Midgut‐Transgenic Crops ExpressingBacillus thuringiensisCry Proteins

The insecticidal activity of Bacillus thuringiensis (Bt) is due mainly to the presence of the insecticidal crystal proteins (Cry proteins) and vegetative insecticidal proteins (Vips). The evolution of resistance in insect populations represents a serious threat to the continued success of Bt crops. Resistance management strategies attempt to prevent or diminish the selection of the rare individuals carrying resistance genes and hence to keep the frequency of resistance genes below levels that would result in inefficient insect control. Bt sprayable biopesticides are generally regarded as safe for use as biological control agents and are promoted in both organic and integrated pest management (IPM) systems. In view of the specificity of Cry proteins, the effect of Bt crops on most nontarget insects can be expected to be minimal, especially when compared with the effects of broad-spectrum insecticides.