When neonicotinoid pesticides came onto the New Zealand market in the early 1990s, growers snapped them up. This new class of insecticides could be sprayed, but they could also simply be coated on grain or vegetable seed at the start of the season. That one dose of poison would move through the plant so that the entire plant became toxic to insects, all season long. What an energy saver for the farmer!

In 2012, however, questions were being asked. Bee populations had been experiencing mysterious die-offs in the US and Europe - in epidemic numbers.

In 2007-2008, over a third of US beehives collapsed, while European countries estimated 30 to 50 per cent of their bee colonies were completely gone. The hives were full of growing brood and food stores - but the adult bees had simply gone missing. It's commonly estimated that a third of the human food supply requires bees for pollination. No bees, no harvest.

By 2012, evidence against neonicotinoids had begun to accumulate. Scientists announced findings that one neonicotinoid, imidacloprid, weakened bees' immune systems, and that feeding imidacloprid to bees produced symptoms identical to the widely observed Colony Collapse Disorder.

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It was found that although the bees may not die from a low dose, the poison can affect their central nervous system, hindering their ability to navigate and communicate - and accounting for why, in collapsing colonies, the bees simply don't make it back to their hives.

International uproar over such findings seems to show the world has learned from past mistakes. The EU quickly moved to ban three neonicotinoids from use on cereals and flowering crops attractive to bees. The ban came into effect in December 2013.

This month, neonicotinoids made global headlines again, as a team at Harvard announced that when hives were treated with neonicotinoids, half of them collapsed.

Yet in New Zealand - virtual silence. Seeds sold to both farmers and home gardeners - especially corn, grass seed and various vegetables - can be pre-coated with neonicotinoids, without any labelling. The only sure way to avoid these is to purchase certified organic or untreated seed.

Last year, after Green MP Steffan Browning approached several garden retailers about the issue, the Warehouse and Placemakers agreed to stop carrying the bee-killing sprays.

So far the government has barely raised an eyebrow. The Environmental Protection Authority (EPA) has the power to reassess the legality of hazardous substances as new research comes to light, but has not yet begun any investigation into neonicotinoids.

In the face of rising public concern about bee losses, with threats ranging from diseases to pesticides, the Primary Production Select Committee is beginning an investigation into bee health.

"The Environmental Protection Authority takes its responsibility to protect the environment very seriously and is concerned about the risks of all insecticides to bees and other beneficial insects," says Sarah Gardner, manager of hazardous substance applications at EPA.

"Specific restrictions have been added to products containing neonicotinoids in order to minimise the risk to pollinator insects. For example, New Zealand prohibits use of neonicotinoids in areas where bees are foraging and we prohibit their use on plants or trees while in flower."

But what farmers see as a boon - that the poison is systemic, and translocates in the plant - could be bees' doom. Whether or not the poison is sprayed directly onto flowers, it finds its way into them.

"It goes right through the plant," says Browning. "The bees are going to the flower to get pollen and nectar, and get minute quantities of neonicotinoids."

There is an anomaly in the New Zealand experience: if neonicotinoids are the true cause of bee deaths overseas, why aren't we seeing the same level of die-off here?

It's possible that New Zealand simply hasn't yet reached a threshold level of neonicotinoids built up in farm soil. (The chemicals can persist in soil for years, or in some cases decades.)

But no one really knows how much of the stuff is out there. Neither the Ministry of Primary Industries, nor the EPA, track levels of use. Neonicotinoids are applied to crops ranging from grasses and maize, to stonefruit and pipfruit.

Contrary to the self-perception of 'clean and green', New Zealand has never been quick to ban pesticides. "A chemical is innocent until proven guilty, and what this means in practice is it's very hard for a chemical to be banned," says Alison White of the Safe Food Campaign, a group which has been campaigning for reduced pesticides and GE-free food in New Zealand.

In one well publicised recent case, Endosulfan, a controversial, highly toxic insecticide in the same chemical class as DDT, had been banned in 55 countries before ERMA finally banned it here in 2008. It was only banned after shipments of New Zealand beef were rejected by Korea due to endosulfan residues.

When the New Zealand government finally nixed endosulfan, activists who had long campaigned on the issue suspected that ERMA was mostly responding to overseas "trade imperatives", says Steffan Browning. "We don't have a pesticide reduction strategy in New Zealand," he says. "And we need to."

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