Sensory compensation occurs when loss of one sense leads to enhanced perception by another sense. We have identified a previously undescribed mechanism of sensory compensation in female
Aedes aegypti
mosquitoes. Odorant receptor co-receptor (
Orco
) mutants show enhanced attraction to human skin temperature and increased heat-evoked neuronal activity in foreleg sensory neurons.
Ir140
, a foreleg-enriched member of the ionotropic receptor (IR) superfamily of sensory receptors, is up-regulated in
Orco
mutant legs.
Ir140
,
Orco
double mutants do not show the enhanced heat seeking seen in
Orco
single mutants, suggesting that up-regulation of
Ir140
in the foreleg is a key mechanism underlying sensory compensation in
Orco
mutants. Because
Orco
expression is sparse in legs, this sensory compensation requires an indirect, long-range mechanism. Our findings highlight how female
Aedes aegypti
mosquitoes, despite suffering olfactory sensory loss, maintain the overall effectiveness of their host-seeking behavior by up-regulating attraction to human skin temperature, further enhancing their status as the most dangerous predator of humans.
