Photos: Getty Images; Illustration by Bloomberg View
Photos: Getty Images; Illustration by Bloomberg View

This winter was another terrible season for U.S. honeybees. Beekeepers reported losing 31 percent of their colonies, a rate on par with the average since 2006, when large numbers of hives began collapsing.

The fate of cultivated honeybees is thought to indicate the health of wild bees, which are also vital pollinators. The farmed bees alone add an estimated $15 billion annually to the value of crops, by ensuring the production of fruit and fertile seeds.

Last month, alarmed over similar trends in Europe, the European Commission took action, banning for two years the use, on flowering crops, of three pesticides suspected of playing a role in bee deaths. Environmentalists are pressuring U.S. authorities to follow suit.

Such a move would be premature. The evidence against the pesticides -- called neonicotinoids -- isn’t damning enough to warrant a ban. Although it’s true that in laboratory studies and experiments within enclosures, some bees exposed to the pesticides got lost, brought home less food and behaved in other ways that could contribute to colony failure, such trials don’t replicate real-world conditions. For one thing, researchers can only guess how to approximate a realistic pesticide dose, and these particular studies erred on the high side.

In trials in which bees have been placed in farm fields treated with neonicotinoids, the colonies have done fine.

The European Commission justifies its temporary ban under the precautionary principle -- the idea that, when human or environmental health is at stake, there’s no need to wait for scientific certainty to take protective action. It’s not clear, however, that the ban will have this effect.

European farmers won’t switch from neonicotinoid fertilizers to nothing. They will return to older formulations, which haven’t been subjected to the same bee studies and may be at least as hazardous. What’s more, the ban will deprive Europeans of the benefits neonics provide for human health and the environment generally. Because they can be applied to seeds, they avoid the risk of contaminating surrounding areas, as spray fertilizers do.

Rather than ban the chemicals, U.S. authorities should take other steps to protect bees.

The biggest problem bees face is the Varroa mite. First detected in the U.S. in 1987, this parasite has since spread and developed resistance to miticides; lethal bee viruses have also evolved to take advantage of Varroa’s disease-spreading potential.

Strange as it sounds, there’s also the problem of bee nutrition. Hives could better withstand the stresses of mites, disease and pesticides if they weren’t also facing dwindling food sources.

High corn and soybean prices, driven by demand for biofuel feedstocks, have accelerated the conversion of open land to cropland, which offers bees (even cultivated ones) nothing to eat outside of the two or three weeks when a crop blossoms. A study published last year documented the loss of 530,000 hectares (1.3 million acres) of grasslands in five corn-belt states from 2006 to 2011.

According to the study, government subsidies of crop insurance encourage farmers to cultivate marginal lands. If left fallow, those areas could feed bees. Here’s one more reason for Congress to limit farmers’ insurance subsidies to protection against catastrophic losses.

There are other steps that should be taken instead of banning neonicotinoids: The government can maintain or increase support for the Conservation Reserve Program, which helps farmers remove environmentally sensitive land from production. States can support bee habitat by letting flowering weeds grow alongside and between highways and, yes, by planting native flowers in parks and public spaces. And awareness can be raised about the home use (and overuse) of herbicides, which kill dandelions, clover and other bee food.

Pollinators fill our plates -- by one estimate, they make possible every third bite we eat. We should return the favor.

To contact the Bloomberg View editorial board: view@bloomberg.net.