Olfactory preferences and chemical differences of fruit odors for <i>Aedes aegypti</i> mosquitoes

Feeding on the nutrients from fruits and flowers is vital for mosquitoes and increases their lifespan, reproduction and flight activity. Olfaction is a key sensory modality in mediating mosquito responses to nutrient sources. Previous studies have demonstrated that fruits and flowers can vary in attractiveness to mosquitoes, with some sources preferred over others. However, how the attractiveness of different fruits relates to the chemical composition of their odor and the responses they evoke from the mosquito's peripheral olfactory system is still not understood. In this study, we used closely related fruit species and their cultivars to examine how changes in odor chemistry can influence the fruit's attractiveness to Aedes aegypti mosquitoes. Our results show that mosquitoes are attracted to the odors of certain fruits (Mangifera indica, Prunus persica and Musa acuminata), whereas others (Pyrus communis and Citrus limon) were not attractive. Chemical analyses of the odors showed that attractive fruits have distinct chemical profiles, and amongst closely related fruits, minor changes in the relative proportions of odor compounds can modify their attractiveness. By contrast, electroantennogram responses showed similar responses across different fruits. Selectively altering the chemical proportion of a single compound in an odor was sufficient to either increase or decrease its attractiveness to levels similar to those of its closely related congener. Our results demonstrate that mosquitoes are sensitive to the proportions of compounds in attractive odors, which have implications for the olfactory processing of complex odor sources, such as those from plants or blood hosts.