Susceptibility of Various Developmental Stages of the Fall Armyworm, Spodoptera frugiperda, to Entomopathogenic Nematodes.

Rajendra Acharya,Yeon-Su Yu,Md Munir Mostafiz,Kyeong-Yeoll Lee,Hwal-Su Hwang

doi:10.3390/insects11120868

Abstract

Simple SummaryThe fall armyworm, Spodoptera frugiperda, native to Central and South America, has recently invaded Africa and Asia, causing serious economic damage to various crops. The chemical control of fall armyworm is not effective due to the development of pesticide resistance as well as environmental contamination. Alternatively, biological control using natural enemies can be used successfully in a sustainable way. Entomopathogenic nematodes are soil-dwelling natural enemies for many underground pest insects including lepidopteran caterpillars. This study evaluates the virulence of several entomopathogenic nematodes on different developmental stages of fall armyworm. We found that all the larval and pupal stages of fall armyworm were highly susceptible to the entomopathogenic nematodes. Our study provides important information of entomopathogenic nematodes for the practical application of biological control of fall armyworm.The fall armyworm, Spodoptera frugiperda, which is native to Central and South America, has recently invaded Africa and Asia, causing serious damage to various crops. Although management to date has been largely unsuccessful, entomopathogenic nematodes (EPNs) are a potential biological control agent that could be used to control the late larval and pupal stages of S. frugiperda that dwell under the ground. Here, we compared the virulence of seven EPNs against larval and pupal stages of S. frugiperda. In a Petri dish assay, both Heterorhabditis indica and Steinernema carpocapsae were highly virulent against younger larvae, whereas S. arenarium and S. longicaudum were highly virulent against older larvae. In contrast, H. bacteriophora, Heterorhabditis sp., and S. kushidai showed low virulence against all larval stages. In soil column and pot assays, H. indica, S. carpocapsae, and S. longicaudum were highly virulent against late larval and pupal stages compared with the other EPN species. Thus, H. indica, S. carpocapsae, and S. longicaudum are recommended for the biological control of S. frugiperda. Our study provides important information of EPNs for the practical application of biological control of fall armyworm.

Highlights

In second-instar larvae, 100% mortality was caused by H. indica, S. carpocapsae, and S. longicaudum, whereas S. arenarium and H. bacteriophora caused 77% and 53% mortality, respectively, at 48 h post-treatment; Heterorhabditis sp. and S. kushidai did not cause any mortality
In third-instar larvae, 100% mortality was obtained with H. indica, S. arenarium, S. carpocapsae, and S. longicaudum at 72 h post-treatment; H. bacteriophora caused 63%
The present study showed that three entomopathogenic nematodes (EPNs) species, namely H. indica, S. carpocapsae, and S. longicaudum, were highly lethal to S. frugiperda pupae, whereas S. kushidai was not effective

Summary

Introduction

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), native to Central and South America, was introduced into Africa in 2016 and rapidly spread into Asia, reaching Korea and Japan by 2019 [1,2,3,4]. The current S. frugiperda strains in Africa mostly infest corn crops, in which they reduce the yield by up to 57% [8]. Various pesticides have been applied in an attempt to control S. frugiperda in the environment. Chemical control has not been efficacious because S. frugiperda has developed resistance to commonly used insecticides such as lambda-cyhalothrin, chlorpyrifos, spinosad, and lufenuron [9,10,11]

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