Sensing pheromones and host volatiles in moths and flies : from molecules to detection to odor-guided behavior

Insects are highly dependent on pheromones and host volatiles for finding a mating partner or host plants for feeding and oviposition, respectively. In this dissertation I elucidated the role of such volatiles in different life stages and sexes of moths and demonstrated the impact of specific host blends on pheromone-driven behavior in moths and flies including the involved mechanism. By the use of electrophysiological methods and immunolabeling I demonstrated in the first chapter of this thesis that larvae of the budworm Heliothis virescens detect female-released sex pheromone components regardless of their sex, and that the molecular elements HR6, HR13, SNMP1, PBP1 and PBP2 are expressed in the larval antenna, as used in adult males for the detection of the same compounds. In the second chapter I characterized trichoid sensilla of female silk moths Bombyx mori using single sensillum recording with ecological relevant odorants by including the impact of the reproductive status. Moreover, I established a two-choice behavioral assay and examined the behavioral consequence of relevant volatiles, being detected by trichoid sensilla. In nature volatiles are always sensed in a background of various plant odors. I therefore investigated plant-pheromone interaction in Heliothis virescens in the third chapter by demonstrating, that single volatiles can reduce pheromone attraction in males, but a complete host plant bouquet does not affect their flight behavior. In my final chapter I elucidated the neuronal mechanism of food-pheromone interaction in the vinegar fly Drosophila melanogaster. Furthermore, the results demonstrate that vinegar enhances the receptivity specifically of females during courtship. With this thesis I investigated pheromone and host volatile perception at different levels of the olfactory pathway focusing on the volatile detection and the behavioral consequences for a deeper understanding of chemical communication in moths and flies.