Modular structure of ectoparasite–mammal interaction networks in a protected area of the Brazilian Cerrado

Understanding host–parasite interactions is essential for interpreting ecological processes in heterogeneous biomes such as the Brazilian Cerrado. In this study, we investigated ectoparasite richness and host associations in small mammals from the Serra das Araras Ecological Station, a well-preserved protected area in southwestern Brazil. Over ten months of sampling, 218 small mammal individuals were captured, with 62 recaptures, totaling 280 capture events across four phytophysiognomies. Nine host species were infested, yielding a total of 15 ectoparasite species, including mites (Laelapidae), fleas (Rhopalopsyllidae and Stephanocircidae), lice (Gyropidae), and ticks (Ixodidae). Rodents exhibited higher ectoparasite richness and infestation rates, whereas marsupials were parasitized less frequently. Host–parasite associations varied among habitats and host guilds: the interaction structure showed low dominance of generalist species and no nested pattern, indicating a significantly modular organization. Generalist taxa, such as Amblyomma sp. and Androlaelaps fahrenholzi , occurred widely, whereas the chewing lice Gyropus cercomydis and G. lenti (Phthiraptera: Gyropidae) were recorded exclusively on Trichomys pachyurus . The modular topology of the network suggests that compartmentalized host–ectoparasite interactions may reduce connectivity among host groups and potentially constrain pathways for parasite or pathogen transmission, although these epidemiological implications were not directly evaluated. Our findings provide a baseline for ectoparasite studies in the Cerrado and highlight the role of protected areas in maintaining host–parasite interactions in natural ecosystems.