Assessment of the Influence of Environmental Factors on the Number of the Great Gerbil Rhombomus opimus and its Fleas in the Eastern Karakum

The Karakum autonomous desert plague focus, located on the territory of Turkmenistan, is characterized by the periodic development of local epizootics with the possible emergence of epidemic complications. Due to climate warming, the structure of rodent communities and the course of their long-term population dynamics have changed. Social problems have also changed, in particular, there has been a significant territorial redistribution of the population, associated with its modern confinement to relatively few permanent sources of fresh water.

The aim of this work is to study the influence of ambient temperature, precipitation and vegetation on the population dynamics of the Yersinia pestis carrier – the great gerbil (Rhombomus opimus) and its fleas in the Eastern Karakum.

Materials and methods. This paper presents long-term zooparasitological research data obtained during annual expeditions conducted in the spring and fall at the Repetek State Biosphere Reserve, located in the Eastern Karakum Desert. A total of 182 expeditions were organized, with capturing of 1,600 great gerbil specimens. A route-colony method was used to determine colony density. At least two survey routes were laid out within the surveyed area.

Results and discussion. Air temperature and vegetation growth in the Eastern Karakum Desert fluctuated in waves – periods of rising temperatures were replaced with periods of decreased average annual values, followed by fluctuations in plant growth seasons. The state of the great gerbil’s food supply directly impacted its population. During a decline in the great gerbil population, the frequency of mating and other intrapopulation contacts decreased. Monitoring of fleas living in the fur of the great gerbil and in their colonies, as well as the specific weight per 1 hectare, showed that the general trend in population dynamics tends to decrease. The current epizootic status is considered as inter-epizootic period. The density of great gerbils and their flea populations indicate the presence of conditions conducive to the development of plague epizootics.

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