Sex ratio and age structure of medical gamasid mites from small mammals in areas surrounding Biluoxueshan in Weixi County of Yunnan Province,China

Abstract

Objective To study the sex ratio and age structure of medical gamasid mites in areas surrounding Biluoxueshan in Yunnan province,China.Methods Using mouse traps(or mouse clips)to capture some small mammals in areas surrounding Biluoxueshan located in Weixi County of Yunnan Province,the ectoparasitic gamasid mites were all collected from the body surface of captured small mammal hosts.Results A total of 43 species of gamasid mites (2 496 individuals) were collected from the body sufrace of 40 species of small mammals (1 560) during an investigation of medical gamasid mites in areas surrounding Biluoxueshan in Weixi County of Yunnan Province,China.Most species of gamasid mites had more females than males.No larva was found in most of the mite species.The proportion of individuals at the immature stages(mainly protonymphs and dertonymphs) in most mite species was low (0.79%～5.55%) compared with that at the aduhs,except Ornithonyssus bacoti whose nymphs Was 54.51%respectively.Conclusion The unbalanced sex ratios might be related to the different blood sucking preferences and parthenogenesis of the gamasid mites.The absence of larvae and a low proportion of nymph stages in most mite species probably reflected that the larvae or nymphs of most mite species were non-feeding or non-blood sucking and were in their hosts'nests.Another possibility was that some species directly produce protonymphs Or even deutonymphs without eggs or larvae.and resuiting in the difficulty of finding the larval stage. Key words: Ectoparasitic infestation; Mite infestation; Acari; Sex ratio; Age structure