COMPARISON OF EAR DAMAGE CAUSED BY CATERPILLAR PESTS IN TRANSGENIC (BT) MAIZE HYBRIDS AND CONVENTIONAL MAIZE HYBRIDS

Aildson Pereira Duarte,Rogério Soares De Freitas,Marcos Doniseti Michelotto,Willians César Carrega

doi:10.18512/rbms2020v19e1099

Abstract

The use of transgenic (Bt) maize hybrids has been an important tool to minimize ear damages caused by the caterpillar pests Helicoverpa zea and Spodoptera frugiperda (Lepidoptera: Noctuidae). The objective of this work was to evaluate ear damages caused by caterpillar pests in maize hybrids with Bt technologies and in their respective conventional versions (non-Bt) for control of caterpillar pests that attack maize ears in the state of São Paulo, Brazil. Experiments were carried out in four regions of the state, in two summer crops (2009/10 and 2010/11), using a randomized block design with 6x2 factorial arrangements. The first factor was the hybrids and the second factor was the use or not of Bt technology. During harvesting, the percentage of damaged ears was evaluated and damage scores were attributed to a sample of 20 ears per plot. It was found that: (i) YieldGard and Total Liberty (both Cry 1Ab), Herculex (Cry 1F), VTPRO (Cry 1A.105 + Cry2Ab2) and Viptera (VIP3Aa20) technologies, regardless of the hybrid and the season crop, significantly reduce the ear damages and the percentage of damaged ears; (ii) hybrids expressing the Cry 1Ab protein are more damaged by caterpillar pests compared with other technologies; and (iii) there is great variability among hybrids when expressing toxins, even among those hybrids with the same Bt event.

Highlights

DANOS OCASIONADOS POR LAGARTAS NA ESPIGA EM HÍBRIDOS DE MILHO TRANSGÊNICOS (Bt) EM COMPARAÇÃO COM SUAS VERSÕES CONVENCIONAIS
Verificou-se que: (i) as tecnologias YieldGard e Total Liberty, Herculex (Cry 1F), VTPRO (Cry 1A.105+Cry2Ab2) e Viptera (VIP3Aa20), independente do híbrido e da safra, reduzem significativamente a porcentagem de espigas danificadas e os danos nas espigas; (ii) os híbridos que expressam a proteína Cry 1Ab são mais danificados pelas lagartas do que em outras tecnologias; e (iii) há grande variabilidade entre os híbridos ao expressarem as toxinas, mesmo entre aqueles híbridos com o mesmo evento Bt
In regard to the percentage of damaged ears and scores for ear damages by caterpillar, a significant difference was verified among the hybrids as to Bt technology

Summary

Introduction

DANOS OCASIONADOS POR LAGARTAS NA ESPIGA EM HÍBRIDOS DE MILHO TRANSGÊNICOS (Bt) EM COMPARAÇÃO COM SUAS VERSÕES CONVENCIONAIS. Resumo – O uso de híbridos de milho transgênicos (Bt) tem sido uma ferramenta importante para minimizar os impactos causados pelas lagartas que ocorrem na espiga, Helicoverpa zea e Spodoptera frugiperda (Lepidoptera: Noctuidae). Santos et al (2016) evaluated the development of the species Helicoverpa armigera (Hubner, 1805) (Lepidoptera: Nocuidae) in maize crop. This pest has been recorded in soybean and cotton crops in Brazil since 2013 (Czepak et al, 2013; Specht et al, 2013). Silva et al (2018) mentioned that the presence of H. zea, S. frugiperda and Euxesta spp. was one of the main causes of maize yield losses. In the 2016/17 crop season, the use of transgenic maize presented an adoption rate of 88.4%; being 63.9% cultivated with IR/HT (insect resistant and herbicide tolerant) events, 20.7% with maize resistant to insects only, and 3.8% with technology tolerant to herbicide only (Céleres, 2018)

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