Impact of climate on biodiversity and season distribution of ticks of sheep in semi-intensive breeding in spread Belgrade area

Abstract

During last decades on Belgrade area were increased. semi-intensive breeding of sheep in village at spread Belgrade area. The rational use of pastures in the period of April-October makes the sheep production sustainable and low input in this period of the year. The specific climate and the unique habitat includes high biodiversity of flora and fauna of the grasslands. Ticks represents one of the indispensable elements of that specific biotope. For this reason tick infestations are common, especially during late spring and autumn months of the year. Examinations of sheep tick fauna from the Belgrade area are periodically carried out in order to monitor the influence of abiotic and climatic factors on their biodiversity. The last research was done in 2013 and in our paper we present the results of research conducted in the period 2019-2020 years. During our examination we examined 53 heards of sheep originated from 23 villages from city districts Mladenovac, Lazarevac, Obrenovac, Grocka, Zemun, Surčin, Palilula, Vozdovac and Zvezdara. İn total we examined 447 animals. The tick species and sex/gender were identified by morphometric characteristics. The main attribute of identification of tick family is a plain dorsal sclerotised scutum or shield, which is often ornate with patterns in white or gold against a brown or grey background and which distinguishes these ticks from other families. This sclerotised plate covers the entire dorsal surface of the male, but only one third of the female's dorsal surface. Second one was the capitulum of hard ticks which just as the mouthparts and is visible from a dorsal view. The peritreme or groove is big and clearly visibly around the stigmal plate. Grooves are deep, linear depressions in the body cuticle, usually on the ventral surface. Hard ticks can be easily differentiated by the shape of the basis capitulum and by the form of anal grooves. Ticks infestation we occured at 51.46% sheep. The most abudant species was İxodes ricinus (41.11%), followed by Dermacentor marginatus (30.21%), Rhipicephalus bursa (15.22%), R.sanguineus (14.72%), Haemaphysalis punctata (5.21%) and D.pictus (1.72%). The sex ratio showed a higher number of females in four species (İ.ricinus, H.punctata, R. sanguineus and D.marginatus), while higher number of males were detected in R.bursa and an equal number of the D.pictus. Climate conditions like air temperature, relative humidity and rainfall have a great influence on the population dynamics of ticks. Microclimatic changes in the area of Belgrade (higher summer temperatures, less precipitation, warmer winters without snow) affected the dynamics of the appearance of ticks. The population dynamics of recorded tick species showed two annual maxima, in spring (April-May) and in autumn (September). İn April population maximum we established for D.marginatus, D.recticulatus and H.punctata and in May for İ.ricinus. The autumn population peak in September and in October occurred for the İ.ricinus, D.marginatus and H.punctata. Compared to earlier research, tick biodiversity has not changed. The prevalence of individual tick species was not statistically significantly changed. At the same time comparing with results from 2013, the first appearance and population maximum of all established tick species was observed earlier, as well as the time of their presence on pastures. The considerable interchange between spring and autumn tick populations can be attributed mainly to environmental conditions which we established during similar research in several regions of Serbia.The study was funded by the Serbian Ministry of Education, Science and Technological Development (Contract No 451- 03-68/2022- 14/200030).