How a Harvard scientist, a sixth-generation bee whisperer, and a retired entrepreneur joined forces to rescue an embattled insect and save the American food supply.
THERE’S A CERTAIN GENIUS to pesticides known as systemics. Unlike traditional pest-killing chemicals, which are usually sprayed on crops, lawns, and trees, systemic pesticides render a plant toxic to bugs from the inside out. Seeds are treated with pesticide before they’re sowed (or sometimes the soil is pre-treated). When the plant grows, the poison essentially grows with it, spreading to all parts of the tissue and killing any snacking corn borers, rootworms, aphids, or stink bugs.
The big systemic pesticides these days are called neonicotinoids, which are derived from nicotine and target insects’ nervous systems. They have exploded in popularity over the past decade, thanks to a perception that they are both safer and more effective than the pesticides they replaced. The vast majority of corn planted in the United States today is pre-treated with neonicotinoids, the seeds colored like candy. So are other major crops such as soybeans and canola.
The wind, not bees, pollinates corn, but bees can collect corn pollen. And neonicotinoid-laced pollen blows onto nearby flowers and crops, exposing honeybees to the poison. Neonicotinoids are also used on plants that bees do pollinate, including cucumbers and watermelons. Unlike older pesticides, neonicotinoids can linger in the soil for months or even years.
The more Lu learned about colony collapse, the more convinced he became that the epidemic’s timing was no coincidence, coming as neonicotinoid use surged in American agriculture. With a $25,000 grant from Harvard, he began designing an experiment to test his hypothesis, aiming to replicate the honeybee disappearances that beekeepers were experiencing. It was clear neonicotinoids were acutely toxic to bees, just as they were to crop-eating insects, but what about at lower levels, over a prolonged period of time?
Lu, Warchol, and Callahan sketched out a plan. In the spring of 2010, they would set up 20 hives at four locations, two in Uxbridge and two in Northbridge. They would feed all the hives high fructose corn syrup, mimicking a common commercial beekeeping practice. (Beekeepers typically supplement their colonies’ food supply with syrup or sugar.) In four of the five hives at each site, the syrup would contain imidacloprid, a commonly used neonicotinoid. The fifth hive, the control in the experiment, would be fed syrup not dosed with pesticide.
They began with a population of roughly 220,000 bees that grew into 1.4 million or so. On July 1, 2010, they started the pesticide regimen, beginning with very low doses, to make sure they didn’t kill the bees right away. They upped the amounts after four weeks to levels that Lu says were on the conservative end of what bees encounter in the real world — through syrup made from corn treated with neonicotinoids or nectar and pollen collected from contaminated flowers and crops. The four pesticide-laced hives at every site were given different concentrations of imidacloprid.
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Part of the hive in Northbridge.
Winter came, and they saw nothing. The hives seemed fine. “We were starting to get discouraged,” Warchol says. “Dick and I were talking, saying, ‘Wow, there’s really nothing going on.’ ” Lu had the same reaction. “At that time,” he says, “I thought my hypothesis was wrong.”
Then everything started to change. Around the beginning of 2011, a beekeeper whose yard they were using as a testing site reported seeing a mass of bees suddenly fleeing one of the hives. It was suicide — to endure the winter, honeybees typically cluster together inside their hive for warmth, surviving on food that a beekeeper has provided to sustain them. Some of the bees had dropped dead on the surrounding snow. The rest had disappeared.
Over the next several weeks, Lu, Warchol, and Callahan lost 15 of the 16 hives they had fed imidacloprid. It resembled colony collapse disorder, with abandoned hives bearing plenty of food. “It was an exciting moment in a sense, even though the bees were dying,” Warchol says. For Lu, it all clicked. “It’s not Mother Nature,” he says. “It’s us.” They lost one of their control hives to disease, but it looked very different from the hives the bees had fled, with dead bees littering the colony.
When Lu, Warchol, and Callahan sought to publish their results, they encountered resistance. Some journals wouldn’t take the manuscript. Peer reviewers raised objections. They finally published in 2012 in an Italian journal called the Bulletin of Insectology. They also wrote a letter alerting the US Environmental Protection Agency to their work, just as two European research teams announced similar findings.