Susceptibility of fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) to natural products and entomopathogenic fungi

Synthetic insecticides have a direct adverse effect on the natural enemies and long-term residual effects causing serious environmental pollution as well. Public awareness of a clean environment increased the attention to developing alternative eco-friendly approaches. The objectives of this study are the detection of the effect of Beauveria bassiana, Metarhizium anisopliae, and natural products of plant-extract origin on the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) under laboratory conditions. The drench-bioassay results showed that mortality of larvae by B. bassiana KACC40224 increased from 10 to 80% as the dose was increased from 10 × 105 to 10 × 109 conidia ml−1. However, mortality by M. anisopliae KACC40029 reached maximally 60% at the dose of 10 × 109 conidia ml−1. All natural-extract products tested against the insect pest were effective, except lavender oil, which caused mortality to vary between 10 and 100%. Rosemary oil was found to be the most effective essential oil, showing 10% to 100% mortality indices at a concentration of 0.1 and 0.2% (v/v), respectively. S. frugiperda eggs tend to be more susceptible to entomopathogenic fungi rather than the larvae. The essential oils exhibited significant insecticidal properties against the larvae of S. frugiperda. This study could help in the development of potential biopesticides for the environment-friendly management of the fall armyworm S. frugiperda pest and emphasize the advantages of entomopathogenic fungi application.