BT Maize and IPM in Europe

For the last 15 years, genetically engineered (GE) crops have been grown on an ever increasing area worldwide, reaching 148 million hectares in 2010. The majority of these crops carry genes that provide resistance against specific herbicides or certain insect pests, or both properties. Compared to the global area of biotech crops, Europe is playing a minor role with less than 100,000 hectares of insect resistant maize (mostly in Spain) and less than 250 hectares of potato with modified starch production (in Germany, Sweden and the Czech Republic) in 2010. Insect-resistance in commercial GE plants is achieved by the insertion of genes from the bacterium Bacillus thuringiensis (Bt) that encode for the production of insecticidal crystal (Cry) or vegetative (Vip) proteins, which in turn cause the mortality of target pests. Microbial Bt products have a long history of safe use as insecticides mainly in organic agriculture because of their narrow spectrum of activity. The most important crop transformed with Bt genes is maize. In the European Union, Spain has been leading commercial production of Bt maize. Portugal, the Czech Republic, Poland, Slovakia, and Romania follow with much smaller areas. In this article, the authors present the major pests in European maize production, how they are controlled in conventional agriculture, benefits and limitations of growing Bt maize, and what role Bt maize can play in integrated pest management (IPM) systems. Bt maize is a highly specific and highly efficient pest control measure that allows growers to produce high quality grain with reduced insecticide inputs and fewer farm operations. Despite higher seed prices and administrative requirements to fulfil licence agreements, Bt maize growers in areas with high pest pressure have generally been able to increase their gross margin considerably. In consequence, the non-authorisation of Bt maize results in foregoing economic benefits for growers in several European countries. Whenever Bt maize replaces broad spectrum insecticides, ecological benefits are evident because valued non-target organisms remain unaffected. However, potential increases in populations of secondary pests and resistance evolution in populations of target pests are risks for the sustainability of Bt maize that require appropriate management plans (refuges, enhancement of natural enemies) and close monitoring. In an IPM context, Bt maize is one highly specific tool, which efficiently solves the main pest problem and allows combination with other preventive or responsive measures to solve problems including biological control of other maize pests.