The latest study revealed that Bee Hives which were exposed to low doses of two neonicotinoid pesticides—imidacloprid and clothianidin were not able to recover from winter losses while the control hives quickly recovered. The study also discounted the other causes of CCD which has been advanced like diet, parasites, and pathogens. The latest study adds one more impeccable proof that clearly links sub lethal exposure neonicotinoid pesticides to rapid bee declines nationwide.
The above mentioned study was conducted in central Massachusetts during the 2012-2013 winters at three different locations with six bee colonies in each location. A third of the colonies were exposed to small doses of the pesticide imidacloprid, another third were exposed to the pesticide clothianidin, both neonicotinoids while the rest of the bees were not exposed to any pesticide. The colonies at each apiary were divided into two groups and were fed with either sucrose water or high-fructose corn syrup (HFCS) over the study period.
During the winter, as expected the honey bees declined in all the 18 colonies according to the seasonal pattern. However by January the untreated hives started to recover while the population of the honey bees in the treated hives continues to decline. By April all the treated hives were empty because the bees had abandoned them, a symptom typical of CCD. The untreated hives were once again repopulated with new emerging bees.
The results of the latest studies once again reaffirmed the earlier conclusions of other studies related to imidacloprid that sub lethal exposure to neonicotinoids is a primary cause of CCD, and the role of mites and pathogens were minimal.