AN ABSTRACT OF THE THESIS OF Gladwin Joseph for the degree of Master of Science in Entomology presented on August 29 1989. Title: Host Suitability Studies of Douglas-fir and White Alder to the Gypsy Moth Abstract Redacted for privacy approved: / f /Jeffrey C.Miller Douglas-fir, Pseudotsuga menziesii and white alder, Alnus rhombifolia, species that are prevalent in the Pacific Northwest, were fed to larvae of the gypsy moth, Lymantria dispar L. Gypsy moth larvae from different familial lines (egg masses) from a single geographic population were evaluated on these hosts. The larvae were fed leaves from the two tree species characterized by different foliar levels of either nitrogen, moisture, phenols, or terpenes. Of the two tree species evaluated as hosts of the gypsy moth, white alder appeared to be a highly suitable host, whereas Douglas-fir was a sub-optimal host. Nitrogen and the allelochemics in the foliage affected larval development. On white alder, foliage from trees that had the higher phenolic levels resulted in increased larval survival and higher fecundity. On Douglas-fir, foliage high in nitrogen had lower phenolics and this resulted in increased larval survival and heavier pupae when compared to foliage with low nitrogen and high phenols. Performance of the gypsy moth on these hosts was affected by unknown intrinsic variation among familial lines. Larval survival and duration varied more than other developmental variables among larval familial lines. The variation in larval survival among familial lines was more pronounced in larvae fed Douglas-fir than those fed white alder. A developmental index involving developmental rate and pupal weight differed more for females among familial lines than for males, suggesting a differential sex response. Experiments, manipulating foliar nitrogen, terpenes and phenols of Douglas-fir were conducted to assess the effects on the development of gypsy moth larvae. Foliar chemicals were manipulated by fertilizing three-year old potted trees with two levels of nitrogen (0 ppm and 200 ppm). Gypsy moth pupal weights were significantly greater at the higher foliar N level (1.69%) than at the lower foliar N level (0.40%). The pupal weights were positively correlated with foliar nitrogen, negatively correlated with foliar phenols, and showed no correlation with foliar terpenes. The number of days to pupation and the number of days from pupation to adult emergence were not significantly different between treatments. The effects of terpenes and phenols on larval development of the gypsy moth were studied using artificial diet. The influence of dietary nitrogen on the response of the gypsy moth to the Douglas-fir allelochemics was also studied. The effects were assayed using neonate and later (third and fourth) instar larvae of the gypsy moth. The terpenes in Douglas-fir foliar extracts had little effect on neonate fitness indices. The phenols, however suppressed larval growth and survival. When terpenes and phenols were combined, larval growth and survival was suppressed suggesting a synergistic effect. This synergism depended on levels of dietary nitrogen. Higher levels of dietary nitrogen alleviated the detrimental effects of Douglas-fir plant extracts on neonate and third instar larvae. However, fourth instars performed better on diets with lower nitrogen (2.5 to 2.7% N) than on diets with higher nitrogen (4.1 to 4.5% N) as demonstrated by higher growth rates, consumption rates, higher assimilation efficiencies and higher efficiencies of conversion of digested food. HOST SUITABILITY STUDIES OF DOUGLAS-FIR AND WHITE ALDER TO THE GYPSY MOTH by Gladwin Joseph A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed August 29, 1989 Commencement June 1990 APPROVED: Redacted for privacy Asl'cjg pitofessor-of Entomology in Charge of major Redacted for privacy Chairifan of CepaE5Aent of Entomology Redacted for privacy Dean of Gradu School (f Date thesis is presented August 29, 1989 Typed by Gladwin Joseph ACKNOWLEDGEMENT I owe my gratitude to several people for the successful completion of this research work. In particular, I would like to thank my major professor, Dr. Jeffrey Miller, for his enthusiastic support and valuable advice through out the period of my research. I thank Dr. Ralph Berry and Dr. Rick Kelsey for their suggestions and timely reviews. I thank Dr. Jim Wernz and Dr. Alison Moldenke for their constant encouragement and for many stimulating discussions. In the laboratory, it was a pleasure to work with both Rick and Jim. Words alone are not enough to thank them for their invaluable help and priceless friendship which made it all worthwhile. A word of thanks to fellow graduate students in the department of entomology, especially Chris Murphy, Adam Asquith, Venkat Srikrishnan and Steve Booth who were always ready to help and for several enlightening discussions. Thanks to Liz Gerson and Alisha Berry for their willing and cheerful technical assistance. This research was funded by USDA, CRGO, Pest science grant #87-CRCR-l-2478. Is there anything of which one can say, "Look! this is something new"? All is meaningless, a chasing after the wind. - Ecclesiastes (The Bible). TABLE OF CONTENTS I. Introduction 1 II. Effect of Novel Host Plants and Larval Familial Lines on the Development of the Gypsy Moth (Lvmantria dispar L.). 