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Order Number 8717738
Bionomics of the frit fly, Oscinella frit(L.) (Diptera: Chloropidae), on golf course turfgrass in Ohio
Tolley, Mike Patrick, Ph.D.
The Ohio State University, 1987
U MI 300 N. Zeeb Rd. Ann Arbor, MI 48106
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BIONOMICS OF THE FRIT FLY, Oscinella frit (L.)
(DIPTERA: CHLOROPIDAE) , ON GOLF COURSE
TURFGRASS IN OHIO
DISSERTATION
Presented in Partial Fulfillment of the Requirements for
the Degree Doctor of Philosophy in the Graduate
School of the Ohio State University
By
Mike Patrick Tolley, B.S., M.S.
k k k k k
The Ohio State University
1987
Dissertation Committee: Approved By
Dr. Harry Niemczyk
Dr. David Nielsen Dr. Richard Hall U a m L ftdv is< Dr. Karl Danneberger Department of Entomology This dissertation is dedicated with love to my parents, Jack and Christa Tolley, and my dear grandmother, Cacilie Schwarz. ACKNOWLEDGMENTS
I would like to thank the members of my Ph.D. committee, Harry Niemczyk, David Nielsen, Richard Hall, and Karl Danneberger for their guidance of my research and educational development.
Funding support for this research provided by the Ohio Turfgrass Foundation and by state and federal funds appropriated to the Ohio Agricultural Research and Development Center.
Special thanks is given to Harry Niemczyk for serving as my mentor. His input has been valuable in the developing of my perspectives. T Appreciation goes to Phil Williams and Gary Rasor for allowing me to pursue my research on the College of Wooster Golf Course and The Ohio State University Golf Course, respectively. I am also very grateful to Kevin Power, Mike Dunlap, Thanh Lu, Gail Hazer, Bob Hancock, Woodbridge Foster, Dave McCartney, Carl Paul, James Chatfield, and Foster Purrington for their help in many aspects of my research.
Much love and appreciation go to my soul mate, Alyce Amstutz, whose support, love, and understanding have seen me through many difficult times during the course of my Ph.D. studies and research.
Finally, the attainment of the Ph.D. would not have been possible without the support and love of my parents and relatives; I am truly grateful and hope I have made them proud. VITA
December 9, 1957 ...... Born, Augsburg, W. Germany
1980 ...... B.S., Biology, Roanoke College, Roanoke, Virginia
1980-1982 ...... Graduate Research Associate, Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
1982 ...... M.S., Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
1983-1987 ...... Graduate Research Associate, Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio
1987 ...... Ph.D., Entomology, The Ohio State University, Columbus, Ohio
PUBLICATIONS
Robinson, W. H & M. P. Tolley. 1982. Sod webworms associated with turfgrass in Virginia. Am. Lawn Applicator 3: 22-25.
Tolley, M. P. 1982. Understanding the complexities of sod webworm control in Virginia. In proceedings, 22nd Annual Virginia Turfgrass Conference and Trade Show. Virginia Cooperative Extension Service, Blacksburg. Tolley, M. P. 1983. Resting site preferences for sod webworm moths. Am. Lawn Applicator 4: 27-28.
Tolley, M. P. & W. H Robinson. 1986. Seasonal abundance and degree-day prediction of sod webworm (Lepidoptera: Pyralidae) adult emergence in Virginia. J. Econ. Entomol. 79: 400-404.
FIELDS OF STUDY
Major Field: Entomology
Urban Entomology Turfgrass Entomology Economic Entomology
v TABLE OF CONTENTS
Page
DEDICATION ...... ii
ACKNOWLEDGMENTS ...... iii
VITA ...... iv
LIST OF TABLES ...... x
LIST OF FIGURES ...... xii
GENERAL INTRODUCTION ...... 1
GENERAL LITERATURE REVIEW ...... 3
Taxonomy ...... 3 Geographic Distribution ...... 3 Morphology ...... 4 Eggs ...... 4 Larvae ...... 4 Pupae ...... 5 Adults ...... 5 Life Cycle and Generations ...... 5 Egg Biology ...... 7 Mating Behavior ...... 7 Oviposition Behavior ...... 7 Fecundity ...... 8 Oviposition Sites ...... 9 Oviposition Hosts...... 10 Abiotic and Biotic Effects ...... 11 Host Oviposition Resistance ...... 11 Larval Biology ...... 12 Larval Migration ...... 12 Temperature Effects ...... 12 Larval Feeding Behavior ...... 13 Density Factors ...... 14 Larval Hosts ...... 15 Host Larval Resistance .... 16
vi l' Page
Pupal Biology ...... 17 Pupation Sites ...... 17 Adult Emergence Behavior ...... 17 Adult Biology ...... 19 Flight Behavior ...... 19 Wind Dispersal ...... 20 Sex Ratio ...... 21 Weather Effects ...... 21 Generations and Phenology ...... 22 Degree-day Relationships ...... 23 Adult Hosts ...... 24 Density Factors and Feeding ...... 24 Parasites and Predators ...... 24 Damage and Chemical Control ...... 28
EXPERIMENTATION ...... 32
UPPER AND LOWER THRESHOLD TEMPERATURE AND DEGREE-DAY ESTIMATES FOR DEVELOPMENT OF THE FRIT FLY, Oscxnella frit, (L.) (DIPTERA: CHLOROPIDAE), AT EIGHT CONSTANT TEMPERATURES . . 33
Introduction ...... 34 Materials and Methods ...... 35 Data Analysis ...... 37 Results and Discussion ...... 38 Behavioral Observations ...... 38 Developmental Thresholds ...... 4 0 References Cited ...... 4 9
SEASONAL ABUNDANCE, OVIPOSITION ACTIVITY, AND DEGREE-DAY PREDICTION OF FRIT FLY, Oscinella frit (L.) (DIPTERA: CHLOROPIDAE), ADULT EMERGENCE ON TURFGRASS IN OHIO ...... 52
Introduction ...... 53 Materials and Methods ...... 54 Seasonal Abundance ...... 54 FF Oviposition Activity ...... 55 Degree-day Prediction of FF Adult Emergence .. 5 6 Results and Discussion ...... 58 Seasonal Abundance ...... 58 FF Oviposition Activity ...... 70 Degree-day Prediction of FF Adult Emergence .. 74 References Cited ...... 91
vii Page
SEASONAL ABUNDANCE AND SPATIAL DISTRIBUTION OF FRIT FLY, Oscinella frit (L.) (DIPTERA: CHLOROPIDAE), IMMATURES IN TURFGRASS ...... 94
Introduction ...... 95 Materials and Methods ...... 96 Statistical Methods ...... 97 Results and Discussion ...... 98 Seasonal Abundance ...... 98 Spatial Distribution ...... 101 References Cited ...... 113
OVERALL DISCUSSION ...... 117
CONCLUSIONS/SIGNIFICANT CONTRIBUTIONS ...... 12 3
GENERAL REFERENCES CITED ...... 125
APPENDICES ...... 141
A. Fig. 4. Technical drawing of the unit net sampling device ...... 141
B. Mean (x) , standard error (S.E.), and the S.E. as a % of the x numbers of frit fly adults captured per Julian date in the sweep net and unit net on the College of Wooster Golf Course during 1984 ...... 143
C. Mean (x), standard error (S.E.), and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the sweep net on the College of Wooster Golf Course during 1984 ...... 144
D. Mean (x), standard error (S.E.), and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the unit net on the College of Wooster Golf Course during 1984 ...... 145
E. Mean (x), standard error (S.E.), and the S.E. as a % of the x numbers of frit fly adults captured per Julian date in the sweep net and unit net on the College of Wooster Golf Course during 1985 ...... 146 Page
F . Mean (x), standard error (S.E.)/ and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the sweep net on the College of Wooster Golf Course during 1985 ...... 147
G. Mean (x) , standard error (S.E.), and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the unit net on the College of Wooster Golf Course during 1985 ...... 148
H. Frit Fly, Oscinella frit (L.) (Diptera: Chloropidae), Seasonal Abundance Plant Phenology Relationships...... 14 9
I . Description of Distribution and Dispersion Indices...... 154 LIST OF TABLES
Table Page
1. Predators of the FF ...... 2 6
2. Hymenopterous parasites of the FF ...... 27
3. Development of immature stages of FF reared at 8 constant temperatures ...... 42
4. Regression equations for the prediction of unit net densities from sweep net samples ...... 65
5. Probit-DD equations of cumulative percent emergence of FF adults at Wooster, Ohio; DD computed from 1 March at 10°C base temperature ...... 83
6. FF adult 40% seasonal abundance flight dates, predicted 40% DD flight dates, 1984 and 1985 pooled predicted 40% DD flight dates, and the maximum deviation in days of all predictions versus actual flight peak daysa ...... 84
7. Probit-DD equations of cumulative percent emergence of FF adults at Wooster, Ohio; DD computed from 1 March at 0°C base temperature ...... 8 6
8. FF adult 40% seasonal abundance flight dates, predicted 40% DD flight dates, 1984 and 1985 pooled predicted 40% DD flight dates, and the maximum deviation in days of all predictions versus actual flight peak daysa ...... 87
X Table Page
9. Validation of first and second adult generation pooled predictive DD models in Wooster and Columbus, Ohio, during 1986; models based on a 1 March starting date with a 0 or 10°C base temperature ...... 89
10. Regression equations of Taylor's power law relating the variances to the mean counts of the FF and the association between mean crowding (m) and the mean ...... 106
11. Correlation coefficients between dispersion indices and sample means of FF adults reared ...... 109
12. Dispersion properties of FF adults reared from turfgrass - 1985...... Ill
13. FF adult 40% emergence and associated botanical phenological events during 1984 and 1985 in Wooster, Ohio. Phenological events validated during 1986 for first and first-and-second adult generations in Wooster and Columbus, Ohio, respectively ...... 152
xi LIST OF FIGURES
Figure Page
1. Development of FF eggs at 8 constant temperatures. The sigmoid line is that generated from the biophysical model of Wagner et al. (1984). Predicted thresholds are 10.32 ± 3.03 (95% CL) (lower), 29.0 (upper), and 34.0°C (lethal) ...... 43
2. Development of FF larvae at 7 constant temperatures. The sigmoid line is that generated from the biophysical model of Wagner et al. (1984). Predicted thresholds are 10.36 ± 2.52 (95% CL) (lower), 29.0 (upper), and 34.0°C (lethal) ...... 44
3. Development of FF pupae at 8 constant temperatures. The sigmoid line is that generated from the biophysical model of Wagner et al. (1984). Predicted thresholds are 10.78 ± 4.79 (95% CL) (lower), 29.0 (upper), and 34.0°C (lethal) ...... 45
4. Technical drawing of the unit net sampling device ...... 141
5. Percent parous females, precipitation (cm), and mean FF caught per sample method from pooled fairways 1 and 3 during 1984 on the College of Wooster Golf Course ...... 59
6. Percent parous females, precipitation (cm), and mean FF caught per sample method from pooled fairways 1 and 3 during 1985 on the College of Wooster Golf Course ...... 61
xii Figure Page
7. Mean male and female FF caught in the sweep net from pooled fairways 1 and 3 during 1984 on the College of Wooster Golf Course. • , No. males significantly different from no. females (paired t = 5.08; df = 40; P < 0.05) ...... 66
8. Mean male and female FF caught in the sweep net from pooled fairways 1 and 3 during 1985 on the College of Wooster Golf Course. • , No. males not significantly different from no. females (paired t = 1.96; df = 34; P > 0.05) 67
9. Mean male and female FF caught in the unit net from pooled fairways 1 and 3 during 1984 on the College of Wooster •Golf Course. • , No. males significantly different from no. females (paired t = 5.75; df = 34; P < 0.05) ...... 68
10. Mean male and female FF caught in the unit net from pooled fairways 1 and 3 during 1985 on the College of Wooster Golf Course. • , No. males significantly different from no. females (paired t = 4.33; df = 18; P < 0.05) 69
11. FF ovarian development grouped into 6 morphological stages. Stages 1-3 nulliparous, stages 4-6 parous. Symbols used: oc, oocyte; nc, nurse cell; yo, yolk; ov, ovum; et, egg tube; fr, follicular relic .... 71
12. Comparison of FF cumulative percent emergence and percent parous females during 1984. = FF cumulative % emergence - - - = % parous females = Relationship between 40% FF emergence and oviposition ...... 7 6
xiii Figure Page
13. Comparison of FF cumulative percent emergence and percent parous females during 1985. = FF cumulative % emergence - - - = % parous females ► = Relationship between 40% FF emergence and oviposition ...... 78
14. Comparison of sum of day differences between actual versus predicted FF 40% adult emergence (adult generations 1-4) at various base temperatures with starting dates, for DD accumulations, of 1 March, 1 January, and 1 January with a 2 9°C upper threshold. Data based on pooled 1984+1985 predictive models ..... 80
15. Density of male and female FF adults reared per 316 cm2 per sample date - 1985. Each data point average is based on 66 samples. Data for October is from forced emergence of adults of the overwintering larval cohort ...... 9 9
16. Association between the mean and variance of male FF adults reared. Each data point based on 66 turf samples of 316 cm2 - 1985. The common K (Kc) = 1.04, intercept (a) = 1.847, and slope (b) = 1.514 ...... 103
17. Association between the mean and variance of female FF adults reared. Each data point based on 66 turf samples of 316 cm2 - 1985. The common K (Kc) = 1.5 6, intercept (a) = 1.502, and slope (b) = 1.233 ...... 104
18. Association between the mean and variance of FF adults reared. Each data point based on 66 turf samples of 316 cm2 - 1985. The common K (Kc) = 1.23, intercept (a) = 1.848, and slope (b) = 1.546 ...... 105
xiv GENERAL INTRODUCTION
THE FRIT FLY (FF), Oscinella frit (L.), is a small, black fly
sometimes present in large numbers on turfgrass and often
seen by golfers when it lands on white clothing or golf balls. The fly is considered a nuisance; larvae can cause
damage to turfgrass, especially greens, collars and aprons
(Schread & Radko 1958, Dahlsson 1971, 1974, Mowat 1974,
Niemczyk 1981, Falk 1982). Adults lay eggs that hatch into
maggots which tunnel into grass stems to feed on growing
tissues. Feeding results in crown damage and shoot death.
Little is known about this insect on turfgrass in the United
States.
Changing cultural practices such as water conservation
and new turf varietal establishment could provide ideal
conditions for the FF to become a major pest. Water
conservation could create hot, dry conditions to which the
flies are well adapted (Pisnyachevskii 1927, Schvetzova
1929). In view of its abundance, damage potential, and the
lack of research on its biology on golf course turf in the
United States, the following objectives were set forth:
1. Determine developmental thresholds for use in degree-
day (DD) accumulation prediction of adult emergence.
1 2. Determine adult seasonal abundance.
3. Develop DD predictive models and plant phenological
indicators to time adult seasonal abundance.
4. Determine the statistical distribution and dispersion
of FF immatures in the field. GENERAL LITERATURE REVIEW
Taxonomy
The FF, Oscinella frit (L.), was first described and named Musca frit by Linneaus in 17 58. The species was named after the Swedish word "frit," which describes the empty grain kernels damaged by maggots. Q. frit is a Holarctic species (Simmonds 1952, Allen 1978) and is variable in morphology and color. Morphological variation has led to the following synonyms: Oscinis frit (L.), Oscinis tibialis
Fitch, Oscinis carbonaria Loew, Oscinis variabilis Loew,
Oscinis niara Tucker, Oscinis soror Macquart, Botanobia obscura Curran, and Oscinis obscura Coquillett. In addition, the 2 varieties ousilla (Meigen) and nitidissima (Meigen) are also synonyms (Aldrich 1920, Sabrosky 1936, 1939). Sabrosky
(1980) includes only the species frit, nitidissima. and crrandissima Sabrosky, in the genus Oscinella Becker within the Nearctic fauna.
Geographic Distribution
The FF is distributed widely throughout the Palearctic
(Collin 1918), but in N America it is most abundant where
3 4 winter wheat, Triticum aestivum (L.), is grown, from the
Great Lakes to the Ohio River and westward to Mo. Its range extends from Canada to Ala. (latitude 58°) (Aldrich 1920) .
The FF has been recorded from the Atlantic to the Pacific and from Ala. to Mexico (Simmonds 1952).
Morphology
Eggs. FF eggs are white with up to 20 ridges on the chorion. At one end lies a cup-shaped protuberance surrounding the micropylar area. Aldrich (1920) noted eggs measured 0.7 (length) by 0.178 mm in greatest diameter
(diam), while Steel (1931) noted measurements .ranged between
0.58 to 0.73 mm (x = 0.68) in length and 0.13 to 0.20 mm
(x = 0.16) in diam.
Larvae. Larvae have 3 instars (Steel 1931). The first instar is transparent with 11 body segments. The anterior end is demarcated by the cephalopharyngeal skeleton with 2 mouth hooks. Aldrich (1920) noted first instars measured
1.06 (length) by 0.14 mm in greatest diam, while Steel (1931) noted measurements ranged between 0.7 to 1.5 mm (x = 1.05) in
length and 0.13 to 0.23 mm (x = 0.16) in diam. Second
instars measured between 1.7 to 2.5 mm (x = 2.04) in length
and 0.2 to 0.4 mm (x = 0.28) in diam (Steel 1931). Third
instar larvae are light yellow and white, due to an
accumulation of fat globules beneath the cuticle. Aldrich 5
(1920) noted third instars measured 3 (length) by 0.4 mm in greatest diam, while Steel (1931) noted measurements ranged between 2.8 to 3.3 mm (x = 3.0) in length and 0.4' to 0.5 mm
(x = 0.45) in diam. Nye (1958) measured third instars up to a maximum of 5 (length) by 0.5 mm (diam).
Pupae. The puparium is formed from the hardened cuticle of the third instar larva. Aldrich (1920) noted the puparium is brown and measures 2.7 (length) by 0.9 mm in greatest diam, while Steel (1931) noted measurements ranged between 2.63 to 3.08 mm (x = 2.8) in length and 0.73 to 0.86 mm (x = 0.8) in diam.
Adults. Detailed descriptions of adults are given by
Aldrich (1920) . Adults are completely black except for yellow trochanters and fore-and-mid tibiae and tarsi. Adults measure 1.1 to 2 mm in length, males are smaller than females. The frontal triangle is shiny black and reaches the frontal suture.
Life Cycle and Generations
FF have multiple generations per year on graminaceous hosts (Aldrich 1920). On cereals, these are tiller, panicle,
and overwintering generations. Adults from the overwintering
generation migrate from grasses and oviposit on seedlings or
tillers of early-sown cereals. Adults from the tiller 6 generation oviposit onto panicles where larvae feed within grain kernels. This grain-infesting sthge occurs in Europe, not N America (Aldrich 1920) . Adults emerging from panicles fly to grasses which serve as overwintering sites for larvae.
The switch to grass hosts for overwintering is usually associated with fall harvesting of cereals. Simmonds (1952) suggests there are American and European races, since wheat is the preferred host in America while oats, Avena sativa L., is preferred in Europe.
FF can have from 2-5 generations per year depending on the geographic locale. Three generations occur in V a . (Allen
& Pienkowski 1974), Britain (Cunliffe 1923a, 1925, Nye 1958,
Anon. 1980, Vickerman 1980), Russia (Reinov 1929, Zhukovskii
1932, Lauva & Shutele 1976), Federal Republic of Germany
(Riggert 1936, Hemer 1959), Scandinavia (Dahlsson 1974),
France (Chevin et al. 1971), and Bulgaria (Lazarov 1935,
Popov 197 6). Only 2 generations occur in N USSR and England
(Andreeva 1926, Rubtzov 1935, Vickerman 1980) and 2-3 in
Norway (Rygg 1967). Up to 4 generations occur in Ind.
(Aldrich 1920), Poland (Chrzanowski 1931, Hubicka 1965), S
England (Cunliffe 1921, Jepson & Southwood 1958, Clements et al. 1983), S Federal Republic of Germany (Blunck & Ludewig
1926), and Denmark (Nielsen & Nielsen 1984). Five generations in S USSR are the most reported for FF (Collin
1918). 7 Egg Biology
Mating Behavior. FF mate on leaves and stems of hosts during the warm part of the day between 0 930 hours and sunset
(Southwood et al. 1961) . After eclosion, males mate within 6 h if suitable females are available. Females usually mate after 2 d following eclosion. Mating behavior begins with the male facing the female. The male sways back and forth until able to mount the female. After fertilization, the female disengages by kicking the male repeatedly with her metathoracic legs. Copulation lasts ca. 45 min (Allen &
Pienkowski 1974) . Females are usually gravid within 5 d after emergence (Aldrich 1920).
Oviposition Behavior. After a 4-5 d preoviposition period (Cunliffe 1923a, Jepson & Southwood 1958, Vickerman
1978a), females fly to hosts and lay eggs. Sanders (1960) has shown that females orient to vertical stripes. Vertical patterns produced by stems of cereals could provide the stimulus for host recognition. Maximum oviposition occurs 3 wk after emergence (Mowat & Jess 1984). Egg-laying behavior involves ovipositor extension while the female rests on the host. The ovipositor tip is moved in and out and from side to side, possibly receiving some form of tactile stimulation.
An effective oviposition stimulus is thought to include a biochemical component from the plant and a proprioceptive component resulting from the disposition of the legs and ovipositor. After stimulation, 3 to 4 abdominal contractions cause an egg to be oviposited. The ovipositor is pressed to the substratum, thereby firmly placing the egg on the host.
No feeding occurs during oviposition; the proboscis remains retracted (Ibbotson 1960).
Fecundity. Lauva & Shutele (1976) noted that oviposition begins in late May and peaks in late June in
Latvia (latitude 51°), while Rubtzov (1935) noted mass oviposition during mid-June in the Irkutsk region of E
Siberia (latitude 52°) . First eggs were noticed 2 wk after adult emergence with peak densities during June and July
(Southwood & Jepson 19 62, Allen & Pienkowski 1974, Vickerman
1980). Eggs were least abundant during August (Allen &
Pienkowski 1974). Oviposition was frequent at 18-30°C, but did not occur below 16°C (Chrzanowski 1931) . No oviposition occurred below 12°C (Kreiter 1930, Riggert 1935a, Roos 1937).
The number of eggs per female has been estimated at 14 (Steel
1931), 30 (Aldrich 1920), 70 (Collin 1918, Blunck & Ludewig
1926), and up to 100 (Southwood & Jepson 1962) . Riggert
(1935a) claimed that females in the field had an average of
18 eggs with a maximum of 24. Rygg (1966) noted there were 3 to 4 eggs per developing ovariole with 12 to 17 ovarioles per ovary. This calculates to an average of 104 eggs per female with a maximum of 136. 9
Oviposition Sites. Females place eggs in different locations depending on the host. On oats, eggs are placed outside the coleoptile if still adhered to the stem. Eggs are placed beneath the coleoptile if loose of the stem. Eggs can also be found behind the basal sheath, secondary shoots, and ligules. Oats in the 2 to 4 leaf stage are preferred and, if tillering, the eggs are placed behind leaf sheaths and between tillers. Few eggs are laid on fresh green tissue
(Andersson 1956, Jones 1969a, Jonasson 1977, 1982a, Vickerman
1978a, Anon. 1980). Jonasson (1982a) determined eggs were dispersed in an aggregated distribution (coefficient of dispersion > 1). This pattern was due to the limited distribution of plants with morphological characteristics conducive to oviposition. In addition, oats on which eggs have been layed are preferred oviposition sites for other females, thereby increasing the number of eggs per plant.
On wheat, barley, Hordeum vulcrare L.; and maize, Zea mays L., eggs are placed on the: 1) lower part of the plant, 2) in soil cracks made by germinating seedlings, and
3) in deep leaf veins, with new leaves preferred to old
(Shapiro & Vilkova 1963a). On grasses, eggs are placed in the leaf axis, on the stem, behind the sheath, within the seed coat after germination, and on soil if the particle diam is ca. 2.5 mm (Collin 1918, Aldrich 1920, Andreeva 1926,
Steel 1931, Zhukovskii 1932, Dahlsson 1971, Allen & 1 0
Pienkowski 1974, Mowat & Jess 1984). Withering leaf sheaths are the preferred oviposition sites with few eggs laid on fresh sheaths. A few eggs are laid on plants in the 3 to 4 leaf stage, but tillering and 5 leafed plants are preferred.
On grasses, eggs are not laid behind the coleoptile which is tightly adhered to the stem or falls away completely
(Vickerman 1978a).
Oviposition Hosts. FF are polyphagous (Nye 1958), but host-specific strains are thought to exist (Allen &
Pienkowski 1974). FF have been noted ovipositing on many hosts including: rye, Secale cereale L. (Mowat & Jess 1984); maize, oats (Agapova 1966), reed canarygrass, Phalaris arundinacea (L.) (Allen & Pienkowski 1974); barley, red fescue, Festuca rubra L.; Italian ryegrass, Lolium multiflorum Lamarck; perennial ryegrass, Lolium perenne L.; quack grass, Aaropyron repens (L.); timothy, Phleum pratense
L.; redtop, Acrrostis alba L.; colonial bentgrass, Aqrostis vulgaris Withering; colonial bent, Aarostis tenuis Sibthorp;
sweet vernal grass, Anthoxanthum odoratum L.; tall oat grass,
Arrhenatherum elatius (L.); orchard grass, Dactylis alomerata
L.; meadow fescue, Festuca .pratensis Hudson; sheep fescue,
Festuca ovina L.; Kentucky bluegrass, Poa pratensis L.;
annual bluegrass, Poa annua L.; yellow oats, Trisetum
flavescens (L.); meadow foxtail, Alooecurus pratensis L.;
Hordeum murinum L., and foxtail, Alopecurus myosuroides 11 Hudson (Cunliffe 1921, 1923b, Vasina 1929, Taimr & Dirlbeck
1968, Vickerman 1978a, 1980) .
Abiotic and Biotic Effects. Predators and weather conditions affect both eggs and oviposition. Females oviposit in protected places during rainy and cool days and on open plant parts (sheath and blade) on clear, warm days
(Shapiro & Vilkova 1963b). Up to 44% egg mortality can be caused by rain, wind, and predators (Jones 1969b). The length of the rain-free period following oviposition is the most important factor in determining the degree of FF infestation on reed canarygrass (Allen & Pienkowski 1975).
