Identifying bridging chains of small mammals and their ectoparasites of an animal farm with its surrounding habitats

Abstract As the intensification of animal husbandry systems amplifies the interfaces between humans, livestock, and wildlife, understanding the pathways of zoonotic pathogen spillover and cross-habitat transmission from a host–vector perspective becomes increasingly important. In this study, we examined the associations between host (small mammal) and ectoparasite communities of an Animal Farm (pigs) with its surrounding habitats including Village, Town, Forest Land, and Beverage Plant in a subtropical area of Hainan Province, China. Our results indicated that the Animal Farm supported the highest host and ectoparasite abundance, resulting in high network density and connectance, despite having the lowest host species richness. Conversely, Forest Land and Beverage Plant served as species-rich reservoirs, while Town habitat exhibited the lowest species abundance and ectoparasite infection intensity. Various ectoparasite groups were recorded, including lice, ticks, and fleas; however, mites were the predominant group. Despite distinct community compositions across habitats, two rodent–ectoparasite bridging chains (Rattus norvegicus–Laelaps turkestanicus and Rattus tanezumi–Laelaps nuttalli) were identified across all habitats, potentially facilitating cross-habitat pathogen transmission. Our study suggests that it is necessary to disrupt these “bridge chains” through habitat management and targeted host/vector control to prevent the cross-habitat transmission of zoonotic pathogens via small mammals and their ectoparasites under the One Health framework.