High-resolution characterisation of diel activity rhythms in Aedes aegypti and Culex quinquefasciatus

Circadian rhythms shape essential traits of mosquito biology – including feeding, mating, oviposition, and host-seeking behaviour – and directly influence mosquito vectorial capacity. Aedes aegypti and Culex quinquefasciatus , two medically important mosquito vectors, exhibit distinct locomotor activity patterns; the former is generally described as diurnal, with activity peaks during morning and late afternoon, whereas the latter is considered nocturnal. However, current knowledge derives largely from short-term laboratory assays or limited field sampling, constraining ecological interpretation and hindering the detection of robust diel rhythms in natural populations. In this study, we analysed field data from automated mosquito traps with a circular statistical framework to characterise high-resolution daily rhythms of Ae. aegypti and Cx. quinquefasciatus . Our findings challenge the canonical view of Ae. aegypti females as bimodal daily biters, revealing complex, population-specific activity patterns that might be triggered by local environmental settings. By contrast, Cx. quinquefasciatus females showed multimodal activity with consistent selection of night-twilight periods. Sex-specific patterns of activity were also detected, with males typically concentrating their activity around dawn. This work provides a robust and replicable methodology to characterise fine-scale mosquito diel rhythms in the field. Beyond advancing mosquito temporal ecology, this approach offers critical insights to refine estimates of vectorial capacity, while also informing the optimal timing of vector control interventions.