UC Irvine

Mosquito disease vector control relies mostly on toxic insecticides. A more environmentally friendly alternative is to make use of light-based behavioral manipulation to attract pests to traps and repel pests away from human habitation. The present technology is based on the assumption that mosquito UV light detection occurs solely through opsin-based photoreception in the eyes. The Holmes Lab has recently found additional UV and short wavelength photoreceptive elements expressed in central brain neurons that strongly modulate complex insect behavioral responses to light. Therefore, there is a need to incorporate these additional elements in disease vector control designs for improved efficiency. Namely, CRYPTOCHROME (CRY), which is classically associated with its role in circadian clock resetting, activates with blue- and UV- light and increases the electrical excitability of circadian/arousal neurons. I hypothesized that CRY and other photoreceptor systems mediate photic input to the circadian/arousal circuit of flies in order to mediate specific light-based behavioral responses. To test this, I modified and adapted light-evoked electrophysiology protocols to test the photoexcitability of primary arousal neurons in response to different stimuli of light using several photoreceptor mutants that lack one of three photoreceptor systems, as well as transgenic flies expressing mosquito CRY1 from a diurnal and nocturnal species. I also modified and adapted several behavioral assays to determine light attraction/avoidance as well as light-pulse arousal behavioral response to these different mutants. These modifications involved developing a new light emitting apparatus that improved on intensity control and spatiotemporal light exposure with a finer tuned spectral emission for UV, violet, blue, and red light. In this dissertation, I found that CRY coordinates with other photoreceptors to mediate light-induced electrical excitability of neurons, which underlie complex sleep/wake and light arousal behaviors. Furthermore, I found that CRY phototransduction persists across species in an intensity-dependent and species-specific manner, controlling light behavioral phototaxis across diurnal and nocturnal mosquito CRY1 profiles. I conclude with non-image forming as an amalgamation of multiple photoreceptor system contributions over a broad spectral range that affect downstream behavioral processes, including CRY as a primary short-wavelength photoreceptor for flies and mosquitos.