Cotton genetically modified to resist crop-damaging insects also protects beneficial bugs, according to a Chinese study that suggests the positive effect may extend into neighboring farms.

Chinese cotton growers were able to cut their use of insecticides that control bollworms after they began planting a crop engineered to make a toxin derived from Bacillus thuringiensis, or Bt, according to a study reported in the journal Nature. The use of fewer chemical sprays allowed the proliferation of insects that feed on crop-damaging aphids, the study said.

The research found the Bt crops also controlled bugs on neighboring farms as more aphid-eating insects such as spiders and ladybugs survived in soybean, peanut and corn fields. The study, based on 20 years of data from northern China, was led by the Chinese Academy of Agricultural Sciences in Beijing.

“The widespread adoption of Bt cotton, as a sustainable measure to reduce insecticide use, has indirectly promoted generalist predator abundance in Bt cotton fields but also to a smaller extent in three common adjacent crops,” according to the study. “Bt crops therefore might enhance biocontrol.”

Bt cotton, approved in 1997, is ChinaΆs only engineered crop authorized for commercial planting. As of last year, about 95 percent of the cotton grown in northern China was genetically modified, according to the report.

Monsanto Co. (MON), the worldΆs largest seed company, said last month itΆs in talks to expand production in China. The St. Louis-based company, which produces Bt crop seeds, also announced a new platform of biological products similar to Bt insecticides that would complement or replace conventional farm chemicals.