Pheromone and Host Plant Odor Detection in Eastern Spruce Budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae)

SIMPLE SUMMARY: The spruce budworm (Choristoneura fumiferana Clemens) is a major defoliating pest of coniferous trees in North America. In recent decades, substantial advances in pheromone-mediated trapping and mating disruption technologies have provided researchers with renewed hope for novel population control strategies of C. fumiferana. While the chemical ecology of spruce budworm is continually being studied, a detailed study of the antennal sensilla in adults has yet to be completed. In this research, we review the state of knowledge of C. fumiferana chemical ecology and behavioral responses to chemical stimuli. Further, extracellular single sensillum recordings (SSR) were used to determine the response of olfactory receptor neurons (ORNs) in the antennal sensilla of male and female C. fumiferana to host plant volatiles, and female sex pheromones with a range of concentrations. Together, these data will improve knowledge of mechanisms by which adult C. fumiferana respond to pheromone and host plant volatiles and will provide insights that may improve development of integrated pest management strategies based on the chemical ecology of spruce budworm. ABSTRACT: Spruce budworm, Choristoneura fumiferana Clemens, is an ecologically significant defoliator of spruce and balsam fir in North America. Optimization of semiochemical-mediated control is needed to improve the existing integrated pest management systems such as mating disruption and population estimation. This study used single sensillum recordings (SSR) to identify the responses of olfactory receptor neurons (ORNs) in the antennal sensilla of adult male and female C. fumiferana to host plant volatiles, and female sex pheromones. There have been few SSR studies done on spruce budworm, and to our knowledge, the present study represents the first attempt to examine the responses of ORNs from antennal sensilla in response to a range of host and conspecific stimuli. A total of 86 sensilla were characterized and sorted into 15 possible sensillum categories based on odor responses. We observed that specialist sensilla responding to few ligands were more abundant in both male and female than sensilla exhibiting more generalized odorant responses. (E/Z)-11-tetradecenal elicited responses from ORNs from any sensilla which were sensitive to pheromones in both males and females. Female C. fumiferana ORNs were able to detect and physiologically respond to female-produced sex pheromones with the same degree of sensitivity as their male counterparts. Together, these data improve our knowledge of mechanisms by which adult budworms respond to pheromone and host plant volatiles and provide insights that may be complementary to existing integrated pest management (IPM) strategies based on the chemical ecology of spruce budworm.