Bees could be getting hooked on nicotine-based pesticides, which might explain why the insects, essential for pollinating many plants, are disappearing around North America and Europe. If this finding is confirmed, then the tiny flying animals could be suffering addiction in much the same way that human smokers do.
Neonicotinoids are a class of modern insecticides that kill insects by acting on their central nervous systems. Once ingested, the chemicals related to nicotine found in tobacco cause paralysis and death.
The European Union and several other nations banned the use of some neonicotinoids after research, starting with studies in Germany, linked their use to colony collapse disorder (CCD).
Imidacloprid, one variety of neonicotinoid, is the most widely used insecticide worldwide. Other forms of this class of chemical include clothianidin, acetamiprid, nitenpyram, nithiazine, thiamethoxam and thiacloprid. These insecticides were first developed in the 1980s and 1990s by Bayer and petroleum giant Shell.
Researchers studied buff-tailed bumblebees and honeybees, providing the insects with a choice of consuming pure sugar water or samples containing trace amounts of neonicotinoids. They found that the insects preferred the insecticide-laced foods. Investigation revealed that the insects are unable to taste the product, suggesting that the addictive properties of nicotine could play a significant role in their choice. The lack of taste receptors for the insecticide also prevents bees from avoiding the chemicals, further potential damage to colonies in the wild.
"Neonicotinoids target the same mechanisms in the bee brain that are affected by nicotine in the human brain. The fact that bees show a preference for food containing neonicotinoids is concerning as it suggests that like nicotine, neonicotinoids may act like a drug to make foods containing these substances more rewarding," Geraldine Wright from the Institute of Neuroscience at Newcastle University said.
Bees that consume the insecticides could be getting a "buzz" from the nicotine-based product in much the same way as humans consuming tobacco. Ironically, tobacco plants produce nicotine as a form of natural insecticide. Although a small dose may just upset the biological functioning of the insects, larger doses can be fatal.
"There's a conundrum that they are attracted to the stuff that actually is having a negative impact on their motor function and their ability to collect food and forage. As soon as it gets into their blood they are getting a little buzz, as it were, and they are responding to that," Wright said.
While opponents of the use of these chemicals state that they could lead to environmental damage, including the widespread loss of bees, supporters claim the products help to increase crop yields.
Analysis of the effects of neonicotinoids on bees and the role insecticides could play in the disappearance of the insects was detailed in the journal Nature.
Photo: Holly Occhipinti | Flickr