On maize, eggs are laid in the soil if dry and on upper plant parts if the relative humidity is high (Oschman 1980). High temperatures in August and September favor oviposition, while cool weather causes inhibition; the oviposition period is extended if humidity is high (Oschman 197 9).
Host Oviposition Resistance. Host resistance to oviposition involves the coleoptile not being suitable for oviposition and the length of this condition. Hosts that develop quickly through the coleoptile-susceptible stage are
less prone to oviposition than hosts which require long developmental periods. In addition, thick coleoptiles are preferred over thin. Jonasson (1980) noted the presence of trichomes offers no resistance to oviposition. 12
Larval Biology
Larval Migration. After egg incubation, larvae emerge by scraping the chorion with their mouth hooks and increasing pressure inside the egg by body movements. A high relative humidity is required for successful egg hatching and emergence (Riggert 1935a). After emergence, the chorion collapses (Steel 1931). Larvae migrate to hosts if eggs are laid on soil (Mesnil 1931). Shapiro & Vilkova (1963a) reported larvae infested hosts wh^n eggs were placed within
0.5 cm, but not 10 cm away. Tomczyk (1929) noted larvae migrated from stem to stem of oats and barley, while Jones
(1969a) noted migration from plants with many eggs to uninfested plants. Whether the plants were 1-5 cm apart made little difference in larval survival. Larval migration can be both horizontal (tiller to tiller) and vertical (from ploughed soil and crop debris) (Nye 1959). Larvae are able to move through 30.5 cm of soil to cereals (Petherbridge
1917, Blunck & Ludewig 1926) and from buried grass to wheat
10 cm away when temperatures are greater than 7.2°C.
Migrating larvae enter wheat below the soil surface and about
4 mm above the base of tillers as early as February and March
(Heard & Hopper 1963).
Temperature Effects. Estimates of lower developmental thresholds for FF vary considerably among workers. Chrzanowski (1931) noted that FF became inactive at 13 temperatures < 8°C. Nye (1959) claims the threshold to be
7.2°C, as indicted by research done by D. Iley at their field station. Jepson & Heard (1959), in their chapter on
"previous work," claim the threshold to be between 6.6-7.7°C, while Kreiter (1930) noted larval inactivity at 6°C. Kreiter
(1930) claims that larvae entered hibernation at < 6°C and pupated when temperatures were > 12°C; larvae did not feed at
< 12°C.
First instar larvae overwinter on pasture grasses in
England (Nye 1959), although second and third instars are the usual overwintering stages (Lazarov 1935, Auersch 1961). The overwintering host in Ind. is winter wheat (Aldrich 1920) ; up to 50% larval mortality can occur depending on the insulation provided by snow cover (Auersch 1961, Southwood & Jepson
1962) .
Larval Feeding Behavior. The period of time before larval host penetration is the key mortality factor regulating FF populations on reed canarygrass (Allen &
Pienkowski 1975). Mortality could be due to either egg predation, failure of larval penetration, or larval desiccation (Southwood & Jepson 1962). Dry conditions increase first instar mortality (Oschman 1980) . After host penetration, larvae begin feeding on plant tissues extra- intestinally. Such feeding involves extra-intestinal digestion of plant tissues by mutualistic Pseudomonas 1 k bacteria, which are thought to break-down plant proteins.
The host is inoculated with bacteria by puncturing tissues with the larval mouth hooks. These bacteria have been isolated from many larval organs and body surfaces (Ryzhkova
1962, Sazanov 1966). Larval excreta produces a foul odor which decreases the acceptability of pasture forage to grazing animals (Wolf 1967).
Once larvae are in the host, they mine leaves (Steel
1931, Heard et al. 1979) or feed directly on the stem or crown. Larvae are thought to be chemotactic since aggregation occurs to drops of maize extract on agar plates
(Ohnesorge 1972). Feeding in the center of the host yields the characteristic damage symptoms of a dying yellow central
shoot surrounded by healthy green outer leaves (Aldrich
1920). Franz (1971) claimed that larvae feed at the bases of
leaf blades on lawn grasses.
Density Factors. Larval density in the field is often determined by management practices and the presence of preferred hosts. Higher populations occur in cut or grazed grass than uncut (Southwood & Jepson 196/, Heard & Hopper
1963, Moore & Clements 1984b). Increased larval densities
could be due to an increase in the time of susceptible host
stages as a result of cutting or grazing, thus providing
succulent tissues for larval penetration (Henderson &
Clements 1977). Moore & Clements (1985a) attribute higher 15 densities to an increase in the number of tillers, while
Mowat (1974) claims it is due to an increase in the preferred host rough bluegrass, Poa trivialis L., in grazed swards than in cut' or pure swards. He found a correlation coefficient of
0.88 between larval density and number of rough bluegrass stems.
High nitrogen applications also increase larval populations, due to production of succulent tissues and a dense stand for oviposition (Moore & Clements 1984a). Larvae of "stemborers" are most abundant during January, September and October, and lowest during mid-April to mid-May in
England (Clements et al. 1983). Larval peak densities follow adult peaks, and populations are low during summer on reed canarygrass due to decreased host vigor as a result of heat and drought stresses (Allen & Pienkowski 1974) . Larval field populations conform to an aggregated distribution with a coefficient of dispersion > 1, but are not as clumped as eggs due to horizontal migration from old shoots to new (Jonasson
1982a).
Larval Hosts. FF larvae arc polyphagous which allows them to survive on many graminaceous hosts (Nye 1959). In general, larvae feed on cereals and grasses in the summer and on grasses and late-sown and volunteer cereals during the winter (Cunliffe 1923a). Hosts include perennial ryegrass,
Italian ryegrass, Lolium italicum Braun; rough bluegrass, 1 6
Kentucky bluegrass, annual bluegrass, colonial bent, redtop, foxtail, velvet grass, Holcus lanatus L.; H. murinum. red fescue, alta fescue, Festuca arundinaceae Schreber; meadow fescue, orchard grass, oats, brome grass, Bromus sterilis L.;
Arrhenatherum avenaceum Beauvois, sweet vernal grass, quack grass, and reed canarygrass (Cunliffe 1922, 1923b, Roos 1937,
Jepson & Heard 1959, Nye 1959, Wolf 1967, Allen & Pienkowski
1974, Moore & Clements 1985b).
Host Larval Resistance. Host larval resistance involves both a decrease in the susceptibility to oviposition and larval penetration (Jonasson 1982b). After a certain age, host tissues become tough, preventing larval penetration of the epidermis (Vickerman 1978b). On oats, resistance occurs after the 4 leaf stage (Jones 1969a). Tissue toughness is thought to be related to an increase in silica content of the host (Moore 1984). In addition, vernalization of wheat and barley produces lower larval infestation than in non-vernalized plants. Lower infestations were due to an
increase in rate of germination and production of tough tissues. The increased rate of wheat and barley growth produced tough tissues before spring adult emergence and were, therefore, less suitable hosts for oviposition (Belizin
1936). Vickerman (1978b) concluded orchard grass exhibited
antibiosis against FF larvae. 1 7
Pupal Biology
Pupation Sites. Once larval development is complete, pupation generally occurs at the site of larval feeding
(Blunck & Ludewig 1926) . Pupae can be found behind the sheath of outer leaves, near roots, or in soil (Collin 1918) .
On wheat and rye, larvae leave the stem and move below the axis of lower leaves and the second tillering node where they pupate (Reinov 192 9); on barley, pupae form in the stem
(Andreeva 192 6). On reed canarygrass, pupae are found at the base of the plant in the spring; late in the season, pupae are formed farther up the plant (Allen & Pienkowski 1974).
Pupation occurs above 4°C. Pupae are present as early as
January from overwintered larvae on cereals in Poland
(Chrzanowski 1931). Pupae are most abundant in mid-May on cereals in Siberia (Shvetzova 1929). Adults have been known to emerge from pupae dug from a soil depth of 11.5 cm
(Tomczyk 1929).
Adult Emergence Behavior. Flies emerge after 1 to 2 wk of pupation depending on the temperature. Adults emerge by increasing pressure within the puparium by the ptilinum
and exit through a V-slit opening at the anterior end (Steel
1931). Eclosion occurs 0.5 h after sunrise and is over by
1000 hours. Emergence is favored by moist air and hindered by dry (Riggert 1935a). Southwood et al. (1961) gave the
following description of adult behavior after eclosion: 1 3
1. adults bright yellow, legs and eyes partly darkened,
wings unexpanded, ptilinum expanded, ovipositor
extended
2. 15 min — can run actively
3. 30 min — femur, tibia, and frontal triangle black,
head and thorax grey yellow, abdomen yellow, wings
expanded — milky, rubbing of abdomen and wings with
hind legs and head with front legs
4. 40 min — ovipositor retracted in 2 movements of
abdomen
5. 60 min — wings still milky
6. 90 min — dorsum of abdomen brown, ptilinum about 3/4
expanded
7. 2 h — wings still milky, buzzing
8. 150 min — hopping flights, ptilinum barely expanded
to length of third antennal segment
9. 3 h 20 min to 4 h — flew vigorously, all black
Teneral adults are first noticed 20-50 min after sunrise, and the last 5 h after sunrise. The teneral stage lasts ca. 4 h.
Most adults emerge between 0430-0900 hours with the maximum at 0600-0700 hours. 19
Adult Biology
Flight Behavior. At sunrise, flies are lethargic and hop if disturbed. Adults eventually move to the top of the host and face the sun. Flight activity begins and ends in the morning and evening, respectively, with the maximum during warm parts of the day, with an intermediate peak at
1500 hours (Wetzel et al. 1972). First flight begins 1-1.5 h after sunrise (0530-0600 hours). Majority of takeoffs are in the morning between 0900-1100 hours. By 1200-1300 hours, most adults have flown straight up into the sky out of sight
(Ibbotson 1958). Adults land in the afternoon between 1600-
1700 hours. There is no flight after 2000-2100 hours. The average flight lasts 1 h (Southwood et al. 1961, Johnson et al. 1962, Calnaido et al. 1965) .
If raining or windy, flies land and make hopping flights to the base of hosts. Flight is arrested at 9°C and when the sky is overcast. Flight increases with increasing temperature up to 23°C and then decreases above 23°C. Most adults are caught between 1100-1500 hours in water dish traps
(Ohnesorge 1971). Hemer (1959) noted greatest flight activity at 20-25°C and that flight was impeded by wind or rain. Few flies were caught between 1700-1900 hours, and when temperatures were low and relative humidity high
(Ibbotson 1958). 2 0
Adults emerge ready for flight and are filled with fat globules until 4 d after eclosion. Flies are ready for flight when 4-6 h old. Females often fly before and after oviposition, with flight decreasing the preoviposition period. The wings are capable of beating an average of 187-
198 cycles per second in still air and 181-189 cycles per second in moving air (Rygg 1966).
Wind Dispersal. Flight is only active long enough for the fly to get into wind currents in which long distance dispersal occurs (Nielsen & Nielsen 1984) . Active flight from grass to maize hosts is within a radius of 600 m
(Oschman 1982). Flies can drift for an average of 24-32 km in air currents, and redistribution and host finding is controlled by wind direction (Southwood et al. 1961, Johnson et al. 1962, Nielsen & Nielsen 1984). Cold weather decreases adult migration (Nordlander 1979).
Adults above 2.5 m are dispersed by circulating air currents and, if less than 0.5 m off the ground, they are still in sensory contact of hosts (Calnaido et al. 1965).
Before 0800 hours, 90% of adults are below 6 m. By 1100-1200 hours, 87% of airborne adults are above 18 m, 84% above 38 m, and 73% above 152 m. Density decreases with increasing height (Johnson et al. 1962) . Calnaido et al. (1965) have collected flies in air currents at 300 m; flies can occur up to 609 m (Hardy & Milne 1938). Wind and rain decrease the 21 height of flight. In England, adults are not abundant on hosts above 200 m (Clements et al. 1982) and can be found at
865 m on cereals in Bulgaria (Lazarov 1935) and up to 1,432-
1,859 m on oats in Switzerland (Roos 1937.)
Sex Ratio. When sampling for adults, males usually predominate even though the sex ratio is 1:1 at emergence
(Jepson & Southwood 1958). In grasses, there is an excess of males, but in the aerial.population between 1.2-8.9 m,
females predominate (Calnaido et al. 1965, Adesiyun &
Southwood 197 9). There are more males than females when
older hosts are infested (Vickerman 1978b) and there may be more males at the onset of eclosion and more females at the
end of emergence on oats (Vickerman 1980). Males are more
active than females (Ibbotson 1958) and are polygamous,
increasing the probability of females being inseminated after
emergence (Adesiyun & Southwood 197 9).
Weather Effects. FF adults are most abundant during high temperatures. Most adult emergence occurs after
rainfall (Cunliffe 1921) . Wilbur & Sabrosky (1936) noted
that chloropid populations emerged after 1.27 cm of rain
during spring. Shvetzova (192 9) claims hot and dry springs
increase fly emergence and that rainfall has no effect.
Second-generation adults are favored by a warm summer and
autumn (Pisnyachevskii 1927). Adult activity stops at 8°C
and > 35°C. Exposure to 35°C for 3-5 d decreases 22 reproduction (Pospelov 1924, Chrzanowski 1931). Zhukovskii
(1961) noted the majority of adults preferred 12-28°C and high temperatures during the day and cool temperatures at night. From 1200-1400 hours, adults preferred 20-35°C and
16-28°C from 1600-1800 hours. Tolerance to high temperature increases if relative humidity is high. Flies orient to light in the yellow-green range and prefer light of intermediate intensity up to 36°C and low intensity at 38°C.
Adult longevity is estimated to be 1 d for males and 2 wk for females in captivity (Collin 1918). In the field, adults live from 10 d (Riggert 1935a) to 3 mo (Chrzanowski 1931).
Allen & Pienkowski (1974) noted that flies lived for
5.5 ± 0.6 d on reed canarygrass.
Generations and Phenology. There were 4 generations in Ind., based on adult sampling (Aldrich 1920) . Adult abundance peaked during early May, late June, mid-July, and mid-August. Allen & Pienkowski (1974) noted 3 generations on reed canarygrass in V a . with adult peaks during April, June, late July, and early August. Plant phenology has been used to predict adult peaks. Riggert (1.936) noted adults first emerged when dandelion, Taraxacum officinale Weber, bloomed and peaked with the flowering of apples, Pyrus spp., in the
Federal Republic of Germany. Hemer (1959) found first adults caught when sweet cherry, Prunus avium L., began to bloom.
He was unable to determine plant phenology peak flight 23 correlations for 3 generations even though 7 plant species were studied at 7 sites.
Degree-Day Relationships. Researchers have attempted to relate DD accumulations to adult FF phenology. In the
Federal Republic of Germany, Ohnesorge (1973) accumulated DD above a base of 7°C with temperatures taken from a soil depth of 2 cm. Adults were first caught when there were 50-80 DD; adults were common after 90 D D . At 120-150 DD, FF adults reached their first maximum. Later in the year, factors other than soil temperature had a dominating influence on adult flight activity and abundance. Nielsen & Nielsen
(1984) noted the DD requirements for a complete generation of
FF is similar to that in England, Norway, Denmark, and the
Federal Republic of Germany (ca. 350-390 DD above 7°C) . The completion of 3 generations of FF required at least 1,050-
1,100 DD above 7°C. Adults of the tiller generation on oats peaked after 580.6 ± 55.2 DD (95% FL) while the panicle generation peaked at 641.6 ± 3.6 DD (base = 7.2°C) (Jepson &
Southwood 1958). Vickerman (1980) noted there was a difference of 380-420 DD between FF adult peaks or 50% emergence (base = 5.5°C). No mention was found regarding the starting date of their DD accumulations; base temperatures differed. Generations overlap if mid-summer temperatures are much higher than in spring (Southwood & Jepson 1962). 24
Adult Hosts. Adults have been sampled from many hosts including oats, maize,.ryegrass, meadow fescue, wheat, rye, barley, Kentucky bluegrass, orchard grass, and brome grass
(Aldrich 1920, Wilbur & Sabrosky 1936, Anon. 1980). Flies are abundant in lawn grasses in the United States and Europe
(Kerr 1957, Dahlsson 1971, 1974). Schread & Radko (1958) found flies most abundant in dense turf such as Kentucky bluegrass 'Merlon' and bentgrass, Aarostis spp., putting greens where they are considered a nuisance to golfers as the flies are attracted to golf balls and other white surfaces.
Density Factors and Feeding. Adult populations are higher in mowed grass than unmowed (Hemer 1960, Nielsen &
Nielsen 1984) . Mowing is thought to increase shoot production (Schread & Radko 1958) and causes wound exudates which attract flies for feeding (Aldrich 1920). Falk (1982) found up to one-half of the adult population moved from unmowed to mowed turf within 1 h but no density differences were found after 24 h. Flies feed from sunrise to sunset on dew, aphid honeydew, raindrops, mold, decaying plant tissues, and a variety of flowers (Riggert 1935a, Southwood et al.
1961) .
Parasites and Predators
Natural reduction of FF numbers is accomplished by parasites and predators. Parasites consist of Hymenoptera, 25 nematodes, yeasts, and ciliate protozoans. Nematode parasites of larvae and adults include Panacrrolaimus spp.
(Poinar 1972), Panaarolaimus riaidus Schneider, a mermithid in the genus Hexamermis. and Howardula (formerly
Tylenchinema) oscinellae (Goodey) (Goodey 1930, Keler 1932,
Riggert 1935b, Moore & Hunt 1984) .
The biology of H. oscinellae involves females entering
FF larvae through the cuticle. The female nematode remains within the larva through metamorphosis to the adult fly. Ihe female produces juveniles within the fly's abdomen.
Juveniles enter the fly's intestine and are voided through the anus onto plant material where fly larvae are again parasitized. Parasitism results in both male and female sterility by impeding development of reproductive organs
(Goodey 1930) . Sterility is also caused by the parasitic mite, Microtrombidium demeiierei Oudemans, which prevents egg development (Vitzthum 1933, Riggert 1935b, Hemer 1960) .
Jepson & Southwood (1958) noted 40% larval parasitism by yeasts and ciliate protozoans. FF predators and
Hymenopterous parasites are listed in Tables 1 and 2, respectively.
Of the Hymenopterous parasites, only Soalanqia drosoohilae Ashmead has been considered for import into
England from Canada for biological control of FF (Simmonds
1952, 1953) . The presence of predators often disturbs female Table 1 . Predators of the FF
Host Life Stage Preyed Upon3
Stage Not Predator Species Family Mentioned Eggs Larvae Pupae Adults
Miris dolobratus L. Miridae A Bembidion lampros (Herbst) Carabidae CDE Trechus quadristriatus (Schrank) Carabidae CDE Tachyporus spp. Staphylinidae CD Peraamasus lonaicornis Berlese Parasitidae D Agonum dor sale. (Pont) Carabidae C B Notiophilus biguttatus (F.) Carabidae C < Nebria brevicollis (F.) Carabidae BC Harpalus ruficornis (F.) Carabidae C Feronia spp. Carabidae BC Tachydromia spp. Empididae D Scatophaaa stercoraria (L.) Anthomyiidae D Medeterus truncorum Meiaen Dolichopodidae D Tachydromia minuta Meiaen Empididae B Tachydromia agilis Meigen Empididae B Anthocoris nemorum (L.) Cimicidae BD D D D "Spiders" ? B
aAr Collin 1918; B, Jones 1965; C, Jones 1968; D, Jones 1969b; E, Nordlander 1979. 27
Table 2. Hymenopterous parasites of the FF
Stage Life Staae of Parfni t-i rpci« Not Parasite Species Family Mentioned Eggs Larvae Pupae Adults
Sigalpkua saudat.ua Nees Braconidae A Pteromalus puparum (L.) Pteromalidae A RhoDtromeris wildhami (Kurd-jumov) Cynipidae A Polvscvtus oscinidis Kurdiumov Pteromalidae A Merisus iaLa.cma.diua Lindeman Pteromalidae A Semiotellus nigripes Lindeman Eulophidae A Pte>-omalus micans Olivier Pteromalidae A Eucaila spp. Cynipidae E Cothonasois hexatoma Hartig Cynipidae E pschacra spp. Cynipidae B Dicy.clua fuasicornis walker Pteromalidae B Aohidius granaries Walker Braconidae B RhoDtromeris heotoma (Hartio) Cynipidae K .Chasmodoa aptecus (Nees) Braconidae B DK IM Eucoila eucera (Hartio) Cynipidae C D Eseudeucaala spp. Cynipidae D LoxotroDa tritoma (Thomson) Diapriidae D DX Ashmeadopria spp. Diapriidae D Halticoneera aena (Walker) Pteromalidae E D J Trichomalus cristatus (Foerster) Pteromalidae AE D Cvrtooaster vulgaris Walker Pteromalidae DF Spalaagia spp. Pteromalidae D Polvscelis s d d . Pteromalidae F Trichomalus pangs (Walker) Pteromalidae K Soalanoia drosoDhilae Ashmead Pteromalidae FJ G Xoxotropa spp. Diapriidae F RhoDtromeris s d d . Cynipidae F Hexacola LeaaLsma (Hartig) Cynipidae JM Platygastec spp. Platygasteridae M Halt icoDtera circulus (Walker) Pteromalidae K LM Asecodes J,a.gus (Walker) Pteromalidae LM RhoDtromeris eucera (Hartigt Cynipidae E IL Tetrastichus s d d . Eulophidae L Rtihekia fallax Gahan Pteromalidae J Callitula bicolor SDinola Pteromalidae CE D FHIJ Hexacola s d d . Cynipidae F Trichomalus statatus (Foerster) Pteromalidae J Rorismenus texaggg (Girault) Eulophidae J Ha IticoDtera fuscicornis (Walker) Pteromalidae I
aA, Collin 1918; B, Cunliffe 1921; C, Lazarov 1935; D, Riggert 1935b; E, Roos 1937; F, Simmonds 1952; G, Simmonds 1953; H, Hemer 1960; X, Jones 1965; J, Allen C Pienkowski 1973; K, Nordlander 1979; L, Howell 1982; M, Moore 1983. 28
FF, thus decreasing oviposition frequency of the fly (Jones
1968). Larval predation is highest during summer (Allen &
Pienkowski 1974) with predators active in May when adults
emerge (Jones 1965). Allen & Pienkowski (1973) noted parasitism is not a density-dependent relationship and that parasites emerge after FF adults.
Damage and Chemical Control
FF and stem borers often cause damage to oats, rye, barley, wheat, maize, and grasses (Collin 1918, Vickerman
1980). Clements et a l . (1983) found a correlation between
larval activity and sward damage, while Clements et al.
(1985) determined a negative correlation exists between yield and larval density. Jepson & Southwood (1958) calculated a
significant regression between the density of oat deadhearts and larval density. FF have been reported to attack up to
30% of young tillers of winter wheat (Nielsen & Nielsen
1984). Lauva & Shutele (1976) noted an infestation of 87.5% on cereals; Rubtzov (1935) claimed a yield loss of 33% in
Siberia. Yield losses ranged up to 69.7 hektoliters (198 bushels) of oats per year (Collin 1918). Miles (1930) determined a 35% yield loss of oats and noted a loss of 9.7 6% was equal to 165,628 hektoliters (470,000 bushels) of grain.
FF can infest up to 80% of barley and oat stalks. Loban
(1979) determined the economic threshold on barley to be 15- 29
20 flies per 100 sweeps (11-13% stalk infestation rate) and
25-30 flies per 100 sweeps on oats (26-28% stalk infestation rate). When there were 30-40 flies per 100 sweeps on barley, there was a 2 6-32% infestation. Insecticide applications were used when there were more than 25 flies per 100 sweeps on oats (Loban 1979). Popov (1976) found that when the infestation rate on cereals was > 0.5-1%, there was a threat to the young crop. He recommended spraying when there were
30-35 flies per 100 sweeps and when 20-25 flies per 100 sweeps if seed is produced.
* Good control of FF on barley has been obtained with demeton, parathion, methyl parathion, and dinitrocresol
(Hemer 1960). Control on oats was best with an insecticide application timed to the 2 leaf stage during the first generation of adults. Spraying for the second generation was not effective unless combined with the first application in which yields increased 15%. Larsson (1984) noted . applications should be timed to kill adults before oviposition. Good control on oats was obtained with omethate
(Lloyd 1976), permethrin, and fenvalerate (Larsson 1977).
Larsson (1984) found that parathion and fenitrothion killed larvae within shoots and stopped further attack.
Heard et al. (1979) reported FF damage to maize with yield losses of 0.138 kg dry matter and 1 ear per plant.
Good control was obtained with seed coats of methiocarb and 30 triazophos. These insecticides gave good control when applied as a field spray timed to the 2-3 leaf stage (Muller
1971, 1974) . Walker & Turner (1976) obtained good control on maize by broadcasting granular phorate in June during the adult peak.
Belyaev (1940) obtained good control of FF on cereals using a bait containing sodium fluosilicate and a 0.5-1% solution of 46-48% crystaline sugar and 15-20% invertase.
Applications were timed as soon as flies appeared on oats or when early varieties of apple were in bloom and again at tillering. Application frequencies were increased when there were more than 50 flies per sweep. When temperature was 18-
26°C, a third application was necessary with spray intervals of 8-10 d. Good control on cereals was achieved with dimethoate and trichlorphos (Lauva & Shutele 197 6).
FF damage to grasses in England is high but cannot be detected visually. Damage becomes evident when yields of pesticide-treated versus untreated plots are compared
(Clements et al. 1982) . Insecticides applied to perennial ryegrass, grass swards, and ryegrass were shown to increase fodder yield due to control of FF and "stem borers." Good control was achieved with phorate, bendiocarb, and aldicarb
(Lemon & Greig 1982, Clements et a l . 1982, 1983, Spaull et al. 1985). Sown Italian ryegrass treated with aldicarb reduced larval populations to 0, while phorate reduced the 31 population from 3,380/m2 to 260/m2 (Clements et a l . 1985).
Chlorpyriphos application at sowing or seedling emergence of
ryegrass gave good control (Anon. 1980), while Mowat (1974) noted little control if applied after the 2-tiller stage.
