Selection of resistance to dsRNA in the wheat aphid (Schizaphis graminum) without detectable fitness trade-offs.

Abstract

BACKGROUND RNA-based insecticides utilize a double-stranded RNA (dsRNA) as an active ingredient to initiate the RNA interference (RNAi) pathway and silence the expression of a vital gene in the target insect. Despite the strong commercial interest in RNA insecticides as both insecticidal traits in transgenic crops and sprayable products, information on resistance to dsRNA is limited to coleopteran species in the Chrysomelidae family. In contrast, the resistance potential in other insect groups remains largely unknown. This study evaluated the capacity of the wheat aphid (Schizaphis graminum), a polyphagous insect known for its adaptability to insecticides, to evolve resistance to a dsRNA targeting the C002 gene (dsC002). The C002 gene was selected as the target due to its essential role in aphid feeding and the strong association between its knockdown and high aphid mortality. Additionally, we assessed through life table parameters whether resistance to dsRNA in S. graminum incurs any fitness costs. RESULTS After ten generations of selection using dsC002 at the half-maximal lethal concentration (LC50) for each generation, the selected S. graminum population exhibited 74.9-fold resistance compared to the parental population. No significant differences in life-history traits were observed between dsRNA-resistant and susceptible S. graminum populations, indicating that dsRNA resistance is not associated with fitness costs under laboratory conditions. CONCLUSION Schizaphis graminum developed high levels of resistance to a dsRNA after only ten generations of selection. Resistance is not associated with fitness costs under laboratory conditions. These findings offer valuable insights for consideration and evaluation before commercial development of RNA aphidicidal products. © 2025 Society of Chemical Industry.