Assessment of risks to non-target organisms of the cultivation of GM crops that express one or more Bt toxins

When an application is made to cultivate a genetically modified (GM) crop, an assessment must be made of the effects this GM crop could have on non-target organisms. Non-target organisms are all the organisms present in the field, with the exception of the pest organism against which the introduced trait in the GM crop is directed. If it is plausible that an inserted gene could have an adverse effect on non-target organisms, information must be provided to permit an assessment of the possible risks to these organisms.

GM crops are made resistant to certain insect pests by introducing genes from the bacterium Bacillus thuringiensis that code for Bt toxins. The trend is now for GM crops to contain several inserted genes that code for different Bt toxins. This raises new questions for the risk assessment that has to be made on applications for the cultivation of such crops, because there may be synergistic interactions between the Bt toxins which could cause non-target organisms that are not affected by the individual toxins to be susceptible to the combined toxins.

To obtain information about any synergism between the many different Bt toxins in preparation for writing this report, COGEM carried out a literature study and organised a symposium on this topic in cooperation with a number of international sister organisations. The insights obtained from that study and the symposium form the basis for the guidance presented by COGEM in this report for assessing the risks to non-target organisms of the cultivation of GM crops that express multiple Bt toxins.