Patterns and drivers of vector-borne microparasites in a classic metapopulation

Abstract

Many organisms live in fragmented populations, which has profound consequences on the dynamics of associated parasites. Metapopulation theory offers a canonical framework for predicting the effects of fragmentation on spatiotemporal host–parasite dynamics. However, empirical studies of parasites in classical metapopulations remain rare, particularly for vector-borne parasites. Here, we quantify spatiotemporal patterns and possible drivers of infection probability for several ectoparasites (fleas, Ixodes trianguliceps and Ixodes ricinus) and vector-borne microparasites (Babesia microti, Bartonella spp., Hepatozoon spp.) in a classically functioning metapopulation of water vole hosts. Results suggest that the relative importance of vector or host dynamics on microparasite infection probabilities is related to parasite life-histories. Bartonella, a microparasite with a fast life-history, was positively associated with both host and vector abundances at several spatial and temporal scales. In contrast, B. microti, a tick-borne parasite with a slow life-history, was only associated with vector dynamics. Further, we provide evidence that life-history shaped parasite dynamics, including occupancy and colonization rates, in the metapopulation. Lastly, our findings were consistent with the hypothesis that landscape connectivity was determined by distance-based dispersal of the focal hosts. We provide essential empirical evidence that contributes to the development of a comprehensive theory of metapopulation processes of vector-borne parasites.

A compartment and metapopulation model of Rocky Mountain spotted fever in southwestern United States and northern Mexico

“…A good but slighter older paper provides a review of such approaches (Wang and Li 2014). A very recent paper compares host and pathogen dynamics in metapopulations of water voles exposed to vector-borne parasites with various life histories ( Mackenzie et al., 2023 ). Coupled single and metapopulation disease models can become highly technical and may suffer in usefulness and tractability as a result (Watts et al., 2005).…”

“…A previous model utilized a metapopulation and SIR framework to describe tick colonization in patches ( Kada et al., 2017 ), and this present model was an extension of a model of mange transmission among canids in a metapopulation (P. Foley et al., 2023 ). Several researchers have highlighted the importance of allowing model parameters to vary among patches due to spatial heterogeneity in host and vector distribution ( Gaff & Gross, 2007 ; Mackenzie et al., 2023 ), a technique that was employed in our model by allowing reproduction rates and tick burdens to vary among patches. Another feature that we considered to be crucial was stochasticity, because it is a feature of natural disease systems and becomes especially important in very early introductions.…”