Are insect-resistant crops toxic to ‘non-target’ organisms, like butterflies?

There is mounting evidence that shows that GM crops have no significant adverse effects on non-target organisms. Many studies have confirmed that GM crops containing a common soil bacterium called Bacillus thuringiensis (or 'Bt') is more specific and has fewer side effects than conventional pesticides.

In fact, Bt has been used in organic farming as an alternative to conventional insecticides for almost 60 years.  Two meta-analysis studies in the renowned scientific magazines Science and Nature Genetics looked at the effects of Bt.

They concluded that: 

  • Non-target organisms are generally more abundant in Bt maize fields than in non-transgenic fields managed with insecticides. 
  • Bt crops grown today are more specific and have fewer side effects on non-target organisms than most insecticides currently used. Bt technology can contribute to natural enemy conservation and can be a useful tool in integrated pest management systems.
Bt has a long history of safe use for more than 40 years, including by organic growers: it has long been known that produces proteins that kill specific insect larvae, though it is harmless to other animals and humans. 
Bt maize is an improvement on spraying with Bt insecticide formulations because it provides insect protection much more selectively, without the need for spraying.