Insect-Resistant Transgenic Crops and Biological Control

Abstract

Natural enemies such as predators and parasitoids fulfil an important ecological and economic function by helping to keep herbivore populations below the economic injury level. Thus, they contribute to sustainable integrated pest management (IPM) systems. It is well established that plant resistance factors that affect herbivores also interact with natural enemies and consequently with the biological control function they provide. Similarly, host plant resistance derived from genetic engineering will have an impact on biological control. There is evidence today that the currently available transgenic crops that express Cry proteins derived from Bacillus thuringiensis (Bt) have no direct effects on natural enemies due to their narrow spectrum of activity. However, the fact that the target pests are efficiently controlled by the deployed Bt crops has inevitable consequences for natural enemies that specialize on these species as hosts or prey. On the other hand, it has become clear that in crop systems where the deployment of Bt varieties has lead to a decline in insecticide use, biological control organisms have benefited significantly. Consequently, this technology can contribute to natural enemy conservation and thus be a useful tool in IPM.