Larval growing conditions affect the daily rhythms and thermal preferences of adult Aedes japonicus

Mosquitoes are considered the deadliest animals in the world due to their ability to transmit a wide range of diseases. However, of the approximately 3,578 mosquito species identified, only a small portion are well-studied. Research has largely focused on a handful of species, such as Aedes aegypti, Ae. albopictus, Culex pipiens, and Anopheles gambiae, due to their epidemiological relevance. However, other species have been largely overlooked, such as Aedes japonicus, a competent vector of West Nile virus, Japanese encephalitis virus, and St. Louis encephalitis. Since its introduction to the eastern United States, Ae. japonicus has rapidly expanded throughout the Midwest. This rapid range expansion is likely due to the species’ ability to adapt to local environmental conditions. But, as a consequence of a lack of colonized lab strains of these species, our knowledge of Ae. japonicus chronobiology and thermal biology has been reliant on observational field studies. To address this gap, we collected eggs and pupae from two field sites and examined adult locomotor activity upon emergence. We found that larval conditions- such as temperature, light intensity, and day length- significantly affected adult mosquitoes’ responses to light cycles and thermal preference. Activity levels also varied based on how long the larvae developed in natural conditions before collection. These results are discussed in the context of environmental adaptation and the impact of larval growing conditions on adult mosquito behavior.