ABSTRACT OF THE THESIS OF Ranaa Rao V. Gangavalli for the degree of Dpctor of Philosophy in Antomology presented on January 9.L985. Title:LatjataceetsLanthe. peveloomental Bioloav of the Obliauebanded Leafroller. Choristoneura rosaceana (Harris) (Lepidontera: Tortricidae), Abstract Approved: Redacted for Privacy Developmental thresholds and thermal unit (degree day) requirements for eggs, different larval instars, pupal stage and preoviposition period were determined for the obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris). Separate thresholds and degree day requirements were determined for males and females, but differences between the sexes were not significant. However, there were significant differences among the developmental thresholds for different larval instars. A total of 700.1 degree days were required for the complete life cycle (egg to egg). Diapause in the obliquebanded leafroller was induced and expressed in the larval stage. Both temperature and photoperiod played a distinct role in diapause induction, maintenance and termination. Under laboratory conditions, the critical photoperiod for diapause induction was between 14-15 hours of light per 24 hr period. Constant high temperatures of28°C and above and fluctuating temperatures (12:12 cycle) with high temperature of 25°C and above also induced diapause. First and second instar larvae were the only stages sensitive to diapause induction. Diapause was mainly expressed in the third and fourth instars. Under Wilimette Vally conditions, 19-22% of the first generation larvae entered diapause during the second week of July, and almost all second generation larvae entered diapause. Diapause in the first generation was expressed mainly in third and fourth instars, while the second generation larvae expressed diapause In second and third instars. The diapause in the field was initially maintained by declining photoperiod in the fall months, thenby falling temperatures in late fall and winter months. It was terminated during spring months in a bimodal fashion in response to increasing temperatures. A phenology model for predicting adult emergence, oviposition, and egg hatch based on time-temperature relationships was developed. The model was validated during 1984. Influence of Temperature and Photoperiod onthe Developmental Biology of the ObliquebandedLeafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). by Ranga Rao Gangavalli V. A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed January 9,1985 Commencement June, 1985 APPROVED: Redacted for Privacy Associate Professor of Entomology in charge of major Redacted for Privacy Head of Department of Entomcpirgy Redacted for Privacy Dean of Grade School° Date thesis Is presented January 9, 1985 Typed by Sai Gangavalli for Ranga Rao Gangavalli ACKNOWLEDGEMENTS Sincere thanks are extended to my major professor, Dr. M. T. AliNiazee, for his suggestions and support, both financial and moral, and to the members of my committee Dr. N. H. Anderson, Dr. Ralph E. Berry, Dr. M. M. Thompson, and Dr. W. D. Anderman for their comments and advice throughout this study. Acknowledgement is also made to Dr. R. Petersen (Statistics) and David G. Niess (Computer Science) for their help in statistical analysis. I would like to thank Steven R. Booth, Russel Messing for their suggestions throughout this study, and Leonard B. Coop and Alan Knight for sparing their time in various discussions. Special thanks are offered to Dr. Parthasarathi Manavalan, (Biophysics) for his generous help in preparing various graphs, and to Dr. Rene Feyereisen, Stuart Sloan (Entomology) for their help in making slides for this study. This endeavour would not have been possible without the sponsorship of Dr. B. N. Samudrala, and financial assistance from my major professor, Dr. M. T. AliNiazee and my employer ICRISAT Plant Quarantine Department for granting me study leave. I am thankful to the late Dr. K. K. Nirula (ICRISAT, India) whose encouragement led me to start this endeavour and to Mr. B. K. Varma, Plant Quarantine Chief (ICRISAT) for his concern in extending my study leave to fulfill this goal.. I especially thank all my family members for their unquestioning support which helped make this study possible. TABLE OF CONTENTS SECTION I. Introduction 1 Review of Literature 5 SECTION II. TEMPERATURE REQUIREMENTS FOR 17 DEVELOPMENT OF THE OBLIQUEBANDED LEAFROLLER, CHORISTONEURA ROSACEANA (LEPIDOPTERA:TORTRICIDAE). Abstract 18 Introduction 19 Materials and Methods 21 Results and Discussion 24 Illustrations 28 References 38 SECTION III. ROLE OF PHOTOPERIOD AND 40 TEMPERATURE IN THE INDUCTION OF DIAPAUSE IN THE OBLIQUEBANDED LEAFROLLER, CHORISTONEURA ROSACEANA (LEPIDOPTERA:TORTRICIDAE). Abstract 