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.

In Thursday’s issue of the journal Science, two teams of researchers published studies suggesting that low levels of a common pesticide can have significant effects on bee colonies. One experiment, conducted by French researchers, indicates that the chemicals fog honeybee brains, making it harder for them to find their way home. The other study, by scientists in Britain, suggests that they keep bumblebees from supplying their hives with enough food to produce new queens.

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 do not conclude that the pesticides, called neonicotinoids, are the sole cause of the US 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. 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 since they are most often introduced directly into the seeds of crops and thus permeate the entire plant as it grows, including the pollen and nectar the bees feed on.                         –ST