Study On The Development And Physiological Metabolism Of Aphis Gossypii Regulated By Lysiphlebia Japonica

The cotton-melon aphid,Aphis gossypii Glover,is a major insect pest worldwide.Lysiphlebia japonica（Ashmead）is the dominant parasitic wasp of A.gossypii which can control the population of cotton aphid effectively.Insect host-parasitoid interactions involve complex physiological,biochemical and genetic interactions.However,little was known about cotton aphid parasitized by L.japonica.In order to understand the control of L.japonica on cotton aphids,this study made a detailed statistical analysis of the biological influence on cotton aphids parasitized by L.japonica,and comprehensively described the changes of cotton aphids after parasitization by using lipidome,fatty acids,transcriptome and proteome.These findings provide better understanding of host-parasite interactions.The main results are as follows:1.The biological characteristics of L.japonica were clarified.Studies had shown that it takes15.6d for L.japonica to complete a generational cycle.L.japonica prefer to parasitize aphids of 2ⁿdd and3^rd,the parasitic rates were 65%and 82%,respectively.The preference of L.japonica to zucchini was preliminarily determined by the weight and parasitic rate of cotton aphid from different host plants（cotton,cucumber,zucchini）.2.The effects of parasitism on the growth and development of aphids were studied.Studies had shown that it is a remarkable fact that the host body length,width,weight and molting time of cotton aphids at different ages after parasitization were all higher than those of unparasitized cotton aphids.The developmental duration and the ecdysone content of cotton aphid was increased obviously after parasitization by L.japonica.In addition,the number of offspring of cotton aphids was significantly lower than aphids which were unparasitized.3.The effect of parasitism on lipid metabolism of cotton aphid was studied.34 triacylglycerols and248 glycerophospholipids were identified in this study.After 3 days of parasitization,the level of TAG increased significantly,the acyl chains of TAG had also changed significantly;Almost all SMs species were decreased in parasitized aphids compared to unparasitized aphids.The contents of PCs,PEs,PSs,PGs,SMs,LPCs,LPEs and acyl chains were all changed.4.The effect of parasitism on fatty acids of cotton aphid was studied.A total of 31 kinds of fatty acids were identified in our study.Almost all fatty acid content increased after parasitization for 8h,16h and 1d,however almost all fatty acid content was significant lower than control after parasitization for3d,the proportions of fatty acids were also changed significantly in cotton aphid after parasitized by 3days.5.The effect of parasitism on transcriptome of cotton aphid was studied.Studies had shown that 14,455 genes were significantly changed after parasitized in cotton aphid,among which 13,015 genes were up-regulated and 1,440 genes were down-regulated;Further analysis had showed that parasitization up-regulate the expression of related genes involved in TAGs synthesis and PLs metabolism;Lipid pathway analysis showed that a higher expression of genes involved in the tricarboxylic acid cycle and glycolysis pathways may contribute to TAGs synthesis in parasitized aphids;Fatty acids pathway analysis showed that genes related to fatty acid synthesis were significantly up-regulate in parasitized aphids.6.The effect of parasitism on transcriptome of cotton aphid was studied.A total of 1056 genes with significant changes at either the protein and（or）the mRNA level were identified.Studies had showed that there were major changes in A.gossypii proteome after 3 d parasitized by L.japonica.We assigned these proteins to functional categories that mainly included immunity,energy metabolism and transport,lipid metabolism,and reproduction.These changed proteins may play a crucial role in the growth and development of L.japonica.