41 Introduction 43 Materials and Methods 45 Results 49 Discussion 53 Illustrations 56 References 61 SECTION IV. SEASONALITY OF DIAPAUSE 64 INDUCTION, MAINTENANCE, AND TERMINATION IN THE OBLIQUEBANDED LEAFROLLER, CHORISTONEURA ROSACEANA (LEPIDOPTERA: TORTRICIDAE) UNDER FIELD CONDITIONS. Abstract 65 Introduction 67 Materials and Methods 70 Results 73 Discussion 81 Illustrations 85 References 92 SECTION V. A FORECASTING SYSTEM OF ADULT 96 EMERGENCE, OVIPOSITION AND EGG HATCH OF OBLIQUEBANDED LEAFROLLER, CHORISTONEURA ROSACEANA (LEPIDOPTERA:TORTRICIDAE) BASED ON PHYSIOLOGICAL TIME. Abstract 97 Introduction 98 Materials and Methods 100 Results 105 Discussion 109 Illustrations 111 References 117 SECTION VI. BIBLIOGRAPHY. 119 APPENDIX. 126 LIST OF FIGURES FIGURE PAGE II-1. Effect of temperature on the developmental 28 rate of different male larval instars. 11-2. Effect of temperature on the developmental 29 rate of different female larval instars. 11-3. Effect of temperature on the developmental 30 rate of different larval instars (males & females combined). 11-4. Effect of temperature on the developmental 31 rate of complete larval stage for males, females and both sexes combined. 11-5. Effect of temperature on the developmental 32 rate of the male, female and combined (male and female) pupal stage. 11-6. Effect of temperature on the preovipositi- 33 onal period. 11-7. Effect of temperature on the developmental 34 rate of the egg stage. III-1. Effect of temperature and photoperiod on 56 diapause induction in the obliquebanded leafroller. IV-1. Percent diapause induction in obliquebanded 85 leafroller under field conditions. Corvallis, OR 1983. IV-2. Percent diapause induction In obliquebanded 86 leafroller under field conditions. Corvallis, OR 1984. IV-3. Percent cumulative diapause induction in 87 obliquebanded leafroller under field conditions. Corvallis, OR 1983-1984. IV-4. Percent diapause termination in oblique- 88 banded leafroller under field conditions. Corvallis, OR 1984. IV-5. Percent cumulative diapause termination in 89 OBLR under field conditions. Corvallis, OR 1984. V-1. Predicted and actual percent cumulative 111 adult emergence of OBLR. Corvallis, OR 1984. V-2. Predicted and actual percent cumulative oviposition of OBLR. Corvallis, OR 1984. V-3. Predicted and actual percent cumulative egg hatch of OBLR. Corvallis, OR 1984. V-4. Oviposition pattern of OBLR under field conditions. Corvallis, OR 1983-1984. APPENDIX FIGURES. Developmental rate of OBLR egg stage at 126 different temperatures showing the lower and upper thresholds for development. 2. Developmental rates of OBLR different 127 larval instars at different temperatures showing lower and upper developmental thresholds. 3. Developmental rate of OBLR total larval 128 stage at different temperatures showing lower and upper developmental thresholds. 4. Developmental rate of OBLR pupal stage at 129 different temperatures showing lower and upper developmental thresholds. 5. Development of a cohort of OBLR larvae 130 under laboratory condition at 28 C. 6. Oviposition pattern of OBLR at different 131 constant and fluctuating temperatures. 7. Regression line showing the relationship 132 of egg mass area vs number of eggs of OBLR under laboratory conditions. 8. Effect of temperature on OBLR post dia- 133 pause larval development at 16L:8D photo- period. LIST OF TABLES TABLE PAGE II-I. Developmental thresholds for immature 35 stages and pre-oviposition period of C. rosaceana. 11-2. Temperature requirements (expressed as 37 thermal units) for development of C. rosaceana eggs, larvae, pupae and pre- oviposition period. III-I. Diapause induction in the obliquebanded 57 leafroller reared at constant tempera- tures and 16L:8D photoperiod. 111-2. Diapause induction in the obliquebanded leafroller reared at fluctuating tempera- 58 tures and 16L:80 photoperiod. 111-3. Obliquebanded leafroller stages sensi- 59 tive to diapause induction reared at 20 C. 111-4. Obliquebanded leafroller stages sensi- 60 tive to diapause induction and expres- sion reared at 2 different temperatures. IV-1. Progression of headcapsule width in 90 different larval instars of oblique- banded leafroller. IV-2. Effect of cold exposure time on the speed 91 of post diapause development at different temperatures and photoperiods. V-1. Summary of OBLR adult emergence pattern 115 in relation to physiological time (degree days) based on 3 year pheromone trap catch data. Corvallis, OR 1981-1983. V-2. Deviation in degree days and calendar 116 days between predicted and actual for different biological events of OBLR Corvallis, OR 1984. APPENDIX TABLES. 1. Body measurements (mm) of obliquebanded 134 leafroller at 24 C and 16L:8D photo- period.