THIRD WORLD NETWORK INFORMATION SERVICE ON BIOSAFETY AND SUSTAINABLE AGRICULTURE
Dear Friends and Colleagues
Applied Pesticide Toxicity Increasing in the US, Even in GM Crops
A recent study (Item 1) in the journal Science shows that, contrary to claims of reduced environmental impacts of pesticide use, the toxicity of applied insecticides to aquatic invertebrates and pollinators has more than doubled between 2005 and 2015 in the US, in sharp contrast to the applied amount. A shift towards usage of pyrethroids and neonicotinoids, respectively, is responsible for this trend. This pattern is evident even for GM crops that were originally designed to reduce pesticide impacts on the environment (Item 2).
The toxicity of pesticides depends not just on amount applied, but on which pesticides are used. This is why the researchers looked at the type, amount, and toxicity of 381 pesticides applied in the US over the last 25 years. The researchers call the toxicity arising from pesticides applied to crops the “Total Applied Toxicity (TAT)”.
For GM crops, the researchers report increasing toxicity of applied pesticides to aquatic invertebrates and pollinators in GM maize and terrestrial plants in herbicide-tolerant soybeans since approximately 2010. Considering only data for maize, of which 79% in the US in 2016 was Bt hybrids, TAT increased for both aquatic invertebrates (mainly because of pyrethroids) and terrestrial pollinators (mainly because of neonicotinoids) at the same rate observed for US agriculture as a whole. The toxicity per hectare of insecticides applied to Bt maize is equal to that for non-Bt maize. The researchers suggest that the increasing insecticide TAT may be a result of preemptive, possibly unnecessary applications or pest resistance to the Bt toxins in Bt maize. (Item 3)
The researchers also report that herbicide use has increased with the spread of herbicide-tolerant GM crops, which has led to a strong increase in the use of glyphosate. The TAT to terrestrial plants has increased steadily since approximately 2008 for herbicides in herbicide-tolerant soybeans, likely in response to glyphosate resistance.
This study highlights the overall trend in the US: while over the years, there has been a reduction in the volume of insecticides sprayed on fields, the insecticides currently applied are much more toxic (Item 4). Consequently, there has been a significant increase in the environmental impact due to pesticides, with and without GM plants. The researchers recommend “a system-centric view” of pest management in agriculture and suggest that organic agriculture can provide one of several useful strategies.
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Item 1
APPLIED PESTICIDE TOXICITY SHIFTS TOWARD PLANTS AND INVERTEBRATES, EVEN IN GM CROPS
Ralf Schulz, Sascha Bub, Lara L. Petschick, Sebastian Stehle, and Jakob Wolfram
Science 372, 81–84 (2021).
2 April 2021
DOI: 10.1126/science.abe1148
https://science.sciencemag.org/content/372/6537/81
Abstract
Pesticide impacts are usually discussed in the context of applied amounts while disregarding the large but environmentally relevant variations in substance-specific toxicity. Here, we systemically interpret changes in the use of 381 pesticides over 25 years by considering 1591 substance-specific acute toxicity threshold values for eight nontarget species groups. We find that the toxicity of applied insecticides to aquatic invertebrates and pollinators has increased considerably—in sharp contrast to the applied amount—and that this increase has been driven by highly toxic pyrethroids and neonicotinoids, respectively. We also report increasing applied toxicity to aquatic invertebrates and pollinators in genetically modified (GM) corn and to terrestrial plants in herbicide-tolerant soybeans since approximately 2010. Our results challenge the claims of a decrease in the environmental impacts of pesticide use.
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Item 2
INCREASING APPLIED PESTICIDE TOXICITY THREATENS PLANTS AND INSECTS
University of Koblenz-Landau
1 April 2021
https://www.eurekalert.org/pub_releases/2021-04/uok-iap032521.php
A group of scientists from the University of Koblenz-Landau, Germany, has shown that for plants and insects the applied pesticide toxicity in agriculture has substantially increased between 2004 and 2016. In a paper published in the current issue of Science, the authors show that this pattern is even relevant in genetically modified (GM) crops that were originally designed to reduce pesticide impacts on the environment.
