Pesticides and mites are among the leading causes of honey bee colonies decline
The number of US honey bee colonies are continuing to decline, the most recent yearly study by the US Department of Agriculture on honeybee health revealed. Specifically, the survey indicated that the number of honey bee colonies nearly halved in the past year.
The study, funded by the U.S. Department of Agriculture (USDA), was conducted by the Bee Informed partnership and the Apiary Inspectors of America between April 2015-April 2016. The initiative gathered data supplied by both large-scale and small-scale beekeepers, the so-called backyard beekeepers, who manage less than 50 honeybee colonies.
According to the survey, the number of US bees in large-scale, commercial colonies decreased by 8.1 percent to 2.59 million in 2015. Overall, US beekeepers who participated in the yearly study lost 44 percent of their colonies during the period under survey. During the previous study year (2014-2015), loss rates were lower and stood at 40.6 percent.
While in wintertime bees’ numbers usually decline, what concerns scientists is the rate of decline in the number of honey bees registered in the summer months. According to Bee Informed Partnership project director Dennis vanEngelsdorp, the drop in honey bees’ numbers over the summer months is a matter of “serious concern”, as it happens for the second year in a row. In the previous study year, summer loss rates went up from 25.3 percent to 28.1 percent, while winter loss rates had an even sharper increase, from 22.3 to 28.1 percent.
Research shows that the leading causes of the decline in the number of honey bee colonies are multifold. Firstly, the large-scale use of pesticides and changes in land use patterns leads to malnutrition and affects commercial honey bee colonies the most. Secondly, the spread of mites has also been listed as a major culprit, with the varroa mite being particularly damaging to bee colonies. The varroa mite, which is linked to numerous viruses, was found to be much more abundant than previously thought. In particular, many small-scale beekeepers are vulnerable to the mite, because they do not yet have a varroa control strategy in place.
The current study is the tenth to record winter losses and the sixth to feature summer loss rates as well as total losses of honey bee colonies.
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