“Of these contaminated samples, 30 percent contained a single neonicotinoid, 45 percent contained two or more, and 10 percent contained four or five.”
The frequency of contamination was highest in the North American samples (86 percent), followed by Asia (80 percent) and Europe (79 percent).
The lowest concentrations were seen in South American samples (57 percent).
“These results suggest that a substantial proportion of world pollinators are probably affected by neonicotinoids,” said the study.
– ‘Serious concern ‘ –
Our planet is home to some 20,000 species of bees, which fertilize more than 90 percent of the world’s 107 major crops.
The United Nations warned in 2016 that 40 percent of invertebrate pollinators — particularly bees and butterflies — risk global extinction.
Experts said that while the findings are not exactly a surprise, the threat posed by neonicotinoids should be taken seriously.
“The levels recorded (up to 56 nanogram per gram) lie within the bioactive range that has been shown to affect bee behavior and colony health,” said plant ecologist Jonathan Storkey, who was not involved in the study.
“Scientists showed earlier this year that levels of less than 9 ng/g reduced wild bee reproductive success,” he added.
“I therefore agree with the authors that the accumulation of pesticides in the environment and the concentrations found in hives is a serious environmental concern and is likely contributing to pollinator declines.”
According to Lynn Dicks, natural environment research council fellow at the University of East Anglia, the findings are “sobering” but don’t offer a precise picture of the threat to bees.
“The severity of the global threat to all wild pollinators from neonicotinoids is not completely clear from this study, because we don’t know how the levels measured in honey relate to actual levels in nectar and pollen that wild pollinators are exposed to,” she said.
The levels of exposure to harmful pesticides may be far higher than what can be measured in honey, said Felix Wackers, a professor at Lancaster University who was not involved in the research.
“This shows that honeybees are commonly exposed to this group of pesticides while collecting neonicotinoid-contaminated nectar from treated crops or from flowers that have come into contact with spray drift or soil residues,” he said.
“The actual level of exposure can be substantially higher, as the honey samples analyzed in this study represents an average of nectar collection over time and space.”