Genetic Diversity And Occurrence Characteristics Of Common Gasterophilus Spp.in Different Habitats

Gasterophilus species are widely distributed around the world,larvae of these flies parasitize the digestive tract of the equids and cause digestive system damage,which hinders the development of the horse farming and the protection of endangered species.Based on the mitochondrial COⅠ and COⅡgenes,this study analyzed the genetic diversity,genetic differentiation,gene flow and origin of Gasterophilus pecorum,G intestinalis,G.nasalis,G nigricornis from three typical grasslands(meadow steppe,desert steppe and alpine steppe)in China.Meanwhile,compared with G.intestinalis from Italy,Poland,Daqing of China,Yili of China and G.nasalis from Italy,Poland.The main conclusions are followed:1)The genetic diversity of mitochondrial genes is generally high in all Gasterophilus populations.2)Due to special natural climatic conditions of alpine steppe,there are high levels of genetic differentiation among geographic populations of G.pecorum and G.nasalis.The difference of the natural geographical environment has an significant influence on the population genetic structure.3)Frequent exchanges in meadow steppe and desert steppe Gasterophilus species caused low genetic differentiation.4)There was a most frequent exchange among populations of G.intestinalis.Genetic differentiation was only found on the large geographical scale.The genetic structure eonfirmed that it was widely distributed.5)G.pecorum,G.intestinalis,G nasalis from meadow steppe were shown a high emigration rate,suggesting that the dispersal direction of Gasterophilus in China is from east to west.Gasterophilosis is a significant threat to Equus przewalskii in Xinjiang.A parasitological survey was done in wild and captive population of Przewalski’s horse to investigate the diversity and parasitic characteristics of Gasterophilus spp.The main conclusions are followed:1)There was a statistic significantly difference between larvae burdens of wild and captive populations.Larval burdens of captive population were reduced by establishing isolated zone and providing special forage grasses.2)There was a obvious difference between wild and captive population in speeies eomposition of Gasterophilus.G.Peeorum was the dominant species in the wild population while it was absent in the captive population,which indicated that unique transmission chain with grass was broken.3)Shannon-Wiener index and evenness index of Gasterophilus spp.shown a striking difference between wild and captive populations,while the latter was rigorous infected by horse gastrointestinal myiasis.4)Different living environment have distinctly different infective charsacteristics of Gasterophilus spp.