Abstract
RNA interference (RNAi) in transgenic maize has recently emerged as an alternative mode of action for western corn rootworm (Diabrotica virgifera virgifera) control which can be combined with protein-based rootworm control options for improved root protection and resistance management. Currently, transgenic RNAi-based control has focused on suppression of genes that when silenced lead to larval mortality. We investigated control of western corn rootworm reproduction through RNAi by targeting two reproductive genes, dvvgr and dvbol, with the goal of reducing insect fecundity as a new tool for pest management. The results demonstrated that exposure of adult beetles, as well as larvae to dvvgr or dvbol dsRNA in artificial diet, caused reduction of fecundity. Furthermore, western corn rootworm beetles that emerged from larval feeding on transgenic maize roots expressing dvbol dsRNA also showed significant fecundity reduction. This is the first report of reduction of insect reproductive fitness through plant-mediated RNAi, demonstrating the feasibility of reproductive RNAi as a management tool for western corn rootworm.
Highlights
Vitellogenin, the precursor of the major yolk protein in most oviparous animals, is transported into oocytes by the vitellogenin receptor (VgR) through an endocytic pathway[15]
VgR proteins belong to the low-density lipoprotein receptor (LDLR) family, which are membrane-bound proteins[15]
We postulated that targeting reproductive genes using RNA interference (RNAi) would be another approach using transgenic maize plants for WCR control and management
Summary
Vitellogenin, the precursor of the major yolk protein in most oviparous animals, is transported into oocytes by the vitellogenin receptor (VgR) through an endocytic pathway[15]. BOL is an RNA-binding protein with an RNA Recognition Motif (RRM) domain[22] It shares homology with the DAZ (Deleted in Azoospermia) protein outside the RRM domain, and mutations in this protein cause severe sperm reduction in animals[23]. Based on this previous characterization of vgr and bol as essential reproductive genes in other insect species, we chose to evaluate WCR homologs of these genes, dvvgr and dvbol, as targets for reproductive RNAi in WCR. Transgenic maize plants expressing dsvgr and dsbol were generated to determine whether fecundity would be affected by larvae feeding on transgenic roots to demonstrate the potential for WCR reproductive RNAi as a transgenic trait. To the best of our knowledge, this is the first report of plant-mediated reproductive RNAi for insect control, and it represents a new rootworm management approach
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