Overview. Researchers have largely ignored close-range courtship behavior by male moths, including the release of close-range sex pheromones, female assessment of the male pheromone, preference, and ultimately acceptance or rejection of the male. This renewal is based on our discovery of novel ‘minor’ compounds in the male pheromone gland with major behavioral effects. While some of these compounds share biosynthetic origins with female-produced pheromones, others are chemically unrelated and appear to be sequestered from larval and adult food. Males appear to use complex close-range signaling that provides females with a dual assessment of the male’s ability (a) of de novo biosynthesis of pheromone compounds similar to hers, and (b) to acquire essential amino acids, and grow on a well-defended plant. We propose to investigate the new male compounds as a novel class of sexual signaling molecules in insects, and to determine how they affect male reproductive success and female choice.
Intellectual Merit. Three major questions in animal sexual communication are: What features of close-range male sexual signals affect female choice? What information do components of the male’s complex signal convey to the female? Is the production of male sexual signals biochemically and genetically linked to production of female signals? Answers to these questions are critical not only for understanding the roles of reciprocal signaling and mate choice in the evolution of sexual communication systems in animals, but will also lead to a better understanding of how the evolution of mating preferences can lead to premating isolation among populations, and ultimately to the origin of new species. Our overall goal is to understand sex pheromone communication by integrating research at the proximate/reductionist level with experimental and observational research in the field, and with research that addresses ultimate/evolutionary questions. That is, we are interested in elucidating the chemical structures of signal molecules and blends, quantifying behavioral acts and their integration into attractant and courtship displays, understanding mechanisms of pheromone production and reception, and identifying genes that underlie all these processes. At the ultimate level, we seek to understand the evolution of pheromone blends in females and response profiles in males across closely related species and among populations. Many moth species are important pests in agricultural crops; therefore this research has practical significance for society. This project integrates insect mate choice with insect-plant interaction strategies. By signaling to the female at close-range with plant-sequestered compounds, males advertise to females that they have fed on a well-defended plant and that they possess the ability to cope with plant defenses. Moreover, by transferring these plant compounds to his mate, she in turn may provision them to her eggs, inhibit local microbial growth at the oviposition site, and downregulate local plant defenses. The integration of research on female choice with de novo biosynthesized male pheromonal signals and plant-sequestered compounds is innovative and transformative in the chemical ecology/ethology community.
Broader Impacts. This project will train a postdoctoral researcher and a graduate student in a multidisciplinary environment that includes electrophysiology, quantitative analysis of behavior, chemical ecology, and genetics. A unique feature of this project is the collaboration with the University of Amsterdam and the Max Planck Institute of Chemical Ecology, which will offer the postdoctoral researcher and graduate student unique opportunities in evolutionary, chemical, and molecular biology, insect physiology, behavior, neurobiology, and plant and analytical chemistry. The project will recruit undergraduates from underrepresented minorities from NCSU and nearby HBUs. We will conduct outreach programs, including hands-on interactive exercises and discussions in biology, live insects and microscopes, and work with the students on biodiversity, insect behavior, and evolutionary biology. Finally, this project will be highlighted in many public education and engagement events in which trainees in this project will participate; these include BugFest, the largest STEM education program in the US (~35,000 participants annually), Science Cafés, the Science of Attraction (300 participants in 2014), and other public education programs.