Western corn rootworm now in Germany

Found primarily in North America, the Western corn rootworm (Diabrotica virgifera virgifera) has also been spreading within Europe over the past 15 years thanks to modern means of transport. The pest first appeared in 1992 near Belgrade airport and from there spread across south-east Europe as far as Poland. In Western Europe it appeared in isolated pockets over the following years, especially in the vicinity of airports: near Venice airport in 1998, in Paris in 2002, in Brussels in 2003, and in Maastricht in 2005. The latest occurrence in Lahr is also in the vicinity of an airport.

It is the beetle’s larvae that are feared most of all because they feed on the maize roots and cause the most damage. In the first two larval stages, the larvae eat the fine roots, while in the third stage, they penetrate the primary roots and stems, thereby severely restricting the uptake of water and nutrients and weakening the plants’ stability. The adult beetles feed on plant parts above the ground and fly to other fields, resulting in the pest spreading further afield.

The damage caused by the Western corn rootworm is immense. Yield losses and the costs for fighting the beetle are estimated to amount to around a billion dollars a year in the USA, which has earned the beetle the name "billion-dollar bug". In Europe the figure is expected to reach around half a billion euros in the long term.

In October 2003 the European Commission decided on minimum measures to prevent the pest spreading in Europe, including setting up safety zones, applying soil insecticides and – the preferred measure – changing the crop rotation. Maize is no longer allowed to be planted on the same field two years in succession. Traps have been set in Bavaria and Baden-Württemberg since 1997 in expectation of the pest, so that its arrival will be spotted early. It is in one such trap primed with an attractant that the beetle has now been found.

Biosafety research is also investigating Diabrotica

A whole range of BMBF-funded biosafety research projects are currently investigating the potential ecological consequences of genetically modified maize that is resistant to the Western corn rootworm. Like the familiar concept with resistance to the European corn borer , these genetically modified maize plants produce a Bt toxin that specifically targets the Western corn rootworm.

In the USA, MON863 Diabrotica-resistant Bt maize was first authorised in 2003 and has since been planted on over two million hectares. MON863 is also authorised in Europe, but not for cultivation. Since August 2005 it has been possible to import MON863 into the EU and to use it as feed. It has been authorised for use as food since January 2006.