Climate change will enable Aedes aegypti larvae to survive desert southwestern winters

Populations of Aedes aegypti mosquitos, which vector dengue, Chikungunya and Zika, have recently increased exponentially in the desert southwestern USA. The highest populations occur in the late summer and fall, with A. aegypti virtually nonexistent in winter. We documented occurrences of A. aegypti larvae and water temperature over two years, and tested the ability of A. aegypti larvae to develop in ambient and artificially warmed (+2°C and +10°C mean) winter mesocosms. Ambient winter temperatures caused 90% mortality and major developmental delays. However, a mean increase in temperature of 2°C allowed 50% of larvae to survive and develop in less than two weeks. Low winter populations of A. aegypti in southwestern desert urban areas are at least partly constrained by low temperature effects on larval development, but small increases in average winter temperatures will allow these pests to persist year-round, and attain much higher population numbers. Supported by Sigma Xi Arizona State Chapter, and The Arizona State University Social Insect Research Group.