Pesticides Are Really Messing With Bees

The world's most widely used insecticides are killing bees and harming their colonies, according to a pair of studies released on Thursday.

The studies focused on neonicotinoids, a class of nicotine-derived chemicals commonly used in agriculture. Scientists have long connected neonicotinoids, often called "neonics," to bee deaths in lab experiments. (Reminder: We need bees to transfer pollen from the male flowers to female flowers of lots produce; without bees, prices would go way up.) Critics, however, argued that those results depended on unrealistic amounts of pesticide. The two new studies are the first large-scale investigations of how neonics affect bee populations in the real world.

The first study, published in Science, focused on 33 farm sites in Germany, Hungary, and the United Kingdom. Researchers compared honeybees, bumblebees, and solitary bees living near insecticide-treated rapeseed fields with those around fields without insecticide. They found that pesticides hurt the survival of honeybee colonies in Hungary and the UK; that didn't happen in Germany, where bees foraged less on the pesticide-treated plants and saw lower levels of disease.

It seems that neonics aren't killing bees outright, but slowly, over time, perhaps by reducing their ability to survive hibernation. Queen bees are particularly threatened, which means lower reproductive rates for colonies. (Both queen and worker honeybees exposed to neonics died sooner than those that weren't.) Neonics have long been suspected of contributing to colony collapse disorder, in which entire hives die out. The new studies support that connection, but they aren't definitive; some experts say that people can no longer claim that neonics don't harm bees.

The problem of neonics may be larger than previously suspected, though. The second study, also published in Science, looked at how water running off treated cornfields spread the pesticides to nearby plants, including willow trees, clovers, and wildflowers. Bees that pollinated those plants were exposed to "a cocktail of poisons," per an accompanying editorial—26 pesticides, including four neonics.

In other words, even bees that didn't forage on pesticide-treated plants could still be exposed to agrochemicals. In fact, bees were exposed to large numbers of chemicals in combinations that made them even more toxic. Neonics combined with a common fungicide, for example, were more than twice as deadly for bees.

Some regulators have long considered cracking down on neonic use; most of them are already banned (temporarily) for use on flowering crops in the European Union, with a complete ban potentially in the works. In the US, Maryland became the first state to prohibit neonics; the Environmental Protection Agency, meanwhile, is scheduled to complete its review of the pesticides next year.

All of which means we may be at a crossroads: a future without neonics, or a future without bees. And we're running out of time to choose.

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