.8 0.011 SUB TOTAL 21 12.8 0.078 Iuly 24th-31st Instar IV 134 Anhropod 4 3.8 0.022 predation Dispersal 10 7.5 0.086 Un1rnown 3 2.2 0.016 SUB TOTAL 17 12.6 0.094 July Sfth- Instar V 124 Anhropod 7 5.6 0.045 Aug. 12th predation Dispersal 24 19.4 0.156 Un1rnown 4 3.2 0.025 SUBTOTAL 35 28.2 0.226

DISCUSSION Information on within tree distribution of the various instars ore. jorda would be useful in developing a sampling scheme within time frame work. This knowledge will enable one to have information on when and on what part of the tree crown to collect desired larval stages. Earlier on, Ande and Fasoranti, (1994) found out that the penultimate larva instar as well as the pre-pupae of e. jorda have superior nutritional qualities and are preferred to any other instar stages. Our findings have indicated that majority of the sixth instar larvae would be found at the lower crown of the trees between the end of July of the first week of August (Figs. 4 and 5). Several other reasons could be responsible for population movement in phytophagous insects. For instance Leonard (1970) proposed that starvation could alter the behavioural movement in the larvae at Porthetria dispar. However in our own experiment we ensured that larva consumption rate did not exceed the recovery capacity of the trees by limiting the number of larvae ~-.~-~-==.----.--

66 Distribution of Emperor Moth Caterpillar on Sheatnut

introduced. Therefore at no time were the trees completed defoliated. Under natural condition, it has been observed by the second author in Mokwa-Bida road a systematic mass movement of some instars of C. jorda from a previously completed defoliated V. paradoxa tree in search for another suitable food source. The result of the life table analysis is not encouraging. Survival rate is very low and may militate against a proposed rearing programme under natural conditions in Borin area. The major setback is attributed to the predation of C. jorda larvae by the tree dwelling ant, Oecophylla sp. In fact, our rearing of 1996 did not survive two subsequent generations as a result of ant predation. No wonder therefore that despite the abundance of sheanut trees in many locations south of Jebba, C. forda larvae are rarely found. Unless and until these natural mortalities can be controlled, the only option that remains feasible therefore if C. forda larvae need to be reared in Borin is to develop an artificial diet feeding programme for mass production.

ACKNOWLEDGEMENT This paper forms part of the thesis submitted to the Department of Biological Sciences, University of Borin and the study was sponsored by the Nigeria Immigration Service, and partly supported by a Senate Research grant by the University of Borin.

REFERENCES AINA, O.A., 1997. The preliminary investigation on the distribution of ant fauna (Hymenoptera: Formicidae) on University at Ilorin main campus unpublished B.Sc. Thesis, Dept. of Biological Sciences, University of Borin. 21 pp. ANDE, A.T., 1991. Some aspects at the biology of CirinajordaWestwood (Lep:Saturniidae) Ph.D. Thesis, Dept. of Biological Sciences, University of Borin, Nigeria. 327 pp. ANDE, A.T. and FASORANTI, J.O. 1994. The effect of harvesting, processing , and stage of larval development on the nutritional qualities of Cirinajorda (Lep. Saturniidae) Ecology oj Food and Nutrition (Accepted). ANDE, A.T.and FASORANTI, J.~. 1995. Determination of the number of instars in Cirinajorda westwood (Lep. Saturniidae). Bioscience Research Communication 757-60. ANDE, A.T. and FASORANTI, J.~. 1997. Life history notes for the pallid emperor moth Cirinajorda (Lep. Saturniidae) in Nigeria. Journal Lepidopterists' Society America 5, 269-271. FASORANTI, J.~. and AJmOYE, D.O. 1993. Some edible insects of Kwara State, Nigeria. American Entomologist 93, 113-116. HUTCHINSON, J. and DAlZIEL, J.M. 1963. Flora of West Tropical Africa Crown Agent for Overseas Government and Administration Millbank, London. 1 (2) 487 pp. KEAY, R.W.J.; ONOCHIE, C.F.A., and STANDFIELD, D.F. 1964. Nigerian M.O. ODEYEMI and 1.0. FASORANTI 67

trees. Dept. of Forest Research, Ibadan, Nigeria. VII 495 pp. LEONARD, O.E. 1970. Effect of starvation instars and developmental rate of Ponnetria dispar . Insect Physiology 16, 25-31.