Vacuolar-ATPase gene mediated RNA interference on Systena frontalis (F) (Coleoptera: Chrysomelidae) adults

Systena frontalis (F) (Coleoptera: Chrysomelidae) is a serious polyphagous pest in containerized ornamental nurseries in the central, mid-west, and eastern United States. Adults feed on plant foliage, causing shothole damage, and the affected plants are rarely salable. We studied the exogenous application of dsRNA on the adult S. frontalis. The dsRNA was designed to inhibit the expression of three vATPase genes, A, D, and E subunits, and assessed how different amounts of cognate dsRNA affect the silencing of these genes. The transcript expression was analyzed through qRT-PCR to check the effectiveness of RNAi. Sixconcentrations: 10, 30, 40, 50, 60, and 70 µg per cm2 leaf of the dsRNA of vATPase-A,-D, and -E subunits were coated on panicled hydrangea leaves. Adult S. frontalis feeding damage was significantly reduced with dsvATPase-A, -D, and -E at 3 d post-exposure. Up to 50% reduction in feeding damage was observed with 70 µg. The survival of adult S. frontalis was not reduced after ingestion of dsvATPase-A, -D, and -E treatment. When the pre-exposed adult S. frontalis to dsvATPase-A, -D, and -E was transferred to nontreated foliage for 1 d, a significant reduction in feeding damage was observed with various concentrations of dsvATPase-A, -D, and -E. A dose-response in the expression of dsRNA was observed in adult S. frontalis exposed to dsvATPase-A, -D, and -E treated foliage after 4 d. The results suggest that these three RNAi products can potentially manage S. frontalis, which needs further research.