Mon, 10 Jun 2013 09:40 CDT
More pest species are becoming resistant to the most popular type of genetically-modified, insect-repellent crops, but not in areas where farmers follow expert advice, a study said on Monday.
The paper delves into a key aspect of so-called Bt corn and cotton -- plants that carry a gene to make them exude a bacterium called Bacillus thuringiensis, which is toxic to insects.
Publishing in the journal Nature Biotechnology
, US and French researchers analysed the findings of 77 studies from eight countries on five continents that reported on data from field monitors.
Of 13 major pest species examined, five were resistant by 2011
, compared with only one in 2005, they found. The benchmark was resistance among more than 50 percent of insects in a location.
Of the five species, three were cotton pests and two were corn pests.
Three of the five cases of resistance were in the United States, which accounts for roughly half of Bt crop plantings, while the others were in South Africa and India.