
Background: This trial evaluated efficacy and effective dosage of Sauveur 62 EC (Acetamiprid 32g/L + lambda-cyhalothrin 30g/L) insecticide for management of fall armyworm (FAW) Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) on maize crop. Methods: The trial was conducted in two ecological zones: forest (Kwadaso) and forest-savanna transitional (Ejura). Three rates of the insecticide were tested, comprising manufacturer’s recommended dose (60ml/15L of water), and 10% increment (66ml/ 15L of water) and decrement (54ml/15L of water). Bypel at rate 15g/15L of water was used as standard insecticide. Larval fall armyworm (FAW) population, leaf damage, plant height and phytotoxicity were assessed. Maize yield was determined by assessing kernel rows/cob, number of kernels/row, yield/plant and yield/ha. Results: Larval mortality on three Sauveur 62 EC rates and Bypel were significantly higher than untreated plots, with high and medium rates recording 100% within 2 days after treatment. Phytotoxicity was strong, medium and slight for Sauveur 62 EC at rate 66ml, 60ml and 54ml per 15L of water. Bypel and control showed no phytotoxicity. Similar number of kernel rows/cob and number of kernels per row were recorded on both treated and control plots. Yield/plant and yield/ha were however higher on treated plots with 60ml/15L rates of the test insecticide giving the best results, although this was significantly lower than Bypel. Conclusion: Sauveur 60 EC at rate of 60ml/15L of water is effective in managing fall armyworm.