Bayer CropScience has reviewed the study for publication in the June issue of the Bulletin of Insectology regarding imidacloprid’s supposed impact on honey bee colony health. According to the company, the study is factually inaccurate and is seriously flawed, both in its methodology and conclusions.
Although the study claims to have established a link between imidacloprid and bee colony collapse, the symptoms observed in the study bees are not consistent with, or even remotely similar to, those of Colony Collapse Disorder (CCD). As such, the authors’ claims that their study explains the causes of CCD are incorrect.
Additionally, the authors assume erroneously that the majority of corn grown in the United States has been treated with imidacloprid. In actuality, over the past 8 years, the annual percentage of total corn acres in the U.S. treated with imidacloprid has been less than half a percent. Thus, the suggestion that imidacloprid is affecting honey bee health via residue found on corn or through corn products is also grossly inaccurate.
The study’s additional flaws include the following:
- The imidacloprid concentrations selected for testing were NOT based on measured residues in high fructose corn syrup (HFCS), but on a series of implausible and unsubstantiated assumptions.
- The study bees were fed HFCS spiked with different levels of imidacloprid that were far above real-world exposure levels.
- In separate research, analysis from actual field grown corn samples, have shown no detectable imidacloprid residues in HFCS.
- The study lacked replication of test colonies within apiaries and the total number of colonies per treatment group were too few to allow a meaningful statistical analysis of colony survival.
- The authors ignored the scientific consensus that bee health is impaired by multiple factors, including inadequate diet, pests and parasites such as the varroa mite, microbial diseases, mismanaged colonies, and loss of genetic diversity.
Imidacloprid and neonicotinoid insecticides, generally, remain safe and effective management tools to control a wide range of destructive insect pests. Throughout the many years that imidacloprid has been commercially available and used, there has been no credible scientific evidence demonstrating a link between this active ingredient – or other neonicotinoids – and increases in honey bee colony losses and declining honey bee colony health. This latest study is no exception.
All new bee research involving bee health is welcome and great care should be taken to avoid sweeping, unsupportable conclusions based on artificial and unrealistic study parameters that are wildly inconsistent with actual field conditions and insecticide use.