RNAi-mediated silencing of vitellogenin and its receptor genes curtails oogenesis in the almond moth Cadra cautella

Cadra cautella (Walker) (Lepidoptera: Pyralideae) causes severe damage to dates on trees as well as under storage, worldwide. We tried to develop an alternative environment friendly strategy to manage this pest. We focused on the major reproduction control genes, vitellogenins (Vgs) and its receptor (the VgR). Both Vg and VgR genes play a vital role in egg production in all oviparous animals including insects, and could be an ideal target for developing the safer pest control strategies for the critical pest insects.

Results of the RNAi-based silencing of CcVgR gene revealed that application of CcVgR-based dsRNA has silenced the expression of VgR gene up to 83% on 72 h of post injection periods in the treated females. Furthermore, the phenotypic impact of RNAi was also observed in terms of low fecundity and low hatchability in addition to prolonged pre-oviposition and reduced oviposition periods in the females treated with CcVgR-based dsRNA, as compared to nuclease free water and no injection control group females. Similarly, for silencing the function of C. cautella VgR genes, RNA interference was performed by injecting CcVgR based dsRNA for different exposure times. The results revealed that CcVgR is 5421 bp long, encoded 1807 amino acids protein, belongs to low-density lipoprotein receptor (LDLR) superfamily, and contains all conserved domain. Expression analysis confirmed that CcVgR is sex-specific and starts to express in female larvae on day 19. Additionally, RNA interference (RNAi) inhibited CcVgR expression up to 83% after 72 h of CcVgR based dsRNA injection.