Temperature is the key weather determinant of Aedes albopictus seasonal activity in southern France

The presence and the activity of Aedes albopictus are a growing concern for nuisance and public health in Europe. Vector control operators, public health officers, and communities look for weather-based decision support systems to inform mosquito management policies. Despite an increasing number of entomological and modelling studies, our incomplete understanding of mosquito population response to weather drivers in natural conditions restricts the development of sound vector management policies.

Here, we aim to clarify the role of weather conditions on Ae. albopictus presence and abundance in four sites in southwestern France. We rely on ovitrap longitudinal records collected on a 1-2 weeks basis and weather time series over 2023 and 2024 to model oviposition activity. Our analysis combines a mechanistic model from literature and a new machine learning model fitted on cross-correlated lagged weather predictors.

Both models satisfactorily reproduce the observed oviposition dynamics, correctly predicting the onset and the end of the activity – periods that existing models have often inadequately captured. Temperature plays a major role in triggering the presence of Ae. albopictus , explaining the interannual variation of oviposition in all sites, especially in spring and autumn. In fact, warm springs and autumns extend the periods in which Ae. albopictus life-history traits (fertility, development, survival) approach their thermal optima. In summer, a more prominent role of rain and humidity emerges among secondary drivers of oviposition intensity.

This work contributes to the development of operational weather-driven forecasting tools for Ae. albopictus activity to support vector control operations in different biogeographical contexts.