Beneficial insects under threat
Mention neonicotinoids in polite company and chances are you will be met with a blank stare.
Most people have never heard of them. And few people realise that neonics, as they are affectionately known by the people who sell them, have been the insecticide of choice on New Zealand markets for more than 20 years.
Neonicotinoids are systemic pesticides widely used to protect hundreds of thousands of hectares of crops in this country from insect attack.
They are now the most widely used insecticides on Earth, accounting for estimated sales of US$2.63 billion in 2011.
Manufacturers confirm that most neonics sold in New Zealand are used as a pre-planting seed treatment, mainly on maize, cereals, pasture grasses and forage brassicas.
They are sold here under the common trade names of Cruiser, Gaucho and Poncho, the active neonicotinoid ingredients of which are thiamethoxam, imidacloprid and clothianidin respectively. Gaucho is also used on potatoes, winter squash and pumpkins.
Manufacturers maintain that seed treatment is a highly targeted method of crop protection, uses lower rates of active ingredient and is generally more environmentally friendly because it avoids the need to use broadcast foliar applications of insecticides.
They say neonics used in seed treatments have largely displaced older and less effective organophosphate insecticides that were more toxic to humans. Their arrival in the early 1990s was good news for an industry looking for alternatives.
The industry estimates that between 20 and 40 per cent of grass seed now sold in New Zealand is pre-treated with a neonicotinoid. Some sources claim sales are more like 90 per cent, but manufacturers dispute that figure.
AgResearch senior scientist Phil Rolston says treated seed is always dyed so users should be aware they are dealing with seed treated with neonics. Bags are also tagged to identify treated seed and advise users of appropriate precautions in handling the product.
"So farmers should know what precautions to take with this product as they would know what precautions to take with any other agrichemicals they use," he said.
Technically, in New Zealand seed coated with neonics can be sold to home gardeners and anyone else without any legal obligation by the manufacturer to identify it. The only option the public have to avoid using treated seed is to buy certified organic or untreated seed.
Several neonic insecticides can be used as foliar sprays but their use is limited in New Zealand, according to Agcarm, a lobby group representing chemical manufacturers.
Agcarm lists the trade names of foliar sprays as Actara (active ingredient thiamethoxam) for kiwifruit, pipfruit and in-furrow application on potatoes. Calypso (active ingredient thiacloprid) is used on avocados, kiwifruit, pipfruit and stonefruit and Confidor (active ingredient imidacloprid) is applied to onions and as a transplant tray treatment of vegetable brassicas and lettuce.
In response to questions from NZFarmer, a spokesman for multinational chemical manufacturer Bayers CropScience said the only use of its neonicotinoids as foliar sprays was in kiwifruit and onions.
The spokesman said onion crops received one application of a "bee-friendly neonicotinoid" to control onion thrips. In kiwifruit, a small quantity of "a bee-friendly neonicotinoid" was used to control scale insects, but usage of neonics in kiwifruit had largely been superseded by new technology.
He said the company did not have a label claim for any of its neonicotinoid insecticides for use on clover.
NOW FOR THE BAD NEWS
Neonics are neurotoxins, chemically similar to nicotine that work by attacking the central nervous systems of insects. Recent research confirms they are water soluble, prone to leaching and can persist, accumulate and remain active in the soil for years.
Fears about the effects of pesticides on a variety of beneficial species have been growing for 20 years, but the science has been dismissed by manufacturers and regulators as inconclusive.
Unlike other pesticides which remain on the surface, systemic pesticides are taken up by the plant and transported to leaves, flowers, roots and stems, as well as pollen and nectar. Beekeepers believe it is the traces of pesticides in pollen and nectar that bees are accumulating and carrying back to their hives, albeit in low, sub- lethal doses.
Neonics have been linked to the collapse of over a third of beehive numbers in the United States and between a third and half of beehives in Europe. In many cases, hives were full of honey stores and brood, but adult bees had simply gone missing in the field, a condition known as colony collapse disorder.
In late June an international task force of independent scientists completed a four-year analysis of 800 peer-reviewed papers on systemic pesticides and found conclusive evidence that neonics are causing significant damage to bees, butterflies, earthworms and birds.
The analysis found the most affected groups of species were terrestrial invertebrates, such as earthworms, making them highly vulnerable to neonics associated with agricultural use. The worms' tunnelling ability was altered.
The study found the next most affected group was insect pollinators, such as bees and butterflies, which were highly vulnerable to long-term exposure to neonics at non-lethal levels.
In honey bees, chronic damage included impaired sense of smell or memory, reduced fecundity, altered feeding behaviour and reduced food intake and foraging, difficulty in flight and increased susceptibility to disease.
While vertebrate animals were generally less susceptible, the report said bird populations were at risk from eating crop seeds treated with systemic insecticides and reptile numbers had declined because of depletion of their insect prey.
"The evidence is very clear," one of the report's lead authors, Dr Jean-Marc Bonmatin of the National Centre for Scientific Research in France, said. "We are witnessing a threat to the productivity of our natural and farmed environment equivalent to that posed by organophosphates or DDT."
"Far from protecting food production, the use of neonics is threatening the very infrastructure which enables it, imperilling the pollinators, habitat engineers and natural pest controllers at the heart of a functioning ecosystem," he said.
The study concluded there was clear evidence of harm sufficient to trigger regulatory action.
From December 1, 2013, the European Commission imposed restrictions on three neonicotinoid compounds - imidacloprid, clothianidin and thiamethoxam - for application as seed treatments, granular or foliar sprays in cereals and crops attractive to bees including sunflowers, oilseed rape, maize and soybean.
The commission plans to review conditions of approval of those three compounds within two years, taking into account relevant scientific and technical developments.
All three compounds are the active ingredients in neonics currently approved by the Environmental Protection Agency for sale in seed treatments and foliar sprays in New Zealand.
The EPA says when the IUCN study is published, it will review the information and assess its relevance to New Zealand.
In response to growing concerns about systemic pesticide use in Europe and the United States, the authority said it is stepping up its requirements for a higher level of scientific evidence regarding the safety and effects of new pesticides before considering them for approval.
Responding to the international study, Agcarm says neonics have been widely used in New Zealand for more than 20 years and there is no verifiable evidence of any adverse effects on the health of this country's bee populations or other species.
Manufacturers claim the majority of crops neonicotinoids are used on are not attractive to bees as they do not flower or are harvested or grazed before they flower.
In its own published fact sheet on neonics, Agcarm acknowledges they are intrinsically very toxic to honey bees when used as a seed treatment. They say it is important to limit bees' exposure to dust off the seed during planting, but residues in pollen and nectar and in the guttation fluid are well below adverse risk levels.
Meanwhile, a new study by a team of researchers at the Harvard School of Public Health in Boston has found the presence of neonicotinoid residues in many fruit, vegetable and pollen sampled from the United States and New Zealand.
The study is the first in the world to examine the presence of neonicotinoid residues in food, including organic food.
Researchers used modern detection methods and the National Beekeepers' Association of New Zealand says the levels detected were significantly below maximum residue levels set by the New Zealand Food Safety Authority.
However, beekeepers' concerns are that the compound imidacloprid, one of the three neonics restricted in Europe, was detected in pollen samples from kiwifruit when the product was not authorised for use on that crop.
Beekeepers say this discovery is "crucial to understanding that the world's most widely used systemic pesticide is now so common throughout our environment that no food stuff can be considered free of any residue."
Environmentalists question why systemic pesticides were ever released on the basis of slick marketing campaigns with little or no evidence of their long-term effects on the environment. They also compare the preventative use of neonics to ward off all insect pests to the dangers of overuse of antibiotics in human health.