Prevalence and seasonal dynamics of botfly (Metacuterebra infulata) parasitism in the rodent Hylaeamys megacephalus in a remnant of Brazilian Cerrado.

Abstract

Parasitism is mediated by environmental factors and intrinsic host attributes, leading to spatio-temporal dynamics of host-parasite infestation. Mammals are the main hosts of larvae of Cuterebrinae flies, which have been observed in the neotropical rodent Hylaeamys megacephalus (Fischer) (Rodentia, Cricetidae) within the Brazilian Cerrado. Besides describing seasonal dynamics of botfly parasitism in this rodent, we also tested the hypothesis that the prevalence of botfly parasitism varies seasonally, with larvae being more prevalent in the warm-wet season, due to favorable climatic conditions for egg development. Second, we tested the hypothesis that the prevalence of botfly parasitism is higher among adults than juveniles, as the former present greater habitat use and larger movements, leading to increased exposure to parasites; and finally, we tested the hypothesis that the prevalence of botfly larvae is male-biased, due to greater male exposure and susceptibility to parasitism. The study was carried out between 2019 and 2023 at Gloria Experimental Farm (Uberlândia, Minas Gerais, Brazil), through the capture-mark-recapture method. The botfly was identified as Metacuterebra infulata (Lutz) (Diptera, Oestridae), being the first report of a host for this parasite and a new botfly species parasitizing H. megacephalus. The prevalence of M. infulata within the host population was 15.28% (24 hosts). Most hosts presented only one botfly, and most of them were in the inguinal region, indicating host specificity, and therefore, H. megacephalus might be the primary host of M. infulata in this region. Contrary to our hypothesis, botfly infestations presented a multivoltine pattern, with a peak in infestations during April (transition from wet to dry season) that may reflect the time interval between the botfly oviposition behavior and the development of the third instar larvae in the host. Finally, we also did not find any difference in M. infulata prevalence between sexes and age classes. This may be associated with the parasite's biology, in which the oviposition behavior of adults leads to similar exposure for both sexes and age classes. The lack of sexual dimorphism between rodents may also contribute to the observed patterns. Our study reports a new host-parasite interaction involving rodents and botflies and pinpoints the importance of parasite life cycle on the seasonal dynamics of parasitism.