title: Venom of Parasitoid Pteromalus puparum Impairs Host Humoral Antimicrobial Activity by Decreasing Host Cecropin and Lysozyme Gene Expression.
abstract: Insect host/parasitoid interactions are co-evolved systems in which host defenses are balanced by parasitoid mechanisms to disable or hide from host immune effectors. Here, we report that Pteromalus puparum venom impairs the antimicrobial activity of its host Pieris rapae. Inhibition zone results showed that bead injection induced the antimicrobial activity of the host hemolymph but that venom inhibited it. The cDNAs encoding cecropin and lysozyme were screened. Relative quantitative PCR results indicated that all of the microorganisms and bead injections up-regulated the transcript levels of the two genes but that venom down-regulated them. At 8 h post bead challenge, there was a peak in the transcript level of the cecropin gene, whereas the peak of lysozyme gene occurred at 24 h. The transcripts levels of the two genes were higher in the granulocytes and fat body than in other tissues. RNA interference decreased the transcript levels of the two genes and the antimicrobial activity of the pupal hemolymph. Venom injections similarly silenced the expression of the two genes during the first 8 h post-treatment in time- and dose-dependent manners, after which the silence effects abated. Additionally, recombinant cecropin and lysozyme had no significant effect on the emergence rate of pupae that were parasitized by P. puparum females. These findings suggest one mechanism of impairing host antimicrobial activity by parasitoid venom.
authors.affiliation: State Key Laboratory of Rice Biology &amp; Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China. fangqi@zju.edu.cn.
authors.forename: Qi
authors.initials: Q
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Rice Biology &amp; Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China. wangbei_zju@163.com.
authors.forename: Bei-Bei
authors.initials: BB
authors.lastname: Wang
authors.affiliation: College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China. yexinhai1204@hotmail.com.
authors.forename: Xin-Hai
authors.initials: XH
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Rice Biology &amp; Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China. wf87670701@163.com.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Rice Biology &amp; Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China. chu@zju.edu.cn.
authors.forename: Gong-Yin
authors.initials: GY
authors.lastname: Ye
mesh_terms: D000818:Animals; D002080:Butterflies / Q000187:drug effects* / Q000235:genetics / Q000276:immunology / Q000469:parasitology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006458:Hemolymph / Q000276:immunology; D006790:Host-Parasite Interactions; D056724:Immunity, Humoral / Q000187:drug effects; D019476:Insect Proteins / Q000235:genetics; D009113:Muramidase / Q000235:genetics; D011679:Pupa / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000469:parasitology; D014862:Wasp Venoms / Q000633:toxicity*; D014863:Wasps / Q000502:physiology*
chemical_list: D019476:Insect Proteins; D014862:Wasp Venoms; D009113:Muramidase
keywords: antimicrobial peptides; innate immunity; insect hosts; parasitoid wasps; venom