Phototaxic Behaviour of Flies with and without an ectoparasitic mite

First, we demonstrated that flies are less likely to be infected by mites when exposed in light environments than dark environments using micro-arena experiments. In baseline conditions (mite-free environments), unmated female flies and mated female flies spent significantly more time in the dark side of the phototaxis chambers. Males did not show significant negative or positive phototaxis. Contrarily, when exposed to mites, neither unmated or mated females displayed significant phototaxis. Flies became less negatively phototaxic when threatened with mites, suggesting phototaxis is a mechanism of behavioural immunity.

Methods
Phototaxis experiments were conducted in phototaxis chambers. Flies were observed and if they were on the light or dark side of the chamber was recorded at each minute interval. Female flies were either exposed to mites or alone in the phototaxis chamber. We also tested the impact of mating status on female phototaxis (and the mating-status, exposure interaction). The phototaxis behaviour of Male flies unexposed to mites was also measured.

Additional experiments followed females in a phototaxis chamber with a single mite. Either 1) a mated female and 1 mite or 2) an unmated female and 1 mite. The location of both the fly and mite were recorded at each interval.

Experiments are described in full (in review).