The Environmental Effects of Genetically Modified Crops Resistant to Insects

Abstract

Efeitos Ambientais de Culturas Geneticamente Modificadas Resistentes a InsetosRESUMO -Cultivares transgênicas de várias culturas estão sendo utilizadas em escala comercial em muitos países. A área dedicada ao cultivo com plantas transgênicas resistentes às pragas em todo o mundo alcançou 13 milhões de hectares em 2001. As cultivares transgênicas proporcionam benefícios, mas também apresentam riscos potenciais. As avaliações do seu impacto no ambiente são conduzidas antes da sua aprovação para uso comercial, como requerido pelas normas de biossegurança. Nesta revisão, serão discutidas as conseqüências ecológicas potenciais do uso comercial na agricultura de cultivares geneticamente modificadas que apresentam resistência aos insetos-pragas. Também serão discutidos os impactos ambientais causados pelas mudanças nas práticas agrícolas, identificando-se falhas e oportunidades de pesquisa, considerando-se essa nova ferramenta tecnológica. Os comentários e análises serão baseados no conhecimento atual que se tem dos riscos e beneficios do uso de cultivares resistentes a insetos, geneticamente modificadas, dentro do contexto dos programas de manejo integrado de pragas tradicionais. PALAVRAS-CHAVE: Planta transgênica, Bacillus thuringiensis, organismo não-alvo, fluxo gênico, biossegurança ABSTRACT -Transgenic crops are currently being cultivated on a commercial scale in many countries. The area devoted to transgenic pest resistant varieties worldwide reached 13 million hectares in 2001. These varieties offer valuable benefits but also pose potential risks. Assessments of their impact on the environment are conducted before they are approved for commercial use, as required by the regulatory biosafety frameworks. In this review, we discuss the potential ecological consequences of the commercial use in agriculture of genetically modified insect resistant crops. We also discuss the impacts caused by the change in agricultural practices, and attempt to identify gaps and possible opportunities for research, considering this new technological tool. We based our analysis and comments on the current knowledge of the risks and benefits of these genetically modified insect resistant crops, within the context of traditional insect management strategies.KEY WORDS: Transgenic crop, Bt gene, non-target organism, gene flow, biosafety affect the environment (Dale et al. 2002). The discussions on GM pest resistant crops in many parts of the world has led to questions about their potential impacts on biodiversity, particularly on their effects on non-target organisms, including insect herbivores and natural enemies, and soil microbiota. Further concern arises from the possibility of resistance development in insect pests, which could endanger important natural resources such as the bacterium Bacillus thuringiensis Berliner, a natural microbial insecticide. Another issue frequently cited as a potential risk of pest resistant GM crops is the possible movement of the inserted gene from crops to wild or weedy relatives, and the consequences of...

Perkembangan Pradewasa dan Kemampuan Hidup Predator Verania lineata Thurnberg (Coleoptera: Coccinellidae) pada Tanaman Padi Varietas Rojolele Transgenik

“…Isu yang sering menjadi perdebatan adalah pengaruhnya terhadap biodiversitas, terutama organisme bukan sasaran, termasuk serangga herbivor bukan sasaran, musuh alami, dan mikrobiota tanah. Isu lainnya adalah serangga yang berkembang menjadi tahan dan perpindahan gen yang diinsersikan dari tanaman ke tanaman liar atau gulma (Fontes et al 2002;Naranjo 2005).…”

“…Tanaman transgenik dapat mempengaruhi musuh alami melalui tiga cara yaitu: (1) langsung makan pada jaringan tanaman transgenik seperti polen, akar; (2) makan pada inang yang makan pada tanaman transgenik; dan (3) melalui pengurangan populasi inang (Losey et al 2004;O'Callaghan et al 2005). Menurut Dutton et al (2003) dan Fontes et al (2002), pengaruh tanaman transgenik terhadap musuh alami dapat terjadi secara langsung maupun tidak langsung. Pengaruh langsung disebabkan oleh pengaruh toxin secara langsung terhadap musuh alami.…”

Genes cry de Bacillus thuringiensis aplicados na engenharia genética de plantas, conferindo resistência a insetos-praga

“…Mandaokar et al (2000) Tabela 1. Vegetais modificados com genes cry de B. thuringiensis, resistentes a insetos-praga de importância agrícola (adaptado de Fontes et al, 2002). Para a avaliação dos riscos em organismos não alvo, uma série de testes é realizada em laboratório visando determinar se o organismo em questão é susceptível à toxina nas condições mais adversas.…”

Tritrophic Effects in Bt Cotton

“…Bt toxin is an insecticide-albeit ecologically softer than most inorganic insecticides-but it is ever present, and this has ecosystem-level consequences that need investigating (Obrycki, Losey, Taylor, & Jesse, 2001). Proposals are in place for pyramiding Bt toxins (Stewart et al, 2001) and developing plantexpressing Bt exotoxins and other biotechnologies (inhibitors of digestive enzymes, digestive protease, alfa-amylase, lectins, herbicide resistance, disease resistance, and environmental stress tolerance; Fontes, Pires, Sujii, & Panizzi, 2002). This is reminiscent of the past misuse of insecticide mixtures to solve emerging and poorly understood pest problems and could lead to a biotechnology treadmill.…”