Flea and tick infestation of a wild rodent in an anthropogenic landscape of the semi-arid Chile

Background: A series of abiotic and biotic modifications occur in an anthropogenic landscape which influence the ecology and physiology of wild hosts and their parasites. How these changes affect the parasitism is highly context-dependent, based on the host-parasite system and the type of perturbation. We aimed to investigate the differences in infestation with fleas and ticks of the native rodent Phyllotis darwini in three sites with different anthropogenic impacts and to evaluate environmental and host factors associated with parasite richness and load. Methods: : We studied wild, rural and peri-urban sites of the semiarid region of Chile in the spring and summer seasons between 2018 and 2020. We applied a multi-level analysis to assess environmental and host variables at the individual and microhabitat level. We used Generalized Linear Mixed Models and Generalized Linear Models to test factor effects on the richness and load of ectoparasites of adult rodents. Results: : Overall, out of 310 rodents trapped, 71% were flea-infested and 22% showed tick infestation. We identified six flea genera, being Hectopsylla sp. and Neotyphloceras sp. the most abundant fleas across sites. Flea richness was significantly higher in male rodents and during the spring and was positively affected by the micromammal species richness. The flea load was also higher in spring, in males, and positively associated to tick load. Hectopsylla sp., one of the most abundant fleas, showed a higher load in the peri-urban site and at grids with lower vegetation index values (NDVI), and Neotyphloceras sp. fleas were associated with tick load and lower temperatures. All ticks were larvae or nymphs of Ixodes sp. and showed a higher load in summer months and higher temperatures. Conclusions: : We discuss possible environmental requirements of fleas and ticks, the association between their loads and male-biased parasitism. Further experimental investigations are needed to seasonally precise microclimate thresholds required for the survival of these ectoparasites.