European corn borers and western corn rootworms: Old and new invasive maize pests challenge farmers on european and North American continents

Since the early 1990s, maize producers in Europe and North America have shared management challenges with two formidable insect foes: the European corn borer (Ostrinia nubilalis Hübner) and the western corn rootworm (Diabrotica virgifera virgifera LeConte). Although considerable progress has been made in the management of European corn borer via the use of commercially available maize hybrids that offer some degree of conventional host plant resistance, the deployment of resistant (antibiosis) alleles in maize for corn rootworm has been disappointing. Producers in the United States have relied largely upon crop rotation and the prophylactic use of soil insecticides in an effort to prevent economic losses caused by corn rootworm larvae. In some areas of the western Corn Belt, an over reliance on insecticides to suppress egg laying by corn rootworm adults has led to the development of insecticide resistance to methyl-parathion and carbaryl. Since the mid-1990s, the non-diversified agroecosystem of the US eastern Corn Belt has led to the development of a variant western corn rootworm that is able to circumvent the cultural management tactic of rotating maize and soybean. The integration of many management strategies (IPM) is critical in prolonging the usefulness of individual control tactics for both of these important insect pests of maize. The receptiveness to transgenic hybrids by producers on each continent remains strikingly different. Although we believe transgenic hybrids offer producers yet another management tool to deploy within an IPM framework for European corn borers and western corn rootworms, they should not be viewed as the ultimate solution for either species. Like all insects, these two pests are versatile and will adapt to any technology if it is abused.