| Laodelphax striatellus is the most important pest of rice and wheat in Asia.L.striatellus destroys the phloem of rice through the spiny mouthpiece,and even transfers the Rice stripe virus(RSV)to host plants,which then develop rice stripe disease.The chemical insecticide is still the main method to control L.striatellus,while extensive application of pesticides leads to the resistance of L.striatellus and the decrease of the population of natural enemies.In addition,recent studies have shown that the use of chemical agents can cause the resurgence of L striatellus.We have already confirmed that triazophos at LC20 can increase the fecundity of L.striatellus,and promote its vertical transmission to RSV.In order to further reveal the mechanism,the effects of triazophos on the protein and fatty body protein content of the ovaries of L.striatellus and the gene expression of RSV related factors were studied.The results are as follows:(1)The sensitivity of triazophos to the 3rd instar nymphs L.striatellus with and without RSV was measured by a drop method.Our result showed that the 3rd instar nymphs L.striatelus without RSV was more sensitive to triazophos than with RSV.With triazophos treatment,the protein content of the ovary and fat body of L.striatellus with and without RSV increased in varying degrees,and the increase of the protein content of the ovaries and fat bodies of L striatellus without RSV.The protein content in L.striatellus with and without RSV increased by 140.8%and 32.9%,respectively,after the treatment of triazophos for 2day,and the protein content in the ovaries of L.striatellus with and without RSV increased by 128.9%and 32.2%,respectively,after the treatment of 2day.The protein content of the fat body of L.striatellus with and without RSV was higher than that of the blank control after the treatment oftriazophos for 2day,and the protein content of the fat body of the triazophos treated without RSV was 33.6%higher than that of L.striatellus with RSV.The content of protein in ovary and fat body increased with triazophos by a drop method.(2)RT-PCR technology was used to determine the effect of triazophos LC20 concentration on the expression of genes related to vertical transmission of stripe virus in L.striatellus.The results showed that triazophos treatment had an obvious effect on the expression level of the gene related genes in the ovary of the first generation of L.striatellus,and the expression of RSV in 1,2,3 and 5day increased by 38.7%,53.4%,86.3%and 82.7%,respectively.After treatment with triazophos for 2,3 and 5day,the expression of CP gene in ovary increased significantly compared with the control,and increased by 89%,126%and 100%respectively.The expression of Vg in ovary increased significantly compared with that of triazophos treated 1,2,3 and 5day,and increased by 14.4%,51.4%,63.6%and 104.5%respectively.There was also a significant difference in the expression level of genes related to ovarian transmission in the two generation of the triazophos of L.striatellus.(3)RNA interference was used to study the expression level of related genes in the ovary of L.striatellus.The relative expression of RSV,CP and Vg in the insect was measured after 1,2 and 3 days after the injection of dsRNA solution.The results showed that the expression of CK and dsGFP decreased significantly with the control CK and the control dsGFP.The expression of RSV,CP and Vg decreased by75%,63%and 56.9%,respectively,after 2 days after interference.Compared with dsGFP,they decreased by 63.5%,75%and 40%respectively.It shows that the effect of RNA interference is obvious. |
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