LE3 .A278 2014

2014

Hillier, Kirk

Acadia University

Bachelor of Science

Honours

Biology

Biology

Pseudaletia unipuncta, the true Armyworm, is an important crop pest and seasonal migrant to Canada, with several generations spanning each migration. Recent evidence has demonstrated that cold temperatures during specific developmental windows will significantly reduce response of male P. unipuncta to pheromones under wind tunnel conditions. It has been proposed that this may provide a functional mechanism to explain seasonal shifts in behavior, such as migration. The objective of this thesis was to investigate whether or not chilling might effect detection of pheromones at the antennal level, or influence neural development within the antennal lobe. Like most moths, P. unipuncta use pheromones to locate mates, and host volatiles to locate oviposition sources. Odours are processed within sexually-dimorphic antennal lobes. Electroantennograms were performed on both male and female P. unipuncta to determine if there was a difference in the olfactory response at the antennal level to male and female sex pheromones and selected host volatiles in moths which had been exposed to cool temperatures for 24 hours immediately after emergence. Male and female brains, chilled and unchilled, were stained and observed using confocal microscopy, then digitally reconstructed in order to compare any variation evident in antennal lobe development. There were no significant differences in detection of odours and pheromones between chilled or unchilled treatments. Volume comparisons of male and female glomeruli showed no major differences in the sizes of male glomeruli but glomeruli in chilled females were larger and fewer. Temperature plays an important role in the life history and behavior of the Armyworm but further investigation into the effects of chilling temperatures on neural development and subsequent odour detection are still required.

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https://scholar.acadiau.ca/islandora/object/theses:1146