A pest-eating ladybug attacks an aphid.
As angry debates about genetic modification continue, GM crops are quietly going about their business—and producing some positive side effects. In China, with Bt cotton reducing the need for insecticides, pest-eating bugs have rebounded and brought natural pest control with them.
China’s genetically modified cotton is not new. Farmers used to spray their cotton with a protein, naturally produced by the Bacillus thuringiensis (Bt) bacteria, which is toxic to certain insects. As research into genetically modified crops advanced, scientists implanted the cotton itself with the Bt genes that code for production of the insect toxin, creating so-called “Bt cotton” and alleviating the need for the sprayed insecticide. Since China approved its use in 1997, Bt cotton has proved itself particularly effective against the cotton bollworm moth, reducing the costs and side effects of spraying pesticides, but it has had may also decrease the number of non-pest insects compared with organic fields.
With the advent of Bt cotton, pesticide use became specialized, only affecting insects that both were vulnerable to Bt’s toxin and that fed on cotton, which allowed the populations of other insect species to rebound. Some of the now-thriving species, like mirids, are pests, but others eat pests, and their recovery is making natural bug control possible.