SYNANTROPIC RODENTS AND THEIR ECTOPARASITES: A FOCUS ON FIVE PROVINCES OF NORTHERN-CENTRAL ITALY

INTRODUCTION: Synanthropic rodents, such as mice and rats, rank among the 100 most invasive and harmful species worldwide, according to the IUCN list. These species can alter ecosystems, change vegetation, and cause the decline or extinction of native species, both through direct predation and by depleting trophic resources (Gotti et al., 2022. L’ eradicazione del Ratto nero (Rattus rattus) dalle isole del Mediterraneo: linee guida, buone pratiche, casi di studio» Ispra, Manuali e Linee Guida 199). Furthermore, due to their close contact with humans, have always been a concern because of their substantial impact on public health. This study aims to investigate the presence of ectoparasites in rodents captured during pest control campaigns in various Italian provinces (bologna, Forlì-Cesena, Rimini, Ravenna, Arezzo). MATERIALS AND METHODS: A total of 140 samples of skin from synanthropic rodents were examined, specifically 49 Rattus rattus, 81 Rattus norvegicus, and 10 Mus musculus, originating from the provinces of bologna, Forlì-Cesena, Ravenna, Rimini, and Arezzo. During the necropsies, the skin was visually examined to collect macroscopic ectoparasites and skin samples measuring about 3x3 cm were collected from the caudal-dorsal area. The skin flaps were submerged in a 10% aqueous solution of sodium hydroxide (NaOH) and incubated for 4 hours at 37 °C to facilitate dissolution. Following the removal of coarse material, the resulting suspension underwent washing cycles via centrifugation and final flotation using a 1300 PS solution (Di Felice and Ferretti, 1962, Nuovi Ann Ig Microbiol, 13:414- 21), followed by microscopic examination. RESULTS AND CONCLUSIONS: A total of 61 rodents (44%) tested positive for ectoparasites. Specifically, polyplax spinulosa lice were found in 36 subjects (26%), comprising 22 R. norvegicus, 13 R. rattus, and 1 M. musculus. Myobiidae mites were detected in 15 subjects (11%), including 10 R. norvegicus, 3 R. rattus, and 2 M. musculus. Laelapidae mites, particularly echinolaelaps echidninus, were identified in 7 subjects (5%) (6 R. norvegicus and 1 R. rattus). Mites causing scabies, notably Notoedres muris, were found in 7 R. norvegicus, and other mite genera such as Steatonyssus sp. were discovered in 1 R. norvegicus and 2 R. rattus. Liponyssoides muris (syn. Dermanyssus muris) was observed in a single R. rattus. Additionally, Nosopsylla fasciatus, known for its potential role as a vector of Yersinia pestis, was found in one R. norvegicus. Other insects and mites, likely due to environmental contamination, were sporadically detected. This research provides a comprehensive overview of the arthropods present on the fur of synanthropic mice and rats in the surveyed provinces. The study represents a valuable baseline investigation, particularly given the lack of nationwide data.