Mosquito heat seeking is driven by an ancestral cooling receptor.

Greppi, Chloe; Laursen, Willem J; Budelli, Gonzalo; Chang, Elaine C; Daniels, Abigail M; van Giesen, Lena; Smidler, Andrea L; Catteruccia, Flaminia et al. · Science · 2020

basic_science · Level V

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Abstract

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 <i>Anopheles gambiae</i> Although <i>Ir21a</i> mediates heat avoidance in <i>Drosophila</i>, we find it drives heat seeking and heat-stimulated blood feeding in <i>Anopheles</i> At a cellular level, <i>Ir21a</i> 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 <i>Anopheles</i> involves repurposing an ancestral thermoreceptor from non-blood-feeding Diptera.

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