4 Abstract 4 Introduction 6 Materials and Methods 9 Results and Discussion 15 III. Gypsy Moth Development on Douglas-fir: Influence of Foliar Nitrogen, Terpenes and Phenols. 34 Abstract 34 Introduction 35 Materials and Methods 37 Results 42 Discussion 48 IV. Gypsy Moth Nutritional Physiology: Effect of Dietary Nitrogen and Douglas-fir Allelochemicals. 51 Abstract 51 Introduction 52 Materials and Methods 55 Results 62 Discussion 71 V. Conclusion 77 VI. References 79 VII. Appendices Appendix A Gypsy Moth Survival 87 Appendix BLarval Acceptability 91 Appendix CEffect of Switching Hosts 95 Appendix DHost Effect on Egg Size 100 Appendix EModified Nutrient Solutionto Varying Levels of Nitrogen 102 LIST OF FIGURES Figure Page 1.1. White alder foliar quality indices (1988). Seasonal levels of total nitrogen, total phenols and moisture. 30 1.2. Douglas-fir foliar quality indices (1988) Seasonal levels of total nitrogen, total phenols, moisture and total terpenes. 31 1.3. Percent survival between familial lines among and within host types. 32 1.4. Relationship of pupal weight to the number of eggs laid by the female for gypsy moth reared on white alder (W) and Douglas-fir (D). 33 II.1. Total phenols vs total nitrogen of foliage from Douglas-fir seedlings fertilized at two levels of nitrogen (0 ppm and 200 ppm). 45 A.1. Trend of percent survival of gypsy moth larvae fed foliage from white alder and Douglas-fir. 89 A.2. Percent survival of early instar gypsy moth fed different aged Douglas-fir foliage, related plant tissue and white alder foliage. 91 B.1. Preference of first instar gypsy moth given a choice of different aged Douglas-fir foliage and related tissue. 93 LIST OF TABLES Table Page 1.1. Developmental parameters (mean ±se) for gypsy moth larva fed foliage from white alder and Douglas-fir. 26 1.2. Developmental parameters (mean ±se) of gypsy moth larvae from familial lines (egg masses) reared on white alder from two different tree types. 27 1.3. Developmental parameters (mean ±se) of gypsy moth larvae from familial lines (egg masses) reared on Douglas-fir from two different tree types. 28 1.4. F-ratios and p-values for main effects from three way-ANOVA for gypsy moth developmental parameters. 29 II.1. Foliar characteristics of Douglas-fir seedlings fertilized at two levels of nitrogen. 44 11.2. Developmental variables (mean ±se) of the gypsy moth (sixth instar females) fed on foliage of Douglas-fir seedlings fertilized at two levels of nitrogen. 46 11.3. Correlation coefficients and significance levels for Douglas-fir foliar chemicals vs gypsy moth developmental variables. 47 III.1. Larval survival, larval weight and larval instar of the gypsy moth fed three different Douglas-fir foliar extracts in artificial diet at two levels of casein (nitrogen) eleven days after eclosion. 66 111.2. Larval survival, larval weight and larval instar of the gypsy moth fed three different Douglas-fir foliar extracts in artificial diet at two levels of casein (nitrogen) twenty days after eclosion. 67 LIST OF TABLES 111.3. Total food consumed, total faeces, initial and final weights, total weight gained and duration of fourth instar (mean ±se) of the gypsy moth fed control diets and diet containing Douglas-fir total terpene extract at two levels of casein (nitrogen). 68 111.4. Growth and consumption rates (mean ±se) of fourth instar larvae of the gypsy moth fed on control diets and diet containing the total terpene extract from Douglas-fir at two levels of casein (Nitrogen). 69 111.5. Growth efficiencies (mean ±se) of fourth instar larvae of the gypsy moth fed on control diets and diet containing the total terpene extract from Douglas-fir at two levels of casein (nitrogen). 70 B.2. Preference of fourth instar gypsy moth larvae (reared on different diets) to artificial diets containing Douglas-fir extracts in a multiple choice arena. 94 C.1. The influence of dietary host switches on the fitness parameters (mean ±se) of gypsy moth. 97 C.2. Influence of dietary host switches on the duration of instars (mean days ±se) of the gypsy moth. 98 C.3. Influence of dietary host switches on gypsy moth gross larval growth efficiency (GLGE) and larval weight gain (LWG) expressed as means ±se. 99 D.1. Egg size (Mean diameter ±se) of gypsy moth familial lines collected and reared on different hosts. 101 E.1. Nutrient solution used to fertilize Douglas-fir seedlings at varying levels of nitrogen.