Additional control on grasses was possible when sown
early enough to develop to the 2-leaf stage before adult
spring emergence (Franz 1971). Permethrin (10-20 d residual)
gave good control on pasture in England when timed to the 3
oviposition periods — 16 May, 18 July, and 9 September
(Clements & Henderson 1982). Skulkina (1980) noted a
decrease in FF populations after the fungicide thiram was
applied. Dimethoate and 2,4-D also decreased larval
densities. Lower densities were attributed to increased
stimulation of plant growth. FF control on lawn turf was obtained with diazinon when applied twice at a 14-d interval as soon as damage appeared. Dimethoate also gave good control if applied when larvae arid adults were exposed.
Preventive sprays are not recommended (Dahlsson 1971, 1974). EXPERIMENTATION
3 2 Upper and Lower Threshold Temperature and
Degree-day Estimates for Development of the
Frit Fly, Oscinella frit (L.) (Diptera: Chloropidae) ,
at Eight Constant Temperatures 34
THE FRIT FLY (FF), Oscinella frit (L.), a. sporadic pest of turfgrass (Schread & Radko 1958, Niemczyk 1981) occurs throughout most turf-growing regions of the United States
(Aldrich 1920). Considerable research exists concerning FF phenology, ecology, and life history on cereals and pasture grasses. However, there exists little information pertaining to FF strains (Allen & Pienkowski 1974) adapted to
■ turfgrasses.
Researchers have attempted to use degree-days (DD) to predict FF occurrence on agricultural grasses. Lower developmental thresholds used as a base to accumulate DD have included 5.5°C (Vickerman 1980), 7°C (Ohnesorge 1973, Nielsen
& Nielsen 1984), and 7.2°C (Jepson & Southwood 1958).
Estimates of FF lower developmental thresholds vary among workers. Lower thresholds were reported to be 6°C (Kreiter
1930), 6.6-7.7°C (Jepson & Heard 1959), 7.2°C (Nye 1959), and
8°C (Chrzanowski 1931).
Differing developmental thresholds were probably the result of different FF host-specific strains, experimental techniques, and hosts on which FF populations were reared.
Well defined developmental thresholds are vital to the generation of predictive DD models to anticipate FF 35 occurrence. Previously, no attempt has been made to investigate the effects of temperature on development of FF strains adapted to turfgrass. Because of this lack of information, studies were initiated to. describe the development of turf-adapted FF, determine upper and lower developmental thresholds, and establish the DD representative of the development of life stages on a turfgrass host in the laboratory.
Materials and Methods
FF adults were collected with a sweep net from fairway 3 on the College of Wooster Golf Course, Wooster, Ohio, in 1985 and from fairway 10 on The Ohio State University Golf Course,
Columbus, Ohio, in 1986.
Fairway 3 was comprised of 60% Lolium perenne L., 20%
Poa pratensis L., and 20% Poa annua reptans L. Fairway 3 physical properties were: thatch = 2.5 cm, soil pH = 6.7, organic matter = 2.8%, cation exchange capacity = 10.2, sand
= 30.4%, silt = 47.6%, and clay = 22.0%. The last
insecticide applied was isofenphos in 1981. Fairway 10 was comprised of 70% P. annua reptans and 30% P. pratensis and
Aqrostis spp. Physical properties were: thatch = 1.3 cm, soil pH = 6.6, and cation exchange capacity = 12.9. The last insecticide applied was aldrin in 197 6. 36
FF adults collected were transferred into 0.236 liter
(1/2 pint) Ball® mason jars. Adults were then shaken into an inverted 3.7 liter battery jar where they were anesthetized by exposure to ether vapors. Anesthetized adults were removed from the battery jar with an aspirator and separated from other chloropids with aid of a binocular microscope.
Anesthetized adults were placed into 2 oviposition chambers, each with one 10 cm pot of 'Pennfine' L. perenne seedlings in the 2 to 3 leaf stage covered with an 8 by 13 cm transparent plastic cylinder screened on one end. The number of adults per chamber ranged from 20-40. Chambers were maintained at room temperatures (20-23°C) and placed by a window for exposure to outdoor photoperiod.
Oviposition chambers were checked every 24 h for eggs.
All eggs were removed with a camel's-hair brush and randomly assigned to 8 groups to be reared at different temperatures.
Oviposition chambers were monitored daily and resupplied with adults to obtain as many eggs as possible. Rearing containers consisted of petri dishes (1006 brand, 50 by 12 mm style) with 1 disc of filter paper per dish moistened with distilled water. Two 2.5 cm long L. perenne leaf blades were placed on the filter paper. One egg was placed on each leaf blade. New eggs were added as they became available. Petri dish lids fitted tightly, maintaining a high relative humidity. 37
Eggs were observed every 24 h until hatched. Larvae were monitored every 2 4 h while feeding and tunneling within leaf blades until pupation. New leaf blades were added when old blades decomposed. Puparia were monitored daily until adults emerged. FF were reared at 15.0, 17.5, 20.0, 22.5,
25.0, 27.5, 30.0, and 35.0 ± 1.0°C. All temperatures were maintained within Sherer-Gillett environmental chambers, rooms, and General Electric model 805 incubators with a photoperiod of 16:8 (L:D).
Data Analysis. The rate of development of each life stage was the reciprocal of the mean number of days of development at each temperature. Development rates were regressed against their respective temperatures to allow for the prediction of lower, upper, and lethal constant threshold temperatures of each life stage. Upper developmental and lethal thresholds were predicted from a biophysical model developed by Wagner et al. (i984).
Lower developmental thresholds were predicted by simple linear regression of development rate versus temperature data taken from the linear part of the development rate sigmoid curve generated by Wagner's model (Ryan et al. 1982). Lower thresholds were estimated by solving the linear regressions for the temperatures at which 0 development occurs (x intercept). 38
Results and Discussion
Behavioral Observations. Adults oviposited in many
locations within oviposition containers. The majority of
eggs were placed behind loose leaf sheaths; many of these
were found within folds of withered sheaths. A few eggs were
found adhered to the plastic cylinder, leaf blades and stems,
soil, and within the leaf shoot axis. Vickerman (1978)
noted withered sheaths to be the preferred oviposition site.
Larvae emerged by scraping the chorion with their mouth
hooks and exiting through a V-shaped opening at the egg's
anterior end. After hatching, the chorion collapsed.
Riggert (1935) noted that larvae emerged with the aid of
their mouth hooks; chorion collapse was documented by Steel
(1931). Larvae emerging from eggs in rearing containers were
found to penetrate leaf epidermis by rasping with their mouth
: hooks. Larvae also gained entrance to the mesophyll through
cut ends of leaf blades.
Once within the mesophyll, larvae fed actively, as
indicated by the intake of green chlorophyll-laden cells
visible through their transparent cuticle. Active feeding
enabled larvae to tunnel within leaf tissues. Leaf mining
was also noted by Steel (1931) and Heard et a l . (1979). Once
constructed, tunnels began to coalesce forming feeding
cavities where larvae spent the majority of the time. 39 Larval feeding within cavities appeared passive due to the absence of whole cell constituents visible through their transparent cuticle. Feeding pockets contained a brown homogenate of decomposed mesophyll cells which larvae apparently fed upon. This larval food source may be the result of bacterial degradation of plant cells. Ryzhkova
(1962) noted that larval feeding involves a mutualistic
relationship with Pseudomonas sp. bacteria that break down plant proteins.
Pupation occurred under leaf blades within feeding pockets lacking the lower epidermis. Blunck & Ludewig (1926) noted that pupation occurred at the site of larval feeding.
Males within the puparium were identified by orange testes visible through the untanned cuticle. Puparia containing
females measured 2.4 ± 0.03 mm (x ± SEM, n = 6) in length and those containing males 2.1 ± 0.03 mm (n = 8). Puparia
lengths differed significantly between sexes (t = 6.29; df =
12; P < 0.05).
Adults emerged by exerting internal pressure with the ptilinum until the puparia split open at the anterior ends.
Eclosion occurred between 0600-1000 hours. Southwood et al.
(1961) noted most adults emerged between 0430-0900 hours with the maximum at 0 600-07 00 hours. Adult characteristics after emergence were observed for one male and one female. No major differences were noted. The following were observed: tfO
1) when half emerged, a drop of white fluid was voided at the posterior end of the puparium, 2) adults were light yellow, with dark legs and eyes after eclosion, 3) adults were able to walk as soon as they emerged, 4) the eyes, abdomen, wing stubs, ptilinum, antennae, and tarsi were cleaned with their ■ legs, 5) wings were expanded apparently by forcing haemolymph into them with 2-15 abdominal contractions, 6) the ptilinum was retracted, and 7) behaviors 1-6 were noted within 10 min after emergence. Adults were completely tanned and flying within 1 h. Southwood et al. (1961) noted similar adult post emergence characteristics.
Adults in oviposition chambers were lethargic at sunrise but eventually more than ca. 90% of flies moved to the top of leaf blades and faced skyward. By midday, the majority of flies were at the top of the plastic cylinder. All flies returned to grass hosts during the evening where they remained until morning. Wetzel et al. (1972) noted flies oriented to the sky with flight activity greatest in the morning and evening, with a maximum during the warm parts of the day. Ibbotson (1958) noted the majority of adults became airborne in the morning between 0900-1100 hours; by 1300 hours most adults had flown up into the sky.
Developmental Thresholds. The development of eggs, larvae, and pupae was monitored at constant temperatures, 41 ranging from 15-35°C. The results are shown in Table 3.
Sixteen eggs incubated at 35°C did not complete development, although all contained fully developed larvae. Fourteen eggs placed into 25°C for 3 wk did not develop; dissection revealed undifferentiated cytoplasm. Nine larvae did not complete development at 15 and 35°C, although some feeding and tunneling occurred. Mortality at 15°C was probably due to sluggish activity and decreasing rates of host penetration, tunneling, and feeding. One of the 7 larvae kept for 66 d at 22.5°C took on a brown color and died.
Riggert (1935) noted larvae died at 36°C. All puparia at
35°C contained fully developed dead adults. Development
rates of all 3 life stages increased with increasing temperature up through 27.5°C; thereafter, the rates
decreased.
The relationships between FF egg, larval, and pupal
development rate and temperature are shown in Fig. 1-3,
respectively. Two of the points (30 and 35°C) were not used
in the calculation of the lower theoretical thresholds
because they were outside the linear range of rate
development and temperature (Campbell et al. 1974).
Based on the rate of development, the lower thresholds
were estimated to be 10.32 ± 3.03 (95% CL) (eggs), 10.36 ±
2.52 (larvae), and 10.78 ± 4.79cC (pupae). The wide 95% CL
were the result of variation about the linear regression. Table 3. Development of immature stages of FF reared at 8 constant temperatures
Eggs Larvae Pupae
Temp (± 1°C) Days (x ± SEM) 1/xDays n DDa Days (x ± SEM) 1/xDays n DDa Days (x ± SEM) 1/xDays n DDa
15.0 10..66 ± 0.33 0.09 15 49.88 b ___b 5 22.00 ± 1.99 0.04 4d 92.84
17.5 5.83 ± 0.30 0.17 16 41.85 38.46 ± 1.58 0.02 5 274.60 15.80 ±0.37 0.06 5 106.17
20.0 4.92 ± 0.39 0.20 13 47.62 30.30 ± 1.84 0.03 6 292.09 11.33 ±0.33 0.08 6 104.46
22.5 4.00 ± 0.00 0.25 15 48.72 23.00 ± 1.16 0.04 6 279.22 9.50 ± 0.28 0.10 4 111.34
25.0 3.00 ± 0.00 0.33 16 44.04 18.50 ± 0.50 0.05 7 270.84 ” 8.33 ± 0.33 0.12 5 118.45
27.5 2.75 ± 0.11 0.36 16 47.24 16.66 ± 1.20 0.06 6 285.55 5.75 ± 0.25 0.17 4 96.14
30.0 3.14 ± 0.45 0.31 17 61.79 18.00 ± 1.34 0.05 5 353.52 7.30 ± 0.33 0.13 5 140.30
35.0 ooc 0.00 16 ooc 0.00 4 ocP 0.00 2d
(xDD ± SEM) 48 .73 ± 2.41 (xDD ± SEM) 292,,63 ± 12.56 (xDD ± SEM) 109 .95 ±6.02
aDD, degree-days needed for development at specific °C. DD calculated from the formula DD = D(T - t), where D = number of days required for development at a certain temperature T and t is the threshold temperature (Price 1984); t (eggs) = 10.32, t(larvae) = 10.36, t(pupae) = 10.78. bAlthough larvae emerged from eggs at 15°C, low temperature slowed feeding within grass blades such that larvae were unable to obtain food to survive and develop. cNo development due to lethal upper temperature (1/°° = 0.00). dPupae taken from 22.5, 25.0, and 27.5°C temperature regimes. to DEVELOPMENT RATE (1/xDAYS) .30- .35- .05- .45- . .15“ .40- biophysical model of Wagner et al. (1984). Predicted Predicted (1984).al.et Wagner of model biophysical 20- .2 0 .25- n 3.° (lethal). (upper), 34.0°C and (lower), 29.0 (95%CL) 3.03 ± 10.32 are thresholds the from generated isthat line sigmoid The temperatures. 10 0 - 10 i. 1. Fig. 10.32 j CL) 3.03(95% Development of FF eggs at 8 constant constant 8 at eggs ofFF Development 15 Y = -.222 +.0215(X) rz = ,984 02 30 25 20 TEMPERATURE(+1°C) EGGS 29.0°C z= rz ,977(n = 8) 35 ,34.0°C 4 3 DEVELOPMENT RATE (1/x DAYS) ipyia oe fWge ta. 18) Predicted (1984).al. et Wagner of model biophysical n 3.° (lethal). (upper), 34.0°C (lower), 29.0and (95% CL) 2.52 ± 10.36 are thresholds temperatures. The sigmoid line is that generated from the from generated is that line sigmoid The temperatures. . . .05- .06- .07- .04- .03- 1 0 02 0 “ - 10 i. 2. Fig. 10.36 CL) ±2.52 (95% eeomn o F avea 7 constant 7at larvae FF of Development 520 15 Yr-.0369+.00356(X) rz = .992(n = 5) TEMPERATURE(±1°C) LARVAE 25 30 29.0°C = , 9 9 3 ( n = 7 ) 35 .34.0°C DEVELOPMENT RATE (1/xDAYS) .12 . .04- .06- .08- . .14- .18- .16- ipyia oe fWge ta. 18) Predicted (1984).al.et Wagner of model biophysical n 3.° (lethal). 34.0°C and (95%4.79 ± 10.78 are thresholds temperatures. The sigmoid line is that generated from the from generated is that line sigmoid The temperatures. 2 0 10 0 - - - 10 i. 3. Fig. /*10.78± 4.79(95% CL) /*10.78± Development of FF pupae at 8 constant constant 8at pupae FF of Development 520 15 Y Y = -.102+.00946(X) 2= r2 .952(n = 6) TEMPERATURE(±1°C) PUPAE CL.) 25 lwr, 90 (upper), (lower), 29.0 30 - r .988(n = 8) 35 34.0°C 45 u 6 This variation was due, in part, to the inability to rear large numbers df FF life stages, and possible genetic differences between FF populations in Columbus and Wooster and host physiology. Larvae were unable to feed when trapped within condensation droplets; other larvae left their hosts and became trapped under the filter paper. Differential feeding rates resulted in variation in larval development. All r2 were greater than 0.95, indicating a strong relationship between temperature and development. Estimates of.FF lower developmental thresholds vary considerably among workers. Chrzanowski (1931) noted adults became inactive at temperatures < 8°C. Nye (1959) claimed the activity threshold for larvae was 7.2°C. Jepson & Heard (1959) claimed the threshold to be between 6.6-7.7°C, while Kreiter (1930) noted larval inactivity at 6°C. Kreiter (1930) claimed larvae entered hibernation at < 6°C and pupated when temperatures were >. 12°C; larvae did not feed at < 12°C. Bases used in the accumulation of DD for prediction of adult emergence also varied among workers. Vickerman (1980) used a base of 5.5°C which he cited from Le Berre (1959). Jepson & Southwood (1958) accumulated DD above 7.2°C with no reference to their base. Nielsen & Nielsen (1984) cited Riggert's (1935) base of 7°C for their DD accumulations. 47 My estimates of FF thresholds of 10.3-10.7°C are greater than those determined by other researchers. Although the 95% CL include many of the other estimates, it is probable that the linear regression extrapolations overestimate the lower thresholds, since the-relation may cease linearity and become asymptotic as development rate approaches 0. "From a practical standpoint, however, location of the x intercept by linear extrapolation has proven useful for predictive purposes in other insects" (Jones & Sterling 1979). It is probable earlier estimates were low, since Riggert (1935) mentions the critical temperature to be 7-8°C. Although no authors mention details of their analysis, it is likely they obtained their threshold predictions from direct observations or estimated extrapolations of hand-drawn plots, since regression techniques were not widely used before the 1950's (J. P. Klein, personal communication). My regression analysis of Riggert's (1935) FF data indicate a threshold of 10.3°C, which is greater than his estimate of 7-8°C. Wagner et al.'s (1984) SAS program and biophysical model estimated the theoretical upper and lethal thresholds from my data to be 29.0 and 34.0°C, respectively, for all 3 life stages. The model line fits are shown in Fig. 1-3. Wagner’s model fit the data well, as indicated by r2 values greater than 0.97. No estimates of the variability of model predictions were provided by the SAS program, and it is 43 uncertain whether these could be developed. When rates of development for all life stages were analyzed by multiple t tests (a = 0.05) all differed from one another. Eggs exhibited the greatest significant rate of development (slope [b] = 0.0215), followed by pupae (b = 0.0094), and larvae (b = 0.0035) . The number of DD required for the development of each life stage per temperature is shown in Table 3. The mean ± SEM DD required for the development of each life stage were obtained by averaging all DD associated with temperature regimes for eggs, larvae, and pupae. ■DD accumulations of 48.73 ± 2.41 (x ± SEM), 292.63 ± 12.56, and 109.95 ± 6.02 were required for completion of the egg, larval, and pupal stages, respectively. A total of 451.31 ± 52.91 (95% CL) DD were required for development from egg to adult. An average of my 3 lower FF theoretical thresholds yields 10.4°C, which can be rounded to 10.0°C as a base for the accumulation of DD for predictive purposes. Rounding to the nearest whole number avoids the use of decimals in DD accumulations and rationalizes the use of standardized thresholds for use in pest management programs (Pruess 1983). Such rounding has minimal effect on predictions, since a difference in the base temperature of i 1 or 2 degrees may be of little practical significance (Arnold 1959). 49 References Cited Aldrich, J. M. 1920. European frit fly in North America. J. Agric. Res. 18(9): 451-473. Arnold, C. Y. 1959. The determination and significance of the base temperature in the linear heat unit system. In Proc. Am. Soc. Horticultural Sci. 74: 430-445. Blunck, H. & K. Ludewig. 1925. Die fritfliege. Biol. Reichsanst. Land-u. Forstw. 9, 4th ed. 4 pp. Abstr, in Rev. Appl. Entomol. Ser. A 1927 15: 11. Campbell, A., B. D. Frazer, N. Gilbert, A. P. Gutierrez & M. Mackauer. 1974. Temperature requirements of some aphids and their parasites. J. Appl. Ecol. 11: 431- 438. Chrzanowski, A. 1931. Oscinella frit. its biology, the damage caused by it in agriculture and its control. Choroby Roslin, i., p t . 2: 23-55'. Abstr. in Rev. Appl. Entomol. Ser. A 1931 19: 591. Heard, A. J., G. C. Lewis & A. B. Joyce. 1979. Effect of stem-boring larvae (Diptera) on the yield of forage maize. Plant Pathol. 28: 150-154. Ibbotson, A. 1958. The behavior of Frit fly in Northhumberland. Ann. of Appl. Biol. 46: 474-479. Jepson, W. F. & T. R. E. Southwood. 1958. Population studies in Oscinella frit L. Ann. of Appl. Biol. 46: 465-474. Jepson, W. F. & A. J. Heard. 1959. The frit fly and allied stem-boring Diptera in winter wheat and host grasses. Ann. of Appl. Biol. 47: 114-130. Jones, D. & W.. L. Sterling. 1979. Rate and thresholds of Boll Weevil locomotory activity in response to temperature. Environ. Entomol. 8: 874-878. 50 Kreiter, E. A. 1930. Experimente und Beobachtungen iiber den Einfluss der Temperatur auf die Entwicklung und das Benehmen (Behaviour) der Fritfliege. Rev. Appl. Entomol., 4(2) pp. 451-470. Abstr. in Rev. Appl. Entomol. Ser. A 1931 19: 283. Le Berre. 1959. Hivernation et zero de developpement chez l'Oscinie Oscinella frit L. (Dipt., Chloropidae). — Acta Symp. de Evolutione Insectorum, Praha 1959: 270- 275 (in French). Nielsen, L. B. & B. O. Nielsen. 1984. Oscinella frit (L.) and Q. pusilla (Mg.) (Diptera, Chloropidae) in agricultural grass in Denmark. Z. Angewandte Entomol. 98: 264-275. Niemczyk, H. D. 1981. Destructive Turf Insects. HDN Books, Ohio. Nye, I. W. B. 1959. The distribution of shoot-fly larvae (Diptera, Acalypterae) within pasture grasses and cereals in England. Bull. Entomol. Res. 50 p t . 1: 53- 62. Ohnesorge, B. 1973. Investigations on the influence of weather on the course of the flight of the frit-fly. Z. fur Pflanzenkrankheiten und Pflanzenschutz 80(5): 24 6-254. Abstr. 7 67 in Rev. Appl. Entomol. Ser. A 1975 63 (3) : 198. Price, P. 1984. Insect Ecology. 2nd ed. John Wiley and Sons, Inc. Pruess, K. P. 1983. Day-degree methods for pest management. Environ. Entomol. 12: 613-619. Riggert, E. 1935. Zur kenntnis der Lebensgewohnheiten von Oscinella frit L „ und ihrer Jugendstadien. Arb. Physiol. Angewandte Entomol. 2(2-3): 101-130, 145-146. Abstr. in Rev. Appl. Entomol. Ser. A 1935 23: 740. Ryan, T. A., B. L. Joinar & B. F. Ryan. 1982. Minitab reference manual. Ryzhkova, E. V. 1962. Phytopathogenic symbionts of the Swedish flies Oscinella frit L. and Q. pusilla Mg. (Diptera: Chloropidae) and their practical use. Rev. Entomol. USSR 41 pt. 4: 788-795. Abstr. in Rev. Appl. Entomol. Ser. A 1965 53: 176. 51 Schread, J. C. & A. M. Radko. 1958. A new turfgrass insect pest? USGA J. and turf management: 2 9-31. Southwood, T. R. E ., W. F. Jepson & H. F. Van Emden. 1961. Studies on the behavior of Oscinella frit L. (Diptera) adults of the panicle generation. Entomol. Exp. Appl. 4: 196-210. Steel, A. 1931. On the structure of the immature stages of the frit fly (Oscinella frit Linn.). Ann. of Appl. Biol. 18: 352-369. Vickerman, G. P. 1978. Host plant preferences of Oscinella sp. (Diptera: Chloropidae) in the laboratory. Ann. of Appl. Biol. 89: 379-386. 1980. The phenology of Oscinella spp. (Diptera: Chloropidae) . Bull. Entomol. Res. 70(4) : 601-620. Wagner, T. L., H. Wu, P. J. Sharpe, R. M. Schoolfield & R. N. Coulson. 1984. Modeling insect development rates: a literature review and application of a biophysical model. Ann. Entomol. Soc. Am. 77: 208-225. Wetzel, T., F. Mende & G. Lutze. 1972. Investigation on the daily rhythm of the wheat bulb fly (Leptohylemyia coarctata Fallen) and the frit fly (Oscinella frit Linne) in wheat fields (Diptera: Brachycera). Nachrichtenblatt fur den Pflanzenschutzdienst in der DDR. 26(3): 54-47. Abstr. 