Beekeepers across the US lost more than 40 per cent of their honey bee colonies between April 2014 to April 2015, according to a survey led by the University of Maryland. For the first time on record, summer losses eclipsed winter losses.
“We traditionally thought of winter losses as a more important indicator of health, because surviving the cold winter months is a crucial test for any bee colony,” said Dennis vanEngelsdorp of the University of Maryland. “But we now know that summer loss rates are significant too. This is especially so for commercial beekeepers, who are now losing more colonies in the summertime compared to the winter. Years ago, this was unheard of.”
The survey, which is conducted each year, asked commercial and small-scale beekeepers to track the health and survival rates of their honey bee colonies. This year’s respondents reported a total loss of 42.1 per cent of their colonies over the course of the year. Winter loss rates decreased from 23.7 per cent to 23.1 per cent, but summer losses jumped from 19.8 per cent to a staggering 27.4 per cent.
Among small-scale or backyard beekepers (those who manage fewer than 50 colonies), the varroa mite – a lethal parasite that easily spreads between colonies – was the clear culprit behind the losses. The causes for commercial beekeepers, who were particularly prone to summer losses, are less clear, explained vanEngelsdorp.
“The winter loss numbers are more hopeful especially combined with the fact that we have not seen much sign of Colony Collapse Disorder (CCD) for several years, but such high colony losses in the summer and year-round remain very troubling,” said Jeffery Pettis from the U.S. Department of Agriculture .
The survey is part of a larger research effort to understand why honey bee colonies are in such poor health, and what can be done to manage the situation. Colony losses can lead to shortages among crops that depend on honey bees as pollinators, such as almonds.