New research, published Thursday, revealed worker and queen honeybees exposed to field levels of pesticides have a shorter life span.
The study, led by biologists at York University, showed that honeybees placed near cornfields planted with neonic-coated seeds were exposed to detectable levels of neonicotinoids for three to four months, longer than researchers originally thought.
Researchers also found that the pesticides remain in the environment long after a treated crop has been harvested. Additionally, bees were exposed to neonics in fields that were never treated.
"The effect of neonicotinoids on honey bees quickly turns from bad to worse when you add the fungicide boscalid to the mix," said Professor Valérie Fournier of Laval University who collaborated with the York U team.
"The researchers found that field realistic levels of boscalid can make neonicotinoids twice as toxic to honeybees."
However, experts say it's too soon to tell if neonicotinoids should be banned for a variety of reasons.