EMERGENCE, DISPERSAL AND REPRODUCTIVE BIOLOGY OF CYDIA NIGRICANA (F. ) (LEPIDOPTERA : TORTRICIDAE) JEREMY CLIFFORD GRAHAM B.Sc. (HONS) BRISTOL A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY OF THE UNIVERSITY OF LONDON AND FOR THE DIPLOMA OF IMPERIAL COLLEGE DEPARTMENT OF PURE AND APPLIED BIOLOGY, IMPERIAL COLLEGE, SILWOOD PARK, ASCOT, BERKSHIRE NOVEMBER 1984 To my Mother and Father Ill ABSTRACT A synthetic sex-attractant monitoring system, developed at Rothamsted Experimental Station, has been available to pea growers for detecting the immigration of male pea moth, Cydia nigricana (F. ), into pea crops, since 1976. Very little information was available as to how the trap catches of male moths related to the arrival of female moths, and whether those females were mated and ready for ovipos ition. This study involved extensive and intensive sampling of moth populations by aerial netting and by suction (D-Vac.), on commercial farms. Both the cereal emergence site, the pea crop and surrounding vegetation were sampled. Sex- attr act ant monitoring traps were positioned at both sites, and the population levels and fluctuations they indicated, were compared with the results from the sampling programme. The dispersion and dispersal of each sex was examined in relation to emergence, maturation and fecundity, mating status and physiological age (as revealed by dissection), as well as to the sex-attractant trap catches. The relation­ ship between larval infestation levels and plant phenology was recorded, and this in turn analysed with respect to immigration as indicated by sex-attractant traps and sampling results. In the laboratory, pea moth was cultured in a controlled environment (following the method developed at Rothamsted). Culture material was used to conduct exper­ iments on the effect of diet, host plant presence and phenology, on potential fecundity, actual fecundity and longevity in the laboratory. IV TABLE OF CONTENTS Page ABSTRACT ........ iii TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES ... ix LIST OF APPENDICES xix 1. INTRODUCTION ... 1 1.1. Introduction and Aims 1 1.2. Description of the Pest 3 1.3. The Control of the Pest 8 1.3.1. Earlier attempts with Control and Forecasting Pest Attack ... ... 8 1.3.2. The Development of a Sex-attractant Monitoring System ... ... ... 11 2. MATERIALS AND METHODS .................... 16 2.1. Field Studies ... ... ... ... 16 2.1.1. Field Site Selection ... ... 16 2.1.2. Field Site Description ... ... 17 2.1.3. Crop Phenology ... ... ... 21 2.1.4. Climatic Records ... ... ... 21 2.1.5. Sample Units ... ... ... 24 2.1.6. Sampling Programme ... ... 30 2.1.7. Sampling Proceedure ... • ... 46 2.1.8. Sorting of Samples ... ... 47 2.1.9. Dissection of Adult Moths ... 51 2.1.10.Infestation Levels ... ... 56 2.1.11. Experimental Use of Sex-attractant 59 2.1.12. Calibration of the D-Vac. ... 60 2.2. Laboratory Studies ... ... ... ... 63 2.2.1. Culturing C.nigricana ... ... 63 2.2.2. Pea Growing ... ... ... ... 65 2.2.3. The Effect of Diet ... ... 66 2.2.4. Effect of Pea Plant Presence ... 67 2.2.5. Treatment of Field Data ... ... 71 3. DISPERSION AND DISPERSAL ... 72 3.1. Introduction ... ... 72 3.2. Dispersion ... ... 75 V P a g e 3.2.1. Spatial Patterns of Dispersion in the Emergence Site ... ... ... 75 3.2.2. Temporal Patterns of Dispersion in the Emergence Site ... ... ... 88 3.2.3. Spatial Patterns of Dispersion in the Pea Field ... ... ... ... 105 3.2.4. Temporal Patterns of Dispersion in the Pea Field ... ... ... ... 117 3.3. Dispersal ... ... ... ... ... 130 3.3.1. Spatial Patterns of Dispersal ... 130 3.3.2. Temporal Patterns of Dispersal 135 3.3.3. Differential Dispersal of the Two S exes ... ... ... ... ... 137 3.4. Relationship Between Dispersion, Dispersal and Other Factors ... ... ... ... 143 3.4.1. Relationship Between Sex-attractant Trap Catch and Dispersion/Dispersal 143 3.4.2. Relationship Between Dispersal and Plant Phenology ... ... ... 169 3.4.3. Relationship Between Dispersal and Larval Infestation 178 3.5. Discussion ... ... 2 00 MATING ... ... ... ... 216 4.1. Introduction ... ... 216 4.2. Site of Mating ... 218 4.3. Time of Mating ... 226 4.4. Frequency of Multiple Mating ... 229 4.5. Discussion ... ... ... ... 231 MATURATION. LONGEVITY AND FECUNDITY ....... 238 5.1. Introduction ... ... ... ... .. 238 5.2. Physiological Age Structure of Moth Populations ... ... ... ... 243 5.3. Fecundity and Maturation in Relation to Dispersal and Mating ... ... 255 5.4. The Effect of Diet on Longevity and F ecundity ... ... ... ... ... 280 5.5. Longevity, Fecundity and Maturation in relation to Host Plant Phenology 2 85 5.6. Discussion ... ... ... ... ... 294 VI Page 6. DISCUSSION 302 7. S U M M A R Y __ 319 ACKNOWLEDGEMENTS 322 REFERENCES 323 APPENDICES -- 345 V l l LIST OF TABLES Page f—( i —1 —1 • TABLE • Duration of various periods in the life cycle of C.niqricana according to different authors ... ... ... ... ... 5 <N i—1 i—1 • TABLE • Explanation of the decimal code for the growth stages of cereals . ... 22 TABLE 2.2. Explanation of the P.G.R.O. numerical code for the growth stages of peas . ... 