Pesticides Suspected in Mass Die-Off of Bees

By Eryn Brown (Los Angeles Times) 3/29/12

Two studies show that a class of chemicals known as neonicotinoids created disorientation among bees and caused colonies to lose weight, which may have contributed to a mysterious die-off.

Scientists have identified a new suspect in the mysterious die-off of bees in recent years — a class of pesticides that appear to be lethal in indirect ways.

The chemicals, known as neonicotinoids, are designed to target a variety of sucking and chewing insects, including aphids and beetles. Bees are known to ingest the poison when they eat the pollen and nectar of treated plants, though in doses so tiny that it was not seen as a threat.

But two reports published online Thursday by the journal Science indicate that the pesticides are not altogether benign. One study found that bumblebee colonies exposed to amounts of the insecticide similar to what they'd encounter in the wild gained less total weight than colonies that weren't exposed. Another study used miniature radio frequency chips to track honeybees and found that the pesticide impaired their ability to navigate back to the hive after a feeding expedition.

"If it's blundering around and can't return to the hive ... the bee might as well be dead," said Christian Krupke, an entomologist at Purdue University in West Lafayette, Ind., who was not involved in either study.

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