Contact Toxicity, Electrophysiology, Anti-Mating, and Repellent Effects of Piper guineense Against Spodoptera frugiperda (Lepidoptera: Noctuidae).

Abstract

The fall armyworm, Spodoptera frugiperda, is a long-distance migratory pest, which invaded the African continent in 2016, causing enormous losses to agricultural crops, especially maize. Synthetic insecticides are primarily used for managing S. frugiperda, but they leave residues on human food and animal feed and also cause environmental hazards. We evaluated the crude ethanolic extract of Piper guineense fruits for contact toxicity on S. frugiperda larvae and determined the lethal concentration (LC₅₀) of the extract. Additionally, we conducted an electrophysiological (EAG) experiment to determine the responses of adult S. frugiperda males and females to P. guineense and determined whether the extract influenced mating, oviposition, and repellence to the adult female. We found that P. guineense extract caused significantly higher mortality to S. frugiperda larvae than an ethanol control. Electrophysiologically, we observed significantly higher responses to the extract than the control, with some variations in response between the sexes. A wind tunnel experiment revealed that females moved more towards the control than towards the extract. Taken together, our results confirm that P. guineense extract is effective against S. frugiperda larvae and adults. Future research should explore the responses of S. frugiperda to P. guineense extract on a field scale.