Dissertation Research: Behavioral Responses to Floral Signals of Nectar Quality Affect Hawkmoth Fitness

Cornell University, Ithaca NY

Investigators

Abstract

A preference for amino acid-rich floral nectar is ubiquitous among adult moths and butterflies that pollinate flowering plants. Moths pollinating yellow evening primrose (Oenothera flava) flowers can use the intensity of its scent to directly assess the nectar amino acid content. Amino acids improve the reproductive potential of these pollinators and nectar is their only dietary source of amino acids. Despite the demonstrated importance of amino acids to reproduction, it remains unknown how this preference translates into increased fecundity; amino acids consumed by the adult are not directly used to produce additional offspring. This project will combine behavioral theory and physiology to assess how floral preference translates into increased reproduction for both sexes of pollinating moth and to investigate potential underlying physiological mechanisms. The researchers will investigate effects of nectar amino acids on male and female moth reproduction, flight muscle maintenance and function, and trade-offs between immune function and reproduction. This project also provides opportunities for research involvement by undergraduates and exchange students with broader nutritional interests. Furthermore, the investigators will continue activities designed to foster scientific interests in underrepresented groups and share their work with local NY communities. The fitness benefits of amino acid preferences have been demonstrated in female Lepidoptera, however the mechanisms behind this preference remain unknown and the impact on male fitness has never been assessed. Once completed, this project will provide a systematic assessment of the contributions of nectar amino acids to mating success and reproduction in both sexes of moth and test two physiological theories involving nutritionally mediated reproductive tradeoffs with somatic maintenance and immune response. Using the white-lined sphinx moth (Hyles lineata), the most abundant pollinator of the evening primrose O. flava, this project will experimentally manipulate the nutritional status of adult moths and conduct mating trials to determine how nutritional status affects mate-choice and overall reproductive output in both sexes of moth. To determine if amino acids improve flight ability, which is important for nectar foraging and reproduction, the researchers will also test moth flight ability and muscle strength in combination with histological assessments of overall muscle cell senescence. Finally, to assess the role of amino acids for nutritionally mediated tradeoffs between reproduction and immune function, standard tests of immune function will be used to investigate how nutritional status influences a moth?s ability to resist pathogens while maintaining reproductive output. Undergraduates from the Cornell Biology Scholars program will participate in the research and be mentored by the researchers. The researchers will disseminate their work through scientific presentations and publications, outreach through Expanding Your Horizons, Insectapalooza and Cornell?s teaching outreach program GRASSHOPR.