Impact of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) infestation on maize growth characteristics and yield loss

Abstract The fall armyworm [FAW; Spodoptera frugiperda (J.E Smith, 1797)] is an invasive and polyphagous insect that infests cereal crops, causing economic losses, and may be led to pose a threat to future the global maize crop in the future. Field trials were conducted to study the negative impacts of S. frugiperda on vegetative growth measurements, yield, and the components of the maize cultivar (Single-Hybrid 168 Yellow) in Luxor Governorate, Egypt. S. frugiperda larvae infestation to maize plants was observed in the 3rd week of June and so continued till the harvest in both 2021 and 2022 seasons. S. frugiperda had three peaks of the seasonal activity/season in the untreated (pesticide-free, control) and in the treated main plots by pesticides. Maize vegetative growth attributes (averages of plant height, stem diameter, and the number of green leaves per plant) displayed higher rates of the treated maize plants by insecticides against S. frugiperda. Maize grain, straw, and biological yield (kg/ha) were decreased in the untreated maize plants (insecticides free) than in the treated by insecticides. Concerning maize yield components, the treated plants were to outperform in the average length of a plant stem (cm), stem diameter (cm), and weight of cob (g), as well as, number of rows/cob, number of grains/ cob, number of grains/cob, maize cob grain weight (g) and weight of 1000-grains (g)], in comparison with the untreated plants. Also, the FAW infestation to untreated maize plants was decreased well in all calculated maize growth attributes, i.e., grain yield, and components. Regarding the relationship between variations in a given variable and the changes in S. frugiperda larvae numbers and plant damage percentage, the simple correlation and regression coefficient revealed a highly significant negative relationship in all the parameters tested. The obtained information may help farmers and decision-makers in the management of FAW populations based on an effective plan related to control measures that should be implemented.