Predicting the ecological impacts of transgenes for insect and virus resistance in natural and feral populations of Brassica species

Oilseed rape is now widely grown in the UK. Nearly 400 000 ha were planted in 1990, compared with only 50 000 ha in 1978 [1]. There is concern that transgenes may be able to escape from cultivated oilseed rape, either by the formation of feral populations that arise from spilled seed [2, 3], or by gene flow into related wild species (including B. oleracea) [4, 5]. This paper describes research to help predict whether transgenes for insect or virus resistance (two of the commonest genetically modified stress-tolerance traits [6]) will increase the weediness of feral and wild Brassica populations in the UK. We also consider resistance to herbivory by molluscs (although we know of no genetic modifications for mollusc resistance) because slugs and snails are common herbivores of Brassica species.