The Present and Future Role of Insect-Resistant Genetically Modified Maize in IPM

Abstract

Commercial, genetically-modified (GM) maize was first planted in the United States (USA, 1996) and Canada (1997) but now is grown in 13 countries on a total of over 35 million hectares (>24% of area worldwide). The first GM maize plants produced a Cry protein derived from the soil bacteriumBacillus thuringiensis (Bt), which made them resistant to European corn borer and other lepidopteran maize pests. New GM maize hybrids not only have resistance to lepidopteran pests but some have resistance to coleopteran pests and tolerance to specific herbicides. Growers are attracted to the Btmaize hybrids for their convenience and because of yield protection, reduced need for chemical insecticides, and improved grain quality. Yet, most growers worldwide still rely on traditional integrated pest management (IPM) methods to control maize pests. They must weigh the appeal of buying insect protection "in the bag" against questions regarding economics, environmental safety, and insect resistance management (IRM). Traditional management of maize insects and the opportunities and challenges presented by GM maize are considered as they relate to current and future insect-resistant products. Four countries, two that currently have commercialize Bt maize (USA and Spain) and two that do not (China and Kenya), are highlighted. As with other insect management tactics (e.g., insecticide use or tillage), GM maize should not be considered inherently compatible or incompatible with IPM. Rather, the effect of GM insect-resistance on maize IPM likely depends on how the technology is developed and used. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. , 1996) and Canada (1997) but now is grown in 13 countries on a total of over 35 million hectares (>24% of area worldwide). The first GM maize plants produced a Cry protein derived from the soil bacterium Bacillus thuringiensis (Bt), which made them resistant to European corn borer and other lepidopteran maize pests. New GM maize hybrids not only have resistance to lepidopteran pests but some have resistance to coleopteran pests and tolerance to specific herbicides. Growers are attracted to the Bt maize hybrids for their convenience and because of yield protection, reduced need for chemical insecticides, and improved grain quality. Yet, most growers worldwide still rely on traditional integrated pest management (IPM) methods to control maize pests. They must weigh the appeal of buying insect protection "in the bag" against questions regarding economics, environmental safety, and insect resistance management (IRM). Traditional management of maize insects and the opportunities and challenges presented by GM maize are considered as they relate to current and future insect-resistant products. Four countries, two that currently have commercialize Bt maize (USA and Spain) and two that do not (China and Kenya), are highlighted. As with other insect management tactic...

Pest resistance to Cry1Ab Bt maize: Field resistance, contributing factors and lessons from South Africa

“…This emphasises the fact that GM crops should not be seen and used in isolation from other pest management measures. GM crops expressing insecticidal proteins should be integrated into IPM strategies of which the primary elements include host plant resistance, cultural control, biological control and limited use of insecticides (Hellmich et al, 2008).…”

Decomposition dynamics and structural plant components of genetically modified Bt maize leaves do not differ from leaves of conventional hybrids

“…Hybrids expressing Cry1 proteins have been commercialized to control stem-boring Lepidoptera, and Cry3-expressing hybrids are protected against corn rootworms (Coleoptera: Chrysomelidae). Bt maize provides substantial benefits, e.g., decreased yield losses to pests, reduced need for insecticides, and improved food safety due to lower levels of mycotoxins (Hellmich et al 2008). …”

Eliminating host-mediated effects demonstrates Bt maize producing Cry1F has no adverse effects on the parasitoid Cotesia marginiventris

“…It has become one of the most serious pests of corn throughout the Americas (Ashley et al 1989;Kumar and Mihm 1996). In 2001, Herculex I Ò (Cry1F) maize was commercially planted in the United States and targeted Lepidoptera, including S. frugiperda (Hellmich et al 2008). Cry1F maize has been shown to substantially reduce losses by S. frugiperda in many areas (Buntin et al 2004;Siebert et al 2008).…”