23 CM CO TABLE • Description of the four fat body types of C.nigricana at various grades of abundance 53 1 CO - • • TABLE 1 Peak density of C.nigricana in vegetation surrounding emergence sites . ... 97 TABLE 3.2. Relationship between number of C.nigricana and distance to nearest pea field 134 TABLE 3.3. Sex ratios (males : females) of populations in various subdivisions of the environment 139 TABLE 3.4. Sex ratios (males : females) of aerial populations over various subdivisions of the environment, 1981 ... ... ... 142 i—1 i—1 TABLE • • Percentage of unmated and mated female C.nigricana in wheat field emergence sites 219 TABLE 4.2. Percentage of unmated and mated female C.nigricana in pea fields . ... 221 TABLE 4.3. Percentage of unmated and mated females confined in laboratory breeding chambers with males and plant material . ... 2 24 TABLE 5.1. Comparison of potential fecundity and mature egg load of mated and unmated female C.nigricana in crop regions of emergence sites ... ... ... ... 276 TABLE 5.2. Comparison of potential fecundity and mature egg load of mated and unmated female C.nigricana of different age groups in crop regions of emergence sites 278 VI11 P a g e TABLE 5.3. Comparison of potential fecundity and mature egg load of mated and unmated female C.nigricana of different age groups in vegetation surrounding emergence sites ... ... ... ... 279 TABLE 5.4. Fecundity and potential fecundity of female C.nigricana provided with different diets ... ... ... ... 284 TABLE 5.5. Potential fecundity, fecundity and percentage of eggs laid on plant material, of female C.nigricana confined without and with plant material at different phenological stages ... ... ... 291 TABLE 5.6. Preferred oviposition microsites on pea plant material ... ... ... ... 293 IX LIST OF FIGURES Page Fig. 1.1. Life cycle of C.niqricana ........ 4 F ig . 2.1. Map showing geographical relationship between emergence sites at Childerley Hall and pea fields at Knapwell Wood Farm, Cambridgeshire, 1980 ... ... ... 18 Fig. 2.2. Map showing geographical relationship between emergence sites and pea fields at Shimpling Park Farm, Suffolk, 1981 ... 19 Fig. 2.3. Map showing geographical relationship between emergence sites and pea fields at Shimpling Park Farm, Suffolk, 1982 ... 20 Fig. 2.4. Wheat field P, emergence site, Childerley Hall, Cambridgeshire, 1980: arrangement and numbering of sample units, and position of sex-attractant monitoring traps ... 25 Fig. 2.5. pea field J, Knapwell Wood Farm, Cambridge- shire, 1980: arrangement and numbering of sample units, and position of sex- attractant monitoring traps ... ... 26 F i g . 2.6. Wheat field WAl, emergence site, Shimpling Park Farm, Suffolk, 1981: arrangement and numbering of sample units, and position of sex-attractant monitoring traps ... 27 Fig. 2.7. Pea field PAl, Shimpling Park Farm, Suffolk, 1981: arrangement and numbering of sample units, and position of sex- attractant monitoring traps ... ... 28 Fig. 2.8. Wheat field WA2, emergence site, Shimpling Park Farm, Suffolk, 1982: arrangement and numbering of sample units, including transect sub-samples ... ... ... 31 Fig. 2.9. Pea field PA2, Shimpling Park Farm, Suffolk, 1982: arrangement and numbering of sample units, including transect sub­ samples, and position of sex-attractant monitoring traps ... ... ... ... 32 X Page Fig. 2.10. Pea field PB2, Shimpling Park Farm, Suffolk, 1982: arrangement and numbering of sample units, including transect sub­ samples, and position of sex-attractant monitoring traps ... ... ... ... 33 Fig. 2.11. Emergence site WA2 and Pea fields PA2 & PB2, Shimpling Park Farm, Suffolk,1982: arrangement and numbering of transect sub-samples ... ... ... ... ... 34 Fig. 2.12. D-Vac. sampling machine showing major components ... ... ... ... ... 37 Fig. 2.13. Cutaway diagram of D-Vac. sampling head showing modifications associated with the use of the trolley attachment 38 Fig. 2.14. Modes of D-Vac. use with conventional sampling head ... ... ... ... 40 Fig. 2.15. Components and design of trolley attach­ ment for use of D-Vac. in crops with tram-lines ... ... ... ... ... 41 F ig. 2.16. Mode of tram-line sampling using D-Vac. and trolley attachment ... ... ... 42 Fig. 2.17. Cutaway diagram of sex-attractant monitoring trap, showing parts and as s embly ... ... ... ... ... 44 Fig. 2.18. Genitalia preparations of C.nigricana to show parts and diagnostic features 48 Fig. 2.19. External appearance of characters recognised as diagnostic from genitalia preparations ... ... ... ... ... 50 F ig . 2.20. Diagrammatic illustration of the four fat body types of C.nigricana at various grades of abundance ... ... ... 52 Fig. 2.21. Relationship of Physiological age (P.A.) to real age ... ... ... ... ... 55 Fig. 2.22. Diagrammatic illustration of breeding chambers for C.nigricana showing main components and assembly ... ... 64 - xi - 2.23. Effect of diet and pea plant presence on fecundity and longevity of C.nigricana 3.1. Relationship between log variance and log mean of populations of male C.niqricana, wheat field emergence site, 1981 .