Sub-lethal effects of dsRNA in Southern Corn Rootworm (Diabrotica undecimpunctata howardi) larva

RNAi has been investigated as part of a management approach to control corn rootworms. The objective of this research was to investigate the effects of RNAi on the development of neonates after exposure to dsRNA. Neonates were exposed to LC₅₀s of vAPTase-A and Snf7 dsRNA/cm² on artificial diet for 1, 2, and 3 days prior to transferring to seedling corn planted in 50 ml tubes. Four larvae were transferred per tube, allowed to feed on the roots, and surviving larvae were recovered after 10 days. Statistical differences for both targeted genes were detected in the number of larvae per tube, with higher numbers found in the control. Differences were also recorded in larval weight and instar between controls and larvae exposed to dsRNA for 2 and 3 days in the vATPase treatment, but no differences were observed for larvae that survived exposure to Snf7 dsRNA. There were differences in the number of 2^nd and 3^rd instar recovered between control and vATPase dsRNA treatments. Almost 100% of larvae recovered in control were 3^rd instars while larvae recovered from the 2 and 3-day exposures to vATPase dsRNA were 76% and 69% of 3^rd instar, respectively. For Snf7, control treatment showed 89% of larvae as 3^rd instars and 11% as 2^nd instars, while the other treatments showed 76.5% as 3^rd instars and 23.5% as 2^nd instars, in average. This research suggests that sublethal exposures to dsRNA significantly impacts larval development and provides insights into the utility of RNAi in pest management for rootworms.