UC Santa Barbara

Female mosquitoes employ a diverse array of sensory cues when finding hosts for blood feeding. Among these cues, the mosquito’s ability to detect body heat while host seeking has been appreciated for decades. This thermosensory system is largely understood to detect convective air currents around warm surfaces that activate thermosensory neurons in the mosquito antenna. Because these convective currents occur quite physically close to the warm surface, we chose to investigate whether mosquitoes can also sense infrared radiation emitted from hosts as well, which could function at a much greater distance. To do this we developed a novel behavioral paradigm that exposes mosquitoes to infrared cues and records their behavioral responses. Using this new paradigm, we found that mosquitoes detect infrared while exposed to other host cues and use this sense to navigate towards host objects. Furthermore, this sense is influenced by both the IR intensity of the source and environmental conditions. Lastly, we found that mosquitoes lacking the thermally activated ion channel TRPA1 completely lose their ability to detect thermal infrared. This work provides the first demonstration that IR is a cue used by mosquitoes for host seeking.