Rapeseed was given a dose of genes to induce lethal stomach upsets in beetles and other pests feeding upon the leaves and stalks of other plants. The genes were supposed to produced protease inhibitors, proteins which scramble the process of digestion by interfering with enzymes in the intestinal tracts of insects.

The bee and the rapeseed plant have a very close interaction. While the plant does not depend on the bees to pollinate them it is the first plant to bloom in spring and bees depend greatly on them for nectar. While protease inhibitors were not found in the pollen and nectar of rapeseed plants researchers suspected they could be present at levels too low to detect.

This could lead to their being concentrated in the honey stored in the hive upon which the bees fed.

Researchers exposed captive bees to sugar solutions containing the protease inhibitors, these bees died 15 days earlier than those fed on ordinary sugar. The ability of bees to recognise flower smells was also impaired. This affected cross pollination between plants as normally bees after visiting a particular plant to harvest nectar visit another of the same species. But in this case bees began randomly visiting plants of different species. Obviously the protease inhibitors had thrown a spanner in the works.