Functional Response and Intraspecific Competition in the Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

Functional responses of the fall armyworm (FAW) larvae at each stage, and their intraspecific competition associated with cannibalism, provide insights into developing pest management strategies for the FAW. To help use insecticides more sparingly, the functional response and intraspecific competition of the FAW larvae were evaluated under the laboratory conditions. The results showed that all stages of the FAW larvae displayed a type II functional response to diet. Based on Holling’s disc equation, the search rate (a) and handling time (Th) of sixth instar larvae (a = 0.493; Th = 0.37 min) were the highest, and the shortest of all larval stages, respectively. Intraspecific competition curves fitted the data for fourth to sixth larval stages of the FAW, and the coefficient of intraspecific competition (m) assessed by the intraspecific competition equation were highest for fifth instar larvae (m = 0.48). The present study indicates that 5th and 6th instar larvae can cause the most plant damage (accounted for 88.9% of larval consumption), and these stages should be the focus of any pest management strategy. Intraspecific competition, especially cannibalism, impacts the feeding patterns of the FAW larvae and needs close attention. Understanding the functional response and intraspecific competition of the FAW larvae contributes greatly to practical applications of insecticides, increasing the effectiveness of chemical sprays and decreasing ecological damage.

Leaf Damage Based Phenotyping Technique and Its Validation Against Fall Armyworm, Spodoptera frugiperda (J. E. Smith), in Maize

“…Therefore, the rating recorded at 14 DAI provides actual host plant and insect pest interaction reflecting the complete leaf damage caused due to FAW and also the response of the host plant against the FAW infestation. Moreover, the feeding rate of earlier instars (First and second) is very less (Ren et al, 2020 ) and this might be the reason for the low rating of 7 DAI. The released neonate larvae become fourth to fifth instar feed heavily by the time when data are taken at 14 DAI resulting in higher damage.…”

Toxicity of Bioactive Compounds of Strychnos pseudoquina (Loganiaceae) in Spodoptera frugiperda (Noctuidae)

“…Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous pest known as the fall armyworm that, during its larval stage, can attack more than 353 plant species of 76 families, including economically important crops such as maize, soybean, cotton, sorghum, and wheat [1]. Despite its being predominantly found in Latin American countries [2], studies have shown occurrences in African and Asian countries and, more recently, in Australia [1,3].…”

Invasion of fall armyworm Spodoptera frugiperda, a new invasive pest, alters native herbivore attack intensity and natural enemy diversity

“…In Africa, the infestation of S. frugiperda can affect the native biodiversity by reducing both native insect pests and other insect communities (Sokame et al 2021b;Sokame et al 2021a). Larvae of S. frugiperda have the ability to compete (intraspecies competition) and predate other larvae (cannibalism) (Chapman et al 2000;Ren et al 2020). S. frugiperda larvae can also reduce the larvae of other lepidopteran pests through interference competition and predation (Wiseman and McMillian 1969;Song et al 2021).…”