Aspectos bionômicos de Rhipicephalus microplus (Canestrini, 1888) em bezerro bubalino (Bubalus bubalis) e análise de fatores de risco para hemopatógenos e seus vetores em propriedades de búfalos na microrregião de Bom Despacho, Minas Gerais, Brasil.

Abstract

Buffalo farming has become an important livestock activity in Brazil, especially due to the adaptability of buffaloes (Bubalus bubalis) to adverse environmental conditions. Despite these advantages, the expansion of buffalo farming faces significant health challenges, mainly related to ectoparasite infestation and the transmission of hemopathogens, factors that impact productivity and animal welfare. This dissertation is structured in two chapters to understand the relationship between ectoparasites, hemopathogens, and risk factors in buffalo calves in the microregion of Bom Despacho, Minas Gerais. Chapter 1 addresses natural and experimental infestations of Rhipicephalus microplus in buffalo calves, assessing the tick’s ability to complete its life cycle and its consequences. The results indicated that the tick completed its cycle for three consecutive generations in one calf (237), which showed lymphadenomegaly, alopecia, diarrhea, dermatophytosis, intense pruritus, and papules, in addition to a reduction in oviposition and female recovery over generations. Another calf (249) experienced severe complications during natural infestation, presenting lymphadenomegaly, prostration, lack of appetite, pale mucous membranes, dehydration, and alopecia, ultimately dying from severe anemia. This animal did not present DNA of tick-borne hemopathogens. Chapter 2 presents an epidemiological study on hemopathogens and their vectors in buffalo calves aged 0 to 12 months in the Bom Despacho (MG) microregion. Hemopathogens of the genera Anaplasma sp., Ehrlichia sp. (monocytes), Mycoplasma sp. (hemotropic), and Babesia spp. were detected, but Theileira spp. was not found. The animals' age, the use of abamectin, and the presence of young males were risk factors for A. marginale seropositivity. For B. bovis, the risk factors were high tick infestation, abamectin use, the presence of cattle, and infestations during the rainy season. For B. bigemina, high tick infestation, injectable treatments, prolonged treatment intervals, and animal age were identified as risk factors. Ticks of the species R. microplus were found in 82% (14/17) of the properties, and the presence of the louse Haematopinus tuberculatus was also confirmed. Thus, this study demonstrates that R. microplus completes its life cycle in B. bubalis for at least three generations and that buffalo calves aged 0 to 12 months in the Bom Despacho (MG) microregion are parasitized not only by these ticks but also by the louse H. tuberculatus and the hemopathogens Anaplasma sp., Ehrlichia sp., Mycoplasma sp., and Babesia spp.