Pathogenicity of bacteria and viruses to Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

Combining integrated pest management and biological control has been an effective, economical, and sustainable strategy for controlling agricultural pests. The larvae of Spodoptera frugiperda, a pest of several crops, cause financial losses to the agribusiness sector, and entomopathogens have been widely used for the biological control of this species. Therefore, the objective of this study was to evaluate the pathogenicity of bacteria and viruses for the control of S. frugiperda under laboratory conditions. Two bioassays were conducted in a completely randomized design, one using second-instar and other using third-instar larvae, with six treatments and five replications. The entomopathogens used were S. frugiperda Multiple nucleopolyhedrovirus (SfMNPV), Autographa californica multiple nucleopolyhedrovirus (AcMNPV), Bacillus subtilis, B. thuringiensis subsp. thoworthy, and B. thuringiensis subsp. kurstaki. Mortality was assessed daily until the end of the larval cycle. Analysis of variance (F-test) was applied, followed by mean comparison through the Scott-Knott test at a 5% significance level. The efficacy of the entomopathogens as bioinsecticides was evaluated using Abbott's formula. Overall, the most effective entomopathogens for controlling second-instar S. frugiperda larvae were SfMNPV and B. subtilis, resulting in 100% control, whereas AcMNPV was the most effective against third-instar larvae, showing maximum lethality in 76.67% of samples.