P07 - Simulated warming drives adaptation and increased vectorial capacity of Culex mosquitoes for West Nile virus

Abstract: Climate change poses a significant challenge to New York State (NYS) with more frequent heat waves, changing precipitation patterns, and warmer annual mean temperatures. In NYS, temperatures have risen approximately 1.5°C since 1900 and are predicted to increase an additional 2.0°C by 2070 . While it is well-documented that daily or seasonal changes to temperature have significant effects on mosquito physiology that influence pathogen transmission, the long-term consequences of warming are not well-studied. This experiment aimed to evaluate the potential for adaptation and consequences of rising temperatures on transmissibility of West Nile virus (WNV) for Culex mosquitoes.

Two populations, Cx. pipiens from Albany, NY and Cx quinquefasciatus from Summerville, GA, were initially reared at a cycling temperature regiment representing an average day during peak WNV transmission in NYS (July-August), with a mean temperature of 25°C and a 16:8 light cycle. After three generations, populations were split into experimental incubators with either no change in temperature (constant) or a mean temperature increase of 0.5°C (warming). Every three generations thereafter, the mean temperature was increased in the warming group until a 2°C change was reached at the 15^th generation. Following passage, temperature-dependent immature development, adult longevity, blood feeding, and fecundity were measured. Vector competence was additionally assessed at both temperature regiments.

Species-specific differences were identified, consistent with adaptation to higher temperatures. In addition, increased competence for WNV was measured at higher temperatures following warming, particularly for Cx. pipiens. Together, these data suggest that regional adaptation resulting from rising temperatures will likely drive increased transmissibility of WNV in future populations of Culex mosquitoes.