LE3 .A278 2023

2023

Hillier, Kirk

Acadia University

Master of Science

Masters

Biology

Biology

Heliothine moths are some of the world’s most important agricultural pest species. Helicoverpa zea (Corn Earworm), and Heliothis virescens (Tobacco Budworm) cause billions in damage and control costs worldwide each year. Given their economic importance, sex pheromones of many species have been studied for development of management techniques such as trapping for population monitoring. The majority of pheromones identified and studied to date have been female-produced sex pheromones. Less emphasis has been placed on male sex pheromones, associated with abdominal hairpencil structures which often function in courtship or to attract females. Studying of male produced sex pheromones is as much as important as female sex pheromone to develop novel integrated pest management techniques. My study examines the composition, detection and behavioral role of male H. zea hairpencil compounds in male autodetection and in courtship. Comparative examination of the hairpencil blend composition of H. zea and H. virescens revealed subtle differences in pheromone blend composition produced by males of these species. Electrophysiological testing demonstrated broad antennal neuron response in both males and females of H. zea to nine key stimuli, with sexual dimorphism present in each species. Behavioral assays suggested that odors released by male hairpencils are important in mate acceptance by female H. zea and may play a role in mate choice and species isolation. Wind tunnel observations indicated that key H. zea hairpencil odors (hexadecanyl acetate, octadecanyl acetate) also function in mate competition, antagonizing responses of downwind conspecific males following a female sex pheromone plume, meaning that males use such compounds to repel competing conspecific males. This finding provides an insight on conspecific males’ olfactory processing of a male sex pheromone, as well as a potential new prospect for managing H. zea pest populations.

The author retains copyright in this thesis. Any substantial copying or any other actions that exceed fair dealing or other exceptions in the Copyright Act require the permission of the author.

https://scholar.acadiau.ca/islandora/object/theses:3870