Mosquito heat seeking is driven by an ancestral cooling receptor

Mosquitoes transmit pathogens that kill >700,000 people annually. These insects use body heat to locate and feed on warm-blooded hosts, but the molecular basis of such behavior is unknown. Here, we identify ionotropic receptor IR21a, a receptor conserved throughout insects, as a key mediator of heat seeking in the malaria vector Anopheles gambiae. Although Ir21a mediates heat avoidance in Drosophila, we find it drives heat seeking and heat-stimulated blood feeding in Anopheles. At a cellular level, Ir21a is essential for the detection of cooling, suggesting that during evolution mosquito heat seeking relied on cooling-mediated repulsion. Our data indicate that the evolution of blood feeding in Anopheles involves repurposing an ancestral thermoreceptor from non–blood-feeding Diptera. Methods These data are collected and processed as described in: Mosquito heat-seeking is driven by an ancestral cooling receptor; Chloe Greppi1†, Willem J. Laursen1†, Gonzalo Budelli1, Elaine C. Chang1, Abigail M. Daniels1, Lena van Giesen1, Andrea L. Smidler2,3, Flaminia Catteruccia2, and Paul A. Garrity1*