Toxins 2016, 8(2), 52; doi:10.3390/toxins8020052
Venom of Parasitoid Pteromalus puparum Impairs Host Humoral Antimicrobial Activity by Decreasing Host Cecropin and Lysozyme Gene Expression
1
State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, China
2
College of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong, China
*
Author to whom correspondence should be addressed.
Academic Editor: Glenn F. King
Received: 13 November 2015 / Revised: 30 January 2016 / Accepted: 4 February 2016 / Published: 20 February 2016
(This article belongs to the Special Issue Arthropod Venoms)
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. View Full-TextKeywords:
parasitoid wasps; venom; insect hosts; innate immunity; antimicrobial peptides
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MDPI and ACS Style
Fang, Q.; Wang, B.-B.; Ye, X.-H.; Wang, F.; Ye, G.-Y. Venom of Parasitoid Pteromalus puparum Impairs Host Humoral Antimicrobial Activity by Decreasing Host Cecropin and Lysozyme Gene Expression. Toxins 2016, 8, 52.
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