Spatio-temporal re-colonization of top-predators modulates zoonotic infections in ticks

Introduction and objectives: Predator community can change abundance and composition of their preys, affecting emergence and spread of tick-borne infectious diseases for which some preys (e.g., ungulates, rodents) are often common hosts. We aim to evaluate if sites with gradual temporal re-colonization of a top-predator, the wolf (Canis lupus), exhibit different infection prevalence in ticks. Materials and methods: We identified four study areas (NV = Non Valley, PP = Paneveggio-Pale di San Martino Natural Park, LV = Laghi Valley and GV = Giudicarie Valley) located in the Autonomous Province of Trento (Italian Alps), each characterized by a temporal gradient of re-colonization from east-to-west of wolf in recent years. Specifically, in NV the species is considered stable since 2017, in PP since 2019, in LV since 2021, while yet sporadic in GV. During 2023 in each study area, we collected host-seeking ticks in forested habitats by dragging the vegetation. PCR-based methods were used to detect infection of Borrelia burgorferi s.l., Anaplasma spp. and Babesia spp. in ticks. Results, discussion and conclusion: During this first year, we collected 394 Ixodes spp. ticks across the study areas. We preliminary obtained higher prevalence of Borrelia spp. in areas historically colonized by wolves (NV: 28.72%; PP: 15.48%), compared to where wolf is sporadic (LV: 13.11%; GV: 11.70%) and the opposite for Anaplasma spp. (NV: 1.06%; GV: 4.25%). Babesia spp. prevalence rates did not show any specific pattern. We speculate that the established presence of wolf may interfere differently with the circulation of tick-borne pathogens, both indirectly affecting Borrelia-competent rodent hosts’ predators, such as foxes, or directly by hunting Anaplasma-competent hosts, such as ungulates. These preliminary findings suggest that predator community may have a crucial role in modulating zoonotic disease circulation by affecting preys local presence or abundance that will be incorporated in our forthcoming analysis. The authors acknowledge the support of NBFC to Fondazione Edmund Mach, funded by the Italian Ministry of University and Research, PNRR.