Humidity sensors that alert mosquitoes to nearby hosts and egg-laying sites

To reproduce and to transmit disease, female mosquitoes must obtain blood meals and locate appropriate sites for egg laying (oviposition). While distinct sensory cues drive each behavior, humidity contributes to both. Here, we identify the mosquito's humidity sensors (hygrosensors). Using generalizable approaches de-signed to simplify genetic analysis in non-traditional model organisms, we demonstrate that the ionotropic receptor Ir93a mediates mosquito hygrosensation as well as thermosensation. We further show that Ir93a- dependent sensors drive human host proximity detection and blood-feeding behavior, consistent with the overlapping short-range heat and humidity gradients these targets generate. After blood feeding, gravid fe-males require Ir93a to seek high humidity associated with preferred egg-laying sites. Reliance on Ir93a-dependent sensors to promote blood feeding and locate potential oviposition sites is shared between the malaria vector Anopheles gambiae and arbovirus vector Aedes aegypti. These Ir93a-dependent systems represent potential targets for efforts to control these human disease vectors.

Automated summary

To reproduce and transmit disease, female mosquitoes need to obtain blood meals and locate suitable egg-laying sites, which are driven by distinct sensory cues including humidity. Researchers have identified the mosquito's humidity sensors (hygrosensors) and found that they are mediated by the ionotropic receptor Ir93a, which also plays a role in thermosensation. This discovery provides potential targets for controlling the spread of human diseases by mosquitoes.