Objective Ribavirin is a broad-spectrum antiviral drug and exhibits good insecticidal activity against lepidopteran pests. To further determine its actual control efficacy, a ribavirin aqueous solution was prepared and evaluated against lepidopteran pests.

Method Based on the high water solubility of ribavirin, the optimal wetting agent was selected from five commonly used ones (Morwet EFW, Morwet D-425, EL-30, EL-40, and Nongru 605) by indicator measurement, and a 5% ribavirin aqueous solution was prepared. Its control efficacy against Spodoptera frugiperda and S. litura was evaluated by stem and leaf spray application.

Result The formulations obtained by mixing ribavirin with the five wetting agents appeared as light yellow homogeneous transparent, brown homogeneous transparent, milky white homogeneous, yellowish-white homogeneous, and colorless homogeneous transparent, respectively, with contact angles of 23.6°, 57.5°, 42.2°, 35.8°, and 46.3°. All five formulations showed homogeneous dilution stability without precipitation, a foaming volume of 0.8 mL, and pH values ranging from 6.6 to 6.8. In thermal storage stability tests, the formulations prepared with Morwet EFW and Morwet D-425 remained homogeneous without precipitation; all formulations showed homogeneous without precipitation under cold storage conditions. These results indicate that the formulation prepared with Morwet EFW exhibited the best overall performance. Indoor efficacy tests showed that the 5% ribavirin aqueous solution diluted to 2 000 mg/L achieved the best control efficacy against S. frugiperda and S. litura on the 5th day after application, with control efficacies of 87.15% and 88.30%, respectively. The control efficacy was comparable to that of the control insecticide RH-5849 (88.83% and 84.80%), and some treatment groups showed better control efficacy than the control.

Conclusion The 5% ribavirin aqueous solution exhibits good control efficacy against S. frugiperda and S. litura. These results provide a theoretical basis for its application in actual agricultural production.