4080 in Rev. Appl. Entomol. Ser. A 1975 63(10): 1113. Seasonal Abundance, Oviposition Activity, and Degree-day Prediction of Frit Fly, Oscinella frit (L.) (Diptera: Chloropidae), Adult Emergence on Turfgrass in Ohio 52 5 3 THE FRIT FLY (FF), Oscinella frit (L.), is a pest often abundant on golf course and home lawn turfgrasses (Kerr 1957, Dahlsson 1974, Niemczyk 1981) . Schread & Radko (1958) noted FF larvae damaged grasses by feeding on the central shoot. In V a ., FF damage turf and pasture grasses by killing the embryonic growing point; adults are often a nuisance to golfers (Allen & Pienkowski 1973). Aldrich (1920) reported 4 FF generations per year in Ind. on winter wheat, Triticum aestivum (L.), while Allen & Pienkowski (1974) noted 3 generations per year in V a . on reed canarygrass, Phalaris arundinaceae (L.). Control of FF is based on application of residual contact insecticides to turfgrass. Larsson (1984) noted that the timing of application was an important aspect of control. He noted applications should be timed to kill adults before oviposition and larval host penetration. Clements & Henderson (1982) obtained control of FF on perennial ryegrass, Lolium perenne L., when permethrin was applied coinciding with FF oviposition periods. There have been several attempts to accumulate degree- days (DD) to predict FF adult occurrence to aid control (Jepson & Southwood 1958, Ohnesorge 1973, Vickerman 1980, 54 Nielsen & Nielsen 1984) . There is a lack of biological information from which control programs of FF on turfgrass may be developed. Therefore, a study of FF seasonal abundance, oviposition activity, and predictive DD models of adult occurrence was conducted on golf course turfgrass in Ohio. Materials and Methods Seasonal Abundance. The seasonal abundance, number of generations, and sex ratio of FF caught were studied in Wooster, Ohio, during 1984 and 1985. FF adults were sampled from the College of Wooster Golf Course fairways 1 and 3. Fairways had similar topography, long periods of no insecticide usage, and high populations of FF adults. Adults were sampled with a 45 cm diam. sweep net and a modified unit area sweep net to obtain relative density estimates over time (Appendix A [Fig. 4], p. 1 4 1) . The modified unit area sweep net estimated the relative density of FF adults/27.87 m2 (100 ft2) . Fairway 1 consisted of 70% Poa annua reptans L. and 30% Poa pratensis L. Fairway 3 was comprised of 60% Lolium perenne L., 20% P. annua reptans. and 20% P.. pratensis. Physical properties for fairway 1 were: thatch =2.5 cm, soil pH = 7.1, organic matter = 3.2%, cation exchange 55 capacity = 10.3, sand = 22.4%, silt = 57.6%, clay = 20.0%, the insecticide last applied was fensulfothion in 1977; fairway 3: thatch =2.5 cm, soil pH = 6.7, organic matter = 2.8%, cation exchange capacity = 10.2, sand = 30.4%, silt = 47.6%, clay = 22.0%, the last insecticide applied was isofenphos in 1981. Fairways were sampled approximately every 3 d in 1984 and weekly in 1985. Flies were sampled from 1 April to 31 October between 1300-1800 hours EDST. Both sampling methods were utilized during each sample date to obtain comparative density estimates. Three sweep net samples (1 sample = X 5 0 sweeps) and 4 unit net samples were taken at random from both fairways in 1984. Samples were increased to 6 (sweep net) and 9 (unit net) in 1985 to decrease variability to a standard error of ca. 30% of the mean. Captured FF were anesthetized by spraying Tradco® engine-starting fluid (ether) onto sample nets. Anesthetized flies were removed and placed into 0.236 liter (1/2 pint) Ball® mason jars and frozen until counted, sex determined, and separated from other chloropids with aid of a binocular microscope. FF Oviposition Activity. FF oviposition data were obtained from random subsamples of 20 females on each sample date. Ovaries were examined with aid of a binocular 56 microscope to determine whether or not they had discharged eggs. Discharged ovaries were identified by the absence of pupal fat globules and the presence of empty ovarioles and follicular relics (yellow bodies). The time of maximum adult abundance before major oviposition activity was determined by plotting percent of FF having oviposited versus FF adult cumulative percent emergence for all adult generations during 1984 and 1985. Degree-day Prediction of FF Adult Emergence. Daily maximum and minimum temperatures were obtained from a weather station at the Ohio Agricultural Research and Development Center in Wooster, Ohio, ca. 5 km from the study site. Accumulated DD were calculated using a modified Allen's program (1976) which measures the area under a sine curve above or between thresholds with amplitude specified by each pair of daily maximum and minimum temperatures. Daily 1 DD were calculated with bases from 0-ll°C, 5-ll°C with an upper threshold of 2 9°C, and from starting dates of 1 January and 1 March in 1984 and 1985. Cumulative percent emergence of FF adults pooled from fairways 1 and 3 were plotted against a DD scale for incorporation into predictive models: Due to the sigmoidal distribution of these data, DD were transformed to Log10 and cumulative percent emergence to probit units. A log-probit 57 line was fit to the data by least-squares regression analysis. Predicted dates of FF adult emergence before significant oviposition activity (40% cumulative emergence) were compared to actual dates by using alternate years data. Data associated with that combination of base and starting date giving the best predictive accuracy were pooled to generate predictive models for all adult FF generations. Only first and second adult generation pooled predictive models were validated during 1986. Predicted first and second generation 40% adult emergence was compared to actual dates of emergence of FF populations in Columbus and Wooster, Ohio, in 1986. Populations in Columbus were sampled from The Ohio State University (OSU) Golf Course fairway 10. Fairway 10 was comprised of 70% P. annua reptans and 30% P. pratensis and Aqrostis spp. Physical properties were: thatch =1.3 cm, soil pH = 6.6, cation exchange capacity = 12.9. The last insecticide applied was aldrin in 197 6. In Wooster, populations were sampled from the College of Wooster Golf Course fairway 3. Temperature data for Columbus DD accumulations were obtained from the National Oceanic and' Atmospheric Administration recording station at Port Columbus ca. 14 km from the OSU Golf Course. 53 Results and Discussion FF Seasonal Abundance. The percent of parou's FF females, precipitation, and mean number of adults caught per sample method from pooled fairways 1 and 3 during 1984 and 1985 on the College of Wooster Golf Course are shown in Fig. 5 and 6, respectively. Adult peak densities occurred during mid-May, late June, late July-early August, and mid-September in 1984. Peak adult periods were ca. 2 wk earlier in 1985 than 1984. Adult peaks occurred during late April, mid-June, mid-July, and late August in 1985. Three and a partial fourth generations of FF were indicated in N Ohio (Wooster). First FF adult peaks were the result of overwintered larvae from a partial fourth generation. The second peaks were part of the first complete generations, third the second generations, and fourth the third generations. Decreases in FF densities during peak adult periods were probably the result of rainfall. There appeared a decrease in the number of adults caught in sweep and unit nets following precipitation > 1.27 cm (0.5 inches) unless flies were emerging as part of the peak produced at the end of a generation. Decreases in the number of FF caught in the sweep net during 1984 coincided with rainfall > 1.27 cm during Julian dates 128 and 207 (Fig. 5). Increases in percent parous females coincided with the latter part of Fig. 5. Percent parous females, precipitation (cm), and mean FF caught per sample method from pooled fairways 1 and 3 during 1984 on the College of Wooster Golf Course. MEAN NO. FRIT FLIES/THREE DAY INTERVALS PRECIPITATION (cm) PERCENT 200 PAROUS FEMALES to 0 1 ro o co CD CD M Z s ->» H m Cl Z T3 CD H m >T1 OlCO a3 *n £ > > 33 -< CD -<> p ® CD CO P® CO o Fig. 6. Percent parous females, precipitation (cm), and mean FF caught per sample method from pooled fairways 1 and 3 during 1985 on the College of Wooster Golf Course. PRECIPITATION (cm) PERCENT H* MEAN NO. FRIT FLIES/WEEK PAROUS FEMALES^ 09 • o 0> (0 10 Ol oo ro o oo o ON o o o o o 0 0 ro co o o o o o 1 1 • 1 _L_ 1 1 i ■ i — i I I L (O' c_ O c r; 2 ro 2 3' m 10 co SEP E(ARAS 1&3) NET(FAIRWAYS =SWEEP o 1&3) NET(FAIRWAYS :UNIT ro O cn NO 63 adult peaks especially for first and second peaks during 1984 and 1985 and the fourth peak in 1984 (Fig. 5 and 6) . A partial fourth generation per year is indicated by the high percent of females having oviposited in late-October as the last flies were noted. Allen & Pienkowski (1974) noted 3 FF generations per year and 4 adult peaks in V a ., while Aldrich (1920) noted 4 generations in Ind. Second and third adult peaks were ca. 4 and 2 times higher during 1984 than 1985, respectively. The sweep and unit net sampling methods generated similar trends in FF populations during 1984 (r2 = 0.758; n = 35) and 1985 (r2 = 0.65 6; n = 21). Sweep and unit net data from 1984 were analyzed to determine the average number of samples needed during 1985 to obtain various standard errors (SE) as a percentage of the mean (Southwood 1978). More unit net samples were required than the sweep net to obtain the same SE as a percentage of the mean; therefore, the sweep net is a more efficient sampling device. The number of samples was increased to 6 (sweep net) and 9 (unit net) during 1985 with sample intervals of 1 wk, instead of ca. 3 d as in 1984, to obtain SE of 30% of the mean. The average SE as a percent of the mean, during 1984, was 30 (range = 9-70) for the unit net and 26 (range = 5-100) for the sweep net. After the increase in sample size during 64 1985, the average SE decreased to 19% (range = 7-37) for the unit net and 15% (range = 5-24) for the sweep net. Regression equations for the prediction of FF densities based on unit net samples versus sweep net samples are shown in Table 4. Regression equations for i984 and 1985 differed significantly in intercepts, indicating that sweep net sample information cannot be used to estimate unit net densities. The mean numbers of male and female FF caught per sample method during 1984 and 1985 are shown in Fig. 7-10. Both sweep and unit net samples were biased toward males. The total number of males caught was significantly greater than females for the unit net during 1984 (paired t = 5.75; df = 34; P < 0.05) and 1985 (paired t = 4.33; df = 18; P < 0.05); and for the sweep net during 1984 (paired t = 6.08; df = 40; P < 0.05). Male density did not differ from females during 1985 sweep net sampling sessions (paired t = 1.96; df = 18; P > 0.05). Male/female ratios ranged from 1.2:1 to 1.7:1 during 1985 and 1984, respectively. Males and females exhibited similar trends in seasonal abundance, as indicated by the sweep net during 1985 (r2 = 0.822; n = 24), unit nets during 1984 (r2 = 0.877; n = 35) and 1985 (r2 = 0.876; n = 21), and the sweep net during 1984 (r2 = 0.893; n = 43). Although males outnumbered females, similar trends in their seasonal Table 4. Regression equations for the prediction of unit net densities from sweep net samples Year Regression equations of unit net on sweep neta 1984 Loge (unit net) = -0.303 + 0.644 Loge (sweep net)b r2 = 0.60 n = 35 1985 Loge (unit net) = -2.22 + 1.11 Loge (sweep net)b r2 = 0.79 n = 18 CM VO o *** Pooled '84+'85 Loge (unit net) = -0.839 + 0.763 Loge (sweep net) H i! n = 53 aEquations based on pooled fairway 1 and 3 data. bEquations followed by the same letter are significantly different (P < 0.05; Snedecor & Cochran 1967). cn m 66 19 84 1 6 0 - SW EEP NET = MALES(FAIRWAYS 1&3) =FEMALES(FAIRWAYS 1&3) 1 4 0 - MALE:FEMALE( 1.4:1)* r 2 = .8 9 3 (n= 4 3 ) > 120- 100 - u. t 6 0 - z 4 0 - ••1 2 0 - oH APRIL MAY JUNEJULY AUG. SEPT. OCT. Fig. 7. Mean male and female FF caught in the sweep net from pooled fairways 1 and 3 during 1984 on the College of Wooster Golf Course. •, No. males significantly different from no. females (paired t = 6.08; df = 40; P < 0.05) . MEAN NO. FRIT FLIES/WEEK - 0 9 - 5 7 - 0 6 - 0 3 - 5 4 - 5 1 oH net from pooled fairways 1 and 3 during 1985 on the College College the on 1985 during 3 1 and fairways from pooled net ifrn fo o fmls pie = .6 d 4 P > P 34; = df 1.96; = (paired t significantly females not no. from males No. •, different Course. Golf Wooster of 0.05) . APRIL i. 8. Fig. !• MAY enml n eaeF cuh i h sweep inthe caught FF female and male Mean JUNE JULY WEP NET EEP SW 5 8 9 1 AUG. FMLSFIWY 1&3) =FEMALES(FAIRWAYS 1&3) =MALES(FAIRWAYS = 822 n=24) 4 2 = (n 2 2 .8 = r (1.2:1) MALE:FEMALE SEPT. OCT. 67 68 1 9 8 4 UNIT NET ■=MALES(FAIRWAYS 1&3) 3 6 - =FEMALES(FAIRWAYS 1&3) MALE:FEMALE( 1.7:1)* r2=.877 (n=35) > 2 4 - 12- 6 - OH APRIL MAYJUNE JULY AUG. P T . O C T .SE Fig. 9. Mean male and female FF caught in the unit net from pooled fairways 1 and 3 during 1984 on the College of Wooster Golf Course. •, No. males significantly different from no. females (paired t = 5.75; df = 34; P < 0.05) . 69 1 9 8 5 UNIT NET =MALES(FAIRWAYS 1&3) 1 8 - FEMALES(FAIRWAYS 1&3) MALEFEMALE (1.2:1) 1 5 - r = .876 (n=21) W 12- 9 - 6- APRIL MAY JUNE JULY AUG. SEPT. OCT. Fig. 10. Mean male and female FF caught in the unit net from pooled fairways 1 and 3 during 1985 on the College of Wooster-Golf Course. •, No. males significantly different from no. females (paired t = 4.33; df = 18; P < 0.05) . 70 abundance reflect an unbiased relationship between males and females and factors affecting FF populations. Male bias was probably due to sample techniques and FF behavior. Jepson & Southwood (1958) noted males usually predominate when sampling for adults even though the sex ratio was 1:1 at emergence. Calnaido et al. (1965) and Adesiyun & Southwood (1979) noted males were most abundant in grass canopies, while females predominated in aerial populations between 1.2-8.9 m. The sweep and unit nets only sampled from the grass canopy; sampling occurred when flight activity was in progress. Wetzel et al. (1972) noted flight activity was greatest in the morning and evening, with the maximum during warm parts of the day, with intermediate peaks at 1500 hours. Net sampling during the morning was not possible due to dew formation, nor in the evening due to golf play. FF Oviposition Activity. FF ovaries were grouped into 6 categories of development according to the reproductive status of flies. The 6 developmental stages are shown in Fig. 11. Stage 1 shows ovary development of newly emerged flies as indicated by the presence of undifferentiated oocytes and the lack of ova. Stage 2 shows development of the oocytes to the nurse-cell-yolk stage, while Stage 3 shows fully developed ova of nulliparous , 71 Fig. 11. FF ovarian development grouped into 6 morphological stages. Stages 1-3 nulliparous, stages 4-6 parous. Symbols used: oc, oocyte; nc, nurse cell; yo, yolk; ov, ovum; et, egg tube; fr, follicular relic. / 72 ,13mm .28mm ,39mm .42mm 44mm Fig.11 73 females. Stages 1, 2, and 3 were always accompanied by pupal fat globules within the haemolymph. However, 90% of the fat globules had disappeared by Stage 3; no fat globules were noted beyond Stage 3. Rygg (1966) noted FF females were often filled with fat globules to 4 d after eclosion. Anderson (1964) showed in females of Musea domestica L., Fannia canicularis (L.), and Muscina stabulans (Fallen) that presence of pupal fat globules was characteristic of the nulliparous state, since depletion of these fat globules was always complete before any eggs were deposited. Stages 4, 5, and 6 represent ovarian development of parous females. Stage 4 shows ovaries after some egg deposition (note empty ovarioles occupied by oocytes accompanied by ovarioles with fully developed ova). Stage 5 shows ovaries that have fully deposited a complement of eggs (note empty uncontracted egg tubes [ovarioles] above which are developing the next complement of oocytes). Stage 6 shows ovaries of parous females with a full complement of eggs (note condensed egg tubes [follicular relics, yellow bodies] at the base of each ovary). Rygg (1966) dissected ovaries to determine the reproductive status of FF females. Kuzina (1942) noted that in females of Stomoxys calcitrans (L.) yellow bodies remained in the ovarioles after eggs were deposited, and this could be used to distinguish between parous and nulliparous females. Miller & Treece (1968) 74 determined nulliparous females of the face fly, Musca autumnalis De Geer, by the presence of pupal fat bodies and the absence of follicular relics within ovarioles or lateral oviducts; the presence of follicular relics was indicative of the parous state. Percent parous FF females over time are shown in Fig. 5 and 6 for 1984 and 1985., respectively. Major ovipositional activity occurred during late May, late June, mid-August, and late September in 1984. In 1985, this activity occurred ca. 2 wk earlier than in 1984, probably due to warmer spring temperatures, and oviposition peaks occurred during early May, mid-June, mid-July, and late August. Parasitic nematodes were found within FF abdomens. Nematodes were not identified since free-living adults are needed for species determination (G.O. Poinar, personal communication). Parasitation rates were 0.26% (1984) and 0.54% (1985). Parasitized FF were all found to contain undifferentiated ovaries. Riggert (1935), Keler (1932), and Goodey (1930) reported the nematode Tvlenchinema oscinellae Goodey from FF adults. Simmonds (1952) indicated nematode parasitation often resulted in adult sterility. Degree-day Prediction of FF Adult Emergence. Larsson (1984) noted control programs should be implemented when adults are most abundant but before significant 75 oviposition activity. Fig. 12 and 13 show the relationship between FF adult cumulative percent emergence and percent parous females for 1984 and 1985, respectively. Five of 8 FF adult emergence periods had significant oviposition activity when ca. 40% of adults emerged. DD models were generated to predict 40% adult emergence in the field. Fig. 14 shows the error, for all 4 adult generations, between actual versus predicted 40% adult emergence using pooled DD model's with base temperatures from 0-ll°C and 1 March and 1 January starting dates. In addition, pooled equations with a 1 January starting date and base temperatures from 5-ll°C were evaluated with the upper developmental threshold of 2 9°C (M.P. Tolley, unpublished data). The data indicate that the later starting date requires a lower base temperature to obtain the least predictive error. A starting date of 1 January and 5°C base temperature gave the least predictive error, with the error increasing with departures from 5°C. A starting date of 1 March gave the lowest predictive error at a base of 0 or 1°C. The starting date of 1 January, with 2 9°C upper threshold, did not decrease predictive error greatly. This lack of accuracy was probably due to the low number of days > 2 9°C during 1984 and 1985. Temperatures were > 29°C for 13 d during 1984 and 7 d during 1985; temperatures never exceeded 35.5°C. 76 Fig. 12. Comparison of FF cumulative percent emergence and percent parous females during 1984. ----- = FF cumulative % emergence - - - = % parous females = Relationship between 40% FF emergence and oviposition Fig.12 PERCENT 100 0 8 0 9 0 3 0 4 0 5 0 6 20 0 7 10 110 0 3 1 0 7 1 0 5 1 0 9 1 ULI TE A D N IA L JU 4 8 9 1 210 • • •• 0 3 2 0 5 2 0 7 2 0 9 2 73 Fig. 13. Comparison of FF cumulative percent emergence and percent parous females during 1985. —:--- = FF cumulative % emergence - - - = % parous females 3P > = Relationship between 40% FF emergence and oviposition 3 ULI DATE N IA L JU 13 . g i F PERCENT 100 20 0 8 0 4 0 6 0 9 0 5 0 3 10 0 7 110 0 5 1 0 3 2 0 7 1 1 30250 5 2 01 9 1 0 3 5 8 9 1 210 0 7 2 • • 0 9 2 <£) so Fig-. 14. Comparison of sum of day differences between actual versus predicted FF 40% adult emergence (adult generations 1-4) at various base temperatures with starting dates, for DD accumulations, of 1 March, 1 January, and 1 January with a 2 9°C upper threshold. Data based on pooled 1984+1985 predictive models. 14 . g i F SUM OF DIFFERENCES BETWEEN ACTUAL VS. PREDICTED 40% ADULT EMERGENCE (GENERATIONS 1-4) - 3 3 - 9 2 5 3 1 4 31 - 7 3 - 9 3 - 7 1 i - 5 1 - 5 2 - 7 2 - 9 1 - 3 2 JN SATN DATE STARTING JAN. = 1 MRH TRIG DATE STARTING MARCH = 1 1 JAN. STARTING DATE WITH 2 9 ° C UPPER THRESHOLD UPPER C ° 9 2 WITH DATE STARTING JAN. 1 OLD 1985 PEITV MODELS PREDICTIVE 5 8 9 -1 4 8 9 1 POOLED AE EPRTR ( C) (° TEMPERATURE BASE 82 The lower theoretical developmental threshold for the FF was determined to be 10°C (M.P. Tolley, unpublished data). Since a starting date of 1 March gave the best overall predictive accuracy, 10 and 0°C bases with a 1 March starting date were evaluated to obtain the best predictive models. Table 5 shows the DD equations for all 4 adult FF generations using a 10°C base temperature. Regression equations in 1984 and 1985 differed significantly (a = 0.05) in variances, slopes, and slopes and intercepts for the second, third, and fourth adult generations, respectively. First generation regression equations were not significantly different. Due to significant differences, the development of second, third, and fourth adult generation pooled models was not statistically valid. Nevertheless, these models were evaluated for their predictive accuracy. Table 6 shows that predictions from pooled equations (base = 10°C) differed from actual 40% adult emergence less less than when using calendar days. Predictions based on calendar days differed by 17 (first generation), 16 (second generation), 11 (third generation), and 18 d (fourth adult generation). Pooled model (base = 10°C) predictions differed from actual 40% emergence by 5 (first generation), 2 (second generation), 4 (third generation), and 9 d (fourth adult generation). ! Table 5. Probit-DD equations of cumulative percent emergence of FF adults at Wooster, Ohio; DD computed from 1 March at 10°C base temperature ______Probit-DD equations A d u l t g e n e i - at ion 1984 1985 P o o l e d (1984+1985) 1st Probit(Y)a - -9.50 + 7.40 Log10(X)b r2 = 0.934 Problt(Y) - -14.45 + 9.42 Log10(X) r2 - 0.991 Probit(Y) = -9.42 + 7.28 Log1Q(X) r2 = 0.910 2nd Probit(Y) = -27.37 + 12.54 Log10(X)c r2 = 0.909 Probit (Y) = -31.02 + 14.31 Log1Q(X)c r2 =* 0.572 Probit(Y) = -27.04 + 12.50 Log10(X) r2 - 0.747 3rd Probit(Y) - -32.57 + 13.11 I/og1Q (X)c r2 = 0.943 Probit (Y) - -30.56 + 12.66 Iog10(X)c r2 = 0.847 Probit(Y) - -26.61 + 12.17 Log1Q(X) r2 - 0.850 4th Probit(Y) = -136.55 + 46.10 Log10(X)c r2 = 0.942 Probit (Y) =■ -52.30 + 18.96 Log10(X)c r2 - 0.881 Probit(Y) = -73.53 + 25.75 Log10(X) r2 - 0.709 aY, cumulative percent emergence (probit 4.75 = 40%). bX, Celsius DD. cRegression equations in each row followed by the same letter are significantly different (P < 0.05; Snedecor & Cochran 1967). co Ul Table 6. FF adult 40% seasonal abundance flight dates, predicted 40% DD flight dates, 1984 and 1985 pooled predicted 40% DD flight dates, and the maximum deviation in days of all predictions versus actual flight peak daysa P o o l e d M a x i m u m M a x i m u m Poo l e d Actual calendar Predicted 40% predicted 40% calendar date predicted DD predicted DD 40% flioht datec DD flioht dateb DD flioht dateb day deviation dav deviation dav deviation Adult g e n e r ation 1984 1985 1984 1985 1984 1985 1984-1985 1984 1985 1984 1985 First 132 115 140 111 137 111 17 8 4 5 4 Second 170 154 165 158 168 154 16 5 4 2 0 Third 201 190 194 198 198 194 11 7 8 3 4 Fourth 246 228 229 245 237 236 18 17 15 9 8 aAll days represented by the Julian calendar. bPredicted dates generated from probit-DD equations with DD calculated from 1 March with a 10°C base temperature. CA11 estimates based on sweep net samples. CD -c- 85 Table 7 shows the DD equations generated from a 0°C base and 1 March starting date. Equations for adult generations 1-3 were not significantly different (a = 0.05), so the generation of pooled predictive models was statistically valid. However, 1984 and 1985 fourth generation equations differed significantly in slopes and intercepts. Although not statistically valid, the pooled equation was nevertheless generated and evaluated for predictive accuracy. Table 8 shows pooled models differed from actual 40% emergence by 1 (first generation), 2 (second generation), 2 (third generation), and 5 d (fourth adult generation). These predictive errors were much less than predictions based on calendar date or a 1 March starting date with 10°C base. Researchers have attempted to relate DD accumulations to FF adult phenology. .Ohnesorge (1973), in the Federal Republic of Germany, accumulated DD above a base of 7°C with temperatures taken from a soil depth of 2 cm. He noted adults were first caught at 50-80 DD and flight occurred regularly at > 90 DD. At 120-150 DD, FF adults reached their first peak. Later in the year, factors other than soil temperature had a dominating influence. Nielsen & Nielsen (1984) noted the DD requirements of a complete generation of FF is similar in England, Norway, Denmark, and the Federal Republic of Germany; ca. 350-390 DD, using a 7°C threshold. They noted the completion of 3 FF generations required at Table 7. Probit-DD equations of cumulative percent emergence of FF adults at Wooster, Ohio; DD computed from 1 March at 0° C base temperature ______Probit-DD equations A d u lt g e n e r - a t i o n 1984 1 9 8 5 Pooled (1984+1985) 1st Probit(Y)a = -25.13 + 11.33 Log10(X)b r2 = 0.954 Probit(Y) = -26.88 + 12.06 Iog1Q(X) r2 - 0.977 Problt(Y) = -25.89 + 11.64 Log10(X) r2 =■ 0.956 2nd Probit(Y) = -56.08 + 20.08 Iog10(X) r2 = 0.947 Probit (Y) - -46.68 + 17.12 Log1Q(X) r2 - 0.878 Probit(Y) = -52.78 + 19.03 Log10(X) r2 = 0.910 3rd Probit (Y) =■ -49.06 + 16.63 Log10(X) r2 = 0.949 Probit (Y) =■ -50.40 + 17.13 Iog1Q(X) r2 = 0.864 Probit (Y) =■ -48.90 + 16.61 Log10(X) r2 = 0.909 4th Probit(Y) = -148.67 + 44.90 Log10(X)c r2 = 0.954 Probit(Y) = -68.59 + 21.65 Log10(X)c r2 = 0.902 Probit(Y) = -95.97 + 29.57 Log10(X) r2 - 0.827 aY, cumulative percent emergence (probit 4.75 = 40%). bX, Cels i u s DD. cRegression equations in each row followed by the same letter are significantly different (P < 0.05; Snedecor & Cochran 1967). 