Species-Specificity in Thermopreference and CO₂-Gated Heat-Seeking in Culex Mosquitoes

Combining thermopreference (T_p) and CO₂-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 CO₂ 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 CO₂ 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 CO₂ levels and exhibited a high T_p. This study provides the first insights into the role of heat and CO₂ in the host seeking behavior of three disease vectors in the Culex genus and highlights differences in preferred resting temperatures.