Aquatic thermal conditions predict the presence of native and invasive rock pool Aedes (Diptera: Culicidae) in the southern Appalachians, U.S.A.

The native rock pool mosquito, Aedes atropalpus (Coquillett), and the invasive Aedes japonicus (Theobald) have been found in many types of artificial and natural containers throughout North America. Little is known about the ecology of these two species in habitats where they co-occur, although multiple investigators have reported the decline of the native species concurrent with the introduction and spread of the invasive species. Here we report the results of riverine rock pool collections (n=503) in the southern Appalachian Mountains between 2009-2015. Surface water temperatures strongly predicted the presence of each species across a broad range of observed temperatures (11-39.8° C). For every unit of increase in temperature (°C) the odds of collecting Ae. atropalpus larvae increased by 0.34 while the odds of collecting Ae. japonicus larvae decreased by 0.28. No Ae. japonicus larvae or pupae were collected at temperatures greater than 36° C; however, immature Ae. atropalpus were found in rock pools with temperatures up to 39.8° C. In contrast, Ae. japonicus were highly abundant in cooler rock pools (<17° C) where Ae. atropalpus were infrequent or absent. Our findings suggest that in spite of the successful invasion by Ae. japonicus, Ae. atropalpus remains well established in the southern Appalachian Mountains. Given the strong correlation of temperature with the presence of the two species and the contrasting absence of each species at observed temperature extremes, the role of thermal conditions should be carefully explored in the context of other ecological factors likely influencing the range and abundance of these mosquitoes.