July 17, 2013 —
Where would we be without bees? This is no idle question. Bees are a primary pollinator of our food crops that account for one quarter of the American diet. That’s why persistent and increasing numbers of bee deaths are so worrisome.
Since 2006, waves of bee deaths have been reported around the world and, in the U.S., it’s estimated that we’re losing 30% of our honeybees population each year. As their numbers decline, the bees can’t generate enough heat to survive the winter and rear a brood in the spring. A survey of beekeepers this year showed a 45% loss of managed honeybee colonies during the winter 2012/2013. The loss among wild bees—bumble bees, carpenter bees, sweat bees, squash bees, leafcutter bees, mining bees, mason bees and more—is simply not known.
While scientific studies are divided, there’s mounting evidence that the most widely used class of insecticide—neonicotinoids, neonics for short—may be a factor. Neonics are highly neurotoxic to insects. They work systemically; as they are absorbed into the plant’s tissue, the entire plant becomes involved, including pollen and nectar.
The manufacturers of neonics say that tests of these nicotine-like chemicals show they are not lethal to honeybees. But neonics are a toxin, and the subtle and cumulative consequences of widespread repeated use on bees, and on soil and water have not been thoroughly studied. Neither are the effects known on bees exposed during foraging to a combination of neonics and other pesticides, nor is there sufficient little data for their effect on wild bees, moths, hoverflies and other pollinators. Finally, it is also suspected that chronic neonic exposure weakens bees, making them more susceptible to parasites and pathogens. Meantime, production of neonics worldwide continues to increase.
Within the last several weeks, two incidents have happened that give one pause to reflect on the widespread use of neonics in agriculture, in landscaping and in backyard gardening.
In one incident, 37 million bees died in Elmwood, Ontario, Canada when a beekeeper lost 600 hives in his honey operation. Dave Schuit blamed it on neonics. “Once the corn started to get planted, our bees died by the millions,” he said. Neonic pesticides are often used to coat corn seed; the corn is planted by blowing the seeds into the air, and with them comes pesticide dust. An examination of the dead bees by Purdue University reportedly showed traces of two neonics: thiamethoxam and clothianidin.