Integrating plant volatile scents in sustainable IPM approaches for fall armyworm control

Authors: KOFFI, DJIMA - University Of Lome; AGBOKA, KOMI - University Of Lome; ADJEVI, M.K.A. - University Of Lome; TOUNOU, K.A. - University Of Lome; Meagher Jr, Robert

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2025
Publication Date: 6/9/2025
Citation: Koffi, D., Agboka, K., Adjevi, M., Tounou, K., Meagher Jr, R.L. 2025. Integrating plant volatile scents in sustainable IPM approaches for fall armyworm control. Journal of Applied Entomology. https://doi.org/10.1111/jen.13458.
DOI: https://doi.org/10.1111/jen.13458

Interpretive Summary: Fall armyworm is a worldwide pest of several agricultural crops. In west Africa, it has been infesting crops since 2016 and mostly affects corn yields. Initial control measures were predominately the use of insecticides, however, recent research has looked at low cost, environmentally-friendly practices to control this pest. Researchers with the Université de Lomé, Lomé, Togo, in collaboration with a scientist with the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, conducted field studies in Togo to assess the effects of placing corn plants next to essential oil plants. These plants naturally release volatile scents that can repel moths and caterpillars. The plants used included several grasses and basil plant species. Although no significant difference was observed in the number of egg masses found on corn plants, fewer caterpillars were found on corn plants that were next to lemon grass, camel grass, African basil, and lemon basil. Larvae from corn plants next to lemon grass and lemon basil had higher parasitism rates. Overall, the number of damaged corn plants was lower next to lemon grass and lemon basil plant rows. The conclusion of the study was that lemon grass and lemon basil plants when arranged next to corn plants reduced fall armyworm damage, and there were no side-effects of the presence of these essential oil plants on the numbers of natural enemies of the pest.

Technical Abstract: Since the invasion of the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) into new regions, studies have oriented toward low-cost management tools and methods. This study assessed the effects of volatile scents that are naturally emitted by essential oil (EO) plants on the severity of FAW and populations of its natural enemies. Plants of Cymbopogon citratus, C. nardus, C. schoenanthus (Poales: Poaceae), Mesosphaerum (Hyptis) suaveolens, Ocimum gratissimum, O. citriodorum, and O. basilicum (Lamiales: Lamiaceae) were planted alongside maize during three on-station experiments. Egg mass and larval densities, damaged leaves and plants, damage scores, and abundance of parasitoids and predators were assessed on maize plots. Although no significant difference was observed for egg masses, maize plants next to C. citratus, C. schoenanthus, O. gratissimum, and O. citriodorum recorded the lowest larval densities. However, percent damaged plants and damage scores were lower on maize plants next to C. schoenanthus and O. citriodorum, and larvae collected from maize next to these plants recorded the highest parasitism rates. These two plants were also among the four treatments that recorded the highest parasitism of egg masses. The natural enemies included one egg parasitoid, one egg-larval parasitoid, three larval parasitoids, and seven species of predators. Plant age was negatively correlated with egg mass and larval densities, and parasitism rates were positively correlated with egg mass and larval densities. Although C. schoenanthus and O. citriodorum plants reduced FAW severity, no side-effects of the presence EO plants was recorded on numbers of natural enemies of the pest.