Effect of physiological and environmental factors on mosquito wingbeat frequency

Wingbeat frequency may serve as a distinctive physical signature for identifying mosquito species. However, variation in wingbeat frequency within species may compromise reliability of wingbeat frequency-based mosquito identification. We examined the impact of mosquito density (number of females), time of day (day or night), gravid status, and age (days post-emergence) on the wingbeat frequency of three important vector mosquito species using infrared optical sensors. Wingbeat frequency of <i>Culex quinquefasciatus</i> was significantly higher (6.2% and 9.5%) for single females compared to groups of five and ten females, respectively, and 9.4% higher during the daytime compared to nighttime. Wingbeat frequency was also significantly higher for gravid <i>Cx. quinquefasciatus</i> (9.4%) and <i>Aedes aegypti</i> (1.4%) than nongravid conspecifics. Within a short age range (five to seven days post-emergence), wingbeat in <i>Cx. quinquefasciatus</i> did not vary significantly. Our results highlight that both extrinsic (density and time of day) and intrinsic (gravid status) factors contribute to wingbeat variation, potentially posing challenges for development of wingbeat profile libraries and the classification of unknown specimens. Traps that aim to use wingbeat frequency and target specific cohorts of the population (i.e., host-seeking or gravid females) will need to account for differences in wingbeat frequency due to multiple factors.