| Diaphania pyloalis walker,the main insect pests of mulberry,brought huge losses to the development of silkworm industry every year.At present,the main method of prevention them is using chemical pesticides,causing harmful to the environment,leading to insect resistance.Therefore,an eco-frendly method needs to be fought urently.The Aulacococentrum confusum,which is the potential biocontrol factor for the prevention and control of its host,is the dominant parasitoids of the D.pyloalis that having the post egression feeding behavior,which is different from traditional endoparasites.Testing the parasitism rate of different instar D.pyloalis to determine the best instar of host can bring the highest parasitism rate by selective and nonselective experiments of parasitism on different instar of host.Describing the parasitic behavior of post egression feeding by dynamic tracking.The effects on the growth and development of parasitoid were studied by testing the content of carbohydrate,protein and body weight chenging between parasitism and no parasitism.The differential expression of the related immune genes between parasitism and no parasitism was determined by analyzing the transcripts of D.pyloalis.Based on the non-selective experiment about different instar of D.pyloalis,the rate of parasitism was 60% or more at L2,L3 and L4.Besides,the difference between them was not significant,but were all greater than that of the 5th instar larvae.When parasite the 3th instar host,the weight of cocoons of offspring was the heaviest(35.5 mg±5.8 mg).The development time was shortest when reared in the 4-year-old 5-year-old host(11 d ± 2.05 d and 11.6 d ± 3.04 d).There were no significant differences in the body size of offspring between parasitoids reared in different age of host,but most descendants were female when the parasitoids reared in the L2,L3 host.The results of selective experiments showed that the larvae had no preference for L2,L3 and L4 larvae.The results showed that the parasitism rate was not affected by the age of host except 5th instar.What's more,the development time was longer and the most descendants were female when the host at L2,L3.Post egression feeding behavior has great effect to the cocooning,weight of cocoons and lifespan A.confusum.After post egression feeding of its host,the rate of cocoons of A.confusum of treat 2 and 3 are 100% and 95%,which are remarkable huger than that un-feeding its host that is 80%.The weight of cocoons of treat 2(32.0 mg ± 9.59 mg)and 3(31.0 mg±5.2 mg)are remarkable huger than the weight treat 1(15.7 mg ± 3.89 mg),which the former two treats are 2.04 and 1.97 times of treat 1.Therefore post egression feeding behavior is vital to the development of A.confusum.The content of saccharides,protein,and host weight of parasitized has no otherness to healthy host based on the post egression feeding behavior.Therefore,The content of saccharides,protein,and host weight of parasitized has no otherness changing in D.pyloalis after parasitized by A.confusum.The expression of genes related to immune and growing development are changed of D.pyloalis after parasitized by A.confusum.197 genes relating to growth and development and immune were identified by differential expression analysis in the transcriptome of D.pyloalis parasitized by A.confusum.These genes are relating to cellular component,molecular function and biological,and the quantity of up-regulation genes is remarkable huger than down-regulation genes.This study through the selective and nonselective experiments of different age host is to determine the development influence between the A.confusum and D.pyloalis.At the same time,this article will offer the theory to control of D.pyloalis by A.confusum. |
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