Camille Ulve; Pioneer Genetique, Chemin de l'Enseigure, F - 31840 Aussonne, France

Corn rootworm is a major insect pest of maize in many regions of the world. Corn rootworm feeding can cause lodging, reduced drought tolerance and crop yield reductions. Western corn rootworm (Diabrotica virgifera virgifera, Le Conte) is one of the main rootworm species that can cause economic damage The primary methods for controlling corn rootworm populations, including Western Corn Rootworm (WCR) are crop rotation and insecticide application. However, some populations of corn rootworm have adapted to both of these commonly used management strategies.

In the near future another management option for rootworm control could be provided to growers: Transgenic rootworm-resistant maize-hybrids.

Pioneer Hi-Bred and Dow Agrosciences are currently conducting extensive research to discover and incorporate corn rootworm resistant gene technologies into maize plants.

A new binary (two-gene) protein toxin system from Bacillus thuringiensis has been discovered and identified as showing excellent efficacy to control Western corn rootworm larvae . These proteins are designated as 149B1 proteins. Researchers at Pioneer are studying the mode of action of these specific proteins.

To evaluate the best 149B1 events, several experiments were planted in 1999 at various locations in the USA. Plots were infested with 1,000 eggs per V2 plant to mimic heavy WCR infestation levels. Transgenic inbreds were compared with insecticide treated (e.g. Counter®,  Force®) and untreated controls.

The first results based on Pioneer Corn rootworm rating showed most of 149B1 events exhibited excellent WCR control over the untreated and insecticide treated controls.

If all development and regulatory challenges could be met, Pioneer could possibly have WCR-resistant products on the U.S. market for by 2002 products.

(Counter® is a trademark of Cyanamid, Force® is a trademark of Zeneca)