A common crop pesticide is making bees dumb

Even tiny doses are affecting the insects badly.

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Mariella Moon
March 2nd, 2016
In this article: bees, green, nature, science
A common crop pesticide is making bees dumb

Poor honeybees. Back in 2010, the USDA found a possible link between pesticides used to kill varroa mites and colony collapse disorder. Now, researchers from the University of Otago in New Zealand have discovered that they can "suffer severe learning and memory deficits" if they ingest even tiny doses of a common pesticide used to keep apples, broccoli, corn and other crops insect-free. That pesticide is a controversial chemical called chlorpyrifos. The Environmental Protection Agency and the state of California proposed banning or at least imposing heavy restrictions on its use in the past due to reports that it makes farm workers sick.

Kim Hageman, an associate professor at the university, also found out back in 2013 just how far the chemical can travel. She and her team discovered very small amounts of chlorpyrifos in the water, air and plant life in parts of the country where the pesticide isn't even sprayed. For this study, the group led by Dr. Elodie Urlacher fed lab bees a slightly lower dose than what Hageman found in her samples. Note that the chemical's lethal dose is around 100 billionths of a gram, and the team used an amount a thousand times lower than that.

They've determined that despite ingesting what's considered a "safe" and extremely small dosage, the lab bees couldn't learn or remember odors as well as specimens that weren't exposed to the chemical could. According to Dr. Urlacher, this means exposure to the pesticide may be stunting honeybees' "effectiveness as nectar foragers and pollinators" since they "rely on such memory mechanisms to target flowers." That is a big issue, because many crops -- a number of which are kept insect-free using this particular pesticide -- rely on honeybees for pollination.

She believes that the group's findings now raise questions about how the pesticide should be regulated. "It's [...] clear that it is not just the lethal effects on bees that need to be taken into account," she said, "but also the serious sub-lethal ones at minute doses."

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