Dynamics of sheep monieziasis and oribatid mites population under hydrometeorological conditions of Bessarabia, Ukraine

Summary A current issue in sheep farming is monieziasis, which affects the survival of young stock and the productivity of adult livestock. The study aimed to assess the dynamics of monieziasis prevalence in sheep and changes in the population of oribatid mites depending on the hydro-meteorological conditions in Bessarabia (Ukraine) from 2014 to 2024. The moisture level during the active vegetation period was evaluated using the hydrothermal coefficient (HTC) based on the Selyaninov method. Oribatid mites were collected monthly, with samples combined by season. A total of 9809 sheep of the Cygaian breed from the southern part of the Odesa region were examined. The Fulleborn flotation method was used to detect Moniezia spp. eggs, and the intensity of invasion was evaluated using the McMaster method in the Reyno modification. Unstable moisture levels characterize the region’s climate: only two years during the study period had sufficient moisture (HTC 1.0), while the other nine years experienced varying degrees of drought (HTC 0.5 – 0.9). For a detailed analysis, 2021 (humid, HTC 1.0) and 2024 (drought, HTC 0.5) were selected. In 2021, the population of oribatid mites increased to 199.2 individuals per 100 cm 2 , while in 2024, it decreased to 135.8 individuals per 100 cm 2 . In humid years, the average infection rate of sheep with Moniezia spp. reached 37.7 %, while in drought years, it decreased to 19.7 %. The maximum infestation (up to 49.4 %) was observed in months with an HTC of ≥1.0. The highest prevalence of infection in sheep was observed in spring and autumn (66.1 %). The study’s results enable the prediction of invasion risks associated with climatic changes and can be used to inform preventive measures in sheep farming.