Pheromone diversity in Heliothine moths

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Insects, and particularly moths, rely heavily on sex pheromones as a means of odor-based communication to draw together opposite sexes. To date, thousands of sex pheromones have been identified, with each species having its own unique blend of chemicals, which will attract a mate (typically produced by females to attract males to prevent costly mating mistakes with the wrong species). As such, there is incredible diversity in pheromone composition, but a poor understanding of the evolution and shifts in production, detection and preference of these chemicals as new species evolve and diverge from one another. In other words, “why are there so many unique pheromone blends?” Despite the wealth of documented pheromones in insects, we are still struggling to understand the mechanisms by which pheromone composition and preferences shift during speciation (or if these features may, in fact, drive speciation). Understanding such shifts are paramount to our understanding of the olfactory system, and moreover, to adapting insect control strategies which use pheromones to monitor and control pests. This research program will create an international collaborative network to characterize and compare pheromones, preference of pheromones, and neurophysiology of pheromone detection and processing across related species of heliothine moths. Heliothine moths represent an excellent model system for examining divergence of pheromone production, and mechanisms of detection and processing in closely related species. Divergence in olfactory communication is evident among heliothine species, based on shifts in the use of key components within each species’ sex pheromone blend. Heliothine species selected for this research range from benign to incredibly devastating (control of Corn Earworm and African Bollworm is estimated to cost US$3-7 billion annually) pest species, from six continents. Moths will be collected, analyzed for pheromone composition, tested for behavioral blend preference and receptors identified to detect pheromone components, and their brains examined for correlates of pheromone preference. Further, the basis for blend complexity will be investigated in the context of speciation. By using a multi-faceted, integrated approach, incorporating ecology, physiology and genetics, we will make groundbreaking discoveries regarding the current theory of the evolution of pheromone-based species isolation, and physiology of olfactory processing. Through a better understanding of pheromone evolution, we will enable development of new, innovative technologies for pesticide-reduced, pheromone-based insect management of many species, benefiting Canadian agriculture, forestry and the environment as well as other countries around the world.