First posted on 05-25-2012
Links between pesticides and honeybee health continue. Researchers at the University of California San Diego discovered that even small doses of a common crop pesticide turned bees into finicky eaters, and inhibited their ability to communicate food sources to the rest of the hive.
Bee colonies throughout the world have been decimated by colony collapse disorder since 2006. North American and European beekeepers report losses of up to one third of their managed colonies as a result of the disorder, the cause of which is not yet known. Recent research points to pesticides as one potential culprit, with both beekeepers and research teams focusing on specific pesticides called “neonicotinoids.”
The San Diego researchers concentrated their study on imidacloprid, a chemical in the neonicotinoids family that was banned in some European countries, but is still in use in the United States.
“In 2006, it was the sixth most commonly used pesticide in California and is sold for agricultural and home garden use,” said James Nieh, who headed the research project. “It is known to affect bee learning and memory.”
Nieh and his team introduced imidacloprid to honeybees in a small, single dose, comparable to what a bee would ingest along with nectar in the field. The bees became picky with regard to their feeding habits. They refused nectar with lower sweetness and fed only on nectars with high sugar content.
To make matters worse, the team discovered that bees that ingested imidacloprid danced and waggled less, which means those bees were not communicating food sources to other members of the hive. In bee talk, the number of waggle dances performed is a good indication of the quality of the nectar or food supply. The colony determines the number of worker bee resources to invest in the food source based on those waggles.
“Remarkably, bees that fed on the pesticide reduced the number of their waggle dances between fourfold and tenfold,” said Nieh. “And in some cases, the affected bees stopped dancing completely.”
Those undesirable traits—selective with nectar sources and failure to convey messages—drastically reduce the available nectar resources for the hive so that fewer food resources are available to the colony.
“Exposure to amounts of pesticide formerly considered safe may negatively affect the health of honey bee colonies,” Nieh said.
The scientist went on to explain that this research has broad implications as to how pesticides are applied, and which pesticides to avoid near bee-pollinated crops.
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