Variations in Time-Dependent Mosquito-Host Interactions Across Aedes Species

Virtually all organisms exhibit circadian rhythms, this includes mosquitoes. Many aspects of their biology are under the control of their circadian clocks like their vision, olfaction, host-seeking, mating, oviposition, metabolism, locomotion, and more. However, how the circadian clock regulates mosquito-host interactions and adapts to specific environmental conditions remains largely unknown, despite its importance to vector disease control. Here, we relied on a multidisciplinary, integrative, and comparative approach to shed light on the mechanisms underlying mosquitoes adaptations to various temporal niches. We use CRISPR/Cas9 to knockout timeless in Aedes aegypti and show this mutation causes an increase in their free running periods under continuous darkness conditions. External factors can also influence a vector's activity pattern like climate, light pollution, as well as host preference and availability. To investigate the influence these factors have on activity patterns, we compare the activity patterns of multiple lab rear strains of Aedes albopictus as well as two field collected populations of Aedes japonicus. Our results suggest host availability and light pollution could cause the differences in activity profiles that we observed. With vision playing an important role in both circadian rhythms, host seeking, and threat detection, we compared a nocturnal mosquito (Aedes japonicus) and a diurnal mosquito (Aedes aegypti). We introduced a looming visual stimulus in an LED arena and found Aedes aegypti to be more responsive to the looming stimulus than Aedes japonicus. Finally, the underlying mechanisms that mediate this threat detection and escape behavior were examined, revealing a possible candidate for a giant fiber neuron in Aedes aegypti. Overall these results provide novel insights into mosquito biology that have the potential to be applied towards vector control methods.