When we think of bees, we think of fuzzy little pollinators zipping among flowers, making them grow. Or busy groups of hundreds of bees, all working furiously to produce honey.
What we don't realize though, is that in the modern world, where pesticides are the norm, some bees are often more attracted to plants with these chemicals, than those without. The problem is, these pesticides often have high levels of nicotine, an addictive and dangerous substance.
A new study by scientists at Newcastle University and Trinity College Dublin has shown a definite preference for pesticide-laden nectar and this could negatively affect the bee population.
There has been a great deal of research on the effects of neonicotinoid pesticides. The three most commonly used pesticides contain this chemical. It's been shown that buff-tailed bumblebees and honeybees cannot taste the chemical in food, so therefore they cannot avoid it. The new study shows that beyond not being able to avoid it, the bees actually prefer food that contains neonicotinoid.
When the bees were given a choice between sugar solution, and sugar solution containing neonicotinoids, they chose the neonicotinoid-laced food. The lab-based study also showed that in addition to a preference for the food containing the pesticides, there was a significant difference in the amounts consumed. The bumblebees especially consumed more of the food containing the chemical and as a result are exposed to higher levels of the toxins contained in neonicotinoids.
It is well known that bees and other pollinating insects are vital to crop yields. Their value is estimated in the billions of dollars when considered globally. When pollinating crops, since they interact with pollen and nectar, they are in direct contact with pesticides. Though some of the research over the years has been controversial, negative effects on foraging and colony fitness have been attributed to neonicotinoid pesticides. In April 2013, the EU introduced a temporary ban on the use of neonicotinoid pesticides on flowering crops, while further scientific and technical evidence was gathered.
Professor Geraldine Wright, who lead the new study at the Institute of Neuroscience at Newcastle University, said: "Bees can't taste neonicotinoids in their food and therefore do not avoid these pesticides. This is putting them at risk of poisoning when they eat contaminated nectar.
Professor Wright goes on to address the preference for the pesticides bees seem to have. She compares it to the effects of nicotine on the human brain, suggesting that the bees brains get some kind of reward.
"Even worse, we now have evidence that bees prefer to eat pesticide-contaminated food. 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. "If foraging bees prefer to collect nectar containing neonicotinoids, this could have a knock-on negative impact on whole colonies and on bee populations."
Jane Stout, Professor of Botany and Principal Investigator in the School of Natural Sciences at Trinity College Dublin, said: "Our findings imply that even if alternative food sources are provided for bees in agricultural landscapes where neonicotinoid pesticides are used, the bees may prefer to forage on the neonicotinoid-contaminated crops. Since neonicotinoids can also end up in wild plants growing adjacent to crops, they could be much more prevalent in bees' diets than previously thought."