Control efficacy and joint toxicity of metaflumizone mixed with chlorantraniliprole or indoxacarb against the fall armyworm, Spodoptera frugiperda

BACKGROUND The fall armyworm (FAW), Spodoptera frugiperda is the main destructive pest of grain crops, and has led to substantial economic losses worldwide. Chemical pesticides are the most effective way to manage FAW. Here, a laboratory test using an artificial diet-incorporated assay was conducted to determine the toxicity of five insecticides and the joint effect of the binary combination insecticides to FAW larvae. A field plot test using foliar spray was carried out to assess the control efficacy of metaflumizone mixed with chlorantraniliprole or indoxacarb against FAW. RESULTS The bioassay results showed that metaflumizone had a stronger insecticidal effect than indoxacarb toward FAW larvae. Furthermore, the mixture of metaflumizone and chlorantraniliprole in a volume ratio of 3:7 had the strongest synergistic effect against FAW, with a co-toxicity coefficient (CTC) of 317.18. The best synergistic effect for mixtures of metaflumizone and indoxacarb was observed at a 1:9 volume ratio, with a CTC of 185.98. However, there was an antagonistic effect of metaflumizone mixed with emamectin benzoate and with lufenuron, because the co-toxic factor was less than -20 at volume ratios of 8:2 and 9:1, respectively. According to the results of the field trial, metaflumizone mixed with chlorantraniliprole or indoxacarb at a 50% reduction of the application rate can effectively control FAW with efficacy ranging from 77.73% to 94.65% 1-7 days postapplication. CONCLUSION Overall, our findings suggest that metaflumizone and its binary combination insecticides can be utilized in FAW integrated pest management programs. (c) 2022 Society of Chemical Industry.

Automated summary

The study found that metaflumizone demonstrated stronger insecticidal effect than indoxacarb on fall armyworm larvae. The mixture of metaflumizone and chlorantraniliprole showed the highest synergistic effect against fall armyworm with a co-toxicity coefficient of 317.18, while the best synergistic effect for mixtures of metaflumizone and indoxacarb was observed at a ratio of 1:9 with a CTC of 185.98. The field trial results showed that metaflumizone mixed with chlorantraniliprole or indoxacarb at a 50% reduction in application rate effectively controlled fall armyworm with efficacy ranging from 77.73% to 94.65% within 1-7 days postapplication.