What Defines a Host? Oviposition Behavior and Larval Performance of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Five Putative Host Plants

Abstract

When an invasive species first breaches quarantine and establishes in yet another country, it invariably causes consternation for growers, in part because of incomplete understanding of the plants that are at risk. The Fall Armyworm, Spodoptera frugiperda (J.E. Smith) is the most recent example in Australia. The number of plants that this polyphagous noctuid is reported to attack is vast, including many crop species. Consequently, initial reactions from grower industry groups that perceived themselves at risk were to demand emergency use of insecticides. Yet the field evidence suggests that many crops might not be at risk and since S. frugiperda arrived in Australia, maize crops have suffered most damage, followed by sorghum. We question the accuracy of some of the claims of reported host plants of S. frugiperda and report experiments that compared oviposition behavior, neonate silking behavior, and larval performance on five crops: the known hosts maize and sorghum, and the putative hosts cotton, peanut, and pigeon pea. Maize ranked highest in all preference and performance measures, followed by sorghum and peanut, with pigeon pea and cotton ranking lowest. Although S. frugiperda can survive, develop, and pupate on the crop species we examined, cotton and pigeon pea are not preferred by the pest in either the larval or adult stages. We suggest that before a plant is listed as a host for a given insect that the evidence should be fully reported and carefully evaluated. Collecting an immature insect from a plant does not make that plant a host!

Dispersal Behavior Characters of Spodoptera frugiperda Larvae

“…In contrast, on a vertical plane, when the corn plant is in the vegetative growth stage, most larvae tend to crawl upward along the stalks and congregate on the upper tissues or reproductive organs of the corn plant. These observations are consistent with the study results of Sparks [ 15 ] and Volp et al [ 46 ]. FAW larvae prefer to feed on the mesophyll of the upper leaves, and when these leaves more fully develop and open, they present the characteristic pattern of paired holes, which is considered a key feature for identifying FAW damage [ 6 , 7 , 10 ].…”

Night Warming Has Mixed Effects on the Development of the Fall Armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae), in Southern China

“…From a genomic analysis of SNPs and gene sequences of 318 S. frugiperda moths collected from 13 provinces, researchers concluded that the S. frugiperda strain that invaded China was derived from “rice-strain” female parent and “corn-strain” male parent [ 9 , 10 ]. Most field populations have been recorded on maize and other Poaceae, as has been found in Africa [ 11 ], India [ 12 ] and Australia [ 6 ]. Some 83% of FAW moths trapped on Yongxing island had fed on C4 plants such as maize, and not rice [ 13 ].…”

The efficacy of Tephrosia vogelii and Azadirachta indica leaf extract combinations against fall Armyworm, Spodoptera frugiperda, in Maize.

“…The brightest part of the day is when larvae tend to hide (Rojas et al, 2004). The larvae stage lasts for around 14 days in the summer and 30 days in the cooler months (Volp & Myron, 2022). Typically, pupation occurs in the earth, 2 to 8 cm below the surface.…”