Comparative effect of biopesticides against the fall armyworm Spodoptera frugiperda (J.E. Smith)

The current study evaluated the effect of microbial-derived insecticides (abamectin and spinosad), two microbials (Beauveria bassiana (Balsamo) Vuillemin, Bacillus thuringiensis Berliner), and three chitin synthesis inhibitors (CSIs) (chlorfluazuron, hexaflumuron and lufenuron) against Spodoptera frugiperda larvae. Spinosad and abamectin caused pronounced mortality against second larval instar of S. frugiperda using the leaf dipping method. Spinosad induced higher toxicity (LC₅₀ = 4.01 mg/L) than abamectin (LC₅₀ = 8.33 mg/L) one day after treatment. The treatments with B. bassiana and B. thuringiensis caused higher mortality of S. frugiperda larvae 7 days after treatment with LC50 values of 3.0 × 10⁵ spores/ml and 8.2 × 10⁶ cells/ml, respectively. In the case of the CSIs, hexaflumuron showed higher toxicity than chlorfluazuron and lufenuron with LC₅₀ values of 0.01, 0.009 and 0.005 mg/L 3, 7 and 10 days after treatment, respectively.