00 CD Table 8. FF adult 40% seasonal abundance flight dates, predicted 40% DD flight dates, 1984 and 1985 pooled predicted 40% DD flight dates, and the maximum deviation in days of all predictions versus actual flight peak daysa P o o l e d M a x i m u m M a x i m u m P o o l e d Actual calendar Predicted 40% predicted 40% calendar date predicted DD predicted DD 40% flioht datec DD fliqht dateb DD flioht dateb day deviation dav deviation dav deviation A dult g e n e r ation 1984 1985 1984 1985 1984 1985 1984-1985 1984 1985 1984 1985 First 132 115 132 115 133 114 17 0 0 1 1 S e c o n d 170 154 167 157 169 156 16 3 3 1 2 T h i r d 201 190 199 193 201 192 11 2 3 0 2 Fou r t h 246 228 236 237 242 233 18 10 9 4 5 aAll days represented by the Julian calendar. bPredicted dates generated from probit-DD equations with DD calculated from 1 March with a 0°C base temperature. cAll estimates based on sweep net samples. oo -j 38 least 1,050-1,100 DD above 7°C. Jepson & Southwood (1958) noted adults of the tiller generation on oats, Avena sativa L., peaked after 580.6 ± 55.2 DD (95% FL) while the panicle generation peaked at 641.6 ± 36 DD (base = 7.2°C) . Vickerman (1980) noted a difference of 380-420 DD between FF adult peaks or 50% emergence (base = 5.5°C) . No researchers mentioned the starting date of their DD accumulations and bases differed. Due to differing methods of accumulating DD, it is impossible to compare my data with those of previous authors. Table 9 shows the validation of both sets of DD models for the first and first-and-second FF adult generations in Wooster and Columbus, Ohio, during 1986, respectively. Predictions from models with a base of 10°C differed from actual 40% FF emergence by 25 d (first generation) in Wooster while calendar dates differed by 17 d; models differed by 22 (first generation) and 10 d (second generation) in Columbus. Predictions from models with a base of 0°C differed from actual 40% FF emergence by 8 d (first generation) in Wooster and 9 (first generation) and 5 d (second generation) in Columbus. Model validations indicated that pooled equations generated from a 1 March starting date with a 0°C base gave the best predictions with errors < 9 d. It is unclear why DD models based on the 10°C FF lower developmental threshold were less accurate in prediction of Table 9. Validation of first and second adult generation pooled predictive DD models in Wooster and Columbus, Ohio, during 1986; models based on a 1 March starting date with a 0 or 10°C base temperature Pooled Predicted 40% Pooled predicted DD flioht date DD day deviations Maximum calendar Base Base date day deviatioi A dult Actual calendar Location g e n e r a t i o n 40% flight date 0° (3 10° C 0° C 10° C 1984-1986 W o o s t e r First 123 115 98 8 25 17 a W o o s t e r S e c o n d --- Columbus First 117 108 95 9 22 b Columbus S e c o n d 152 147 142 5 10 b aSampling discontinued before completion of second adult generation. bNo previous FF phenology known for Columbus. CO 90 40% adult cumulative emergence than models generated from a 0°C base temperature. Contributing factors may include relationships between FF and turfgrass-temperature response, availability of nutrients and enzymes, photoperiod, microhabitat conditions, and fluctuating temperatures. Methods to estimate developmental thresholds often involve optimal diets and constant temperatures; thus, development times must be regarded as minimums (Higley et al. 1986) . Variability in accuracy of validation of models was due, in part, to the estimation of temperatures at the experimental site from the Port Columbus weather recording station ca. 14 km away. FF adult 40% cumulative emergence in Ohio was best predicted with DD models generated from a 1 March starting date with a 0°C base temperature. These models may be used to optimize timing of short residual insecticide applications to minimize FF attack and damage. Recommendations for FF control involve 2 insecticide applications at 10-14 d intervals when adults or larvae are present (Tashiro 1987) . Although my DD models exhibited errors < 9 d in predicting FF occurrence, they were nevertheless better than reliance on calendar dates to time insecticide applications. This DD approach may provide the turfgrass manager and researcher an important tool in maximizing the efficacy of short residual insecticides. 91 References Cited Adesiyun, A. A. & T. R. E. Southwood. 1979. Differential migration of the sexes in Oscinella frit (Diptera: Chloropidae). Entomol. Exp. Appl. 25 (1): 5 9-63. Aldrich, J. M. 1920. European frit fly in North America. J. Agric. Res. 18(9): 451-473. Allen, J. C. 197 6. A modified sine wave method for calculating degree-days. Environ. Entomol. 5: 380- 396. Allen, W. A. & R. L. Pienkowski. 1973. Parasites reared from puparia of the frit fly, Oscinella frit. in Virginia. Environ. Entomol. 2: 615-617. 1974. The biology and seasonal abundance of the frit fly, Oscinella frit. in reed canarygrass in Virginia. Ann. Entomol. Soc. Am. 67: 539-544. Anderson, J. R. 1964. Methods for distinguishing nulliparous from parous flies and for estimating the ages of Fannia canicularis and some other cyclorrhaphous diptera. Ann. Entomol. Soc. Am. 57: 226-236. Calnaido, D ., R. A. French & L. R. Taylor. 1965. Low altitude flight of Oscinella frit L. (Diptera: Chloropidae). J. Animal Evolution 34(1) : 45-61. Abstr. in Rev. Appl. Entomol. Ser. A 1966 54: 233. Clements, R. 0. & I. F. Henderson. 1982. Screening of pesticides for use on established grassland to improve herbage yield. Pesticide Sci. 13: 617-622. Dahlsson, S. 0. 1974. Frit fly damage to turfgrass. In Proc. of the 2nd Int. Turfgrass Res. Conf.: 418-420. Goodey, T. 1930. On a remarkable new nematode, Tylenchinema oscinellae gen. et sp. n., parasitic on the frit-fly, Oscinella frit L., attacking oats. Phil. Trans. R. Soc. (B) ccxviii: 315-343. Abstr. in Rev. Appl. Entomol. Ser. A 1930 18: 567. 92 Higley, L. G., L. P. Pedigo & K. R. Ostlie. 1986. Degday: a program for calculating degree-days, and assumtions behind the degree-day approach. Environ. Entomol. 15: 999-1016. Jepson, W. F. & T. R. E. Southwood. 1958. Population studies in Oscinella frit L. Ann. of Appl. Biol. 46: 465-474 . Keler, S. 1932. A contribution towards the knowledge of the parasites of Oscinis frit L. Prace Wydz. Chorob Roslin panstw. Inst. Naukow. Gospod. wiejsk. Bydgoszczy 11: 1-3. Abstr. in Rev. Appl. Entomol. Ser. A 1932 20: 457. Kerr, T. W. 1957. Leafhoppers infesting lawns in Rhode Island. J. Econ. Entomol. 50: 372. Kuzina, O. S. 1942. On the gonotrophic relationships in Stomoxys calcitrans L. and Haematobia stimulans L. Med. Parasitology 11(3): 70-78. Abstr. in Rev. Appl. Entomol. Ser. B 1944 32: 51-52. Larsson, H. A. 1984. Frit fly (Oscinella frit L.) damage in oats and its chemical control by synthetic pyrethroids. Z. Angewandte Entomol. 97: 470-480. Miller, T. A. & R. E. Treece. 1968. Gonadotrophic cycles in the Face Fly, Musea autumnalis. Ann. Entomol. Soc. Am. 61: 690-696. Nielsen, L. B. & B. O. Nielsen. 1984. Oscinella frit (L.) and Q. pusilla (Mg.) (Diptera, Chloropidae) in agricultural grass in Denmark. Z. Angewandte Entomol. 98: 264-275. Niemczyk, H. D. 1981. Destructive Turf Insects. HDN Books, Ohio. Ohnesorge, B. 1973. Investigations on the influence of weather on the course of the flight of the frit-fly. Z. fur Pflanzenkrankheiten und Pflanzenschutz 80(5): 246-254. Abstr. 767 in Rev. Appl. Entomol. Ser. A 1975 63 (3) : 198. Riggert, E. 1935. Untersuchungen uber die Parasiten der Fritfliege. Arb. Physiol. Angewandte Entomol. Berlin. 2(1): 1-23. Abstr. in Rev. Appl. Entomol. Ser. A 1935 23: 225. 93 Rygg, T. D. 1966. Flight of Oscinella frit L. (Diptera, Chloropidae) females in relation to age and ovary development. Ann. Exp. Appl. 9: 7 4-84. Schread, J. C. & A. M. Radko. 1958. A new turfgrass insect pest? USGA J. and turf management: 29-31. Simmonds, F. J. 1952. Parasites of the Frit fly, Oscinella frit (L.), in eastern North America. Bull. Entomol. Res. 43: 503-542. Snedecor, G. W. & W. G. Cochran. 1967. Statistical methods, Iowa State University, Ames. Southwood, T. R. E. 1978. Ecological methods with particular reference to the study of insect populations. Chapman & Hall, London. Tashiro, H. 1987. Turfgrass insects of the United States and Canada. Cornell Univ. Press, Ithaca and London. Vickerman, G. P. 1980. The phenology of Oscinella spp. (Diptera: Chloropidae). Bull. Entomol. Res. 70(4): 601-620. Wetzel, T., F. Mende & G. Lutze. 1972. Investigation on the daily rhythm of the wheat bulb fly (Leptohylemyia coarctata Fallen) and the frit fly (Oscinella frit Linne) in wheat fields (Diptera: Brachycera). Nachrichtenblatt fur den Pflanzenschutzdienst in der DDR. 26(3): 54-47. Abstr. 4080 in Rev. Appl. Entomol. Ser. A 1975 63(10): 1113. Seasonal Abundance and Spatial Distribution of Frit Fly, Oscinella frit (L.) (Diptera: Chloropidae), Imxnatures in Turfgrass 94 9 5 A PRIMARY REQUISITE to understanding an organism in its ecosystem is knowledge of spatial distribution (Sevacherian & Stern 1972) . Information on spatial patterns aid in life table studies, population surveys, and recognition of subspecies (Harcourt 1965). Moreover, understanding spatial patterns is vital in constructing sequential sampling plans (Waters 1955), selecting variance stabilizing transformations (Southwood 1978), and determining sample size (Karandinos 1976) . Research on the spatial patterns of turfgrass insect pests has focused on the black turfgrass ataenius, Ataenius spretulus (Haldeman) (Wegner & Niemczyk 1981); hairy chinch bug, Blissus leucopterus hirtus Montandon (Liu & McEwen 1979); Japanese beetle, Popillia iaponica Newman (Ng et a l . 1983); and Phyllophaqa spp. (Guppy & Harcourt 1970). Jonasson (1982) determined that frit fly (FF), Oscinella frit (L.) , eggs and larvae exhibited an aggregated spatial pattern on oats, Avena sativa L. The FF is a pest commonly abundant in turfgrass (Schread & Radko 1958, Franz 1971, Dahlsson 1974, Niemczyk 1981) . Damage to turfgrass results from FF larval feeding on the crown and central shoot. Although larvae are the damaging 96 stage, most studies on FF biology have focused on information gathered from adults. Jepson & Southwood (1958) and Allen & Pienkowski (1975) determined larval density in oats and reed canarygrass, Phalaris arundinacea (L.), by dissecting stems to expose larvae. Clements et al. (1983) noted "stemborers" were most abundant during February, June, and November in perennial ryegrass, Lolium perenne L., in England. Determination of spatial distribution of FF larvae in turfgrass requires dissection of many grass plants. To circumvent such labor-intensive effort, an attempt was made to obtain information by rearing adults from turfgrass samples placed in a greenhouse. Materials and Methods Estimates of FF larval densities were obtained by rearing adults from turf samples placed in a greenhouse for 4 w k . On each sampling date, 66 turf samples (316 cm2 per sample) were collected at random with an 18 cm wide spade from fairway 3 at the College of Wooster Golf Course every 2 wk from mid-April to mid-October. Sample locations were determined by a scaled map with locations specified by a table of random numbers. Replacement sod was used to fill sample holes left in the fairway. Fairway 3 was comprised of ca. 60% Lolium perenne L., 20% Poa pratensis L., and 20% Poa 97 annua reptans L. Physical properties were: thatch =2.5 cm, soil pH = 6.7, organic matter = 2.8%, cation exchange capacity = 10.2, sand = 30.4%, silt = 47.6%, and clay = 22.0%. The last insecticide applied was isofenphos in 1981. Samples were planted into a punctured, plastic-lined planter bed filled with Metro-mix® 350 growing medium. The planter bed and samples were initially irrigated to moisten throughout. Thereafter, a tubing drip irrigation system was used weekly to sustain grass growth. An emergence trap was placed over each sample for 4 wk to capture emerging FF adults. Each trap consisted of a cone of sheer drapery cloth attached to the mouth of a 0.263 liter (1/2 pint) Ball® mason jar supported 45 cm above each sample by a 6 mm diameter wooden dowel. Tapetrap® was applied to the inside of each jar to capture adults as they flew up the cloth cone into the jar. Adults were removed from the Tapetrap® with a camel1 s- hair brush and paint thinner. Flies were identified, sex determined, and their field location noted. Statistical Methods. Two FORTRAN programs (Davies 1971) were used to fit field data to the Poisson and negative binomial distributions. In addition, the negative binomial program also calculated K and tested for overdispersion. The common K (Kc) was approximated by the method of Southwood (1978). The following dispersion indices were calculated: 93 variance/mean, Taylor's power law (Taylor 1961), index of David and Moore (David & Moore 1954), Morisita's coefficient (Morisita 1962), standardized Morisita's coefficient (Smith- Gill 1975), Green's coefficient (Green 1966), mean crowding (m) and patchiness (Lloyd 1967), and Iwao's mean crowding mean relationship (Iwao 1968, Iwao & Kuno 1971). All indices were correlated to their respective means and tested for significant dispersion patterns (Myers 1978). The Poisson and negative binomial distributions were tested for goodness-of-fit by the X 2. The variance/mean, standardized Morisita's coefficient, and Green's coefficient were tested for the degree of aggregation by the X 2 and Morisita's coefficient by the F test (Southwood 1966). The aggregation index b of Taylor's power law and Iwao's mean crowding mean relationship were tested for departure from unity by Student's t test. The mean crowding (m) and patchiness were tested for departure from randomness by the 95% Cl overlap of the mean and 1, respectively (Appendix I, p . 154). Results and Discussion Seasonal Abundance. The number (x ± SEM) of male and female FF adults reared after 4 wk, per sample date, is shown in Fig. 15. Rearing was necessary due to the cryptic nature per 316 cm2 per sample date - 1985. Each data point average average point data Each 1985.- date sample cm2 316per per mrec o dls fteoewneig avl cohort. larval overwintering the of adults of emergence MEAN + S.E. NO. OF FRIT FLY ADULTS REARED/316 cm AFTER FOUR WEEKS is based on 66 samples. Data for October is from forced forced from is forOctober Data 66 samples. on isbased 1 1 1 3- 0 2 4- 6 5- 8 7- 9- 0 2 ------i. 15. Fig. APRIL Density of male and female FF adults reared reared adults FF female and ofmale Density MAY JUNE APE DATE SAMPLE 1 985 AUG. MALES FEMALES — = r.902(n=12) OCT.SEPT.JULY 99 1 0 0 of larvae and pupae and the prohibitive cost of manually dissecting immatures from grass stems. The maximum FF density reared was 15.6/316 cm2 (ca. 44/ft2) during mid-May. Populations rapidly declined by early July and disappeared by late September. The overwintering population density was 0.74/316 cm2 (ca. 2/ft2) obtained by rearing adults in October from the larval cohort that would have overwintered. Males were significantly more abundant than females (Student's t test; a = 0^05) on all sample dates except those associated with the overwintering populations (mid-April, late September, mid-October). Flies reared from the overwintering stages conformed to a 1:1 sex ratio. It is probable that FF adult sex ratios are 1:1. Jepson & Southwood (1958) noted a 1:1 sex ratio at adult emergence, with males predominating over females thereafter. Vickerman (1978b) noted a predominance of males when older hosts were infested. There may be more males at the onset of eclosion and more females at the end of emergence on oats (Vickerman 1980). Males are more abundant within a host canopy, while females abound 1.2-8.9 m above the canopy (Calnaido et al. 1965, Adesiyun & Southwood 1979) . Bias toward males was probably due to the close association between the host canopy and emergence traps. 10 1 Males are more active than females (Ibbotson 1958), thus increasing their probability of encountering the trap jar on top the emergence tent. In addition, turfgrass often grew up to the rim of the trap jar, producing vertical patterns to which females are attracted (Sanders 1960). Although the density of males and females differed, they exhibited similar seasonal abundance fluctuations (r2 = 0.90; n = 12) . Spatial Distribution. Computer programs by Davies (1971) were used to determine the best fitting distributions for males, females, and pooled male+females for each sampling day. The negative binomial was the best fitting distribution for 67, 58, and 67% of the 12 sampling days for males, females, and pooled sexes, respectively. The Poisson distribution was found to fit 17, 8, and 25% of the sampling days for males, females, and pooled sexes, respectively. Estimates of the dispersion index K of the negative binomial for all 3 classes ranged between 0.71 and 7.8. Southwood (1966) notes a K value < 8 indicates an aggregated distribution; thus, K reflects the clumped nature of FF immatures. Since samples were taken at different times, the determination of a common K (Kc) was necessary from the individual K's. Kc was determined to be 1.04, 1.56, and 1.23 for males, females, and pooled sexes, respectively. The validity of Kc was determined by the tests: there were 1 0 2 nonsignificant correlation coefficients between 1/K values and sample means for males (r = 0.31; df = 6; P > 0.05), females (r = 0.01; df = 5; P > 0.05), and pooled sexes (r = 0.45; df = 6; P > 0.05); the t test indicated all intercepts not significantly different from 0 for males (t = 0.62; df = 6; P > 0.05), females (t = 0.7 6; df = 5; P > 0.05), and pooled sexes (t = 0.65; df = 6; P > 0.05), respectively. The existence of' a common K is a significant finding, since it is vital to the development of sequential sampling plans, selecting variance stabilizing transformations, and for direct comparison of means between 2 or more distributions (Bliss & Owen 1958). Fig. 16-18 show the pattern of association between the variance and mean for the 3 classes. The aggregated pattern of these data is evident from the plotted values, which depart from the line of a Poisson distribution (S2 = x), pass through a line in the form of Taylor's power law (S2 = axb) , and approach the line of a negative binomial distribution with a common K (S2 = x + x2/Kc) . Table 10 shows Taylor's power law fitted to the means and variances of adults reared and the association between mean crowding (m) and the mean. The aggregated pattern of FF is evident since the slopes (b; index of aggregation) of Taylor's power law are significantly different from the Poisson distribution, where b = 1, for males (t = 6.57; df = male FF adults reared. Each data point based on 66 turf 66turf on based point data Each reared. adults FF male necp () 187 adsoe (b) 1.514. = slope and (a) 1.847, = (Kc) intercept 1.04,K = common The cm2 1985. 