Induction of stress‐ and immune‐associated genes in the Indian meal moth Plodia interpunctella against envenomation by the ectoparasitoid Bracon hebetor

Abstract

Envenomation is an important process in parasitism by parasitic wasps; it suppresses the immune and development of host insects. However, the molecular mechanisms of host responses to envenomation are not yet clear. This study aimed to determine the transcription-level responses of the Indian meal moth Plodia interpunctella against envenomation of the ectoparasitoid Bracon hebetor. Quantitative real-time reverse-transcription PCR was used to determine the transcriptional changes of 13 selected genes, which are associated with development, metabolism, stress, or immunity, in the feeding and wandering fifth instar larvae over a 4-day period after envenomation. The effects of envenomation on the feeding-stage larvae were compared with those of starvation in the transcriptional levels of the 13 genes. Most selected genes were altered in their expression by either envenomation or starvation. In particular, a heat shock protein, hsp70, was highly upregulated in envenomated larvae in both the feeding and wandering stages as well as in starved larvae. Further, some genes were upregulated by envenomation in a stage-specific manner. For example, hsp25 was upregulated after envenomation in the feeding larvae, but hsp90 and an immune-associated gene, hemolin, were upregulated in the wandering larvae. However, both envenomation and starvation resulted in the downregulation of genes associated with development and metabolism. Taken together, P. interpunctella upregulated stress- and immune-responsive genes, but downregulated genes associated with development and metabolism after envenomation. This study provides important information for understanding the molecular mechanisms of host responses to parasitism.

A venom protein of ectoparasitoid Pachycrepoideus vindemiae, PvG6PDH, contributes to parasitism by inhibiting host glucose‐6‐phosphate metabolism

“…For example, Cotesia flavipes influences host metabolism by enhancing the activity of amylase and trehalase in the host Diatraea saccharalis (Rossi et al ., 2014). In contrast, envenomation by the ectoparasitoid Bracon hebetor downregulates the transcription levels of several genes associated with metabolism in the host Plodia interpunctella (Shafeeq et al ., 2017). In a similar investigation into Habrobracon hebetor , researchers measured a significant decline in carbohydrate metabolism in parasitized Pyrrhocoris apterus by monitoring carbon dioxide production (Shaik et al ., 2017).…”

CmHem, a hemolin-like gene identified from Cnaphalocrocis medinalis, involved in metamorphosis and baculovirus infection

“…We suppressed the CmHem expression by RNAi, and the mature larvae could not pupate normally. Further, Plodia interpunctella hemolin is expressed only in epidermis, suggesting its functional association with metamorphosis ( Aye et al, 2008 ; Shafeeq, Ulabdin & Lee, 2017 ). The proteomic analysis of hemolymph proteins during larva-to-pupal metamorphosis of B. mori further supports the functional role of hemolin in the metamorphosis process, as many immune-associated proteins, including hemolin, were found to be related to metamorphosis ( Hou et al, 2010 ).…”

Transcriptome Analysis Reveals the Venom Genes of the Ectoparasitoid Habrobracon hebetor (Hymenoptera: Braconidae)

“…Venom of H. hebetor , or its envenomation, has been shown to play a crucial role in manipulating the physiological processes of paralyzed host larvae. This includes actions such as blocking neuromuscular transmission [ 27 , 28 , 29 ]; changing the level of adipokinetic hormone [ 30 , 31 ]; inducing the expression of stress- and immune-associated genes [ 32 , 33 ]; inhibiting eicosanoid biosynthesis, leading to increased oxidative stress [ 34 ]; altering the midgut bacterial community [ 35 ]; and suppressing immunity through the inhibition of phenoloxidase activity, as well as a reduction in hemocyte encapsulation [ 36 ]. In addition, venom of H. hebetor has been found to exhibit anti-inflammatory properties by inhibiting nitric oxide production and reducing the levels of proinflammatory mediators and cytokines through modulation of the nuclear factor kappa B and mitogen-activated protein kinase pathways [ 37 ].…”