The Infestation of Fleas of the Long-Tailed Souslik with Entomoparasitic Nematodes in Tuva Mountain Natural Plague Focus

Abstract

Entomoparasitic nematodes are supposed to be a link between parts of Yersinia pestis population in the environment and the flea vector. The aim of the study was to assess the prevalence and intensity of infestation in the fleas of the long-tailed souslik with entomoparasitic nematodes on the territory of Mongun-Taiginsky station in the Tuva natural plague focus. Materials and methods. Fleas were collected during the scheduled epizootiological surveys in 2019–2021. In the course of taxonomic identification the presence of parasitic nematodes was registered. In order to evaluate the intensity of nematode invasion, a total of 190 fleas were dissected. The number of adult parasitizing females and presence of larvae was recorded. Statistical processing of the data was performed with the help of conventional methods using the Excel software. The criterion χ2 was applied; the influence of various factors (species, gender of fleas) on the studied parameters was assessed through single- and two-factor analysis of variance. Results and discussion. During three years of observations, entomoparasitic nematodes were found in six species of fleas: Citellophilus tesquorum, Frontopsylla elatoides, Rhadinopsylla li transbaikalica, Frontopsylla hetera, Oropsylla alaskensis, and Neopsylla mana. The differences in infestation with nematodes between the species are presented. The highest invasion rate – 25.1–25.6 % – is observed in Rh. li transbaikalica. The gender of leas does not influence their infestation. It is established that invaded fleas are more often found in the nest than in the fur of animals, they are less actively migrate to the burrow entrance compared to not invaded ones. Evaluation of infestation prevalence has revealed that fleas Rh. li transbaikalica are the hosts for nematodes of mono- or oligoxenic species, which do not occur in other fleas.