Avoiding Insect Resistance to Cry Toxins from Bacillus thuringiensis

TLDR: Transgenic plants as an alternative to insect control As the world faces a skyrocketing food shortage crisis, the agricultural community is challenged with the task of increasing food production to meet this demand through the use of Bt plants that express insecticidal proteins.

Abstract: Transgenic plants as an alternative to insect control As the world faces a skyrocketing food shortage crisis, the agricultural community is challenged with the task of increasing food production to meet this demand. Because 35% of crops are lost from pest damage due to insects, fungus, bacteria, and viruses, an efficient pest control program is an important component of any effort to increase crop yields. Some of the chemical insecticides currently used to control insect pests are extremely toxic to non-target organisms and often deleterious to human and animal health. They pollute soils and water, since most are recalcitrant to breakdown. In addition, due to the high use of these compounds, many insects have developed resistance to different pesticides. One alternative to chemical insecticides is the use of the Bt plants that express insecticidal proteins. In 2006, more than 32 million hectares were cultivated with Bt crops worldwide1. The insecticidal proteins in these transgenic crops originate from the cry genes of Bacillus thuringiensis (Bt) bacteria. Cry proteins have been classified into 54 groups according to their amino acid sequence. They are highly specific; all show activity against a limited number of susceptible insects. Cry proteins are active against some lepidopteran, coleopteran, or dipteran insects, and a few are toxic to nematodes. Bt corn and Bt cotton produce the Cry1Ab and Cry1Ac proteins, respectively, active against the main lepidopteran insect pests in these crops.