Transgenic Plants for the Control of Insect Pests

Abstract

Insects have always been a major cause of yield loss in agriculture. Many approaches have been used with varying degrees of success to reduce losses caused by insect damage. Natural resistance to insects that provides reasonable protection from some insect pests is available in some crops. Plant breeding can move these resistances into different crop varieties; however, this is frequently a difficult and time-consuming procedure. For other plants, resistance to a given insect pest is not present in the current gene pool of a particular crop. In such instances, breeding alone cannot provide protection against insect damage. Insecticides have been quite successful in reducing crop losses caused by insects. Most insecticides currently used are chemicals, but there are successful biological insecticides, notably microbial sprays using the bacterium Bacillus thuringiensis (Bt). Resistance to chemical insecticides has occurred in several insect species. Management of such resistance remains a challenge, and new methods of controlling such species are needed. The need to control insect pests in agriculture will always exist. As new tools become available, they will be integrated into the pest management system. The ability to introduce new genes into a crop species provides the opportunity to introduce new insect control genes into a crop’s gene pool. Once introduced, the new trait can be moved into the other varieties of that crop using traditional breeding. To introduce a new trait into a crop, several components are required: a transformation system for the target crop, a gene encoding an insecticidal protein active against an insect pest of the target crop, and expression of the introduced gene(s). The ability to transform crop species varies from crop to crop, as do effective ways of obtaining insecticidal levels of expression of the introduced gene(s). Various proteins have been identified as possessing insecticidal activity. These proteins include protease inhibitors, α-amylase, lectins, and insecticidal proteins from Bacillus species. The proteins produced by the Bacillus species possess the most potent insecticidal activities. Some of these proteins, therefore, have been worked with for several years to produce insect-resistant plants. The