Respostas da lagarta‑do‑cartucho a milho geneticamente modificado expressando a toxina Cry 1A(b)

Abstract

Resumo -O objetivo deste trabalho foi avaliar parâmetros biológicos da lagarta-do-cartucho do milho (Spodoptera frugiperda), alimentada com híbridos de milho Bt, que expressam a toxina Cry 1A(b), e com seus respectivos isogênicos não Bt. Os experimentos foram realizados no laboratório da Embrapa Milho e Sorgo, em Sete Lagoas, MG. Os parâmetros avaliados foram: sobrevivência de larvas após 48 horas, sobrevivência da fase larval e pré-imaginal, biomassa de larvas aos 14 dias de idade, biomassa de pupas, período de desenvolvimento larval, e não preferência alimentar de larvas do primeiro ínstar. Larvas de S. frugiperda apresentam menor sobrevivência nas primeiras 48 horas de alimentação e durante toda a fase larval, na maioria dos híbridos de milho Bt, em comparação ao milho não Bt. A biomassa de larvas e pupas foi sempre menor no milho Bt, e o período larval e o pré-imaginal, maior. Houve interação entre a toxina Cry 1A(b) e a base genética dos híbridos transgênicos, quanto à sobrevivência e à biomassa larval. Larvas recém-eclodidas de S. frugiperda apresentam preferência pela alimentação em milho não Bt.Termos para indexação: Spodoptera frugiperda, manejo de resistência de insetos, manejo integrado de pragas, resistência de plantas, transgenia. Fall armyworm responses to genetically modified maize expressing the toxin Cry 1A(b)Abstract -The objective of this work was to evaluate biological parameters of maize fall armyworm (Spodoptera frugiperda) fed with Bt maize hybrids expressing the Cry 1A(b) toxin, and with its isogenic non-Bt hybrids. The experiments were carried out in the laboratory of Embrapa Milho e Sorgo, Sete Lagoas, MG, Brazil. The parameters evaluated were: survival of larvae after 48 hours, survival of larval and preimaginal phases, larvae biomass at 14 days of age, pupae biomass, larval development period, and feeding non-preference of first instar larvae. Larvae of S. frugiperda show less resistance in the first 48 hours of feeding and during the entire larval phase in most Bt maize hybrids, in comparison to non-Bt maize. The biomass of larvae and pupae developed in Bt maize was always smaller, and the larval and preimaginal period were longer. There was interaction between the Cry 1A(b) toxin and the genetic base of the transgenic hybrids regarding survival and larval biomass. Newly hatched S. frugiperda larvae show preference for feeding on non-Bt maize.

Toxicidad sobre Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) de la proteína Bt expresada en hojas de diferentes eventos de maíz transgénico iberados en Paraguay

“…En este trabajo; larvas de S. frugiperda alimentadas con Fórmula TL™ presentaron mayor duración del estadio con relación al híbrido convencional. Mendes et al, (2011) en estudios con S. frugiperda concluyeron que la etapa larval es mayor en los insectos alimentados con maíz Bt.…”

Diversity of insects under the effect of Bt maize and insecticides

“…Several studies have been carried out to evaluate the effect of genetically modified maize on pest insects (MENDES et al, 2011;VOJTECH et al, 2005) and on non-target organisms, both under laboratory MENDES et al, 2012) and under the field conditions (CANDOLFI et al, 2004;LOPEZ et al, 2005;FERNANDES et al, 2007). However, few studies have evaluated the effect of genetically modified maize on the insect community (CANDOLFI et al, 2004;ROSE;DIVELY, 2007).…”

Resistência de híbridos de milho convencionais e isogênicos transgênicos a Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…Toxins Cry1A(b) and Cry1F have activity on lepidopteran maize pests and have high specificity for this group, although toxicological studies reveal significant differences in toxicity for each species. Mendes et al (2011) evaluated biological parameters of fall armyworm fed Bt maize hybrids expressing Cry1A(b) toxin, and their respective non-Bt isogenic, observed an interaction between the toxin Bt Cry1A(b) and the genetic basis of transgenic hybrids as to the survival and larval biomass of S. frugiperda. There are little information regarding the use of Bt technology and different events with other toxins in brazilian's conditions; there is a need for further field studies to evaluate the efficacy of Bt technology compared to non-Bt commercial hybrids (Omoto et al, 2012).…”