LE3 .A278 2009

2009

Hillier, Kirk

Acadia University

Bachelor of Science

Honours

Biology

Biology

Octopamine is a very important neurohormone, neuromodulator and neurotransmitter in invertebrates. Octopamine increases male moth sensitivity to female sex pheromones, however, relatively little is known as to the role of octopamine (if any) in the female olfactory system. The tobacco budworm moth, Heliothis virescens, demonstrate sexual dimorphism in their antennal sensilla lengths and by male moths possessing a large, exclusively female sex pheromone neuron targeted, macroglomerular complex. This sexual dimorphism was previously thought to reflect the ability of only males to detect conspecific female sex pheromone. However, female Heliothis virescens moths do detect their own sex pheromone. In addition, female sex pheromone detecting olfactory receptor neurons target a centrally located large glomerulus at the base of the antennal nerve named the central large female glomerulus (cLFG) which appears to be analogous to the macroglomerular complex in male moths. The purpose of this study was to determine whether octopamine increases sensitivity of female olfactory receptor neurons to conspecific female sex pheromone. Studies in this area will reveal more details on the emergence and degree of sexual dimorphism in H. virescens and may be used in insecticide development. Extracellular recordings were made from female moths both injected and not injected with octopamine, and responses to odour stimulations and signals were recorded and amplified. Results indicate that octopamine plays a significant modulatory role in female sex pheromone detection in female moths; and that male and female pheromone detection neurons share distinct pharmacological and physiological similarities in H. virescens despite their morphological differences at the antennal level.

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