Species-Specificity in Thermopreference and CO 2 -Gated Heat-Seeking in Culex Mosquitoes.

Combining thermopreference (T p ) and CO 2 -gated heat-seeking assays, we studied the thermal preferendum and response to thermal cues in three Culex mosquito species exhibiting differences in native habitat and host preference (e.g., biting cold and/or warm-blooded animals). Results show that these species differ in both T p and heat-seeking behavior. In particular, we found that Culex territans , which feed primarily on cold-blood hosts, did not respond to heat during heat-seeking assays, regardless of the CO 2 concentration, but exhibited an intermediate T p during resting. In contrast, Cx. quinquefasciatus , which feeds on warm blooded hosts, sought the coolest locations on a thermal gradient and responded only moderately to thermal stimuli when paired with CO 2 at higher concentrations. The third species, Cx. tarsalis , which has been shown to feed on a wide range of hosts, responded to heat when paired with high CO 2 levels and exhibited a high T p . This study provides the first insights into the role of heat and CO 2 in the host seeking behavior of three disease vectors in the Culex genus and highlights differences in preferred resting temperatures.