Assistant Professor The Ohio State University Columbus, Ohio
Culex mosquitoes are the major vector of West Nile virus in North America. Fortunately, disease transmission to humans predominantly occurs within a few months in late summer and early fall. In autumn, female Culex mosquitoes enter an adult, reproductive diapause where they divert resources from reproduction and towards winter survival. While we understand the photoperiodic and temperature cues that trigger diapause, we do not know when mosquitoes cease biting vertebrate hosts and enter diapause in the field. Moreover, it is unclear when mosquitoes terminate diapause in the spring and how seasonal cycles of West Nile virus infection reinitiate. Although some research suggests that Culex mosquitoes transition from biting birds, the primary reservoirs of the disease, to biting humans in late summer, other studies have not found seasonal changes in host use. To address these critical gaps in knowledge, we collected mosquitoes from the spring of 2021 through the spring of 2022 using above-ground gravid, BG-sentinel, and CDC light traps, and additionally by aspirating females from culverts around Columbus, Ohio. We found that Culex mosquitoes are actively blood feeding until early-November and that non-diapausing females can be found within culverts into mid-November. We also collected blood-fed and gravid mosquitoes in mid-March, and our preliminary data suggest that mosquitoes bite a wide range of hosts throughout the year, especially avian hosts. Combined, our results provide key insights into seasonal changes in the reproductive physiology and biting behaviour of mosquitoes that have important implications for West Nile virus transmission dynamics.