Though you may have read otherwise, numerous studies from China, Spain and the United States have have found that the biodiversity of insects and related arthropods is not reduced by genetically modified (GM) rice, cotton, or maize fields.
A new study from South Africa published in Environmental Entomology shows similar results, that biodiversity is the same as that among conventional crops.
A total of 8,771 arthropod individuals, comprising 288 morphospecies, were collected from 480 plants sampled from Bt maize and non-Bt maize fields over a two-year period. The researchers found no significant differences in abundance or diversity in detritivores, herbivores, predators, or parasitoids.
"The aims of the study were to compile a checklist of arthropods that occur on maize in South Africa and to compare the diversity and abundance of arthropods and functional groups on Bt maize and non-Bt maize," the authors wrote. "Results from this short-term study indicated that abundance and diversity of arthropods in maize and the different functional guilds were not significantly affected by Bt maize, either in terms of diversity or abundance."
"The results of our study indicate that arthropod diversity, even in high-input farming systems, is as high as in subsistence farming systems" said Dr. Johnnie van den Berg, a professor at North-West University and one of the co-authors of the article. "More recently, surveys of arthropod and plant beta-diversity inside and adjacent to maize fields have been completed during which 30,000 arthropods and 15,000 plant individuals were surveyed along a 1,000 kilometer transect. It seems that maize field diversity is homogenized and field margins had a high beta diversity," he added.