316 - of samples VARIANCE 1 16 40 80 2 0 i. 16. Fig. 0 - - - soito ewe h enadvrac of variance and mean the between Association s = ax s = _2 MEAN MALE 103 104 24 - FEMALE s = ax 20 - -2 L Lt o z < DC < > 8 - MEAN Fig. 17. Association between the mean and variance of female FF adults reared. Each data point based on 6 6 turf samples of 316 cm2 - 1985. The common K (Kc) = 1.56, intercept (a) = 1.502, and slope (b) = 1.233. F dls erd Ec aapitbsdo 6 uf samples 66 turf on based point data Each reared. adults FF f36 m 18. h cmo (c =12/ necp (a) = (Kc) intercept 1.23/ K = common The cm2 1985.316- of .4/ n lp (b) 1.546. = slope and 1.848/ VARIANCE 1 - 0 6 240- 280- 200 1 - 0 4 - 0 8 20 - - i. 18. Fig. s = X + — s = ax _b2 soito ewe h enadvrac of variance and mean the between Association x2 2 _ OLD MALE/FEMALE POOLED MEAN 105 Table 10. Regression equations of Taylor's power law relating the variances to the mean counts of the FF and the association between mean crowding (m) and the mean Sex Index M a l e (n = 12) Fe m a l e (n = 12) P o o l e d (n = 12) Taylor's power law Log(s2) = 0.333 + 1.514(Log”) Logts2) = 0.269 + 1.233(Logx) Log(s2) = 0.302 + 1.546(Logx) r = 0.98* r = 0.97* r = 0.98* m-x regression m = -0.628 + 2.06(x) m = -0.009 + 1.74(x) m = -0.690 + 1.958(x) r = 0.96* r = 0.93* r = 0.96* *, significantly different from 0; P < 0.05; t test. 106 107 10; P < 0.05), females (t = 2.80; df = 10; P < 0.05), and pooled sexes (t = 6.38; df = 10; P < 0.05). The y intercept of the regression of mean crowding on the mean indicates dispersion due to behavior such as oviposition of egg masses, mutual attraction, or repulsion of individuals. The slope of the m-x regression reflects aggregation due to habitat heterogeneity in relation to population density. All intercepts from the m-x regression have low values and are not significantly different from 0 for males (t = 0.73; df = 10; P > 0.05), females (t = 0.02; df = 10; P > 0.05), and pooled sexes (t = 0.59; df = 10; P > 0.05); thus, the number of immatures in the sample unit (316 cm2) exhibit a low degree of aggregation. Low aggregation may be the result of larval migration from the main shoot to tillers and other plants (Jones 1969) . The slopes were significantly greater than 1 for males (t = 6.09; df = 10; P < 0.05), females (t = 3.40; df = 10; P < 0.05), and pooled sexes (t = 5.68; df = 10; P < 0.05), and, thus, indicate the highly aggregated distribution of samples containing FF due to habitat heterogeneity (Iwao 1968) . Such aggregation could result from a patchy distribution of turfgrass hosts with withered leaves which are preferred by females as multiple oviposition sites (Vickerman 1978a). Jonasson (1982) noted an aggregated distribution of eggs on oats due to distribution of hosts with morphological characteristics 103 conducive for oviposition. In addition, he noted larvae exhibited less aggregation than eggs due to migration from old shoots to new tillers. Determination of population distribution is often complicated because dispersion indices are biased by the mean. Myers (1978) used a simulation model to generate patterns of egg dispersion controlled by a clumping variable. The clumping variable approximated the underlying determinant of the behavior pattern which influences the dispersion of eggs in the field. She noted indices which predicted the actual dispersion most accurately were not correlated to mean density and correlated to the clumping variable. Of the 7 indices studied, only Green's coefficient and standardized Morisita's coefficient were not correlated to mean density. Although the variance/mean was weakly correlated to mean density, it had the highest correlation to the clumping variable. She recommends the use of the above 3 indices when studying changes in dispersion with changing density. If the indices agree, then a strong statement can be made about dispersion. The correlation coefficients between the means and dispersion indices are shown in Table 11. Of the dispersion indices, only the K, standardized Morisita, Green's coefficient, Morisita's coefficient, and patchiness index were not significantly correlated to mean density. However, Table 11. Correlation coefficients between dispersion indices and sample means of FF adults reared Correlation Coefficients (r) Dispersion Index Male (n) Female (n) Pooled (n) Mean Crowding (m) 0.966 (12)* 0.930 (12)* 0.965 (12)* Variance/Mean 0.903 (12)* 0.704 (12)* 0.898 (12)* Index of David and Moore 0.903 (12)* 0.703 (12)* 0.898 (12)* K (Negative Binomial) 0.192 (8) 0.284 (7) 0.133 (8) Morisita's Coefficient 0.462 (12) 0.257 (12) 0.170 (12) Standardized Morisita 0.504 (12) 0.551 (12) 0.500 (12) Green's Coefficient 0.458 (12) 0.248 (12) 0.185 (12) Patchiness Index (m/x) 0.557 (12) 0.266 (12) 0.306 (12) *, significantly different from 0; P < 0.05; t test. 110 the variance/mean, index of David and Moore, and mean crowding were highly correlated to the means. Dispersion indices of the FF and their percentages fitting a random, uniform, or aggregated pattern are shown in Table 12. Three of 4 unbiased indices indicated identical trends in the spatial pattern of FF immatures. Morisita's coefficient, standardized Morisita, and Green's coefficient indicate a significant departure from randomness for 75, 57, and 75% of the sample dates for males, females, and pooled sexes, respectively. The patchiness index showed an aggregated spatial pattern for 67, 50, and 75% of the sample dates for males, females, and pooled sexes. All 4 indices indicate that a large majority of the samples conformed to an aggregated distribution. The 4 indices showed an average of 2 9% of the sample dates conforming to a random or uniform spatial pattern. These patterns were associated with the low densities of the overwintering populations (mid-April, late September, mid- October) . These indices probably do not indicate true randomness since they were associated with mean densities < 0.6/316 cm2. Taylor (1984) notes that small samples (< 1 individual per sample unit) often indicate randomness when, in fact, such data sets cannot distinguish true from pseudo randomness due to inadequate information. Table 12. Dispersion properties of FF adults reared from turfgrass - 1985 % of samples fitting a random, uniform, or aggregated distribution Dispersion Index Sex (n) Range of Dispersion Index Random Uniform Aggregated Mean Crowding (m) Male (12) 0.01-25.93 42 0 58 Female (12) 0.01- 9.50 83 0 17 Pooled (12) 0.26-35.18 33 0 67 Index of David & Moore Male (12) -0.17-13.87 8 9 83 Female (12) -0.03- 3.96 25 0 75 Pooled (12) -0.04-16.56 8 0 92 Variance/Mean Male (12) 0.83-14.87 25 0 75 Female (12) 0.96- 4.96 33 0 67 Pooled (12) 0.95-17.56 25 0 75 Morisita's Coefficient Male (12) 0.00- 2.32 25 0 75 Female (12) 0.00- 3.66 33 0 67 Pooled (12) 0.85- 2.35 25 0 75 Standardized Morisita Male (12) 0.082-0.50 25 0 75 Female (12) 0.004-0.51 33 0 67 Pooled (12) 0.062-0.50 25 0 75 Green's Coefficient Male (12) -0.015-0.02 25 0 75 Female (12) -0.015-0.04 33 0 67 Pooled (12) -0.002-0.02 25 0 75 Patchiness Index (m/x) Male (12) 0.14- 2.40 25 8 67 Female (12) 0.25- 3.66 50 0 50 Pooled (12) 0.87- 2.28 25 0 75 1 1 2 Of the 3 biased indices, only the variance/mean indicated the same dispersion as was predicted by Green's, Morisita's, and standardized Morisita's coefficients. This similarity was probably due to the relationship between the variance/mean and factors responsible for the clumping of FF populations. Myers (1978) noted that although the variance/mean was weakly correlated to mean density, it was highly correlated to the clumping variable. Mean crowding (m) and the index of David and Moore conflicted with all indices in predicting FF dispersion because of their high correlation to mean density. This research indicates that FF immatures are distributed in an aggregated pattern. Aggregation of FF may be due to the distribution of hosts with withered leaves onto which females oviposit and larval migration from old shoots to new tillers and plants. This aggregation conforms to a negative binomial distribution with a common K (Kc) . In addition, aggregation is supported by similar trends of 4 unbiased dispersion indices and the variance/mean. References Cited Adesiyun, A. A. & T. R. E. Southwood. 1979. Differential migration of the sexes in Oscinella frit (Diptera: Chloropidae). Entomol. Exp. Appl. 25 (1): 5 9-63. Allen, W. A. & R. L. Pienkowski. 1975. Life tables for the frit fly, Oscinella frit, in reed canarygrass in Virginia. Ann. Entomol. Soc. Am. 68: 1001-1007. Bliss, C. I. & A. R. G. Owen. 1958. Negative binomial distributions with a common K. Biometrika 45: 37-58. Calnaido, D., R. A. French & L. R. Taylor. 1965. Low altitude flight of Oscinella frit L. (Diptera: Chloropidae) . J. Animal Evolution 34(1) : 45-61. Abstr. in Rev. Appl. Entomol. Ser. A 1966 54: 233. Clements, R. O., P. F. Chapman & I. F. Henderson. 1983. Seasonal distribution of stem-boring larvae including frit fly (Diptera: Oscinella frit L.) and pest damage on perennial ryegrass. Grass and Forage Sci. 38: 283- 286. Dahlsson, S. 0. 1974. Frit fly damage to turfgrass. In Proc. of the 2nd Int. Turfgrass Res. Conf.: 418-420. David, F. N. & P. G. Moore. 1954. Notes on contagious distributions in plant populations. Ann. of Bot. 18: 47-53. Davies, R. G. 1971. Computer programming in quantitative biology. Academic, New York and London. Franz, W. 1971. A new pest of lawns. Ein neuer rasenschadling. Gesunde Pflanzen. 23(7): 124-125. Abstr. 145 in Rev. Appl. Entomol. Ser. A 1974 62: 33. Green, R. H. 1966. Measurement of non-randomness in spatial distributions. Res. Population Ecol. 8: 1-7. Guppy, J. C. & D. G. Harcourt. 1973. A sampling plan for studies on the population dynamics of white grubs, Phyllophaga spp. (Coleoptera: Scarabaeidae). Can. Entomol. 105: 47Q-483. 114 Harcourt, D. G. 1965. Spatial pattern of the cabbage looper, Trichoplusia ni. on Crucifers. Ann. Entomol. Soc. Am. 58: 89-94. Ibbotson, A. 1958. The behavior of Frit fly in Northhumberland. Ann. of Appl. Biol. 46: 474-47 9. Iwao, S. 1968. A new regression method for analyzing the aggregation pattern of animal populations. Res. Population Ecol. 10: 1-20. Iwao, S. & E. Kuno. 1971. An approach to the analysis of aggregation pattern in biological populations. In G. P. Patil, E. C. Pielou & W. E. Waters [eds.], Statistical Ecology vol. 1. Spatial Patterns and Statistical Distributions. Penn. State Univ. Press. Jepson, W. F. & T. R. E. Southwood. 1958. Population studies in Oscinella frit L. Ann. of Appl. Biol. 46: 465-474. Jonasson, T. 1982. Frit fly (Oscinella frit) oviposition on oat seedlings: evidence for contagious distribution of eggs. Entomol. Exp. Appl. 32: 98-100. Jones, M. G. 1969. Oviposition of frit fly, Oscinella frit L. (Dipt., Chloropidae) on oat seedlings and subsequent larval development. J. Appl. Ecol. 6: 411- 424 . Karandinos, M. G. 1976. Optimum sample size and comments on some published formulae. Bull. Entomol. Soc. Am. 22: 417-421. Liu, H. J. & F. L. McEwen. 1979. The use of temperature accumulations and sequential sampling in predicting damaging populations of Blissus leucopterus hirtus. Environ. Entomol. 8: 512-515. Lloyd, M. 1967. Mean crowding. J. Animal Ecol. 36: 1-30. Morisita, M. 1962. Ig-Index, a measure of dispersion of individuals. Res. Population Ecol. 4: 1-7. Myers, J. H. 1978. Selecting a measure of dispersion. Environ. Entomol. 7: 619-621. 115 Ng Yuen-Shaung, J. R. Trout & S. Ahmad. 1983. Spatial distribution of the larval populations of the Japanese Beetle (Coleoptera: Scarabaeidae) in turfgrass. J. Econ. Entomol. 76: 2 6-30. Niemczyk, H. D. 1981. Destructive Turf Insects. HDN Books, Ohio. Sanders, W. 1960. Ein beitrag zum Verhalten von Oscinella frit L. bei der Eiablage. Z. Angewandte Zool. 47 pt. 3: 335-341. Abstr. in Rev. Appl. Entomol. Ser. A 1962 50: 255. Schread, J. C. & A. M. Radko. 1958. A new turfgrass insect, pest? USGA J. and turf management: 29-31. Sevacherian, V. & V. M. Stern. 1972. Spatial distribution patterns of Lygus Bugs in California cotton fields. Environ. Entomol. 1: 695-704. Smith-Gill, S. J. 1975. Cytophysiological basis of disruptive pigmentary patterns in the Leopard Frog Rana pipiens. II. Wild type and mutant cell-specific patterns. J. Morphol. 14 6: 35-54. Southwood, T. R. E. 1966. Ecological methods with particular reference to the study of insect populations. Methuen, London. 1978. Ecological methods with particular reference to the study of insect populations. Chapman & Hall, London. Taylor, L. R. 1961. Aggregation, variance and the mean. Nature 189: 732-735. 1984. Assessing and interpreting the spatial distributions of insect populations. Ann. Rev. Entomol. 29: 321- 357. Vickerman, G. P. 1978a. Host plant preferences of Oscinella sp. (Diptera: Chloropidae) in the laboratory. Ann. of Appl. Biol. 89: 37 9-38 6. 1978b. Survival and duration .of development of Oscinella spp. (Diptera: Chloropidae) on different Graminae in the laboratory. Ann. of Appl. Biol. 89: 387-3 93. 1980. The phenology of Oscinella spp. (Diptera: Chloropidae). Bull. Entomol. Res. 70 (4) : 601-620. 116 Waters, W. E. 1955. Sequential sampling in forest insect surveys. For. Sci. 1: 68-7 9. Wegner, G. S. & H. D. Niemczyk. 1981. Bionomics and phenology of Ataenius spretulus. Ann. Entomol. Soc. Am. 74: 374-384. OVERALL DISCUSSION The frit fly (FF) , Oscinella frit (L.), is a small, black fly often abundant on golf course and home lawn turfgrasses (Kerr 1957, Schread & Radko 1958, Niemczyk 1981). The larval stages cause damage to turfgrasses by feeding on the central shoot and meristematic areas; adults are considered a nuisance to golfers (Allen & Pienkowski 1973). 9 The present study was initiated to provide the following biological information which may be useful in the development of FF control programs. Attempts at efficiently surveying FF adults included sampling with a sweep net and a modified unit area sweep net. The unit area net estimated the relative density of FF adults/27.87 m2 (100 ft2). The method of Southwood (1978) was used with 1984 data to suggest the desired number of samples per occasion to be taken during 1985, to achieve a standard error of 10-15%. The recommended number of samples was too large to be practical. However, the number of samples was doubled in 1985 to 6 (sweep net) and 9 (unit net) at the expense of precision, resulting in a standard error of < 24% for the sweep net and < 37% for the unit net. It was 1 1 7 118 impossible to predict unit net densities from sweep net samples due to large standard errors and small sample size. The reproductive status of FF females was determined by ovarian morphology. Females < 4 d contain pupal fat globules within abdominal haemolymph (Rygg 1966). I noted fat globules disappeared as eggs matured, possibly providing nutrients for vitellogenesis. There were no fat globules by the time oviposition began. Parous females often contained follicular relics, which are remnants of old egg,tubes condensed at the base of ovaries. Parous and nulliparous females were determined by the presence of follicular relics and pupal fat globules, respectively. Similar evidence for determining the reproductive status of female Diptera was reported by Anderson (1964) and Miller & Treece (1968). Dissections revealed low rates of nematode parasitism of FF. Nematodes were not identified since free living adults are needed for species determination (G.O. Poinar, personal communication). Information about ovarian morphology may aid in determination of oviposition activity and age-grading of adults. Three and a partial fourth FF generations per year with 4 major periods of adult emergence were indicated in N Ohio (Wooster). Increased numbers of adults collected in sampling nets during late April (1985) and mid-May (1984) indicated completion of the overwintering fourth generation. It was 119 reasoned there should be a low proportion of parous versus nulliparous females atT the beginning of an adult emergence period and vice versa. This phenomenon is due to a 4-5 d preoviposition period (Cunliffe 1923a, Jepson & Southwood 1958, Vickerman 1978a) and time required for mating and egg maturation. Evidence for the first complete FF generation (egg to adult) per year was a second period of adult emergence in mid-June. This activity followed a decrease and then an increase in the percent parous females during the latter half of the emergence period. This same rationale existed for the second FF generations ending during late July. A third complete generation was indicated by an abundance of newly emerged flies during August (1985) and September (1984), some of which still had the ptilinum expanded. In addition, there was an increase in percent parous females toward the end of the emergence period indicating oviposition producing life stages for an overwintering partial fourth generation. Allen & Pienkowski (1974) also noted 3 FF generations and 4 adult emergence periods in V a ., while Aldrich (1920) noted 4 generations in Ind. Information about adult emergence periods is vital for developing degree-day (DD) predictive models. FF lower and upper developmental and lethal temperature thresholds were estimated to permit the use of DD 120 accumulations in predicting FF adult seasonal abundance in the field and development in the laboratory. A lower developmental threshold of 10°C was determined for the FF to be used in DD models to estimate development. A total of 451.31 ± 52.91 (95% CL) DD were required for complete development from egg to adult in the laboratory. Thus, 3 and 4 generations would require 1,354 and 1,805 DD, respectively. The total DD accumulated during 1984 and 1985 (base = 10°C) were 1,514 and 1,517, respectively. Yearly DD accumulations support the proposed 3.5 FF generations per year. Nielsen & Nielsen (1984) noted the completion of 3 FF generations throughout Europe required at least 1,050-1,100 DD (base = 7°C). Vickerman (1980) noted a difference of 380-420 DD between FF adult 50% emergence periods (base = 5.5°C). Due to differing methods of accumulating DD and lack of starting date information, it is impossible to compare my data with those of previous authors. DD models were generated from 1 January and 1 March starting dates with base temperatures from 0-ll°C. DD models generated from a 1 March starting date with a 0°C base temperature gave the best predictions of FF adult occurrence when compared with other DD models and calendar dates. Model validations during 198 6 indicated errors < 9 d in predicting first and second FF adult emergence. DD models representative of third and fourth FF emergence periods were 121 not validated. Akers & Nielsen (1984) developed DD models to predict bronze birch borer (BBB), Aqrilus anxius Gory, emergence in Ohio. They noted errors < 5 d in predicting BBB emergence when DD equations were validated with data from years not incorporated into their models. It is unclear why DD models based on the 10°C FF lower developmental threshold were less accurate in predicting FF occurrence than models generated from a 0°C base temperature. Contributing factors may include relationships between FF and turfgrass-temperature response, availability of nutrients and enzymes, photoperiod, microhabitat conditions, and fluctuating temperatures (Higley et al. 1986). Although the DD models exhibited errors < 9 d in predicting FF adult occurrence, they were nevertheless better than reliance on calendar dates. This DD approach may provide the turfgrass manager and researcher an important tool in maximizing the timing of control programs. Statistical analysis of sampling data indicated the dispersion pattern of FF in golf course turfgrass was better described by the negative binomial distribution than the Poisson distribution. All K values of the negative binomial were < 8 , indicating an aggregated distribution of males, females, and pooled sexes (Southwood 1966). Common K's ranged from 1-1.5 for all 3 classes. The existence of a common K was a significant finding, since it is vital to the 122 development of sequential sampling plans, selecting variance stabilizing transformations, and for direct comparison of means between 2 or more distributions (Bliss & Owen 1958). A clumped dispersion of FF was also indicated by Taylor's power law, regression of mean crowding or mean density, Morisita's coefficient, standardized Morisita, Green's coefficient, patchiness index, and the variance/mean. It is unclear whether the dispersion pattern of FF was dictated by the effect of patchiness of hosts suitable for oviposition. Vickerman (1978a) noted FF females preferred hosts with withered leaves as multiple oviposition sites. Jonasson (1982a) noted FF eggs exhibited an aggregated dispersion on oats, Avena sativa L., due to distribution of hosts suitable for oviposition. In addition, larvae exhibited less aggregation than eggs due to migration from old shoots to new tillers. Information on FF spatial patterns may be useful in life table studies, population surveys (Harcourt 1965), sequential sampling plans (Waters 1955), data transformation (Southwood 1978), and determining sample size (Karandinos 197 6). The information gathered from this study of FF seasonal abundance, developmental thresholds, generations, oviposition, DD prediction, and spatial patterns may provide a foundation of knowledge for development of control programs and maximizing timing of pesticide applications. CONCLUSIONS/SIGNIFICANT CONTRIBUTIONS 1) Frit fly (FF) lower developmental thresholds were estimated to be 10.32 ± 3.03 (95% CL), 10.36 ± 2.52, and 10.78 ± 4.79°C for eggs, larvae, and pupae, respectively. Maximum developmental and lethal temperature thresholds were estimated to be 29.0 and 34.0°C, respectively, for all 3 life stages. Development from egg to adult required 451.31 ± 52.91 (95% CL) degree-days in the laboratory under constant temperature conditions. 2) FF exhibited 3 and a partial fourth generations per year with 4 major periods of adult activity in N Ohio. Adults were efficiently sampled with a sweep net. Seasonal abundance patterns of males did not differ greatly from those of females. Of 31 plant species studied, none could be efficiently used as phenological indicators of FF adult seasonal occurrence. 3) FF oviposition activity increased after 40% cumulative adult emergence. Morphological changes in ovarian development can be used to indicate the reproductive status of females. 123 124 4) FF adult 40% cumulative emergence was best predicted with degree-days generated from a 1 March starting with a 0°C base temperature. 5) FF immatures were most abundant during mid-May (15.6/316 cm2; = 44/ft2) in 1985. Density of overwintering FF estimated to be 0.74/316 cm2 (= 2/ft2) . FF exhibited an aggregated spatial pattern relative to sample size. GENERAL REFERENCES CITED Adesiyun, A. A. & T. R. E. Southwood. 1979. Differential migration of the sexes in Oscinella frit (Diptera: Chloropidae). Entomol. Exp. Appl. 25 (1): 5 9-63. Agapova, E. G. 1966. The role of food plants in the differentiation of species of Oscinella. Trudy rs. nauchno-issled. Inst. Zashch. Rast. 26: 185-192. Abstr. 1430 in Rev. Appl. Entomol. Ser. A 1969 57: 361. Aldrich, J'. M. 1920. European frit fly in North America. J. Agric. Res. 18(9): 451-473. Allen, J. C. 197 6 . A modified sine wave method for calculating degree-days. Environ. Entomol. 5: 380- 396. Allen, W. A. 1978. The geographic distribution of the frit fly, Oscinella frit (L.) (Diptera: Chloropidae) in Virginia. USDA Cooperative Plant Pest Rep. 3(6): 52- 54 . Allen, W. A. & R. L. Pienkowski. 1973. Parasites reared from puparia of the frit fly, Oscinella frit, in Virginia. Environ. Entomol. 2: 615-617. 1974. The biology and seasonal abundance of the frit fly, Oscinella fritr in reed canarygrass in Virginia. Ann. Entomol. Soc. Am. 67: 539-544. 1975. Life tables for the frit fly, Oscinella frit, in reed canarygrass in Virginia. Ann. Entomol. Soc. Am. 6 8 : 1001-1007. Anderson, J. R. 1964. Methods for distinguishing nulliparous from parous flies and for estimating the ages of Fannia canicularis and some other cyclorrhaphous diptera. Ann. Entomol. Soc. Am. 57: 226-236. 125 126 Andersson, H. 1956. Investigations on the common frit fly, £). frit. Sverig. Utsadesforen Tidskr. 66 p t . 5 : 249- 280. Abstr. in Rev. Appl. Entomol. Ser. A 1958 46: 243. Andreeva, N. V. 1926. Biological cycle of the Swedish fly Oscinella (Oscinis) frit. L. Defense des Plantes 3(4- 5): 378-383. Abstr. in Rev. Appl. Entomol. Ser. A 1927 15: 159. Anon. 1980. Frit Fly. Ministry of Agric., Fish, and Food, leaflet 1 1 0 . Arnold, C. Y. 1959. The determination and significance of the base temperature in the linear heat unit system. In Proc. Am. Soc. Horticultural Sci. 74: 430-445. Auersch, D. 1961. New investigations on the frit fly (Oscinella frit L.) Anz. Schadlingsk. 34 p t .12: ISO- 184. Abstr. in Rev. Appl. Entomol. Ser. A 1963 151: 433 . Belizin, A. 1936. Influence of vernalization on the comparative infestation of cereals with insect pests. Plant Protection 9: 54-67. Abstr. in Rev. Appl. Entomol. Ser. A 1937 25: 393. Belyaev, I. M. 1940. A chemical control measure against the frit fly. Bull. Plant Protection number 4: 43-52. Abstr. in Rev. Appl. Entomol. Ser. A 1942 30: 296. Bliss, C. I. & R. A. Fisher. 1953. Fitting the negative binomial distribution to biological data. Biometrics 9: 176-200. Bliss, C. I. & A. R. G. Owen. 1958. Negative binomial distributions with a common K. Biometrika 45: 37-58. Blunck, H. & K. Ludewig. 1926. Die fritfliege. Biol. Reichsanst. Land-u. Forstw. 9, 4th ed. 4 p p . Abstr. in Rev. Appl. Entomol. Ser. A 1927 15: 11. Calnaido, D., R. A. French & L. R. Taylor. 1965. Low altitude flight of Oscinella frit L. (Diptera: Chloropidae). J. Animal Evolution 34(1): 45-61. Abstr. in Rev. Appl. Entomol. Ser. A 1966 54: 233. Campbell, A., B. D. Frazer, N. Gilbert, A. P. Gutierrez & M, Mackauer. 1974. Temperature requirements of some aphids and their parasites. J. Appl. Ecol. 11: 431- 438. 127 Chevin, H., Y. Durand, J. R. Le Berre & J. P. Moreau. 1971. Study on some factors affecting the proliferation of two species of Oscinella. £). frit and Q.. pusilla Mg. Ann. de Zool., Ecol. Animale 3(3): 347-359. Abstr. 1333 in Rev. Appl. Entomol. Ser. A 1974 62(4): 335. Chrzanowski, A. 1931. Oscinella frit. its biology, the damage caused by it in agriculture and its control. Choroby Roslin, i., p t . 2: 23-55. Abstr. in Rev. Appl. Entomol. Ser. A 1931 19: 5 91. Clements, R. 0., N. French, C. T. Guile, W. H. Golightly, S. Lewis & M. J. Savage. 1982. The effect of pesticides on establishment of grass swards in England and Wales. Ann. Appl. Biol. 101: 305-313. Clements, R. 0. & I. F. Henderson. 1982. Screening of pesticides for use on established grassland to improve herbage yield. Pesticide Sci. 13: 617-622. Clements, R. 0., I. F. Henderson & B. R. Bentley. 1982. The effects of pesticide application on upland permanent, pasture. Grass and Forage Sci. 37: 123-138. Clements, R. 0., P. F. Chapman & I. F. Henderson. 