Factors Influencing Expression of Antixenosis in Soybean to Anticarsia gemmatalis and Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

This study aimed to evaluate some factors that influence the expression of antixenosis in soybean genotypes against Anticarsia gemmatalis Hübner and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Free-choice and no-choice feeding assays were performed with the resistant soybean genotype IAC 100 and the susceptible genotype BRSGO 8360 using A. gemmatalis and S. frugiperda larvae. The following factors that may affect expression of resistance were evaluated: one larva versus two larvae per leaf disc; use of larvae without prior feeding suspension versus larvae starved for 3 h prior to the assay; leaf discs versus entire leaflets; upper part versus lower part of the plant; and, vegetative versus reproductive growth stages. The level of resistance exhibited by the genotype IAC 100 was high enough to not be obscured by the effects of all factors assayed in the present study upon the feeding preference of A. gemmatalis and S. frugiperda larvae. However, our results demonstrate the importance of knowing the optimal conditions for conducting an assay for evaluating resistance of genotypes for specialist and generalist insect species. Utilization of two larvae of A. gemmatalis per leaf disc, not starved before the assays, with leaf discs from the upper part of plants at the reproductive growth stage provided better discrimination of differences in antixenosis expression in soybean genotypes. For S. frugiperda, use of one larva per leaf disc, not starved before the assays, with leaf discs from the lower part of plants at the reproductive growth stage gave more satisfactory results for feeding preference tests.

Soybean defense induction to Spodoptera cosmioides herbivory is dependent on plant genotype and leaf position

“…as soon as they are synthesized by metabolic processes throughout plant development (Panda and Kush 1995). Upon preparation of leaf discs with a cork borer, rupture of cells or organelles storing the secondary metabolites probably occurred, resulting in their release and thereby greater exposure to insects during the course of the bioassay (Boiça Júnior et al 2015b). Effects were less pronounced in entire leaflets than leaf discs probably because larvae must first disrupt the structures storing defensive secondary compounds prior to being in contact with them.…”

<b>Effect of the flavonoid rutin on the biology of <i>Spodoptera frugiperda</i> (Lepidoptera: Noctuidae)

“…Spodoptera frugiperda is a polyphagous species that infests cotton (Campos, Boiça-Júnior, Valério Filho, Campos, & Campos, 2012;Jesus, Boiça Junior, Alves, & Zanuncio, 2014), rice, millet, sorghum (Busato et al, 2004), soybean (Boiça Junior, Souza, Neves, Ribeiro, & Stout, 2015) and other crops. In Brazil, one of the factors that contribute to failures in the control of S. frugiperda is the large number of hosts caused by the succession of crops with different phenologies (Sá, Fonseca, Boregas, & Waquil, 2009;Barros, Torres, & Bueno, 2010).…”

Antixenosis to Chrysodeixis includens (Lepidoptera: Noctuidae) among soybean genotypes

“…It is important to emphasize that although several studies related to the development and/or preferences of the Noctuidae insect family have been performed for soybeans Boiça Júnior et al 2015), there are no studies specifically concerned with the attractiveness of C. includens in relation to the genotype 'IAC 100' , which demonstrates the importance of the present research. Recent studies have identified 'IAC-100' as a good progenitor candidate for breeding intended to generate promising lineages that exhibit both insect resistance characteristics and high productivity (Maia et al 2009).…”