A pitched battle about why bee populations around the world are declining so rapidly has been joined by two new studies pointing directly at the harm from insecticides most commonly used by grain, cotton, bean and vegetable farmers.
Pesticides were an early suspect, but many additional factors appear to be at play — including a relatively new invasive mite that kills bees in their hives, loss of open land for foraging, and the stresses on honeybee colonies caused by moving them from site to site for agricultural pollinating.
The new bee research, some of the most extensive done involving complex field studies rather than simpler laboratory work, found that exposure to neonicotinoid pesticides did not kill the bees directly, but changed their behavior in harmful ways. In particular, the insecticide made the honeybees and bumblebees somewhat less able to forage for food and return with it to their hives.
While the authors of the studies published Thursday in the journal Science do not conclude that the pesticides are the sole cause of the American and international decline in bees or the more immediate and worrisome phenomenon known as colony collapse disorder, they say that the omnipresent chemicals have a clearly harmful effect on beehives.