It’s getting harder and harder for Bayer to continue to deny the link between neonicotinoids and bee decline, especially with this new study from Harvard. Unlike the “facts” from Bayer — which claims insecticides are perfectly harmless when it comes to bees — Harvard scientists have used actual field studies to come to their conclusions. Mother Jones called the report a “smoking gun” that targets the neonics imidacloprid and clothianidin as causes of Colony Collapse Disorder.
The study tracked the progress of 18 hives beginning in July 2012. Twelve hives were fed sublethal amounts of pesticides via sugar syrup over 13 weeks, and the other six hives were kept as controls. According to the report, all 18 hives exhibited similar behavior throughout the summer months, but during the winter, bees from six of the 12 contaminated colonies failed to return to their hives, demonstrating classic behavior of CCD. On the other hand, none of the control hives displayed signs of CCD, but one showed symptoms of nosema.
What’s exciting about this study is scientists were able to replicate Colony Collapse Disorder through the experiment. Previous tests — like the ones cited by Bayer — have just occurred in laboratories and often only focused on bees in one stage of life. The Harvard study actually administered the insecticide to full colonies from July through September and monitored their response.
However, it could be said that the sample size in this latest study was too small. Jeff Pettis from the USDA said an 18-colony study was too small to confirm the link between neonicotinoids and CCD.
Bayer, interestingly, did not take issue with the sample size, but instead claimed the amount of neonics fed to the hives was “10 times” what honey bees would normally encounter in nature. The experiment used 0.74 micrograms of insecticide per bee per day over the 13 weeks. This was calculated by estimating the summer colonies to contain 50,000 bees on any given day. To put this in perspective, the Mother Jones article adds that a grain of table salt weighs in at 64,800 micrograms.
The study aimed to mimic how honey bees used for commercial pollination are thought to encounter neonicotinoids — via high fructose corn syrup that sustains the bees as they’re trucked around the country. According to Chensheng Lu, the lead author of the Harvard study, because the neonics are systemic pesticides, they are absorbed into the plant tissue and remain in the kernels that are processed to make syrup.
The Center for Environmental Health interviewed Lu last year about his initial look into the effects of neonics. In the interview, Lu also points out that CCD does not appear to be caused by a perfect storm of factors — such as additional pesticides, disease and pests — as the EPA and Bayer are citing. Instead, he says the proof that neonics cause CCD can be found in the timeline of when neonicotinoids were first intorduced, and when the first incident of CCD occurred — both around 2005.