“We have taken a large body of pesticide use data from the US and have expressed changes of amounts applied in agriculture over time as changes in total applied pesticide toxicity,” says lead author Ralf Schulz, professor for environmental sciences in Landau. “This provides a new view on the potential consequences that pesticide use in agriculture has on biodiversity and ecosystems”.
The amount of insecticides used in US agriculture has decreased substantially by more than 40% between 1992 and 2016. Fish, mammals, and birds face lower applied toxicities than in the 1990s, because insecticide classes such as organophosphates, which show high vertebrate toxicity, are used less today. Aquatic invertebrates and pollinators, such as honeybees, yet experience the opposite: despite reduced applied amounts, applied toxicity for these species groups has more than doubled between 2005 and 2015. A shift in the insecticides used towards usage of pyrethroid and neonicotinoid insecticides is responsible for this trend.
The applied toxicity increases for herbicides as well, alongside the applied amount. In this case, terrestrial plants are facing the highest increase in applied toxicity. Plants and pollinators are ecologically strongly connected. Simultaneously increasing applied toxicities in both groups thus alert to potential strong overall negative effects on plant and insect biodiversity.
GM crops have been developed to reduce the dependency of agriculture on chemical pesticide use. The results of the new study, however, clearly reveal that even in the two most important GM crops in the US, corn and soybean, the applied toxicity increases, along with increasing GM adoption, at the same rates as for conventional crops.
According to the authors, the results of the study likely apply to many other regions dominated by modern agriculture, though often the data for a thorough evaluation of trends in applied toxicity are not publicly available. Ralf Schulz adds: “These results challenge the claims of decreasing environmental impact of chemical pesticides in both conventional and GM crops and call for action to reduce the pesticide toxicity applied in agriculture worldwide.”
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Item 3
PESTICIDE TOXICITY TO INVERTEBRATES AND POLLINATORS INCREASING IN GM CROPS
Claire Robinson and Jonathan Matthews
GM Watch
2 April 2021
https://gmwatch.org/en/news/latest-news/19748
Some just published research in the journal Science completely demolishes claims that the impact of pesticides is declining and that GM crops are contributing to this positive trend.
In fact, the new study shows that not only is the toxic impact of pesticides increasing in the US but that GM crops are no better than conventional non-GM crops in that regard. As The Guardian notes in its report on the study by German researchers, using US government data, it “shows that the toxic impact of pesticides used on genetically modified crops remains the same as conventional crops, despite claims that GM crops would reduce the need for pesticides”.
And it quotes the lead researcher Prof Ralf Schulz, of the University Koblenz and Landau in Germany, as saying, “GM crops were introduced using the argument that they would reduce the dependency of agriculture on chemical pesticides. This is obviously not true if you look at toxicity levels.”
Check the toxicity, not just the quantity
Debates about the effects of pesticides on humans and the environment have been dominated by the comparison of use rates (e.g. kilograms per hectare) or applied amounts (e.g. kilograms per year). But these weight-based measures are not necessarily informative because the toxicity of different pesticides varies hugely. In other words, the toxicity will depend not just on amount applied, but which pesticides are used.
That is why when the researchers looked at the type, amount, and toxicity of pesticides applied in the US over the last 25 years, they found that despite decreasing total amounts applied, toxicity — in particular to insects and aquatic invertebrates — has increased substantially.
With regard to GM crops, the researchers report increasing toxicity of applied pesticides to aquatic invertebrates and pollinators in GM maize and to terrestrial plants in herbicide-tolerant soybeans since approximately 2010.
The researchers call the toxicity arising from pesticides applied to crops the “Total Applied Toxicity (TAT)”.
GM Bt crops
In the most widely grown GM crop that produces a Bacillus thuringiensis (Bt) insecticidal toxin, maize, the insecticide TAT increased. Considering only data for maize, of which 79% in the US in 2016 was Bt hybrids, TAT increased for both aquatic invertebrates (mainly because of pyrethroids) and terrestrial pollinators (mainly because of neonicotinoids) at the same rate observed for US agriculture as a whole.
The researchers verified that the toxicity per hectare of insecticides applied to Bt maize is equal to that for non-Bt maize. They suggest that the increasing insecticide TAT may be a result of preemptive, possibly unnecessary applications or pest resistance to the Bt toxins in Bt maize.
