Delaying resistance of corn insect pests to Bacillus thuringiensis biocontrol: mode of action of new Bt products

点击翻译按钮获取中文摘要

Bacillus thuringiensis (Bt) bacteria produce a large variety of insecticidal proteins that are active against caterpillars, beetles and other pest insects. Contrary to chemical insecticides, Bt bio-insecticides are specific to target insects, are harmless to humans and other vertebrates, and are environment- and biodiversity friendly. Bt toxins are intestinal poisons. Insect pests that live and feed on above-the-ground plants can be destroyed by available Bt commercial preparations sprayed on accessible plant parts. However, pests that attack the plant roots or bore into, feed, and tunnel within other parts of plants cannot be reached by spraying. An efficient solution to this problem is provided by transgenic plants in which Bt genes are inserted so that the toxins are expressed in the plants (Bt-crops), rendering them resistant to insect pests. Bt-crops have been widely adopted in 29 nations, including Canada, which ranks 5th, with over 10 million hectares of transgenic canola, corn, soybean and sugar beet crops planted in 2011. However, insect pests may become resistant to this strategy with time and particular agricultural practices. Therefore, careful insect resistance management programs have to be designed and implemented. In-depth scientific knowledge on the biology of plants, pests and their environment, and on the mechanisms of Bt toxicity is critical to the success of preventing or delaying the onset of resistance of pests to Bt. This collaborative research and development grant proposal addresses the problems of corn rootworm control by Bt and development of corn rootworm resistance to Bt. This pest causes major economic damages to corn crop (over one million dollars losses annually in North America). The aim of the project is to elucidate, in partnership with Dow AgroSciences Canada Inc., the mechanisms by which a group of the company's Bt toxins destroy this pest. It is expected that this research partnership will help providing Canada with new Bt-based insect-resistant plants. These will be better targeted and less susceptible to elicit resistance of the target insects to Bt, the most successful biological control tool in the integrated pest management tool box.