GM Bt Cotton and Aphids - Law of Unintended Consequences

Recent field trials seem to have confirmed that BT cotton has had some unintended outcomes with aphids proliferating, and damaging cotton crops.

It seems that the Bt gene has prevented production of natural plant defence chemicals which are stimulated by caterpillar attacks on the plants, and these chemicals in turn deter aphids.

The story is more complex but the link provides a reasonably neat summary.

http://www.enn.com/top_stories/article/45830

Up until recently it seemed that the GM cotton story was one that generally had been a very successful option with pesticide use reducing substantially on Bt cotton varieties.

It is not totally clear if economic damage is occurring but it does seem likely that aphids are now a pest in some situations and in some areas.