Two widely used pesticides appear to be making honeybees abandon their hives during inopportune seasons, a new study suggests.
According to the study, published in the Bulletin of Insectology, a pair of neonicotinoids - a type of insecticide popular in developed countries - appears to be directly related to the collapse of honeybee colonies over cold winter seasons.
You may be familiar with the plight of the world's honeybees, even if you found out about it just because of the ever-increasing price of pure honey. The total population of these insects appears to be declining, despite efforts to protect them from the effects of climate change - one of the original factors theorized to be behind an increasing number of failed hives. Other studies have revealed a recent influx of flower pollen transmitted diseases which can destroy a hive from the inside out.
Researchers are mostly finding that Colony Collapse Disorder (CCD) is causing the largest number of honey bee deaths. CCD is a mysterious behavioral problem that appears to make bee colonies descend into chaos during the worst season for the insects to be active, winter. During the winter seasons, a colony affected with CCD will dissolve, with the hive's workers leaving the hive, only to die in an unforgiving environment.
United States beekeepers have reported seeing this unusual phenomenon since 2006, soon after initial honeybee populations began to drop. However, the cause of this phenomenon is still unknown.
Some scientists have determined that CCD can be caused by invasive mites, which can destroy a hive, essentially evicting the honeybees in the process. However, the US National Pesticide Information Center, has also linked the phenomenon to potential pesticide exposure.
Now, researchers from the Harvard School of Public Health have discovered that exposure to even low dose neonicotinoids have a 50 percent chance to lead to CCD. This was determined after researchers exposed 18 colonies in three locations to either the pesticide compound or a control substance.
Six of the 12 colonies treated with neonincotinoids developed CCD by the winter, resulting in an average 94 percent mortality rate for each hive.
According to lead author of the study Chensheng Lu, he believes these findings concretely associate the insecticides with CCD. However, why this happens remains unclear.
"Future research could help elucidate the biological mechanism that is responsible for linking sub-lethal neonicotinoid exposures to CCD," Lu said in a related press release.
The study was published in the Bulletin of Insectology on May 9.