U.S. honeybee numbers continue to drop, according to two new studies, with scientists blaming mite infestations while the pace of the phenomenon known as colony collapse disorder accelerated in the first quarter.
The number of commercial U.S. honeybee colonies declined 8.1 percent to 2.59 million in 2015, according to the U.S. Department of Agriculture’s first-ever honeybee health survey released last week. Beekeepers needed to replace 44 percent of all their hives last year to maintain insects pollinating almonds, apples and other key crops, according to a separate study published May 10 by a group of researchers.
Honeybees pollinate about $15 billion worth of crops annually, according to the USDA. Environmental groups have expressed alarm over the 90 percent decline during the past two decades in the population of pollinators, from wild bees to monarch butterflies. Some point to a class of pesticides called neonicotinoids as a possible cause, a link rejected by Bayer AG and other manufacturers.
“There’s no question that exposure to agrochemicals is a risk factor for honeybees, but there are a lot of very complicated issues in science,” said Robert Sears, president of the Eastern Missouri Beekeepers Association in St. Louis.
In the USDA study, beekeepers who owned at least five colonies, or hives, reported the most losses from varroa mites, a parasite that lives only in beehives and survives by sucking insect blood. The scourge, present in the U.S. since 1987, was reported in 43 percent of commercial hives between April and June last year.
Losses due to colony collapse disorder — a malady first isolated amid a spike in bee death rates a decade ago — increased over the past year, the USDA said. About 114,000 colonies were lost the first three months of this year, compared with 92,000 in the same period in 2013.
The Bee Informed Partnership study — a collaboration between the USDA, the University of Maryland and other research and beekeeper groups — showed bee mortality during one year at 44 percent, the second-highest level ever and almost triple the normal rate seen until roughly a decade ago.