1983. Seasonal distribution of stem-boring larvae including frit fly (Diptera: Oscinella frit L.) and pest damage on perennial ryegrass. Grass and Forage Sci. 38: 283- 286. Clements, R. 0., B. R. Bentley, D. Moore & A. M. Spaull. 1985. The impact of a range of pesticide treatments on newly sown Italian ryegrass (Lolium multiflorum) and on frit-fly (Oscinella spp.) infestation. Crop Protection 4(2): 245-254. Collin, J. E. 1918. A short summary of our knowledge of the Frit-fly. Ann. Appl. Biol. 5: 81-96. Cunliffe, N. 1921. Preliminary observations on the habits of Oscinella fritf Linn. Ann. of Appl. Biol. 8 : 105- 134. 1922. Additional host plants of Oscinella frit, Linn, among grasses. Ann. of Appl. Biol. 9: 165-168. 1923a. Further observations on the prevalence and habits of Oscinella frit, Linn. Ann. of Appl. Biol. 11: 54-72. 123 1923b. On the relative importance of certain common grasses as host plants of Oscinella frit. Linn. ‘Ann. of Appl. Biol. 10: 210-212. 1925. Studies on Oscinella frit, Linn. A note on the seasonal regularity of the maximum prevalence periods of the fly in the field. Ann. of Appl. Biol. 12: 527- 528. Dahlsson, S. O. 1971. Fritflugen - Skadegorare i grasmotter. Weibulls Grastips: 3-9 (in Swedish, with English summary). 1974. Frit fly damage to turfgrass. In Proc. of the 2nd, Int. Turfgrass Res. Conf.: 418-420. David, F. N. & P. G. Moore. 1954. Notes on contagious distributions in plant populations. Ann. of Bot. 18: 47-53. Davies, R. G. 1971. Computer programming in quantitative biology. Academic, New York and London. Falk, J. H. 1982. Response of two turf insects, Endria inimica and Oscinella frit to mowing. Environ. Entomol. 11: 2 9-31. Fisher, R. A. 1953. Note on the efficient fitting of the negative binomial. Biometrics 9: 197-200. Franz, W. 1971. A new pest of lawns. Ein neuer rasenschadling. Gesunde Pflanzen. 23(7): 124-125. Abstr. 145 in Rev. Appl. Entomol. Ser. A 1974 62: 33. Goodey, T. 1930. On a remarkable new nematode, Tylenchinema oscinellae gen. et sp. n., parasitic on the frit-fly, Oscinella frit L., attacking oats. Phil. Trans. R. Soc. (B) ccxviii: 315-343. Abstr. in Rev. Appl. Entomol. Ser. A 1930 18: 567. Green, R. H. 1966. Measurement of non-randomness in spatial distributions. Res. Population Ecol. 8 : 1-7. Guppy, J. C. & D. G. Harcourt. 1973. A sampling plan for studies on the population dynamics of white grubs, Phyllophaaa spp. (Coleoptera: Scarabaeidae). Can. Entomol. 105: 479-483. Harcourt, D. G. 1965. Spatial pattern of the cabbage looper, Trichoplusia ni. on Crucifers. Ann. Entomol. Soc. Am. 58: 89-94. 129 Hardy, A. C. & P. S. Milne. 1938. Studies in the distribution of insects by aerial currents. Experiments in aerial tow-netting from kites. J. Animal Ecol. 7(2): 199-229. Abstr. in Rev. Appl. Entomol. Ser. A 1939 27: 167. Heard, A. J. & M. J. Hopper. 1963. Populations of stem- boring Diptera in leys and in subsequent winter wheat and the effects of aldrin and phorate. Ann. of Appl. Biol. 51: 301-311. Heard, A. J., G. C. Lewis & A. B. Joyce. 1979. Effect of stem-boring larvae (Diptera) on the yield of forage maize. Plant Pathol. 28: 150-154. Hemer, M. 1959. Zur Biologie, wirtschaftlichen bedeutung und bekampfung der Fritfliege (Oscinis frit L.) an Gerste. I. Teil. Z. Angewandte Entomol. 44 pt. 3: 314- 339. 1960. Zur Biologie, wirtschaftlichen bedeutung und bekampfung der Fritfliege (Oscinis frit L.) an Gerste. II. Teil. (Nach beobachtungen in Westfalen in den Jahren 1948 bis 1952. Z. Angewandte Entomol. 46 p t . 1: 71-119. Abstr. in Rev. Appl. Entomol. Ser. A 1962 50: 45. Henderson, I. F. & R. O. Clements. 1977. Stem-boring Diptera in grassland in relation to management practice. Ann. of Appl. Biol. 87: 524-527. Higley, L. G., L. P. Pedigo & K. R. Ostlie. 1986. Degday: a program for calculating degree-days, and assumptions behind the degree-day approach. Environ. Entomol. 15: 999-1016. Howell, J. 1982. Parasitism and host-plant relationships in the Dipterous stem borer complex of ryegrass. Pesticide Sci. 13: 367-372. Hubicka, J. 1965. [the generations of the frit fly Q. frit occurring in the annual cycle in the surroundings of Lublin]. Ann. Univ. Mariae Curie - Sklodowska Section C Biol. 20: 73-103. Abstr. 409 in Rev. Appl. Entomol. Ser. A 1968 56: 98. Ibbotson, A. 1958. The behavior of Frit fly in Northhumberland. Ann. of Appl. Biol. 46: 474-479. 130 1960. Observations on the oviposition behavior of the frit fly (Oscinella frit L. Dipt. Chloropidae). Entomol. Exp. Appl. 3: 84-92. Iwao, S. 1968. A new regression method for analyzing the aggregation pattern of animal populations. Res. Population Ecol. 10: 1-20. Iwao, S. & E. Kuno. 1971. An approach to the analysis of aggregation pattern in biological populations. In G. P. Patil, E. C. Pielou & W. E. Waters [eds.], Statistical Ecology vol. 1. Spatial Patterns and Statistical Distributions. Penn. State Univ. Press. Jepson, W. F. & A. J. Heard. 1959. The frit fly and allied stem-boring Diptera in winter wheat and host grasses. Ann. of Appl. Biol. 47: 114-130. Jepson, W. F. & T. R. E. Southwood. 1958. Population studies in Oscinella frit L. Ann. of Appl. Biol. 46: 465-474. Johnson, C. G., L. R. Taylor & T. R. E. Southwood. 19 62. High altitude migration of Oscinella frit L. (Diptera Chloropidae). J. Animal Ecol. 31: 373-383. Jonasson, T. 1977. Frit fly Oscinella frit oviposition on oat seedlings: ecological significance of the host plant selection. Oikos. 29(4): 104-111. 1980. Susceptibility of oat seedlings to oviposition by the frit fly, Oscinella frit L. (Dipt., Chloropidae). Z. Angewandte Entomol. 89(3): 263-268. 1982a. Frit fly (Oscinella frit) oviposition on oat seedlings: evidence for contagious distribution of eggs. Entomol. Exp. Appl. 32: 98-100. 1982b. Resistance of oat plants to larval attack by the frit fly, Oscinella frit L. (Dipt., Chloropidae). Z. Angewandte Entomol. 93: 508-512. Jones, D. & W. L. Sterling. 1979. Rate and thresholds of Boll Weevil locomotory activity in response to temperature. Environ. Entomol. 8 : 874-878. Jones, M. G. 1965. The effects of some insecticides on populations of frit fly (Oscinella frit) and its enemies. J. Appl. Ecol. 2: 391-401. 131 1968. The effect of moving carabids on oviposition by frit fly (Oscinella frit L.) Entomol. Mon. Mag. 104: 85- 87 . 1969a. Oviposition of frit fly, Oscinella frit L. (Dipt., Chloropidae) on oat seedlings and subsequent larval development. J. Appl. Ecol. 6 : 411-424. 1969b. The effect of weather on frit fly (Oscinella frit L.) and its predators. J. Appl. Ecol. 6 : 425-441. Karandinos, M. G. 1976. Optimum sample size and comments on some published formulae. Bull. Entomol. Soc. Am. 22: 417-421. Keler, S. 1932. A contribution towards the knowledge of the parasites of Oscinis frit L. Prace Wydz. Chorob Roslin panstw. Inst. Naukow. Gospod. wiejsk. Bydgoszczy 11: 1-3. Abstr. in Rev. Appl. Entomol. Ser. A 1932 20: 457. Kerr, T. W. 1957. Leafhoppers infesting lawns in Rhode Island. J. Econ. Entomol. 50: 372. Kreiter, E. A. 1930. Experimente und Beobachtungen iiber den Einfluss der Temperatur auf die Entwicklung und das Benehmen (Behaviour) der Fritfliege. Rev. Appl. Entomol., 4(2) pp. 451-470. Abstr. in Rev. Appl. Entomol. Ser. A 1931 19: 283. Kuzina, O. S. 1942. On the gonotrophic relationships in Stomoxys calcitrans L . and Haematobia stimulans L . Med. Parasitology 11(3): 70-78. Abstr. in Rev. Appl. Entomol. Ser. B 1944 32: 51-52. Larsson, H. A. 1977. Control experiments against wheat- blossom midges and the frit fly in Skane in 1977. Bekampnings forsok mot vetemyggor och fritfluga i Skane 1977: 149-157, Abstr. 2990 in Rev. Appl. Entomol. Ser. A 1979 67: 365. 1984. Frit fly (Oscinella frit L.) damage in oats and its chemical control by synthetic pyrethroids. Z. Angewandte Entomol. 97: 470-480. Lauva, R. E. & I. R. Shutele. 1976. Frit flies in Latvia. Zashch. Rast. No. 6, 11. Abstr. 3208 in Rev. Appl. Entomol. Ser. A 1977 65(6): 859. 132 Lazarov, A. V. 1935. Die Fritfliege, Oscinis frit. L. (Dipt., Oscinidae) als Schadling der Getreide pflanzen in Bulgarien und die Bekampfungsmassnahmen. ’Minist. Volksw. Pflscbdienst. 5 9 pp. Abstr. in Rev. Appl. Entomol. Ser. A193 624: 49. Le Berre. 1959. Hivernation et zero de developpement chez l'Oscinie Oscinella frit L. (Dipt., Chloropidae). — Acta Symp. de Evolutione Insectorum, Praha 1959: 270- 275 (in French). Lemon, R. W. & R. J. Greig. 1982. The use of bendiocarb in ryegrass establishment. Pesticide Sci. 13: 523-528. Liu, H. J. & F. L. McEwen. 1979. The use of temperature accumulations and sequential sampling in predicting damaging populations of Blissus leucopterus hirtus. Environ. Entomol. 8 : 512-515. Lloyd, M. 1967. Mean crowding. J. Animal Ecol. 36: 1-30. Lloyd, R. J. 1976. The use of Folimat for controlling shoot mining pests in cereals. Bayer Agrochem Courier No. 1, 2-3. Loban, N. A. 1979. Losses of yield of spring grain due to the frit fly. Zashch. Rast. No. 10, 45. Abstr. 3361 in Rev. Appl. Entomol. Ser. A 1980 68(7) : 421. Mesnil, L. 1931. Recoltes de Muscides nuisibles aux cereales. Rev. Pathol. Veg. Entomol. Agric. 18(8-9): 266-274. Abstr. in Rev. Appl. Entomol. Ser. A 1932 20: 238. Miles, H. W. 1930. The frit fly problem in the North West of England. J. R. Lancs. Agric. Soc. 11 pp. Abstr. in Rev. Appl. Entomol. Ser. A 1931 19: 51. Miller, T. A. & R. E. Treece. 1968. Gonadotrophic cycles in the Face Fly, Musea autumnalis. Ann. Entomol. Soc. Am. 61: 690-696. Moore, D. 1983. Hymenopterous parasitoids of stem-boring Diptera (e.g. Oscinella frit (L.)) in perennial ryegrass (Lolium perenne) in Britain. Bull. Entomol. Res. 73: 601-608. 1984. The role of silica in protecting Italian ryegrass (Lolium multiflorum) from attack by dipterous stem- boring larvae (Oscinella frit and other related species). Ann. of Appl. Biol. 104: 161-166. 1 3 3 Moore, D. & D. J. Hunt. 1984. Nematodes associated with dipterous stem-boring larvae (Chloropidae and Opomyzidae) in ryegrass. Ann. of Appl. Biol. 104: 291-296. Moore, D. & R. 0. Clements. 1984a. Stem-boring Diptera in perennial ryegrass in relation to fertilizer. I. Nitrogen level and form. Ann. of Appl. Biol. 10 6 : 31- 37. 1984b. Stem-borer larval infestation of ryegrass swards under rotationally grazed and cut conditions. J. Appl. Ecol. 21: 581-590. 1985a. Stem-boring Diptera in perennial ryegrass in relation to fertilizer. II. The effect of varying the timing of fertilizer application. Ann. of Appl. Biol. 106: 31-37. 1985b. Patterns of infestation by stem-borers (Chloropidae and Opomyzidae) in grassland. Entomol. Exp. Appl. 37: 183-186. Morisita, M. 1962. 15-Index, a measure of dispersion of individuals. Res. Population Ecol. 4: 1-7. Mowat, D. J. 1974. Factors affecting the abundance of shoot-flies (Diptera) in grassland. J. Appl. Ecol. 2: 951-962. Mowat, D. J. & S. Jess. 1984. Oviposition by frit fly, Oscinella frit. on young ryegrass seedlings. J. Appl. Ecol. 21 (3) : 915-920. Muller, H. W. K. 1971. Control of frit fly, Oscinella frit L. on silage maize with mercaptodimethur and methamidophos. Pflanzenschutz - nachrichten 24(2): 321-326. 1974. Neue Aspekte zur Bekampfung der Fritfliege Oscinella frit L. an Mais. Nachrichtenblatt des Deutschen Pflanzenschutz-dienstes 26(4): 49-52. Abstr. 3583 in Rev. Appl. Entomol. Ser. A 1976 64(6): 1010. Myers, J. H. 1978. Selecting a measure of dispersion. Environ. Entomol. 7: 619-621. Ng Yuen-Shaung, J. R. Trout & S. Ahmad. 1983. Spatial distribution of the larval populations of the Japanese Beetle (Coleoptera: Scarabaeidae) in turfgrass. J. Econ. Entomol. 76: 2 6-30. 134 Nielsen, L. B. & B. 0. Nielsen. 1984. Oscinella frit (L.) and O. pusilla (Mg.) (Diptera, Chloropidae) in agricultural grass in Denmark. Z. Angewandte Entomol 98: 264-275. Niemczyk, H. D. 1981. Destructive Turf Insects. HDN Books, Ohio. Nordlander, G. 1979. Population ecology of the frit fly, Oscinella frit (L.). Population sekologi hos fritflugan, Oscinella frit (L.). 41-51 [Sv, en, p. 243]. Abstr. 2984 in Rev. Appl. Entomol. Ser. A 197 9 67: 365. Nye, I. W. B. 1958. The external morphology of some of the Dipterous larvae living in the Graminae in Britain. Trans. R. Entomol. Soc. London 110 p t . 15: 411-487. 1959. The distribution of shoot-fly larvae (Diptera, Acalypterae) within pasture grasses and cereals in England. Bull. Entomol. Res. 50 p t . 1: 53-62. Ohnesorge, B. 1971. Observations on the effect of external factors on the catches in frit-fly traps (Oscinella frit L., Dipt., Chlorop.). Z. Angewandte Zool. 58(1) 105-116. Abstr. 3246 in Rev. Appl. Entomol. Ser. A 1973 61(9): 835. 1972. Studies on the feeding behavior of the frit-fly, Oscinella frit L. (Dipt., Chloropidae) in the maize plant. Z. Angewandte Entomol. 70(4): 344-346. Abstr 2726 in Rev. Appl. Entomol. Ser. A 1974 62(7): 705. 1973. Investigations on the influence of weather on the course of the flight of the frit-fly. Z. fur Pflanzenkrankheiten und Pflanzenschutz 80(5): 246-254 Abstr. 767 in Rev. Appl. Entomol. Ser. A 1975 63(3): 198. Oschmann, M. 1979. Effect of weather on population development of the spring generation of the frit fly (Oscinella frit (L.)). Arch, fur Phytopathologie und Pflanzenschutz 15(6): 415-419. Abstr. 5383 in Rev. Appl. Entomol. Ser. A 1980 68(11): 672. 1980. Temperature and humidity as factors influencing the damage of maize by the frit fly (Oscinella frit (L.)) Arch, fur Phytopathologie und Pflanzenschutz 16(1): 35-44. Abstr. 188 in Rev. Appl. Entomol. Ser. A 1981 69 (1) : 29. 135 1982. Studies.on the dispersal dynamics of the frit fly (Oscinella frit (L.)). Arch, fur Phytopathologie und Pflanzenschutz 18(3): 175-184. Abstr. 6484 in Rev. Appl. Entomol. Ser. A 1982 70(11): 798. Petherbridge, F. R. 1917. Frit fly (Oscinis frit) attacking winter wheat. Ann. of Appl. Biol. 4: 1. Pisnyachevskii, A. A. 1927. The injury to winter cereal crops in relation to the time of sowing in the Nizhnii-Novgorod Government in 1923-1926. Defense des Plantes 4(4): 636-655. Abstr. in Rev. Appl. Entomol. Ser. A 1928 16: 366. Poinar, G. 0. 1972. Nematodes as Facultative Parasites of Insects. Annu. Rev. of Entomol. 17: 103-122. Popov, P. 1976. The Swedish fly hazard. Rastitelna Zashchita 24(3) : 38-40. Abstr. 7230 in Rev. Appl. Entomol. Ser. A 1976 64(12): 2001. Pospelov, V. P. 1924. Annual report of the Dept, of Applied Entomology, Oct. 1923-Oct. 1924. Ann. State Inst. Exp. Agronomy. 2(6):. 243-252. Abstr. in Rev. Appl. Entomol. Ser. A 1926 14: 604. Price, P. 1984. Insect Ecology. 2nd ed. John Wiley and Sons, Inc. Pruess, K. P. 1983. Day-degree methods for pest management. Environ. Entomol. 12: 613-619. Reinov, A. I. 1929. Data on the biology of the Swedish fly (Oscinella frit L.) under the conditions of the Omsk Region. Izv. Sibirsk. Kraev. Stantz. Zashch. Rast., no. 3(6): 85-91. Abstr. in Rev. Appl. Entomol. Ser. A 1930 18: 52. Riggert, E. 1935a. Zur kenntnis der Lebensgewohnheiten von Oscinella frit L . und ihrer Jugendstadien. Arb. Physiol. Angewandte Entomol. 2(2-3): 101-130, 145-146. Abstr. in Rev. Appl. Entomol. Ser. A 1935 23: 740. 1935b. Untersuchungen liber die Parasiten der Fritfliege. Arb. Physiol. Angewandte Entomol. Berlin. 2(1): 1-23. Abstr. in Rev. Appl. Entomol. Ser. A 1935 23: 225. 136 1936. Studien iiber den jahrlichen Generationscyclus von Oscinella frit L. in Schleswig-Holstein. Z. Pflkrankh. 46(3-4): 171-203. Abstr. in Rev. Appl. Entomol. Ser. A 1936 24: 486. Roos, K. 1937. Untersuchungen iiber die Fritfliege (Oscinella frit L.) und ihr Auftreten in verschiedenen Hohenlagen der Schweiz. Landw. Jb. Schweiz 51(6): 585-666. Abstr. in Rev. Appl. Entomol. Ser. A 1937 25: 609. Rubtzov, I. A. 1935. Pests of the stems of cultivated graminaceous plants in Eastern Siberia. Trud. Zashch. Rast. Vost. Sibiri no. 2(4): 66-98. Abstr. in Rev. Appl. Entomol. Ser. A 1936 24: 356. Ryan, T. A., B. L. Joinar & B. F. Ryan. 1982. Minitab reference manual. Rygg, T. D. 1966. Flight of Oscinella frit L. (Diptera, Chloropidae) females in relation to age and ovary development. Ann. Exp. Appl. 9: 74-84. Rygg/ T. 1967. Emergence periods and population fluctuations of the frit fly Oscinella frit L. (Dipt.: Chloropidae) in Norway. Norsk. Entomol. Tidsskr. 14 p t . 1: 12-23. Abstr. 758 in Rev. Appl. Entomol. Ser. A 1968 56: 188. Ryzhkova, E. V. 1962. Phytopathogenic symbionts of the Swedish flies Oscinella frit L. and £>. pusilla Mg. (Diptera: Chloropidae) and their practical use. Rev. Entomol. USSR 41 pt. 4: 788-7 95. Abstr. in Rev. Appl. Entomol. Ser. A 1965 53: 176. Sabrosky, C. W. 1936. A synopsis of the nearctic species of Oscinella and Madiza. based on a study of the types (Diptera: Chloropidae). Ann. Entomol. Soc. Am. 29: 707-728. 1939. The European frit fly and its forms in North America. Ann. Entomol. Soc. Am. 32: 321-324. 1980. New genera and new combinations in nearctic Chloropidae (Diptera). Proc. Entomol. Soc. Wash. 82(3): 412-429. Sanders, W. 1960. Ein beitrag zum Verhalten von Oscinella frit L. bei der Eiablage. Z. Angewandte Zool. 47 p t . 3: 335-341. Abstr. in Rev. Appl. Entomol. Ser. A 1962 50: 255. 137 Sazonov, A. P. 1966. On the role of micro-organisms in the correlation between the larvae of the Swedish fly and its food-plant. Trudy rs. nauchno-issled. Inst. Zashch. Rast. 26: 180-184. Abstr. 142 9 in Rev. Appl. Entomoi. Ser. A 1969 57: 361. Schread, J. C. & A. M. Radko. 1958. A new turfgrass insect pest? USGA J. and turf management: 2 9-31. Sevacherian, V. & V. M. Stern. 1972. Spatial distribution patterns of Lygus Bugs in California cotton fields. Environ. Entomol. 1: 695-704. Shapiro, I. D. & M. A. Vilkova. 1963a. On the oviposition sites of Oscinella frit L. (Diptera, Chloropidae). Rev. Entomol. USSR 42 pt. 1: 138-150. Abstr. in Rev. Appl. Entomol. Ser. A 1965 53: 434. 1963b. Oviposition sites of the frit fly Oscinella frit L. (Diptera: Chloropidae). Entomol. Rev. 42: 74-80. Shvetzova, A. N. 1929. An entomological Valuation of Economic-Technical Methods in Agriculture. Izv. Sibirsk. Kraev. Stantz. Zashch. Rast. no. 3(6): 58-74. Abstr. in Rev. Appl. Entomol. Ser. A 1930 18: 51. Simmonds, F. J. 1952. Parasites of the Frit fly, Oscinella frit (L.), in eastern North America. Bull. Entomol. Res. 43: 503-542. 1953. Observations on the biology and mass-breeding of Spalanqia drosophilae Ashm. (Hymenoptera, Spalangiidae), a parasite of the frit-fly, Oscinella frit (L.). Bull. Entomol. Res. 44: 773-778. Abstr. in Rev. Appl. Entomol. Ser. A 1954 42: 43. Skulkina, A. F. 1980. Control of pests and weeds on seed crops of timothy. Zashch. Rast. No. 9, 30. Abstr. 4541 in Rev. Appl. Entomol. Ser. A 1981 69(8): 561. Smith-Gill, S. J. 1975. Cytophysiological basis of disruptive pigmentary patterns in the Leopard Frog Rana pipiens. II. Wild type and mutant cell-specific patterns. J. Morphol. 14 6 : 35-54. Snedecor, G. W. & W. G. Cochran. 1967. Statistical methods. Iowa State University, Ames. 138 Southwood, T. R. E., W. F. Jepson & H. F. Van Emden. 1961. Studies on the behavior of Oscinella frit L. (Diptera) adults of the panicle generation. Entomol. Exp. Appl. 4: 196-210. Southwood, T. R. E. & W. F. Jepson. 1962. Studies on the populations of Oscinella frit L. (Dipt., Chloropidae) in the oat crop. J. Animal Ecol. 31: 481-495. Southwood, T. R. E. 1966. Ecological methods with particular reference to the study of insect populations. Methuen, London. 1978. Ecological methods with particular reference to the study of insect populations. Chapman & Hall, London. Spaull, A. M., P. G. Mewton & R. 0. Clements. 1985. Establishment and yield of three ryegrasses following aldicarb use, and changes in abundance of plant parasitic nematodes. Ann. of Appl. Biol. 106: 313- 321. Steel, A. 1931. On the structure of the immature stages of the frit fly (Oscinella frit Linn.). Ann. of Appl. Biol. 18: 352-369. Stiteler, W. M. & G. P. Patil. 1971. Variance-to-mean ratio and Morisita's index as measures of spatial patterns in ecological populations. In G. P. Patil, E. C. Pielou & W. E. Waters [eds.], Statistical Ecology Vol. 1. Spatial Patterns and Statistical Distributions. Penn. State Univ. Press. Taimr, L. & J. Dirlbek. 1968. Definition of the range of food-plants of the frit fly (Q. frit) by means of 32P in the food of the insects. Ved. Pr. Vyzk. Ust. Rostl. Vyroby Praze-Ruzyni 12: 29-36. Abstr. 2200 in Rev. Appl. Entomol. Ser. A 1969 57: 54 7. Tashiro, H. & F. L. Gambrell. 1963. Correlation of European chafer development with the flowering period of common plants. Ann. Entomol. Soc. Am. 56: 239-243. Tashiro, H. 1987. Turfgrass insects of the United States and Canada. Cornell Univ. Press, Ithaca and London. Taylor, L. R. 1961. Aggregation, variance and the mean. Nature 189: 732-735. 139 1984. Assessing and interpreting the spatial distributions of insect populations. Ann. Rev. Entomol. 29: 321- 357. Tomczyk, W. 1929. Beitrag zur Kenntnis von Oscinis frit L. in der umgebung von Wilno in den Jahren 1925 u. 1926. Trans. Soc. Sci. Lett. Vilno. 5(13) 10 pp. Abstr. in Rev. Appl. Entomol. Ser. A 1929 17: 700. Vasina, A. N. 1929. On the occurrence of Oscinella frit L. on wild grasses. Plant Protection 6 (1-2) : 63-70. Vickerman, G. P. 1978a. Host plant preferences of Oscinella sp. (Diptera: Chloropidae) in the laboratory. Ann. of Appl. Biol. 89: 379-386. 197 8b. Survival and duration of development of Oscinella spp. (Diptera: Chloropidae) on different Graminae in the laboratory. Ann. of Appl. Biol. 89: 387-393. 1980. The phenology of Oscinella spp. (Diptera: Chloropidae). Bull. Entomol. Res. 70(4) : 601-620. Vitzthum, H. 1933. Einiges iiber Microtrombidium demeiierei und sein Atmungssystem. Zool. Anz. Civ, no. 7-8: 217- 220. Abstr. in Rev. Appl. Entomol. Ser. A 1933 21: 668. Wagner, T. L., H. Wu, P. J. Sharpe, R. M. Schoolfield & R. N. Coulson. 1984. Modeling insect development rates: a literature review and application of a biophysical model. Ann. Entomol. Soc. Am. 77: 208-225. Walker, P. T. & C. R. Turner. 197 6. Uptake of radioactive phorate by maize in relation to granule placement and to control of frit fly. Centre for Overseas Pest Research, Porton Down, Salisbury, Wiltshire, U.K. Abstr. in Rev. Appl. Entomol. Ser. A 1976 64(6): 1106. Waters, W. E. 1955. Sequential sampling in forest insect surveys. For. Sci. 1: 68-7 9. Wegner, G. S. & H. D. Niemczyk. 1981. Bionomics and phenology of Ataenius soretulus. Ann. Entomol. Soc. Am. 74: 374-384. 140 Wetzel, T., F. Mende & G. Lutze. 1972. Investigation on the daily rhythm of the wheat bulb fly (Leptohylemyia coarctata Fallen) and the frit fly (Oscinella frit Linne) in wheat fields (Diptera: Brachycera). Nachrichtenblatt fur den Pflanzenschutzdienst in der DDR. 26(3): 54-47. Abstr. 4080 in Rev. Appl. Entomol. Ser. A 1975 63(10): 1113. Wilbur, D. A. & C. W. Sabrosky. 1936. Chloropid populations on pasture grasses in Kansas. J. Econ. Entomol. 29: 384-389. Wolf, D. D. 1967. Yield reductions in reed canarygrass by frit fly infestation. Crop Sci. 7(3): 239-240. Zhukovskii, A. V. 1932. The causes which determine the infestation of summer crops by Oscinella frit L. Plant Protection 8(5-6): 514-530. Abstr. in Rev. Appl. Entomol. Ser. A 1932 20: 347. Zhukovskii, S. G. 1961. The effect of air temperature and intensity of light in the behavior of Oscinella frit. Zool. Z. 40 pt. 3: 386-392. Abstr. in Rev. Appl. Entomol. Ser. A 1962 50: 446. APPENDIX A Fig. 4. Technical drawing of the unit net sampling device. 