Environmental and demographic determinants of Aedes albopictus seasonal activity in southern France: A modeling study.

The presence and the activity of Aedes albopictus are a growing concern for nuisance and public health in Europe. 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 explore 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 machine learning model fitted on cross-correlated lagged weather predictors. Temperature showed a strong association with the presence of Ae. albopictus, and captured a substantial part of the interannual variation in oviposition across sites, particularly in spring and autumn. 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. 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. This work will also contribute to conceiving and developing operational weather-driven forecasting tools for Ae. albopictus activity to support vector control operations in different biogeographical contexts.