Purdue researcher finds improving honey bee population

WASHINGTON, April 8, 2015 – The honeybee population in Indiana survived the winter in better shape than a year ago, with estimated losses at about 29 percent compared to a mortality rate of about 65 percent after the winter of 2013-2014, according to Purdue University honeybee specialist Greg Hunt.

He estimated bee die-offs based on his primary investigation and discussions with beekeepers, according to a Purdue University press release.

"It seems much better than the year before, even though it was another cold winter," Hunt said.

According to the USDA, honeybee pollination is worth about $15 billion a year in crop production. However, the population has been declining for years, with the U.S. losing about one-third of its hives annually, Hunt said. The number of honeybee colonies in the U.S. dropped from about 4 million in the 1970s to about 2.5 million now, according to some estimates.

The reasons for the bees’ decline aren't entirely clear, Hunt said, although there are likely a number of contributing factors.

The phenomenon known as colony collapse disorder (CCD), a syndrome in which worker bees from a honey bee colony abruptly disappear is still a mystery to scientists, after gaining attention about a decade ago.

“Although colony collapse disorder has generated a lot of attention, symptoms haven't been seen in Indiana or in other states in the past two years," Hunt said.

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A significant danger to the bee population is a parasite known as a varroa mite. The mites feed on bee larva and transmit viruses.Beekeepers who notice too many mites in their hive should use a commercially available pesticide designed specifically to control varroa mites, Hunt said.
 

"The earlier an infestation is identified, the better chance you have of saving the colony," he said.

Replacing a hive that has been lost or damaged by varroa mites or other causes can be expensive and time-consuming, Hunt said. “Normally, the bees are ready to pollinate in mid-May,” he said. “If a beekeeper has to replace a colony, pollination could be delayed until mid-June.”

A class of insecticides called neonicotinoids, commonly used on soybean and corn seeds, has also been identified as a threat. In a 2012 study, Hunt and other researchers found high levels of concentrated neonicotinoids in dead bees around agricultural fields. It is believed the neonicotinoids are absorbed by the talc used in planting and spread to surrounding plants and soil when the talc is released as exhaust from the planting machinery.

Environmental groups are putting pressure on the EPA to rein in agricultural chemical companies on the production and use of neonicotinoids. However, Syngenta, Bayer and Valent U.S.A. commissioned a study from AgInfomatics, which says that if neonicotinoids are banned, growers and horticulturalists will turn to older, more toxic chemicals that must be applied more heavily.

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