Spatial distribution of Gasterophilus pecorum (Diptera) eggs in the desert steppe of the Kalamaili Nature Reserve (Xinjiang, China)

Ke Zhang,Make Ente,Dong Zhang,Chen Wang,Kai Li,Changliang Shao,Heqing Huang,Zhenbiao Wang

doi:10.1186/s12862-021-01897-4

Abstract

BackgroundThe dominant Gasterophilus species in the desert steppe (Xinjiang, China) Gasterophilus pecorum poses a serious threat to the reintroduced Przewalski’s horses. We investigated the distribution pattern of G. pecorum eggs in June 2017.MethodsTwo sampling methods, transect and grid, were used, and the results were analyzed via geostatistics by semivariance. The nest quadrat was used to determine the optimal quadrat size.ResultsEggs were found in 99 quadrats (63.1%) and 187 clusters (1.5%) of Stipa caucasica on the steppe. The mean oviposition count of a cluster was 3.8 ± 1.6. Three-eggs is the mode of which females oviposit on each ovigerous S. caucasica (22.0%). Semivariogram analysis revealed that the distance of spatial dependence for eggs was 921 m, 1233 m and 1097 m for transect 1, transect 2 and grid methods, respectively, while spatial continuity was 62%, 77% and 57.0% for transect 1, transect 2 and grid, respectively. The eggs showed a patchy, aggregated distribution pattern. This suggested the spherical model is most applicable. The proportion of ovigerous S. caucasica was significantly correlated with the distance from water resources (r = − 0.382, p = 0).ConclusionOur findings indicated that diversification of G. pecorum oviposition was a new adaptative strategy for its survival in the desert steppe ecological niche. This made it more efficient at infecting hosts in the local environment. Areas surrounding water resources, especially around the drinking paths of equids (500 m radius surrounding the water), were concentrated epidemic areas. It is suggested that more attention to be paid to the ecological characteristics of G. pecorum in order to develop control measures that would reduce the infection risk for Przewalski’s horses.

Highlights

The dominant Gasterophilus species in the desert steppe (Xinjiang, China) Gasterophilus pecorum poses a serious threat to the reintroduced Przewalski’s horses
Previous studies have reported that the main epidemic areas of G. pecorum in the Kalamaili Nature Reserve (KNR) were those in the proximity of water resources [11]
Data obtained from them indicate that the frequency of eggs increased and the percentage of ovigerous S. caucasica decreased as the quadrat size increased

Summary

Introduction

The dominant Gasterophilus species in the desert steppe (Xinjiang, China) Gasterophilus pecorum poses a serious threat to the reintroduced Przewalski’s horses. Six of nine Gasterophilus species, G. haemorrhoidalis, G. inermis, G. intestinalis, G. nasalis, G. nigricornis, and G. pecorum, are known to be present in China [1, 2]. All these species have been reported to infect wild populations of Przewalski’s horse (Equus przewalskii) in the Kalamaili Nature Reserve (KNR) [3]. G. pecorum to be the dominant species in the KNR. Previous studies have reported that the main epidemic areas of G. pecorum in the KNR were those in the proximity of water resources [11]. The adults usually oviposit on Stipa caucasica within 2000 m of the water resource [3]

Methods

Results

Discussion

Conclusion