Drivers of Ixodes ricinus population dynamics in Northeast France: a Bayesian modelling approach

Ixodes ricinus is the primary vector for Lyme disease and tick-borne encephalitis across Europe. To better understand the environmental and ecological drivers of its population dynamics, we collected monthly tick density data over ten years (2013–2022) in four sites in Northeast France, where I. ricinus has established, and developed and fitted a mathematical model using a Bayesian approach. Our model estimated oviposition, hatching, and moulting rates across a range of temperature or saturation deficit, as well as questing and vertebrate host contact rates. Furthermore, we showed the importance of diapause in reproducing the observed seasonal population dynamics. Finally, model projections indicated a significant decrease in I. ricinus abundance over the next 20 years under several climate change scenarios. This study elucidates I. ricinus population dynamics in Northeast France, provides foundations for developing models of I. ricinus -borne pathogen transmission, and is adaptable to other Ixodidae populations of public health significance.