141 142 GENERAL VIEW handle- s p i k e aluminum crossbar eye bolt adjustable e y e bolt aluminum pipe ro p e hook ring clo th n< aluminum side brace dow el spike * All measurements in cm unless otherwise noted. Fig. 4 UNIT NET SAMPLING DEVICE * r o p e I___ TOP VIEW - 5 0 ------15.24 m SIDE VIEW ALUMINUM SIDE BRACE (release mechanism-tii - 21- A ■to aluminum hinge brace —• e y e bolt sp rin g 3.8 eye bolt dow el —"C etrlng loop 7.6 clo th n e t aluminum side brace aluminum hinge brace aluminum flap 1.3 hinge wood croaabar O— stopper hole sto p p er— i felt FRONT VIEW 0 aluminum aide brace cloth net 9.5 IAPLING DEVICE * r o p e T e I___ V l “ > 4° TOP VIEW - 5 0 ------15.24 m 4UM SIDE BRACE SIDE VIEW (release mechanism-tire omitted) hinge aluminum hinge brace, e y e bolt fe lt sp rin g rubbor sto p p er 4 0 x 1.3- string loop eye bolts^ / wood crossbar aluminum flap c o tte r pin aluminum sldo brace 1.3 stopper FRONT VIEW aluminum flap aluminum side brace tire « cloth L 1 threaded rod through copper pipe Mean(x),standard error(S.E.),and the S.E. as a % of the x numbers of frit fly adults captured per Julian date in the sweep net and unit net on the College of Wooster Golf Course during 1984. SWEEP NET UNIT NET JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X .. 11 5.0 0.0 ■ v JU 1 21 .0 0.0 * • y ■y. 122.u 9.0 V S * r S a ■a. 126.0 1 56.0 * -IT •V* * 1 3 C . 6 42.5 6.5 15.3 4.3 1.7 38.9 133.0 7.8 3.1 40.6 13.0 8.9 68.4 1 36. C 160.5 7C .2 47.3 23.5 9.8 41.5 1 39.0 1 24.2 36.0 3C.6 6.3 1.6 28.8 192.0 96.2 16.8 1 S.6 32.0 6.1 19.0 145.0 71 .3 17.0 23.8 11.8 1 .1 9.6 151 .0 24.3 3.4 14.0 3.5 0.9 25.9 1 54 . 0 24.2 5.1 21 .1 3.6 0.7 20.1 157.0 10.5 2.7 •’5.9 2.e 0.6 29.8 1 C 1 . 0 13.3 4.2 J1 .9 5.8 1.7 29.0 165.0 ■106.2 33.3 31.4 22.9 9.6 42.0 16S.G 169.7 6C .9 35.9 51 .1 18.0 35.3 173.0 266.0 51 .7 19.3 56.3 6.6 16.2 176.0 169.7 5.8 5.1 43.3 e.4 1 9.3 175.0 256.0 46.2 18.0 37.3 6.9 1 8.5 >«. 1E2.C 1 25.2 26 .4 21 .1 y y n r # 1 68.0 63.0 2C.3 32.3 5.6 2.2 39.1 191 .0 127.5 6.9 5.4 17.C 3.7 21 .9 154.0 143.3 35.8 27.7 21.5 5.3 24.6 158.0 145.0 36.6 23.9 20.3 9.4 46.2 2C4.0 1 62.0 75.9 41.7 40.9 19.2 47.1 2Ce.G 61.3 6.0 9.8 9.6 3.4 34.9 212.0 179.5 10.8 6.0 27.0 5.1 1 8.7 216.0 168.7 14.0 8.3 1 7.e 3.3 1 8.4 222.0 77.0 19.6 25.4 7.9 1.6 22.3 225.0 95.7 £ .4 8.8 11.4 1.1 1 0.1 229.0 63.6 10.1 15.8 4.4 1.1 24.8 232.0 31 .0 6.5 27.5 8.0 5.6 70.0 226.0 15.2 1.7 11.2 1.1 0.4 31.1 23S.O 15. S 3.4 21 .4 2.1 0.6 30.1 243.0 10.2 5.8 32.1 2.4 0.6 32.7 246.0 30.5 8.9 23.1 4.9 1 .2 25.3 253 .C 19.7 . 6.3 21.8 5.4 1.9 34.4 257.0 25.2 6 .4 17.5 6.1 1.6 26.8 26 5.0 41.0 4.0 S.7 5.5 i .e 32.4 273.0 0.0 0.5 57.3 2.4 o.e 34.6 279.0 3.6 0.5 14.2 T * ■ . 293.0 0.3 0.2 63.2 V » 300.0 0.2 0 . ^ 100.0 J. * * No data. 14 3 APPENDIX _C Mean(x),standard error(S.E.),and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the sweep net on the College of Wooster Golf Course during 1984. MALE FEMALE JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X A 115.0 0.0 S * 0.0 «v» it. it. 121 .0 0.0 ■ V 0.0 Jt. 122.0 6.0 3.0 *«* 126.0 91 .0 s • n 67.0 » 130.0 25.0 2.0 6.0 17.5 4.5 25.7 133.0 3.3 1 .3 40.5 4.5 2.0 44.9 136.0 74. C 35.2 47.1 73.8 35.1 47.5 1 39.0 55.8 17.6 31 .6 66.5 22.3 32.6 142.0 46.2 10.1 20.9 ue.o 8.9 1 8.4 1 US .0 44.0 12.2 27.8 27.3 4.6 17.7 151 .0 14.2 2.0 13.9 10.2 1.9 18.9 15U.0 14.0 3.4 24.0 10.2 2.2 21 .2 1 57.0 6.2 2.4 39.1 4.3 0.7 1 6.5 161. .0 8.7 3.2 36.7 4.7 1.2 26.3 165.0 68.5 21 .0 30.7 37.7 12.4 32.8 169.0 84.0 31 .0 36.9 85.7 31.1 36.3 173.0 147.3 2b .6 19.4 120.7 25.7 21 .3 176.0 1 09. 8 9.1 6.3 79.8 4.9 6.1 179.0 154.3 30.3 19.6 101 .7 16.5 1 6.2 ie2.c 72.5 17.4 24.0 52.7 9.5 17.9 186.0 31 .5 ' 11.8 37.6 31 .5 8.7 27.5 1 91 .0 77.7 5.3 6 . B 49.8 4.0 8.1 19U.C 67.5 27. 8 31 .8 55.8 12.2 21.9 198.0 96.6 23*6 24.3 48.2 11.4 23.7 20U.0 119.0 53.9 45.3 63.0 22.5 35.8 206.0 48.2 6.3 13.1 33.2 2.7 8.3 212.0 116.2 7.4 6.4 63.3 4.7 7.5 216.C 98.3 7.1 7.2 70.3 7.9 11.2 222.0 43.3 13.6 31 .4 33.7 7.4 22.1 22S.0 60.7 6.8 11 .2 35.0 2.7 7.7 229.0 45.7 7.8 17.0 18.2 2.6 14.4 232.0 25.3 6.8 27.0 5.7 1.9 34.0 236.0 10.8 1 .4 13.1 4.3 0.8 17.5 239 .0 11.2 2.4 21 .6 4.7 1 .4 30.1 243 .0 12.3 4.5 36.4 5.8 1 .4 24.4 246.0 26.7 7.0 26.3 11.8 2.5 21 .4 253.0 10.e 2 .1 1 9.1 8.8 2.6 31.7 257.C 12.2 2.4 20.0 13.0 2.6 20.1 265.0 22.0 2.7 12.3 19.0 2.2 11.5 273.0 0.5 0.2 44.7 0.3 0.3 100.0 279.C 2.2 C . 6 27.7 1.7 0.2 1 2.6 293.0 0.2 C.2 100.0 0.2 0.2 100.0 300.0 0.0 c.o # 0.2 0.2 100.0 * No data. 14 4 APPENDIX D Mean(x),standard error(S.E.),and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date In the unit net on the College of Wooster Golf Course during 1984. MALE FEMALE JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X 115.0 * # $ 121 .0 * * $ 3* * ^p db 122.0 * ■V* ** * » 126.0 ** *# e * 1 30.0 2.0 0.9 45.6 2.3 0.9 38.0 133.0 6.6 4 .0 58.8 6.3 5.3 84.0 136.0 12.6 5.7 44.8 10.8 4.5 42.2 139.0 1 .6 0.6 36.0 4.5 1.3 29.4 142.0 21 .9 4 .8 22.0 10.1 1 .8 1 8.1 145.0 7.3 1 .0 14.2 4.5 0.7 16.3 151 .0 2.3 0.8 33.3 1.3 0.5 42.1 154.0 2.0 0.4 21 .1 1 .6 0.5 28.3 157.0 1.6 0.7 41 .8 1 .1 0.3 26.2 161 .0 2.9 1 .1 39.1 2.9 0.9 29.7 165.0 14.1 5.7 40.6 8.8 3.9 45.0 169 .0 33.4 12.0 35.9 17.8 6.2 34.9 173.0 35.8 7.6 21 .3 ie.5 2.5 1 3.6 176. C 25.8 6.3 24.4 17.5 2.9 16.6 179.0 22.9 4.7 20.4 14.4 2.e 19.5 db 182.0 •»“ « **■ #* 188.0 3.3 1 .6 48.6 2.5 0.7 29.3 191 .0 10.8 2.9 27.1 6.3 0.9 1 4.4 194.C 12.3 3.3 27.3 9.3 2.4 26.1 198.0 14.1 6.5 45.9 6.1 3.0 48.5 204.0 30.5 14.0 45.9 10.4 5.6 54.4 208.0 5.9 2.7 46.3 3.9 0.9 24.1 212.0 17.1 3.0 17.5 9.9 2.6 26.3 218.0 11.1 2.5 22.2 6.6 1.0 14.5 222.0 5.0 1 .2 24.8 2.9 0.6 27.4 225.0 6.1 0.8 1 2.5 5.3 0.9 17.5 229.C 2.8 0.6 23.6 1.6 0.5 32.8 232.0 7.1 5.1 72.1 0.9 0.5 54.8 236.0 0.9 0.3 33.7 0.3 0.2 65.5 239.0 1.8 0.5 30.1 0.4 0.2 48.8 243.0 2.0 0.7 32.7 0.4 0.2 48.8 246.0 3.5 0.8 24.1 1 .4 0.5 33.5 253.0 3.4 0.9 25.6 2.0 1.0 52.4 257.0 3.1 1 .0 32.8 3.0 0.9 28.9 265.0 3.3 1 .0 31 .7 2.3 0.8 35.4 273.0 2.1 0.7 33.8 0.3 0.2 65.5 279.0 # * db * « db 293.0 V * $ 300.0 ** , * a * No data. 145 APPENDIX E Mean(x),standard error(S.E.),and the S.E. as a % of the x numbers of frit fly adults captured per Julian date in the sweep net and unit net on the College of Wooster Golf Course during 1985. SWEEP NET UNIT NET JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X 103. 0 0.0 0.0 $ $ 106. C 0.0 0.0 # « 112.0 59.0 3.0 5.1 #* * 115.0 173.2 36.1 22.0 33.6 3.7 10.9 123.0 72.3 15.3 21 .1 8.9 1 .2 13.1 130.0 45.8 6.8 19.2 7.8 1.6 20.3 140.0 7.8 1 .7 21 .2 2.7 0.6 22.0 155.0 61 .4 6.4 10.4 15.4 2.6 17.1 170.0 60.1 11.5 19.2 34 .8 2.6 7.5 170.0 41.7 4.2 10.1 10.1 1.6 1 6.1 166.0 71 .5 9.6 1 3.4 10.3 1.5 1 4.5 197.0 68.5 12.0 17.6 15.7 2.1 1 3.2 206. C 69.3 5.4 7.8 14.9 1 .8 1 2.0 213.0 44.6 4.2 9.3 7.3 0.9 11 .8 221 .0 39.5 6.2 15.8 3.0 0.5 1 5.7 231 .0 66.8 9.7 14.5 6.1 1 .1 18.8 241 .0 25.2 4.9 19.3 3.5 0.5 15.7 246.0 24.5 3.4 13.9 1 .7 0.3 20.0 256.0 9.4 1 .3 13.3 1.3 0.5 37.3 265.0 6.2 1 .5 24.0 0.7 0.2 , 32.1 272.0 6.7 2.0 22.6 0.9 0.3 30.2 278.0 0.0 0.0 « 0.9 0.3 35.1 293.0 0.0 0.0 * 0.0 0.0 e 299.0 0.0 0.0 * 0.0 O.C * No data. 14 6 ft?PENPIX_.,F. Mean(x).standard error(S.E.),and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the sweep net on the College of Wooster Golf Course during 1985. MALE FEMALE JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X 103.0 0.0 0.0 * 0.0 0.0 •A. 106.0 0.0 0.0 # 0.0 0.0 V 112.0 31 .0 2.0 6.5 28.0 1.0 3.6 115.0 88.0 19.1 21 .7 85.2 19.4 22.8 123.0 31 .2 7.1 22.9 41.2 9.4 22.9 130.0 25.3 5.5 21 .9 20.5 3.7 18.1 140.0 5.2 1 .0 19.6 2.7 0.8 30.7 155.0 41.3 4.4 10.6 20.1 2.5 1 2.2 170.0 22.1 3.5 1 5.8 38.0 8.7 22.8 178.0 15.4 3.1 15.9 22.3 1.8 8.1 186.0 36.8 6.6 17.9 34.7 3.5 1 0.0 197.0 41.3 8.7 21 .0 27.3 4.0 1 4.6 206.0 48.6 4.0 8.1 20.6 2.3 1 0.9 213.0 29.2 3.5 1 2.0 15.4 1.3 8.2 221 .0 21.8 3.3 15.1 17.7 3.0 17.1 231 .0 35.6 5.0 14.1 31 .2 5.0 1 6.1 241 .0 15.3 3.0 19.6 9.9 2.2 22.0 248.0 14.9 2.4 1 5.9 9.6 1.3 1 3.5 256.0 5.6 1 .0 17.1 3.8 0.6 1 5.3 265.0 3.5 1 .1 31 .6 2.7 0.6 20.8 272.0 5.1 1 .2 24.0 3.6 0.9 24.9 278.0 0.0 0.0 « 0.0 0.0 # 293.0 0.0 0.0 * 0.0 0.0 * 299.0 0.0 0.0 0.0 0.0 « * No data. 14 7 APPENDIX G Mean(x),standard error(S.E.),and the S.E. as a % of the x numbers of male and female frit fly adults captured per Julian date in the unit net on the College of Wooster Golf Course during 19S5. MALE FEMALE JULIAN DATE X S.E. S.E. % OF X X S.E. S.E. % OF X 103.0 A $ S * $ 106.0 •A. « * * * 112.0 » 6 « « *« 115.0 16.0 1.8 11.3 17.6 2.1 1 1.9 123.0 4.4 C .8 17.6 4.4 0.5 1 2.1 130.0 4.6 1 .1 23.1 3.2 0.6 20.0 140.0 2.1 0.5 24.7 0.7 0.2 29.7 155.0 10.6 1 .9 17.9 4.8 0.9 1 8.5 170.0 16.4 1 .3 6.0 18.4 1.6 8.5 178.0 4.8 0.8 15.6 5.3 1..1 20.3 186.0 4.8 0.9 19.1 5.5 0.9 1 6.0 197.0 8.2 1.1 13.7 7.5 1.1 1 5.3 206.0 10.1 1.4 14.3 4.9 0.7 1 3.3 213.0 4.7 0.6 11.7 2.6 0.5 21.3 221 .0 2.1 C.3 15.7 0.9 0.3 28.6 231.0 3.4 0.7 20.1 2.7 0.6 21.2 241 .0 2.3 0.5 20.6 1.2 0.3 22.5 248.0 1.1 0.3 25.9 0.6 0.2 35.3 256.0 0.9 0.4 47.2 0.4 0.2 47.1 265.0 0.3 0.2 48.5 0.3 0.1 42.0 272.0 0.7 0.3 38.3 0.3 0.1 48.7 278.0 0.6 0.2 36.3 0.3 0.1 42.0 293.0 0.0 0.0 # 0.0 0.0 S 299.0 0.0 0.0 * 0.0 0.0 « * No data. 143 APPENDIX H Frit Fly, Oscinella frit (L.) (Diptera: Chloropidae), Seasonal Abundance Plant Phenology Relationships THE FRIT FLY (FF), Oscinella frit (L.), is an occasional pest of turfgrass and a nuisance to golfers (Schread & Radko 1958, Allen & Pienkowski 1973, Niemczyk 1981). FF control programs are generally aimed at adults since larvae are protected from insecticide contact by residing behind turfgrass sheaths and mining leaves. Larsson (1984) noted that insecticides should be applied when FF adults are abundant but before significant oviposition activity. Tashiro (1986) recommended insecticides be applied when flies and larvae are present, with a second application 10-14 d later. Such timing methods are often influenced by weather and are dependent upon direct observation of adult activity. Sampling for adults may be tedious due to their small size (1-2 mm in length). An alternative method of estimating adult occurrence is desired. Seasonal life history events of insects have been correlated to that of plants. Tashiro & Gambrell (1963) noted correlations between flowering of various plants and 149 150 development of European chafer, Rhizotroaus maialis (Razoumowsky). Hemer (1959) was unable to correlate phenology of 7 plant species with FF adult occurrence. Riggert (1935) noted a correlation between flowering of dandelion, Taraxacum officinale Weber, and apples, Pyrus spp., and FF adult occurrence. The present study was an attempt to correlate flowering of various plant species with FF adult occurrence in N Ohio. Such information may be useful in timing control programs in lieu of intensive sampling for adult occurrence. Materials and Methods The flowering of 31 plant species in Wooster, Ohio, was observed weekly whenever FF adults were present in 1984 and 1985. Plants with similar flowering periods associated with FF adult abundance before significant oviposition activity (40% emergence) were noted. In addition, the first 2 adult generations of FF were monitored in Columbus and Wooster, Ohio, during 198 6 to validate plant phenology adult abundance relationships observed during 1984 and 1985. 151 Results and Discussion Six of 31 plant species observed were flowering at the time of FF 40% adult emergence (Table 13). The 6 species were dogwood (Cornus florida L.), lilac (Syrinaa vulgaris L .) , common privet (Liaustrum vulaare L.), Canada goldenrod (Solidaqo canadensis L .), common evening primrose (Oenothera biennis L.), and wingstem (Actinomeris alterniflora L.). The onset of flowering of dogwood and lilac coincided with FF first generation 40% adult emergence and privet with the second adult generation during both 1984 and 1985 in Wooster. The onset of flowering of common evening primrose was the only species associated with FF third adult generations; however, it trailed the 1984 40% emergence by 6 d and 1985 by 18 d. The onset of flowering of goldenrod and wingstem coincided with fourth adult generation 40% emergence during 1985 but preceded it by 21 d in 1984. Validation of these associations during 1986 indicated dogwood and lilac were poor predictors of FF first generation adult 40% emergence, with a maximum error of 2 6 d in Columbus and 11 d in Wooster. However, the onset of flowering of privet coincided with FF second adult generation 40% emergence, by 5 d in Columbus . Other researchers have attempted to correlate plant phenology with FF emergence. Riggert (1936) noted adults Table 13. FF adult 40% emergence and associated botanical phenological events during 1984 and 1985 in Wooster, Ohio. Phenological events validated during 1986 for first and first-and-second adult generations in Wooster and Columbus, Ohio, respectively Validation 1984 1984 1985 1985 1986 1986 Adult 40% Adult Botanical 40% Adult Botanical 40% Adult Botanical Location Generation Emergence Event Emergence Event Emergence Event Wooster First Hay 12 May 12 Dogwood (FB)a Apr. 25. Apr.27 Dogwood (FB) May 3 Apr.22 Dogwood (FB) May 16 Lilac (FB)b Apr. 27 Lilac (FB) Apr.26 Lilac (FB) Wooster Second June 19 June 18 Privet (FB) c June 3 June 1Privet (FB) h June 2 Privet (FB) June 22 Privet (FFB)g June 4 Privet (FFB) June S Privet (FFB) Wooster Third July 20 July 26 Primrose (FB)d July 9 July 27 Primrose (FB) i i Wooster Fourth Sept. 3 Aug. 13 Goldenrod (FB)e Aug. 16 Aug. 19 Goldenrod (FB) i i Aug. 13 Wingstem (FB)^ Aug. 19 Wingstem (FB) Columbus First Apr. 27 Apr. 1 Lilac (FB) Apr. 7 Dogwood (FB) Columbus Second June 1 May 20 Privet (FB) May 27 Privet (FFB) Columbus Third i i Columbus Fourth i i aDogwood (Cornus florida L.); FB, first bloom bLilac (Syrinoa vulgaris. L.) cCommon privet (Licrustrum vulgare L .) dCanada goldenrod (Solidacro canadensis L.) eCommon evening primrose (Oenothera biennia L.) fWingstem (Actinomeris alterniflora (L.)) gFFB, first full bloom hSampling discontinued before completion of second adult generation. 1Third and fourth adult generations not sampled. 153 first emerged when dandelion bloomed and peaked with the flowering of apples in the Federal Republic of Germany. Hemer (1959) noted first adults caught when sweet cherry, Prunus avium L., was in bloom in the Federal Republic of Germany. However, he was unable to determine correlations for 3 FF generations, even though 7 plant species were studied at 7 sites. Of the 6 plant species studied in Ohio, only common privet was the most consistent in onset of flowering when second generation FF 40% adult emergence occurred in both Wooster and Columbus. With the exception of common privet, it was impossible to develop useful plant phenology characteristics to estimate FF adult occurrence. APPENDIX I Description of Distribution and Dispersion Indices Negative Binomial. Data in which the variance is greater than the mean is often described by the negative binomial distribution. This distribution is described by the mean, and K, which measures the degree of aggregation. The observed frequencies of individuals can be compared to the expected frequencies of a negative binomial distribution by the X 2 goodness-oi'-fit test. The expected negative binomial frequencies of sample units containing 0, 1, 2, 3, ... x individuals is calculated by: * (K + x - 1) ! pX f (x) = x I (K - 1) 1 K + x • ^ ' • (1 + p) where p = x/K. K can be calculated most efficiently by the maximum likelihood method (Fisher 1953) . In summary, Fisher's method requires an estimate of K that reduces ZL in the following equation to 0: 154 155 Zi = S (k.+x)-N l0% ( 1 + K, ) where Ax = the accumulated frequencies, N = total number of samples, and loge = Napierian logarithms. K is a dispersion index which measures the amount of clumping. The smaller the value of K, the greater the aggregation while a large K (> 8) indicates less aggregation as the distribution approaches the Poisson (random) (Southwood 1966). Fractional values of K tend toward the logarithmic distribution, which occurs when K = 0 (Southwood 1978). Samples taken from different fields, or time, will often have different K values. The calculation of an average (common) K represents all the individual K's and is of value in determining sequential sampling plans and variance stabilizing transformations. An approximate estimate of the common K (Kc) is determined by: J_ Jkl Kc ~ Ix1 1 2 - 1 -2 where y = S - x and x = x - (t ) One is justified in calculating Kc vilien a plot of y1 on x1 passes through the origin. In addition, plotting 1/K 156 against the mean should show no trend or clustering (Southwood 1978). Davies (1971) gives a FORTRAN program for fitting the negative binomial distribution, testing for overdispersion, and calculating K. Poisson. Data in which the variance is equal to the mean is often described by the Poisson distribution. As with the negative binomial, the observed frequencies can be compared to the expected Poisson frequencies by a X 2 goodness-of-fit test. The expected Poisson frequencies are calculated by: -X X f (x) = e ■£- x ! where x = the number of individuals of a given age class per sample, x = mean, and e = the base of natural logarithms (ca. 2.72). Davies (1971) gives a FORTRAN program which fits data to the Poisson distribution and calculates the X2 values and degrees of freedom. Variance-Mean Relationships. Organisms are considered contagious (clumped) if the variance (S2) is greater than the mean (x), random if S2 = x, and regular (uniform) if S2 < x. Departures of the S2/x ratio from unity (1) indicate a departure from randomness. The following is 157 used for testing the null hypothesis that the pattern is random: = s2 where n = the number of samples. ID is tested for significance by the X 2 where the table value has n - 1 degrees of freedom (Southwood 1978). The above is the same test Davies (1971) uses to test for overdispersion. The S2 is not independent of the x. Taylor (1961) has shown that the S2 is related to the x by the power law: 2 — b S = a x where ax is a sampling coefficient and b an aggregation index of the species. A linear regression of log S2 on log x will result in 2 — Log 3 = a + b(log x) yielding ax = a + b from trie above equation. The aggregation index, b, ranges from near-regular (uniform) (b —» 0) , through random (b —» 1) / to highly aggregated (b —» <*>) . Southwood (1978) notes that: 153 high values of b show strong contagion, but if the regression line crosses the Poisson line (slope b = 1) this shows a change to random distribution at lower densities, hence, unless a = 1, the value of b in itself cannot be taken as a test of randomness. Index of David and Mooce - I. The index of clumping (David & Moore 1954) is described by the variance and the mean, and is calculated by: 2 _ S__ x which gives a value of 0 for a random population (Southwood 1978). David & Moore (1954) give tests to determine the significant difference between the indices of clumping for 2 species or with the same species in 2 different locales. No test is given for significant departures from randomness. Values of I > 0 are assumed contagious, 1 = 0 random, and I < 0 regular. Morisita's Coefficient - I5. Morisita (1962) developed an index of dispersion which was thought independent of the mean per sample unit and did not rely on the assumptions of any type of contagious distribution. His index is calculated by: 159 Xx - Ex I. = n 8 (Xx)2 - Xx Values of I5 > 1 are assumed contagious, I5 = 1 random, and I5 < 1 regular. Southwood (1966) gives the following test of the significance of departure of I5 from randomness. The test is made by comparing Fo: I (Xx - 1) + n - Xx Fo = -2------(n - 1) with the table F with degrees of freedom Vx = n - 1, V2 = 00. Stiteler & Patil (1971) have shown that Fo is nothing more than the variance/mean, and any statements as to the significance of the index are made on the basis of the variance-to-mean ratio. Standardized Morisita's Coefficient - Ip . Smith- Gill (1975) developed a new pattern index, Ip, derived from Morisita's coefficient, I5. She found that I5 was "nearly free" of density and that Ip was density independent. To compare samples of different densities, I5 is transformed and scaled from -1.0 to +1.0, thus yielding Ip. Ninety-nine percent confidence levels are set to distinguish biological from mathematical changes in I5 by minimizing Type I errors. 160 Confidence limits are scaled from +0.5 to -0.5, and I_ is determined as follows: - CL when Ig > CL clumped >1.0, Ip=0.5+0.5 Z5 (^)n -- CL T - 1 CL clumped > Ig > 1.0, Ip = 0.5 8 CL - 1 when { (^) T - 1 1.0 > I > CL uniform, I = -0.5 8 5 P CL - 1 T - CL when 1.0 > CL uniform > I„, I = -0.5 + 0.5 8 8 P (^) x2 - n + Ex where CL clumped = —1----—------2.x - 1 X , - n + £ x CL^ uniform . r- = ----- •025 (n-l)—------Sx - 1 Samples are significantly contagious if Ip > 0.5, random if -0.5 < Ip < 0.5, and regular if Ip < -0.5. Green's Coefficient - Cx. Green (1966) developed a new index to measure non-randomness in spatial distributions as an alternative to testing for departure from the Poisson distribution. His index is calculated by: and is independent of variation in x , n, or Ex. Cx = 0 when the samples are random (S2 = x), and equal to 1 when all individuals are in 1 of n samples (extremely contagious). Cx is tested for departure from randomness by calculating: X 2 l-ot(n-ldf) _ n - 1 Cxl-a ~ Ex - 1 Thus: if C > C reject randomness x xl-a if C < C fail to reject randomness xl-a J Mean Crowding Index - m. Lloyd (1967) developed an index of mean crowding which measures the mean number per individual of other individuals in the same quadrat. This index is calculated by: m = -x+ ( i - i ) or if the data fit the negative binomial: 162 m = x + x K If the data conform to a Poisson distribution, then m = x (Southwood 1978). Lloyd (1967) gives the following methods for determining the standard error (S.E.) and confidence intervals (Cl) of m. If the population conforms to a negative binomial distribution, the S.E. of m is: K(x + K) (1 + K) 2 S.E.m » — _ / Var(K) + ------=------nx ' iK y f ' K largest i «. “ K smallest where Var K = — - --- Z _ z largest smallest where K and Z are the final coordinates used to interpolate K (Bliss & Fisher 1953). If the population does not conform to a negative binomial, then the S.E. is estimated by: S.E.m » * < • ) d ) ( “ t 1) Ninety-five percent Cl are calculated by: 163 95% Cl = m ± t (S.E.m) .05 (n—1) Thus, if the 95% Cl contains the mean, crowding is of a random nature. Lack of overlap indicates a departure from randomness. The ratio of m/x is termed "patchiness" and measures how many times as crowded an individual is, on the average, as it would have to be if the population conformed to a random distribution. If m/x = 1, then the individual crowding conforms to a random pattern. If the population conforms to a negative binomial distribution, the S.E. of m/x is: K If the population does not conform to the negative binomial, then the S.E. is estimated by: Ninety-five percent Cl are calculated by-: m 95% Cl ± t x .05 (n-1) 164 Thus, if the 95% Cl contains the number 1, crowding is of a random nature. Lack of overlap would indicate how many times as crowded individuals would be as if they were in a random distribution. Iwao (1968) determined that the relation .of m to x can be fitted to a linear regression such that: m = a + Px where a is the intercept and P the regression coefficient, a and (3 are considered indices which describe different aspects of the dispersion of populations. a is considered an index of basic contagion which indicates that at infinitesimal density an individual would be expected to live together with a other individuals in the same quadrat. Thus, a can reflect the clumping of a species which could be due to oviposition of egg masses or mutual attraction of individuals. The slope (3 is termed the "density-contagiousness coefficient" and indicates the manner in which individuals or groups distribute themselves with a changing density. a = 0 when a single individual is the basic component of the distribution, a > 0 when there is a positive attraction between individuals, and a < 0 when there is an antagonistic interaction between individuals. p = 1 when the population 165 follows a Poisson distribution, P > 1 for contagious distributions, and P < 1 for regular (uniform) distributions (Iwao 1968, Iwao & Kuno 1971).