Mortality and food consumption in Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae treated with spinosad alone or in mixtures with a nucleopolyhedrovirus

The combined and individual effects of spinosad and Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) (Baculoviridae) on the mortality and food consumption of 3rd instars of S. frugiperda were evaluated using maize-leaf bioassays. The mortality data from spinosad (0.001 mg/L)-SfMNPV (10(6) OBs/mL) mixtures showed a low synergistic effect at 144 h after treatment. The consumption rate was significantly reduced by 2- to 12-fold in the spinosad-SfMNPV mixture treatment compared with the control, but no difference in consumption rate was observed between this treatment and the treatment with spinosad alone. Laboratory observations on the efficiency of spinosad-SfMNPV mixtures require validation in field studies under commercial growing conditions.