A new study has detected high levels of a specific class of insecticide known to pose a risk to honeybees.
Chris Pook, a fellow of Liggins Institute, the organisation behind the study, told TVNZ1’s Breakfast traces of neonicotinoids have been found in soil at sites across the North Island, tested after local beekeepers had reported unexplained losses of hives.
Tests revealed that, in 43 out of 45 samples, concentrations of neonicotinoid residues exceeded the environmental exposure limit set by the New Zealand Environmental Protection Agency (NZEPA).
According to the Liggins Institute, the average concentration of imidacloprid across all sites was 5.1 parts per billion; the highest measured was 13.7 parts per billion.
“Either the NZEPA has overestimated the hazard from neonicotinoids, and these levels are nothing to worry about, or it’s got its threshold right and these findings flag up a huge problem,” says Mr Pook.
“There’s robust evidence that these kinds of concentrations are accessible to pollinators via a multitude of routes - via flowering plants, or residues leeched into surface water, for example.”
In Europe, the use of neonicotinoid insecticides has been heavily restricted after the European Food Safety Agency heard concerns raised by scientists and conservationists.
In New Zealand, there are no such restrictions, and there isn't any requirement to keep sales records, so it is not possible to tell whether neonicotinoid use is rising or falling.
Regardless, Mr Pook said it’s a classic example of how you can’t manage what you don’t measure.
“Even if New Zealand’s use of neonicotinoids is not increasing, the annual application of neonicotinoids, whose residues persist for more than a year, may cause their accumulation in the soil of the country’s fields."