D3002: Mosquito optomotor responses to environmental cues

Throughout their life cycle, mosquitoes encounter visual, auditory, and chemical stimuli that they recognize and interpret in order to find food sources. While host-seeking, females rely on CO2 emanations, heat, and body odors to locate vertebrate hosts and obtain the blood meal needed to complete their reproduction cycle. Although the mosquito visual system also participates in the host quest, relatively less is understood about the visual cues that guide flying mosquitoes. Moreover, the relevance of female physiological state in vision-driven behaviors has not been explored. We used a custom-built flight arena that delivers visual stimulation to rigidly tethered insects and records their steering responses during flight. We measured the relative amplitudes of right and left-wing beats, which serve as an indicator of steering effort. To test the effects of blood-fed status in response to visual cues, two groups of females from the Orlando Aedes aegypti laboratory strain were tested. The gravid group was blood-fed 72 hours prior to experimentation while the non-gravid group was kept on a 10% sucrose diet. We found that host-seeking females readily track a dark vertical bar in motion, a visual hint analogous to a moving host, while gravid females showed no interest in this type of stimulus. These results suggest that blood satiation is sufficient to cause a shift in their interest for certain visual cues. Our next directions include comparing the visual anatomy and contrast resolution of diurnal and nocturnal mosquito species.