A new generation of scientists, Page 2
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|Tree swallow nestlings wait for food.|
A breakthrough in insecticides
When neonicotinoids came on the market 20 years ago, ecotoxicologists and pesticide regulators were optimistic. Older generations of pesticides, including carbofuran, were severely toxic to warm-blooded animals. The cholinesterase-inhibitors essentially cause the “biological equivalent of a short-circuit” in nerves, Mineau said. In fact, they were derived from nerve-gas research in Germany during World War II, he said. Neonics, derived from nicotine, also are nerve toxins but they have a much greater effect on insects than on birds or people. They were seen as a breakthrough.
report that this means there are environmental pluses to neonics. Because coating seeds is a precise method of delivering pesticide to a plant, whole fields no longer need to be sprayed. That means the chemical is targeted to the plant itself. The chemicals infuse each part of the plant as it grows, pushing the pesticide molecules into roots, stalks, seeds, leaves, pollen and nectar. This is known as a systemic pesticide because it affects all tissues, all cells. Sometimes, farmers apply the pesticide after the plants have grown as well.Not only that, but neonics are used in agriculture differently than earlier pesticides. Manufacturers, including Bayer AG and Syngenta AG, coat seeds with the pesticide and then seal the seed with plastic. The manufacturers point out in a recent
But Morrissey and Mineau point out that the phenomenon of coating seeds means that for lots of crops, including canola, soybeans and corn, seeds are treated whether the crop is at risk of pest damage or not. Overall, that means the pesticides are applied to vast numbers of acres. The old pesticides such as carbofuran had a half-life in the environment of three or four days; for neonics, it's over a year in the soil, and in some cases, as much as 12 years.
For insects, a growing body of research suggests that neonic molecules are having unexpected effects. Alex Lu of Harvard University and others have linked them to colony collapse disorder, a phenomenon affecting farmed honeybees whose adults mysteriously die or vanish. Also, because the pesticide remains in pollen and nectar in small quantities, it can have chronic effects on pollinators, not just honeybees but others as well. For example, a recent study in England found that bees equipped with microchip radio tags didn’t show big effects before at least two weeks of low exposure. Rather than being able to hone and improve skills of collecting and bringing back pollen, the bees exposed to neonics actually got worse at those tasks over four weeks, said Nigel Raine, study co-author and research chair in pollinator conservation at the University of Guelph in Ontario.
This implies that the pesticides are altering bumblebees’ learning and memory. And that, in turn, implies that there could be other unforeseen consequences.
|Blood is collected from a tree swallow.|
Cataloging their effects
Two years ago, once Morrissey realized that neonics could leach into water long after they were applied, and that they had lethal effects on so many beneficial insects, she began the second stage of her research, which is still in progress: cataloging their effects on specific insects in the wild, and analyzing the health of tree swallows in areas of intensive farming with neonics. This is notoriously difficult science because it is about indirect effects. It takes stages of analysis: First, what is happening to insects; second, what is happening to birds; and then, third, whether the first is connected to the second. Most scientists shy away from this study design because it is painstaking. “Thank god that didn’t deter me,” she says.
She’s parked the truck next to a row of wooden boxes where tree swallows have built their nests, a proxy for the tree cavities they like. This is one of five research sites, some near intensive farming using neonics and some in unfarmed land. She wades through the tall grass, flicking off ticks and batting away mosquitoes, and opens the box. Inside are 12-day-old tree swallows, peeping. Morrissey collects three in a cloth bag and wades back to the truck. She bands each tiny leg with a number that will identify the bird if it’s caught again, then measures and weighs each nestling, draws a few drops of blood from each and carefully plucks a couple of downy feathers for chemical analysis that will give a signal of how much food stress each bird is under. She repeats this ritual throughout the day, marking her actions on a chart. Morrissey and her grad students will band every 12-day-old tree swallow chick across the five research sites – hundreds of birds in all.
Over the years, Morrissey and her team will track whether these birds return to the nesting sites to make their own families, whether they have their own chicks and, maybe, whether they die or survive. Preliminary results indicate that the birds at agricultural sites are in poorer condition than those farther away from the chemicals. There’s a slight delay in the breeding time of the adults in the neonic-treated areas and their chicks are less healthy. “We’re starting to build a picture of who they are and what their survival rate is,” she says.
The hypothesis she’s testing is that these birds are having a tougher time finding the flying insects they eat, and that affects this crucial period of the birds’ life history after their migration. When they arrive on these prairies in the spring to breed, they are thin and depleted so they need food – lots of it. Then they need more food as they lay eggs and even more to feed their nestlings. The life of these birds revolves around bugs. Her research has already determined that tree swallows vastly prefer midges to other food, and midges are exquisitely sensitive to neonics even in tiny amounts.
|Mike Cavallaro and Anson Main wade into a wetland with a device called a limnocorral for trapping insects.|
In the Netherlands, insect-eating birds have declined in numbers since neonics began to be used on crops there, and the decline worsened with higher water concentrations of the chemicals, according to a studypublished in the journal Nature in July. “Our results suggest that the impact of neonicotinoids on the natural environment is even more substantial than has recently been reported and is reminiscent of the effects of persistent insecticides in the past. Future legislation should take into account the potential cascading effects of neonicotinoids on ecosystems,” concluded the study by Caspar Hallman and others of Radboud University.
study in Spain that fed partridges neonic-coated seeds reported that the chemicals led to smaller, thinner eggs and fewer surviving chicks, as well as suppressed immune systems. The scientists said their results “suggest that treated seeds…may constitute a risk for farm-land birds,“ although they added that the real-life exposure of wild birds has not been quantified.In addition, a
A groundbreaking 2013 report by Mineau and Palmer for the American Bird Conservancy argued that birds might die from eating just one or two coated seeds. So far, however, there are only a few reports of birds being possibly poisoned in fields.
