{"id":7438,"date":"2012-05-25T00:47:17","date_gmt":"2012-05-25T04:47:17","guid":{"rendered":"https:\/\/www.beyondpesticides.org\/dailynewsblog\/?p=7438"},"modified":"2012-05-25T00:47:17","modified_gmt":"2012-05-25T04:47:17","slug":"research-shows-imidacloprid-depresses-honey-bee-feeding-and-communication","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2012\/05\/research-shows-imidacloprid-depresses-honey-bee-feeding-and-communication\/","title":{"rendered":"Research Shows Imidacloprid Depresses Honey Bee Feeding and Communication"},"content":{"rendered":"

(Beyond Pesticides<\/em>, May 25, 2012) Biologists at the University of California at San Diego (UCSD) have discovered that a small dose of the commonly used neonicotinoid crop pesticide imidacloprid<\/a> turns honey bees into \u201cpicky eaters\u201d and affects their ability to recruit their nestmates to otherwise good sources of food. The results of the experiments, detailed in this week\u2019s issue of the Journal of Experimental Biology<\/em> (abstract<\/a>), shed light on one of the main culprits suspected to be behind the recent declines in honey bee colonies and detail the particular ways that the substance impedes the functions of the colony. <\/p>\n

Since 2006, beekeepers in North America and Europe have lost about one-third of their managed bee colonies each year due to \u201ccolony collapse disorder.\u201d While the exact cause is unknown, researchers believe pesticides have contributed to this decline. One group of crop pesticides, called \u201cneonicotinoids,\u201d has received particular attention from beekeepers and researchers. Neonicotinoids<\/a>, including clothianidin<\/a> and thiamethoxam<\/a>, in addition to imidacloprid, are highly toxic to a range of insects, including honey bees and other pollinators. They are taken up by a plant\u2019s vascular system and expressed through pollen, nectar and gutation droplets from which bees forage and drink. They are particularly dangerous because, in addition to being acutely toxic in high doses, they also result in serious sublethal effects when insects are exposed to chronic low doses, as they are through pollen and water droplets laced with the chemical as well as dust that is released into the air when treated seeds that have been coated with the chemicals are planted. Previous<\/a> research<\/a> has shown<\/a> that these effects cause significant problems for the health of individual honey bees as well as the overall health of honey bee colonies, including disruptions in mobility, navigation, feeding behavior, foraging activity, memory and learning, and overall hive activity.<\/p>\n

The UCSD biologists focused this particular study on imidaclprid, which has been banned for use in certain crops in some European countries and is being increasingly scrutinized in the United States. \u201cIn 2006, it was the sixth most commonly used pesticide in California and is sold for agricultural and home garden use,\u201d said James Nieh, PhD, a professor of biology at UCSD who headed the research project with graduate student Daren Eiri, the first author of the study. \u201cIt is known to affect bee learning and memory.\u201d<\/p>\n

The two biologists found in their experiments that honey bees treated with a small, single dose of imidacloprid, comparable to what they would receive in nectar, became \u201cpicky eaters.\u201d \u201cIn other words, the bees preferred to only feed on sweeter nectar and refused nectars of lower sweetness that they would normally feed on and that would have provided important sustenance for the colony,\u201d said Mr. Eiri. \u201cIn addition, bees typically recruit their nestmates to good food with waggle dances, and we discovered that the treated bees also danced less.\u201d<\/p>\n

The two researchers point out that honey bees that prefer only very sweet foods can dramatically reduce the amount of resources brought back to the colony. Further reductions in their food stores can occur when bees no longer communicate to their kin the location of the food source. \u201cExposure to amounts of pesticide formerly considered safe may negatively affect the health of honey bee colonies,\u201d said Dr. Nieh.<\/p>\n

To test how the preference of sugary sources changed due to imidacloprid, the scientists individually harnessed the bees so only their heads could move. By stimulating the bees\u2019 antennae with sugar water, the researchers were able to determine at what concentrations the sugar water was rewarding enough to feed on. Using an ascending range of sugar water from 0 to 50 percent, the researchers touched the antennae of each bee to see if it extended its mouthparts. Bees treated with imidacloprid are less willing to feed on low concentrations of sugar water than those that were not treated. A video showing the experiments can be found on UCSD\u2019s YouTube page<\/a>:<\/p>\n