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Abstract

Parasite-host interaction between ectoparasites (Ixodida & Siphonaptera) and common opossum Didelphis aurita Wied-Neuwied, 1826 (Mammalia: Didelphimorphia), on the mainland and on Santa Catarina coastal islands, Southern Brazil. This is the fi rst study about the ecological interaction between the ectoparasites and marsupials of the Didelphis genus and the second one about mammals in Santa Catarina State. Three insular populations and a mainland population were sampled. The fleas Leptopsylla segnis and Xenopsylla cheopis and the mites Amblyomma cajennense, A. aureolatum and Ixodes loricatus were new records for this state. Leptopsylla segnis is also a new record for Didelphis. The numbers of ectoparasite species were between two on Arvoredo Island (IA) and four on Santa Catarina Island. The hosts on IA had an ectoparasite prevalence of 14.3% and the others had a prevalence of 100%. The mean infestation varied between 0.4 (IA) and 128 (Ratones Grande Island) ectoparasites per host. Although the common opossum hosted few species of ectoparasites, the degree of infestation on the Santa Catarina coast was high. The results had no relationship with either the with hosts’ population density or with the possible numbers of host species. A suitable interpretation of the results depends on information such as the colonization and extinction history of the fauna of each location. Nevertheless, the study contributes with new records and corroborates the idea that this ecological interaction can be wide and complex.