Benjamin Matthews

There are over 3,500 species of mosquito, occupying a huge range of environments including inland and coastal habitats. Salinity tolerance plays a crucial role in the ecology of mosquitoes as it can determine whether a particular habitat is suitable for larvae. Understanding how aquatic larvae physiologically cope with salt and how adult mosquitoes detect salt is of critical importance to understanding the biology of important vector species. In this study, the larval salinity tolerance, oviposition preference and breeding habitat ecology of a widespread (Ae. aegypti) and restricted (Ae. togoi) mosquito species was investigated to try to understand key physiological and behavioral differences. Ae. aegypti breed and develop in freshwater containers associated with urban environments while Ae. togoi develop in high fluctuating salt-water rockpools. By conducting larval survival studies, I found that, although Ae. togoi larvae are capable of surviving in extremely high concentrations of seawater, Ae. aegypti larvae can tolerate a wider range of ions at intermediate concentrations. This ability to survive in a wide variety of water types could partially explain how Ae. aegypti have been able to spread globally while Ae. togoi remains restricted to coastal areas. Oviposition bioassays found that salinity may not be a key driver of oviposition for Ae. togoi, as it is for Ae. aegypti. Finally, a field study of Ae. togoi in metro Vancouver uncovered that temperature, precipitation, salinity and the interaction of these factors are important predictors of larval abundance. This study has highlighted the importance of investigating field populations as well as conducting laboratory experiments when investigating the biology of a species. In reality, a suite of interacting factors modulates the ability of species to survive in their habitat and these factors can only be uncovered by examining field populations. In addition, a two-species comparison can aid into providing preliminary insight about how evolution has shaped osmoregulatory strategies as well as the chemosensory system in the face of exploiting new habitats. Investigating mosquito physiology and behavior can aid in predicting distribution of mosquito populations and eventually this can aid in developing targeted control strategies for vector species.

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