Susceptibility of Spodoptera frugiperda to Commercial Entomopathogenic Fungi Formulations in South Africa

Chemical control using synthetic insecticides is the most widely used method for controlling the fall armyworm (FAW), <i>Spodoptera frugiperda</i> (J.E. Smith) (Lepidoptera: Noctuidae) in Sub-Saharan Africa (SSA). However, the application of insecticides is not a long-term or sustainable solution. Biological control is an important pillar of integrated pest management, and entomopathogenic fungi (EPFs) are becoming increasingly important as biocontrol agents. However, no EPF biopesticides have been registered in South Africa for the control of <i>S. frugiperda</i>. Few studies have been conducted on the efficacy of commercial formulations of biopesticides against all <i>S. frugiperda</i> life stages. The objective of this study was, therefore, to assess the potential of two <i>Beauveria bassiana</i> (Balsamo-Crivelli) Vuillemin (Hypocreales: Clavicipitaceae) and two <i>Metarhizium anisopliae</i> (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) based commercial biopesticides registered in South Africa against other pests, for their efficacy against <i>S. frugiperda</i>. The effects of these EPF formulations were evaluated on larval and prepupal mortality, moth emergence, fecundity, and longevity of the emerged moths. The results indicated that <i>S. frugiperda</i> second- and sixth-instar larvae were not susceptible to the biopesticides. Moth emergence, fecundity, and longevity were not significantly affected. However, prepupae were susceptible to both <i>Metarhizium</i> formulations, with <i>Metarhizium anisopliae</i> ICIPE 78 resulting in the highest mortality (56.7%). This biopesticide holds potential for the management of <i>S. frugiperda</i> when applied to the soil for the control of pupating larvae.