Biological And Morphological Study Of The Water Mite Unionicola. (Polytatax) Chelata

Unionicola (Polytatax) chelata is the only parasite mite which was found that hada close relation to Cipangopaludina chinensis (Cray) and Cipangopaludina cathayensis(Heude). It has important academic value and practical value in doing research to itslife cycle observation, micro- and submicro- structure, the distribution, prevalenceregulation and relation with the host.In thesis, life cycle of Unionicola (Polytatax) chelata Wen & Zhu, 1999 wasinvestigated, and its developmental stages were described. The investigating resultshows that there are all developmental stages of U. chelata in the Chinese snailCipangopaludina chinensis (Cray), including egg, prelarva, larva, nymphophan,nymph, teleiophan and adult. The result indicates U. chelata can finish all the stagesin its host Chinese freshwater snail without any midhost.The structure of leg claws and glandularia,gnathosoma and genital field wereobserved for the adult and nymph U. chelata with electron microscope. The scanningresults show that the most obvious difference is about the genital field. The nymphonly has two pair acetabulums without other sub-structure of genital field, but theadult has more than five pair acetabulums and completely developed ejaculating orlaying structure. The leg claws of is an integer that includes claws, ventral pad andsetae. Legâ… is the same with legâ…£. Legâ…¡is the same with legâ…¢. There are fewdifferences between the two groups. The scanning result of the gnathosoma revealsthat the chelicerae extending from the mouth, with four setae around the mouth, thereis a structure looks which can move together with the chelicerae like gill (calledgill-like structure). The genital field of U. chelata is composed of many acetabulums,excretory pore, genital seta, ejaculatory complex or oviposit structure. Both adult andnymph's acetebulums have setae aroud.Population dynamics of the water mite U. chelata was investigated in freshwatersnail Cipangopaludina chinensis (Cray) during the period from May 2006 to April2007 in Nanchang which is belong to Poyang lake water system. A pattern of seasonalvariation was observed, with prevalence and abundance peaked in early spring andautumn. The number of mites in individual host was significantly correlated with thesize of snail. The changes in infection level of the mite on different infection siteswere significant, with more mites found on the gill.