Field Studies Assessing Arthropod Nontarget Effects in <I>Bt</I> Transgenic Crops: Introduction

Abstract

TEN YEARS AGO THE Þrst crops modiÞed through genetic engineering to produce novel in-plant protectants became commercially available in the United States. Since that time, the adoption and use of crops with built-in resistance to lepidopteran and coleopteran insect pests and tolerance to certain herbicides has grown rapidly in both industrial and developing countries worldwide. By 2004, 17 countries had adopted transgenic crops ranging from corn and cotton producing insecticidal proteins of Bacillus thuringiensis Berliner (Bt) to corn, cotton, soybean, and canolacontaining genetic constructs conferring tolerance to the herbicides glyphosate or glufosinate. It is estimated that in 2004, 81 million hectares of transgenic crops were cultivated in these 17 countries, the United States leading the way with 47.6 million hectares (James 2004). In 2004, 32% of the Þeld corn and 46% of the upland cotton acreage in the United States was planted with genetically modiÞed cultivars producing one or more Bt toxins (USDA 2004). The rapid and widespread adoption of transgenic crops in the United States and elsewhere has prompted extensive debate over multiple issues related to human safety and environmental risk. The putative environmental risks that have been articulated include outcrossing of nontransgenic plants through pollen drift, horizontal transfer of transgenes to unrelated organisms, loss of susceptibility to Bt toxins in target pests, disruption of ecosystem processes, and direct or indirect effects on nontarget organisms and biodiversity. There has been equal discourse expounding the potential beneÞts associated with the use of transgenic crops in agricultural production systems, including signiÞcant reductions in use of conventional, broad-spectrum insecticides, improved suppression of target pests, improved yields, reductions in production costs leading to increased proÞtability, and increased opportunities for biological control. Governmental agencies such as the U.S. Environmental Protection Agency (EPA) in the United States require toxicological testing of a limited number of representative nontarget organisms as one component of the commercial registration process for transgenic crops producing insecticidal proteins. However, there have been calls by research advisory groups (e.g., National Research Council, EPA-FIFRA ScientiÞc Advisory Panels) and private advocacy groups for