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我们曾发现菜蛾盘绒茧蜂Cotesia vestalis和半闭弯尾姬蜂Diadegma semiclausum寄生严重阻碍小菜蛾Plutellaxylostella幼虫的精子发生。本研究着重比较2种蜂寄生对小菜蛾精巢生长和精子束形成的影响,以探明寄生因子对昆虫生殖调控的作用途径。采取过寄生和假寄生方法,对2种蜂各自寄生后的小菜蛾精巢生长体积,精子发生和形成过程中生精细胞、精子束的显微形态变化进行了比较。结果表明:茧蜂和姬蜂寄生均明显降低小菜蛾精子束的数量,严重阻碍了寄主幼虫的精子发生和精子形成。姬蜂寄生造成小菜蛾精巢畸形,而茧蜂则造成小菜蛾精子束畸形,且茧蜂对小菜蛾精巢生长的抑制程度明显强于姬蜂。过寄生造成寄主寄生性去势程度加剧,茧蜂和姬蜂过寄生后的小菜蛾精巢体积分别为0.005mm3和0.008mm3,仅为各自只寄生1次后精巢体积的33.1%和36.3%。假寄生后,发现只有寄生蜂母代物质存在的前提下,对小菜蛾精巢生长的抑制程度基本模拟了正常寄生时的状态,说明多分DNA病毒(polydnavirus,PDV)和毒液发挥了主要作用。由此推断分属姬蜂属PDV和茧蜂属PDV的2类PDV功能基因对小菜蛾精巢生长发育的调控机制可能存在较大差异。
We have previously found that parasitism of Cotesia vestalis and Diadegma semiclausum of the diamondback moth, Plutella xylostella, is seriously impeded by the parasitism of Plutella xylostella larvae. In this study, the effects of two kinds of bee parasitism on the growth of testis and the formation of sperm bundles in Plutella xylostella were compared to find out the ways of parasitism on the reproductive regulation of insects. Parasitic and pseudoparasitic methods were used to compare the morphological changes of spermatogenic cells and sperm bundles in the testis growth volume, spermatogenesis and formation of Plutella xylostella after parasitization. The results showed that the parasitism of both Braconidae and Apis mellifera both significantly reduced the number of sperm bundles in Plutella xylostella and seriously hindered the spermatogenesis and sperm formation of host larvae. The moth parasitoids caused the oviposition of the diamondback moth in the ovary, whereas the caterpillars caused the sperm deformity in the diamondback moth. The inhibition of the growth of the diamondback moth to the diamondback moth was significantly stronger than that of the wasps. Parasitic host parasitism caused by the degree of escalation, Braconidae and haddock after parasitized diamondback moth testis volume were 0.005mm3 and 0.008mm3, only the parasitic only once after the testis volume of 33.1% and 36.3%. After false-parasitized, we found that the inhibitory effect on the development of testis in the diamondback moth (Plutella xylostella) simulated the normal state of parasite only under the premise of the existence of the parent material, indicating that polydnavirus (PDV) and venom played a major role. It is concluded that there may be a large difference in the regulatory mechanisms of PDV functional genes belonging to the genus Myrmeceti PDV and the Braconid PDV on the growth and development of the diamondback moth testis.