Contact toxicity, Electrophysiology, Anti-mating and Repellent effects of Piper guineense against Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda (J. E. Smith) 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 in the management of S. frugiperda , but they leave residues on human food and animal feed and also cause environmental hazards. Assessing the toxicity of plant extracts on S. frugiperda may offer a more effective control which can reduce the excessive use of synthetic insecticides. We evaluated the crude ethanolic extract of Piper guineense fruits for contact toxicity on S. frugiperda larvae and determined the lethal concentration (LC ₅₀ ) of the extract. Additionally, we conducted electrophysiological (EAG) experiment to determine the responses of male and female adult S. frugiperda to P. guineense extract. We also determined whether the extract influenced mating, oviposition and repellence to adult female S. frugiperda. 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 extracts than control, with some variations in response between the sexes. When checking the repellent effect of P. guineense extract on adult S. frugiperda females in a wind tunnel, we found that females moved more towards the control than towards the extract. Taken together, our results confirm P. guineense extract as a potent extract that could be incorporated in the integrated management of S. frugiperda. Future research should explore the responses of S. frugiperda to P. guineense extract on a field scale.