关键词: 马胃蝇, 感染率, 多样性, 蒙新区, 青藏区

Abstract: [Objective] A survey of infection in equids Gasterophilus spp. was conducted in Inner Mongol-Xinjiang region and Qinghai Tibet region in order to examine the infection diversity and parasitic characteristics of Gasterophilosis epidemic in the three regions.[Method] Equids in the Kalamaili Nature Reserve, Xinjiang, and Duolun, Inner Mongolia Autonomous Region in Mongol-Xinjiang region, Maduo, Qinghai Province in Qinghai Tibet region were treated with ivermectin to investigate and analyze the number and species of Gasterophilus spp. in the desert, desert-steppe and cold alpine steppe of these regions in the same winter.[Result] 1) Infection with Gasterophilus larvae was very common in horses in all these regions with an infection rate of 100%. 2) Gasterophilus spp. infecting the horses in both Xinjiang and Inner Mongolia belonged to six species of the genus, including G. pecorum, G. nasalis, G. intestinalis, G. nigricornis, G. haemorrhoidalis and G. inermis, which have been all reported in China, while only two species of the genus (G. pecorum and G. nasalis) were found in Qinghai. The component similarity index of Gasterophilus spp. was 1 (Xinjiang and Inner Mongolia), 0.33 (Xinjiang and Qinghai) and 0.33 (Inner Mongolia and Qinghai), respectively. 3) Shannon-Wiener index of Gasterophilus spp. that infected hosts was 1.31 in Duolun, Inner Mongolia, significantly higher than Maduo, Qinghai(0.23)and Kalamaili, Xinjiang (0.21), which also being part of Mongol-Xinjiang region. The evenness index of Gasterophilus spp. that infected hosts was highest in Duolun, Inner Mongolia (0.73), followed by that in Maduo, Qinghai (0.34), and lowest in Kalamaili, Xinjiang (0.12). This indicated a wider variety of Gasterophilus spp. species in Duolun, Inner Mongolia. 4) G. pecorum accounted for 96.17% and 93.17% of the larvae in Kalamaili, Xinjiang and Maduo, Qinghai, respectively, and was absolutely the dominant species in these two regions, while G. intestinalis (infection rate was 52.40%) and G. nasalis (infection rate was 23.80%) were the dominant species in Duolun, Inner Mongolia.[Conclusion] 1) The intensity of infection in Mongol-Xinjiang region was higher than that in Qinghai Tibet region. 2) More species were found in Mongol-Xinjiang region than Qinghai Tibet region. 3) The diversity of Gasterophilus spp. was influenced by the environmental conditions of its hosts. There would be a direct relationship between the differences of Gasterophilus species in Mongol-Xinjiang region and Qinghai Tibet region and the big differences of natural conditions of the two regions. Lower diversity was discovered under harsh conditions because there was oversize in some individual species or the small number of species. 4) G. pecorum would have successful reproductive strategies that adapts to the harsh environmental conditions. The prevalence of G. pecorum infection was more than 90% in both desert-steppe and cold alpine environment, and this might be closely related with its unique mode of transmission that laid eggs on grass and contaminated the pasture.

Key words: Gasterophilus spp., infection rate, diversity, Mongol-Xinjiang region, Qinghai Tibet region