Some of the most popular genetically modified (GM) crops carry the gene for an insecticide which occurs naturally in the soil bacterium Bacillus thuringiensis. GM crops of this kind, called Bt crops, make the insecticide (Bt toxin) in their own tissues.
The idea of growing Bt crops is that you’ll need less insecticide spray. Sounds good, doesn’t it?
But as Susan Jongeneel at AgProfessional tells us, there’s evidence of quite a different reality. Dr Jongeneel describes science by Mike Gray, a University of Illinois professor of agricultural entomology. Prof Gray has found that farmers sowing Bt corn (maize, Zea mays) are actually spraying their Bt corn fields with insecticide to control corn rootworm (Diabrotica spp.) Prof Gray says that one of the reasons why farmers do this is that the pests are becoming resistant to the Bt toxin.
Bt corn, that makes insecticide, needing to be sprayed with insecticide? Yes, that’s what Prof Gray reports.
‘I think it is worth mentioning that one of the key benefits touted concerning the use of Bt hybrids for corn rootworm management was the reduction of soil insecticide use,’ says Prof Gray. ‘It is a bit surprising that 10 years after the first Bt hybrids entered the marketplace for corn rootworms in 2003 that a heightened interest in the use of soil insecticides has surfaced in such a significant fashion.’
I’m grateful to GM Watch for drawing attention to this.