Population density of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) and its response to some ecological phenomena in maize crop

Abstract

The fall armyworm [FAW; Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)], is considered a serious invasive pest that poses a serious threat to world food security. It can completely devastate a whole country's cereal crops. Therefore, the present work is the 1st field trial in Egypt to elucidate some ecological aspects of S. frugiperda on maize plants (Single-Hybrid 168 Yellow Corn cultivar) at Esna district, Luxor Governorate, Egypt, throughout two sequential growing seasons of maize (2021-2022). Three insect parameters were used, i.e., egg masses, number of larvae, and percentage of damaged corn plants. Effects of certain climatic conditions and corn plant ages on S. frugiperda seasonal activity and damaged plants percentage were also estimated. S. frugiperda population initiated to attack maize plants from the 3rd week of June until the harvest in every season. S. frugiperda had two seasonal activity peaks in terms of egg masses numbers and three peaks regarding the larval population density/season. Its damage percentage increased with increasing plant age weekly. The mean of S. frugiperda egg masses were 2.83 ± 0.40 and 2.96 ± 0.45 mass /10 corn plants in 2021 and 2022, respectively. While, the overall mean larval populations were 13.41 ± 0.52 and 13.03 ± 0.46 larvae/10 plants, during the two growing seasons, respectively. Corn plant damage percentages reached 68.54 ± 2.71 and 60.42 ± 2.92% in 2021 and 2022, respectively. The combined effects of both the weather conditions and maize plant ages were highly significant on egg masses, larvae population density, and damage percentage, and varied from one season to another. The mean daily maximum temperature was the most effective variable on egg masses and the larval population. Maize plant age had a clear effect on the damage percentage caused by the larvae in the field during the two years of the study. The dramatic spread of FAW and the consequent damage (that appeared in different countries of America, Africa, and Asia) mean that different management approaches must be sought for the small and large-scale producers by using available technologies for smallholder farmers will eliminate pest damage without access to reach to an economic Injury level. This information may assist the decision maker when planning the S. frugiperda IPM program for maize plants and its surveillance.

The Striped Mealybug Ferrisia virgata (Hemiptera: Pseudococcidae)Monitoring and Population Dispersion on Acalypha Shrubs and its Control in Luxor Region, Egypt

“…This rate of increase is considered an indicator of the appropriate time for insect activity and expresses the variation in insect activity throughout the year. When the rate of increase >1 expresses increased activity in this period, <1 expresses a decrease in activity in this period, and = one expresses no variance in activity (Bakry and Fathipour 2023;Bakry and Abdel-Baky, 2023).…”

Biochemical and Histopathological Impacts Induced by the Lethal Toxicity of Chlorpyriphos, Methomyl, and Spinosad against the Fall Armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) in Egypt

“…S. frugiperda recorded its first onset in Western Africa in 2016 (Goergen et al, 2016), and it speedily expanded all over the continent (Prasanna et al, 2018) and resumed extending to Asia (Maino et al, 2021). Because of its widespread, armyworm is currently the most destructive agricultural pest affecting maize in Egypt and other nations Bakry et al (2023).…”

The impact of maize irrigation intervals and potassium fertiliser rates on mealybug populations, vegetative growth, and resulting yield

“…It can be utilised as human food, animal feed, and raw material to manufacture numerous industrial products (Moghazy, 2021). In 2020, 871,076.12 ha of maize were grown in Egypt, with an average productivity of 8.154 Mg•ha -1 (Bakry and Abdel-Baky, 2023).…”