Role of semiochemicals in oviposition and mating behaviour of Aedes aegypti (Diptera: Culicidae)

Abstract

Aedes aegypti (Diptera: Culicidae) is the major vector of a number of arboviruses including dengue. Understanding how semiochemicals might mediate the key behaviours of mating and oviposition should lead to a better understanding of the biology of Aedes aegypti and might also lead to practical vector control applications. The results of behavioural investigations into putative egg associated oviposition pheromone have been contradictory and incomplete in that they failed to control numbers of eggs in their experimental design. A previous study found behavioural evidence for a male produced sex pheromone, but an upwind anemotactic response of females was not tested and it could be argued that the experimental design was not robust. For this thesis no-choice and choice bioassays were carried out to test the oviposition response of gravid females to both specific numbers of con-specific eggs and methanol extract of eggs. An olfactometer was designed to test the upwind anemotactic response of virgin females to male headspace volatiles with and without host odour cues. These male odours were also used to bait BG-sentinel traps in the field. While no evidence was found that was consistent with an egg associated oviposition pheromone in Aedes aegypti, results from both laboratory and field based experiments suggest that males might emit a pheromone in response to host odour that attracts virgin females. Results from experiments in which males were not exposed to host odour suggest that host odour might be required to stimulate pheromone release.