Physiological Characteristic Of Diadegma Semiclausum(Hymenoptera)on Its Host Plutella Xylostella(Lepidoptera)

The regulation of parasite to host is a complex process. Parasitic factors (PDV, venom, calyx fluid) injected by the majority of the parasitic wasps which are spawning as well as the teratocytes released by their eggs that are hatching seriously disturb the physiology, biochemistry, survival and reproduction of the host. In this paper, Diadegma semiclausum and its host Plutella xylostella were studying objects. On the basis of three parasitism factors having been studied clearly, the physiological regulation of Diadegma semiclausum to its host was studied. The major contents are as follows:1.Effects of Diadegma semiclausum on the development of two kinds of instar larvae of Plutella xylostellaThe growth of mass, the developmental time as well as the change of mortality rate, rate of cocoon formation and lethiferous rate of2nd,3rd instar host larvae and that which had not been parasitized were compared. The results showed the slow growth of mass of the two instar host larvae, the longer developmental time, and the great growth of mortality rate with remarkable difference, also the remarkable difference of the lethiferous rate of parasitism group and non-parasitized controls. The experiment datas showed that the3rd instar larvae was fit for Diadegma semiclausum to parasitize better.2. Effects of Diadegma semiclausum on the protein in hemolymph of Plutella xylostellaThe protein content in the hemolymph of Plutella xylostella parasitized by Diadegma semiclausum had been tested by means of Bradford. The results showed that the content of the protein decreased sharply to4.35±0.15mg/mL. The result of SDS-PAGE electrophoresis showed that the kinds of the protein also changed, with more kinds of major protein in the later period after being parasitized. Several specific proteins bands appeared on the5th day, with molecular weight of140.90kDa、89.44kDa、54.02kDa. The content of the free amino acids in the hemolymph had been analysed by HPLC. The whole content of the amino acids decreased, and the contents of different free amino acids had great differences.3. Effects of the host respiratory metabolism parasited by Diadegma semiclausumWe examined the host CO2production at the same time and the same temperature everyday, then weight the lavae.The results showed that CO2production changed apparently after wasp oviposition,but also increased with the host growing, and the CO2production had a relativity with the host body mass. 4. The restrain effect of Diadegma semiclausum on the host humour and cell immunityThe melanize rate of the hemolymph of Plutella xylostella parasitized by Diadegma semiclausum was observed in vitro. The results showed that the melanize degree decreased, following the prolonging of the time after being parasitized. Furthermore, the fact that the activity of phenoloxidase (PO) being restrained was also confirmed. And the PO activity between the two groups had a remarkable difference.Then we observed the ovary and venom of Diadegma semiclausum and the effects on host hemocytes conformation when injected by Diadegma semiclausum venom in vitro and in vivo.The results showed the conformation of two major immunity hemocytes (granular and plasmatocytes cells) in host hemocytes changed partially, for example, the pseudopod of the plasmatocytes was not obvious, in addition, cytolysis was observed.