Test systems to determine the ecological risks posed by toxin release from Bacillus thuringiensis genes in crop plants


  • Paul Jepson is a senior lecturer at Southampton University and directs the Ecotoxicology Research Group and Agrochemical Evaluation Unit: he has a special interest in the ecotoxicological effects of agrochemicals on beneficial invertebrates. Brian Croft is a Professor in the Entomology Department at Oregon State University and directs a program of research into pest management, especially of phytophagous mites. Grahame Pratt works with Brian Croft at Oregon State University on an EPA-sponsored programme of research into the development of test systems for the toxic effects of transgenic plants gene products.

Biology Department, Southampton University, Bassett Crescent East, Southampton S09 3TU, UK. Fax 0703 594270.


Procedures for the selection of species for ecotoxicological risk assessment of Bacillus thuringiensis (Bt) gene products in the epigeal and hypogeal environments are proposed. Although species can be selected on the basis of ecological realism and functional importance, the number of organisms requiring testing and the nature of the test procedures remain uncertain with such a selectively toxic material. The heterogeneity of the soil environment, the stratification of plant material at different stages of breakdown and decomposition and the aggregation and patterns of movement of the soil fauna and flora impose problems for the design of ecologically relevant test methods. Similarly, the impact upon beneficial invertebrates, if toxic effects are detected, will be mediated by the scale and pattern of transgenic plant release in the fragmented agricultural landscape. To properly assess the ecological risks posed by a widely released toxin with a narrow spectrum of effects, a combination of laboratory tests, field experiments and longer-term monitoring will be required.