Bees don’t avoid pesticide-contaminated food, in fact, new research shows they prefer it and may actually be addicted to tainted nectar.
Two new studies in Nature show that bees may find neonicotinoids act like a drug similar to nicotine.
Neonicotinoids contain synthetic chemicals similar to nicotine, which as a plant toxin is damaging to insects.
It will be interesting to see if insects become addicted to neonicotinoids over time as humans become addicted to nicotine
Neuroscientists at Newcastle University tested whether honeybees and bumblebees preferred food containing neonicotinoids over untreated food in the laboratory.
They were surprised to find that sugar solution containing two of three neonicotinoid pesticides appeared to be attractive to bees and “may act like a drug” targeting the brain.
“Bees can’t taste neonicotinoids in their food and therefore do not avoid these pesticides,” said lead researcher Prof Geraldine Wright. “This is putting them at risk of poisoning when they eat contaminated nectar.
“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 next step is to study whether bees can become addicted to the substances, Prof Wright added.
“As soon as it gets into their blood they’re getting a little buzz, as it were, and they’re responding to that… We don’t have any evidence that it’s addictive, but it could be.
Neonicotinoids are lab-synthesised pesticides based on the chemical structure of nicotine.
They are used to treat crop seeds and are absorbed by the plant, but then attack the nervous system of insect pests.
Research, however, has linked them to scrambling bees’ memory and navigation functions, affecting their ability to forage.
Researchers actually set it up so that bees could choose to forage on other available flowers and hence avoid or dilute exposure.
Moreover, bees of both species prefer to eat more of sucrose solutions laced with IMD or TMX than sucrose alone.
Bees have suffered colony collapse disorder, which has been blamed on mites, a virus or fungus, pesticides, or a combination of factors.
Pending clarity on the safety of neonicotinoids – a topic debated by scientists, environmentalists and agrochemical producers – the European Commission restricted their use in bee-attracting plants on December 1, 2013, for two years.
A second study by Nature last week found further evidence of risk for some bee species from neonicotinoids, which come in three types: clothianidin, imidacloprid and thiamethoxam.
Scientists in Sweden sowed eight fields with clothianidin-treated canola seeds, while another eight were untreated.
“The most dramatic result that we found was that bumble bee colonies almost didn’t grow at all at the treated sites, compared to the control sites, said project coordinator Maj Rundloef of Lund University.