The authors reach a devastating conclusion for proponents of GM Bt crops: “Our analysis suggests that claims of reduced chemical insecticide use in US Bt crops simply reflect the considerably lower application rates required for more recently developed, more toxic insecticide classes,” whereas the TAT for pollinators and for aquatic invertebrates both continue to increase.
This finding will come as no surprise to regular readers of GMWatch as we flagged up flaws in the claims of reduced need for insecticides with GM crops that researchers were pointing to in 2012 and again in 2015, based on the failure to take account of rising toxicity in the insecticides applied.
Herbicide-tolerant GM crops
The researchers note that herbicide use has increased with the spread of herbicide-tolerant GM crops, which has led to a strong increase in the use of glyphosate. The TAT to terrestrial plants has increased steadily since approximately 2008 for herbicides in herbicide-tolerant soybeans, likely in response to glyphosate resistance.
While the researchers cite previous research as showing a downward trends for GM soybean herbicide toxicity to humans, this is false because the paper cited assumes a “relatively low chronic toxicity” for glyphosate. This assumption has been blown out of the water by the success of the lawsuits in the US, which blame exposure to Roundup (a glyphosate-based herbicide) for causing cancer. It is also belied by numerous studies attesting to other long-term toxic effects of glyphosate-based herbicides, including birth defects, neurological disease and DNA damage.
The focus of the paper is firmly on environmental effects, but the researchers point out that there are implications for human health, too: “Because 61% of US drinking water originates from surface waters, according to the EPA, TAT-based pesticide evaluations may also benefit human health evaluations.”
The researchers recommend “a system-centric view” of pest management in agriculture and suggest that organic agriculture can provide one of several useful strategies.
GMWatch agrees with the “system-centric” approach and notes that it is diametrically opposed to the reductionist approach of gene editing proponents, who claim that pesticide use can be reduced by altering individual genes in individual crops. An agriculture that relies on such supposed solutions is doomed to repeat the mistakes of the first-generation of GM crops, which are clearly laid out in the new paper.
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Item 4
TRANSGENIC PLANTS FAILING IN THE FIELDS
Testbiotech
10 April 2021
https://www.testbiotech.org/en/news/transgenic-plants-failing-fields
Increased environmental impact of toxic pesticides
Expectations that the cultivation of transgenic plants would lower the impact of pesticides on the environment have failed to materialise. This failure was confirmed in a recent study published in the magazine, Science, based on official data from the US. The experts compared volume and toxicity of pesticides applied in fields with genetically engineered (GE) plants to fields with conventional agriculture. The conclusion: in recent years there has been a strong increase in pesticides impacting the environment, with and without transgenic plants.
Most of the plants cultivated in the US produce insecticides and are resistant to herbicides such as glyphosate. The environmental impact due to pesticides has increased in both variants.
One reason is a growing number of weedy species that have adapted to glyphosate. Transgenic plants are also a crucial driver in this context since GE is used to make plants glyphosate-resistant, e.g. soybeans, maize, cotton, oilseed rape and sugar beet. The crops are subsequently intensively sprayed with the herbicide. Whereas all weeds were susceptible to glyphosate prior to the introduction of transgenic plant cultivation, meanwhile in the US, more than 15 weedy species have become glyphosate-resistant. The current study uses GE soybeans as an example to show that the volume of sprayed herbicides has strongly increased.
Similar effects have been observed in insecticidal plants. They produce a toxin (Bt) which occurs naturally in soil bacteria (Bacillus thuringiensis). Meanwhile, pest insects, such as the root worm, have adapted to the toxins to such a degree that the cultivation of Bt plants has been restricted in the US. Maize plants engineered to produce a specific insecticidal RNA have also not brought the expected breakthrough. The current study shows there was no reduction in the use of controversial insecticides, i.e. neonicotinoids used against corn borer, in fields where the insecticidal GE maize is grown.
The new publication highlights an overall trend in the US: while over the years there has been a reduction in the volume of insecticides sprayed on fields, the insecticides currently applied are much more toxic. Consequently, there has been a significant increase in the environmental impact due to pesticides, with and without GE plants.
Industry and experts close to industry claim there has been a reduction in pesticides ascribable to the cultivation of transgenic plants. However, as has also been shown in other publications, this is not the case.
Contact
Christoph Then, info@testbiotech.org, Tel + 49 (0) 151 54638040