SUSCEPTIBILITY OF ORIENTAL FRUIT MOTH, (GRAPHOLITA MOLESTA (BUSCK)) TO SELECTED INSECTICIDES AND MIXTURES BY MONEEN M. JONES DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Natural Resources and Environmental Sciences in the Graduate College of the University of Illinois at Urbana-Champaign, 2010 Urbana, Illinois Doctoral Committee: Professor Richard Weinzierl, Chair Professor Germán Bollero Professor Lawrence Hanks Associate Professor Mosbah Kushad Associate Research Joseph Spencer Jacqueline Robertson, USDA Forest Service [retired] and LeOra Software Co. ABSTRACT A series of experiments assessed the susceptibility of Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), to selected insecticides and mixtures. Two populations – a laboratory colony from Rutgers University and a colony established in 2007 from orchards in Calhoun County, Illinois – were tested. Both colonies were reared concurrently on lima bean diet and ‘Gala’ apples to reduce the likelihood that either colony would be lost to diseases or other factors. Bioassays were analyzed separately for each colony and for progeny of parents reared on each food source. To determine the baseline susceptibility of G. molesta to chlorantraniliprole, spinetoram, spinosad, acetamiprid, thiamethoxam, esfenvalerate, and lambda-cyhalothrin, neonates were placed on wheat germ diet containing a range of concentrations of each insecticide. Overall, the two colonies responded similarly to these insecticides, regardless of parental food source. Results of these bioassays provide baseline data for future monitoring of of resistance. To develop and test a diagnostic dose for estimation of pyrethroid resistance in the field, the dose-mortality relationship was described for esfenvalerate applied topically to adult males. A range of concentrations was applied in 1 µl of acetone to male moths from the Rutgers colony, and the LD99 was estimated to be 0.022 µg per moth. Application of 0.022 µg esfenvalerate per moth to ca. 600 male moths from two putatively susceptible populations resulted in mean survivorship approximately equal to the expected level of 1.0%. Application of this dose to ca. 375 moths captured in two Calhoun County orchards with histories of pyrethroid use resulted in mean survivorship of 9.4% and 82%. It is proposed that 0.022 µg of esfenvalerate in 1 µl of acetone be used as a diagnostic dose for monitoring pyrethroid resistance. ii The toxicities of three mixtures of insecticides to neonates were estimated. Chlorantraniliprole was mixed with acetamiprid, esfenvalerate, or thiamethoxam. These insecticides may be mixed or rotated to provide broad spectrum control of orchard pests. Mixtures of chlorantraniliprole with acetamiprid or thiamethoxam did not exhibit consistent synergism or antagonism. For chlorantraniliprole plus esfenvalerate, mortality was less than expected at nearly all concentrations for both colonies, suggesting antagonism despite different modes of action for the two compounds. The effectiveness of one or both insecticides to Oriental fruit moth might be reduced if they are combined in field applications. To estimate the toxicity of novaluron, an insect growth regulator, to eggs of the two colonies, eggs on waxed paper were dipped into a range of concentrations. Eggs from the Calhoun colony were more tolerant to novaluron than eggs from the Rutgers colony. Differences in the responses of these colonies may represent natural variation among populations or may be the result of selection by other insecticides used in orchards in Calhoun County before larvae were collected to establish this colony. Key Words: bioassays, insecticide resistance, chlorantraniliprole, spinetoram, spinosad, acetamiprid, thiamethoxam, esfenvalerate, lambda-cyhalothrin, novaluron, resistance monitoring iii To my Mother, Constance M. Jones, The 12th Rose and my Guardian Angel Rest in Peace iv ACKNOWLEDGMENT First, I thank God for giving me the strength, courage, wisdom, and tenacity necessary to reach my goals (even though it took me awhile to get there). I thank my Dad, Aunt Penny, Mr. and Mrs. Stach & family, Heather Jakob-Short, Nina Roberts, Marijo Readey, Terry Puryear, Karen Claus, Piper Hodson, and Sue Ratcliffe for their love, understanding, and words of encouragement. I could not be more blessed and have made it this far without you; I thank you from the bottom of my heart. I thank Rick Weinzierl, my Ph. D. advisor and co-author, and Jacqueline Robertson, Ph. D. committee member and co-author, for all the time and effort they devoted to assisting me with the completion of my doctorate. Special thanks to Jackie for all the expert advice and training on bioassays. In addition, I thank my Ph. D. committee members, German Bollero, Mosbah Kushad, Larry Hanks, and Joe Spencer for their time, advice, and encouragement. Thanks to Ann Rucker and Peter Shearer for providing Oriental fruit moth pupae from the Rutgers Colony. Thanks to Steven Koeller and Stephanie Dold, for help with the initial laboratory bioassays. I offer a large sum of gratitude to summer employees Steven Koeller, Patrick Halbig, Max Behle, and Jeremy Funk, whose help with colony maintenance and field work made the bulk of this research possible. I also thank Leonard Fortschneider, Hagen Orchards, Ringhausen Orchards, and Eilerman Farms in Calhoun County, IL, for access and cooperation. This work was supported in part by a Sentinel Grant from the Illinois Council on Food and Agricultural Research and by a University of Illinois Agricultural Experiment Station Hatch Project. v TABLE OF CONTENTS CHAPTER 1: INTRODUCTION AND LITERATURE REVIEW………………................................................1 SYSTEMATICS AND TAXONOMY .................................................................................................................................1 DISTRIBUTION AND HOST PLANTS ..............................................................................................................................3 LIFE HISTORY AND PHENOLOGY .................................................................................................................................5 ECONOMIC IMPACTS, MANAGEMENT, AND MONITORING ............................................................................................7 INSECTICIDES AND MODES OF ACTION......................................................................................................................10 INSECTICIDE RESISTANCE, RESISTANCE MONITORING, AND RESISTANCE MANAGEMENT ..........................................12 RATIONALE AND OBJECTIVES...................................................................................................................................20 REFERENCES CITED .................................................................................................................................................22 CHAPTER 2: SUSCEPTIBILITY OF ORIENTAL FRUIT MOTH (LEPIDOPTERA: TORTRICIDAE) LARVAE TO SELECTED REDUCED-RISK INSECTICIDES...........................................................................41 ABSTRACT................................................................................................................................................................41 MATERIALS AND METHODS.....................................................................................................................................44 RESULTS AND DISCUSSION ......................................................................................................................................48 REFERENCES CITED .................................................................................................................................................51 TABLES ....................................................................................................................................................................54 CHAPTER 3: SUSCEPTIBILITY OF ORIENTAL FRUIT MOTH (LEPIDOPTERA: TORTRICIDAE) TO TWO PYRETHROIDS AND A PROPOSED DIAGNOSTIC DOSE FOR FIELD DETECTION OF RESISTANCE.............................................................................................................................................................59 ABSTRACT................................................................................................................................................................59 MATERIALS AND METHODS.....................................................................................................................................63 RESULTS AND DISCUSSION ......................................................................................................................................68 REFERENCES CITED .................................................................................................................................................74 TABLES ....................................................................................................................................................................79 CHAPTER 4: TOXICITY OF THIAMETHOXAM AND MIXTURES OF CHLORANTRANILIPROLE PLUS ACETAMIPRID, ESFENVALERATE, OR THIAMETHOXAM TO NEONATES OF ORIENTAL FRUIT MOTH (LEPIDOPTERA: TORTRICIDAE).............................................................................................84 ABSTRACT................................................................................................................................................................84