By Marc Kaufman, Published: March 29
New research has begun to unravel the mystery of why bees are disappearing in alarming numbers worldwide: Some of the pesticides most commonly used by farmers appear to be changing bee behavior in small but fatal ways.
Two new studies found that honeybees and bumblebees had trouble foraging for food and returning with it to their hives after exposure to the class of insecticides, which is widely used to protect grains, cotton, beans, vegetables and many other crops.
Ironically, the relatively new pesticides have been welcomed as an environmental plus because they are, by almost all accounts, less harmful to other wildlife than previous generations of pesticides.
Although the authors of the studies published Thursday in the journal Science do not conclude that the pesticides, called neonicotinoids, 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.
“People have asked me to sign petitions to ban or limit the use of the neonicotinoids for some time, but I never did because I really didn’t know if they were having a major impact on the bees,” said David Goulson of the University of Stirling in Britain, co-author of one of the studies.
“After seeing what we and the others found, I’m much more inclined to sign.”
Unlike older pesticides, the neonicotinoid pesticides are most often introduced directly into the seeds of crops planted by farmers and thus permeate the entire plant as it grows, including the pollen and nectar the bees feed on.
Spraying of the older pesticides could be halted when plants were flowering so bees and other pollinators would not be harmed. With the neonicotinoids, which kill pest insects by attacking their central nervous systems and are derived from the same nicotine found in tobacco, that kind of timing is not possible.