We agree with Obrycki et al. (2001) that a broad-based ecological approach for new pest management technologies is desirable, but we unanimously and strongly disagree with some of their assumptions and conclusions about Bt corn. Bt corn is corn that has been genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis. Because Bt corn is important for effective and ecologically sound management of lepidopteran pests of corn,we provide here relevant data, some of which is new, to help clarify the issues raised by Obrycki et al. (2001). Obrycki et al. (2001), citing Barry and Darrah (1991), claim that traditional plant breeding has developed corn plants that adequately protect against European corn borer. However, Barry and Darrah (1991) reported only “some resistance to whorl leaf feeding...[or] some resistance to sheath and sheath collar feeding,” which is not comparable with the nearly complete protection provided by Bt corn. Carpenter and Gianessi (2001) estimated that, nationally, during “10 of the 13 years between 1986 and 1998, European corn borer infestations...were such that corn growers would have realized a gain from planting Bt corn.” Similarly, the Environmental Protection Agency (USEPA 2000) estimated a net benefit to growers of $8.18 per hectare on 8 million hectares of Bt corn planted in 1999, or a national benefit of $65.4 million (USEPA 2000). Even considering the inherent year-to-year variability in pest population density, the EPA estimated the annual benefit to corn growers at $38–$219 million (USEPA 2001).
Available at: http://works.bepress.com/gary_munkvold/78/