Morrissey also is conducting a novel experiment on a Saskatchewan pond where she and her grad students have set up 21 separated columns in the water, anchored in the sediment. Each is covered with a tent and Plexiglas traps filled with alcohol to capture all the insects that emerge from the water. The columns, called limnocorrals, are dosed with different levels and combinations of neonics – in addition to two controls not dosed – at concentrations already common in prairie wetlands. The aim is to measure whether the abundance of insects in the wild is affected by neonics, the first study of its kind. Early results suggest that the same insects shown in lab tests to be affected at the levels commonly found in wetlands are failing to hatch in the wild pond as well.
This summer, an analysis of more than 800 peer-reviewed studies of neonics and other systemic pesticides, conducted by an independent task force of scientists including Morrissey and Mineau, concluded that the chemicals are “likely to have a wide range of negative biological and ecological impacts.” Harkening back to DDT and the cholinesterase-inhibitor chemicals, the task force said that systemic insecticides, including neonics, “represent a new chapter in the apparent shortcomings of the regulatory pesticide review and approval process that do not fully consider the risks posed by large-scale applications of broad-spectrum insecticides.” The potential risks to people are unknown; no substantial studies of human effects have been conducted.
|Behind Morrissey, limnocorrals capture insects rising to the surface.|
"A concerted and ill-conceived campaign"
Manufacturers of neonicotinoids see all these studies in a different light. The European Crop Protection Association, representing the manufacturers, said in a statement that the task force’s conclusions do not represent a “robust assessment of the safety of systemic pesticides under realistic conditions of use,” and accused the scientists of relying on worst-case scenarios and of being “part of a movement that brings together some academics and NGOs whose primary objective is to restrict or ban the use of neonicotinoid technology regardless of what the evidence may show.”
The industry group said the scientists are overlooking the economic and environmental benefits of using neonics. A European study paid for by Bayer CropScience and Syngenta, two of the largest manufacturers of neonics in the world, found that neonic seed treatments contribute more than 2 billion Euros a year to commodity crop revenues in Europe and reduce the cost of producing them by nearly another billion Euros.
The European industry association accused the authors of the Netherlands bird study of being part of “a concerted and ill-conceived campaign against neonicotinoids rather than a genuine pursuit of good science and solutions for safeguarding our environment.” The group added that the bird declines could stem from other problems, such as climate change.
Mike Leggett, senior director of environmental policy at CropLife America, which represents pesticide companies, noted that the study in the Netherlands failed to assess whether the birds’ nutritional needs were met or not, and noted that just six of the 15 bird species investigated were in decline.
|Morrissey's son Riley uses a dipnet to sample a wetland.|
When it comes to Morrissey’s work, Leggett said that he’s keenly interested to see her results on aquatic insects and wonders whether she will prove any effects on birds. “The notion that you’re really going to be able to extend that potential indirect effect to an effect on birds is a pretty big stretch,” he said. “We really haven’t seen any evidence of that in the environment.”
Leggett emphasized that the neonic levels Morrissey is finding in wetland waters are “very, very low,” and that they are not “a cause for concern.” He said that the levels in prairie potholes and their persistence are “not entirely unexpected” given industry’s own scientific models. “They don’t suggest to me an imminent risk to aquatic life in prairie potholes or to any other organisms depending on that aquatic life, like birds,” he said.
Morrissey isn’t surprised by what industry is saying about her work or the claims that the levels found in those prairie potholes are safe. It’s industry’s job to promote the products; it’s hers to investigate their safety. “We have different perspectives on the issue and I accept that we will always likely disagree,” she said.
Carson faced virulent attacks when she published her results and so have others who have tried to investigate the safety of pesticides worth billions of dollars a year in sales. So far, apart from general accusations that some scientists are on an anti-neonic “campaign,” industry’s criticisms have not been personal, only vehement.
Few answers, lots of questions
Morrissey, who is back in her truck heading home after a day in the field, doesn’t claim to have all the answers yet. In fact, the answers she has collected simply lead to more questions. “I feel like we’re just getting the glasses on, starting to sharpen the picture little bits here and there. As it sharpens, as we see things, we start asking more questions,” she says.
For instance, there is not just one neonic; there are several. It’s unknown whether they add up in toxicity to aquatic bugs, but early signs suggest they do. And as they break down, they produce other chemicals that also may be toxic.
She shrugs. Finding answers to these questions is a first step toward decoding the puzzle.
If neonics are dangerous, regulators can do something about it, just as they did with DDT after Carson’s work.
“We’re losing birds. That’s what’s happening. It’s indisputable,” she says, eyes scanning the fields and ponds. “If we talk about really conserving birds, then we need to figure out whether neonics are the biggest factor or whether it’s something else. If it is one of the major problems, it’s one we can actually do something about.”