Like nicotine for humans, certain pesticides seem to hold an addictive attraction for bees, which seek out tainted food even if it may be bad for them, research shows.
Not only did bees show no signs of avoiding neonicotinoid-laced food in lab tests, they seemed to prefer it, said a study published on Wednesday (local time) in the science journal Nature.
"We now have evidence that bees prefer to eat pesticide-contaminated foods," study author Geraldine Wright of Newcastle University said.
This suggests, she said, "that like nicotine, neonicotinoids may act like a drug to make foods containing these substances more rewarding".
Neonicotinoids are lab-synthesised pesticides based on the chemical structure of nicotine.
They are widely used to treat crop seeds - designed to be absorbed by the growing plant and attack the nervous system of insect pests.
Previous research, however, has linked them to scrambling memory and navigation function in bees, affecting the pollinators' ability to forage.
Bees have been hit in Europe, North America and elsewhere by a phenomenon called "colony collapse disorder", which has alternatively been blamed on mites, a virus or fungus, pesticides, or a combination of factors.
Bees account for 80 percent of plant pollination by insects – a function estimated to be worth at least US$153 billion a year globally.
Pending clarity on the safety of neonicotinoids, a topic that is fiercely debated among scientists, environmentalists and agrochemical producers, the European Commission has restricted their use in bee-attracting plants for two years since December, 2013.
A second study carried out by Nature 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," project co-ordinator Maj Rundloef of Lund University said.
There were also fewer wild bees in the contaminated sites, but honeybee colonies did not appear to be affected.
source: newshub archive