Claims of reduced pesticide use with GM crops are baseless, new study shows

Study exposes massive increase in bee-toxic neonicotinoid seed treatments in parallel with GM crops’ spread; one group of chemical insecticides has been replaced with another. Claire Robinson comments

Studies that claim decreases in pesticide use from GM crops are cast into question by a new study on the use of highly toxic neonicotinoid insecticidal seed treatments* in major field crops like corn and soy.



The new study (abstract below) found that neonicotinoid use increased rapidly in the US between 2003 and 2011, with 34−44% of soybeans and 79−100% of corn hectares being treated in 2011. The authors concluded that “insecticide use in field crops has expanded dramatically” with neonicotinoid seed treatments.



Margaret Douglas, graduate student in entomology at Pennsylvania State University and an author of the study, commented, “Previous studies suggested that the percentage of corn acres treated with insecticides decreased during the 2000s, but once we took seed treatments into account we found the opposite pattern. Our results show that application of neonicotinoids to seed of corn and soybeans has driven a major surge in the U.S. cropland treated with insecticides since the mid-2000s.”



The study also found that neonicotinoid seed treatments are being used over a very large area (40 million hectares). In corn and soybeans, Douglas and her co-author John F. Tooker found that neonicotinoid seed treatments are often used as part of “an insurance-based approach to pest management that may be reinforced in the seed market by limited availability of neonicotinoid-free seed”.



Studies claiming insecticide reductions from GM Bt crops mislead



Douglas and Tooker noted that their findings contradict other recent analyses which concluded that insecticides are used today on fewer corn hectares than a decade or two ago. In particular, they stated that studies claiming that Bt crops have decreased insecticide use “do not seem to have considered seed treatments, and so may have overstated reductions in insecticide use”.



As an example of such misleading studies, Douglas and Tooker cited the recent meta-analysis by Klumper and Qaim, which claimed a 37% reduction in chemical pesticide use from GM crops overall and a 42% reduction from Bt insecticidal crops. While Klumper and Qaim’s study was much hyped by the pro-GMO lobby and the recent UK House of Commons Select Committee report on GM crops, its claim is exposed as baseless by Douglas and Tooker’s analysis.



The failure of GMO proponents to consider insecticidal seed treatments when claiming reductions in chemical insecticide use from GM crops was previously highlighted by the authors of GMO Myths and Truths, as well as by Dr Doug Gurian-Sherman. Gurian-Sherman said, “In reality, corn engineered to kill certain insect pests – AKA Bt corn – has mainly resulted in the replacement of one group of chemical insecticides with another.” The new study proves the point with hard data.



Trend not compatible with Integrated Pest Management



The trend of increasing use of neonicotinoid seed treatments marks what Douglas and Tooker call “an unprecedented shift toward large-scale, preemptive insecticide use”.



By “preemptive” they mean that the insecticides are applied in advance, regardless of what the actual pest pressure turns out to be in a particular year and location. In their study, Douglas and Tooker asked how the extensive use of these products might relate to Integrated Pest Management (IPM), which is supposed to have been the guiding framework for US pest management policy since the 1970s. In IPM, insecticides are reserved for situations where pest damage reaches levels of economic concern.



Douglas and Tooker pointed out that many pest attacks are sporadic and not troublesome, which may explain why studies have not found consistent yield benefits from the use of neonicotinoids. They concluded that neonicotinoid seed treatments are being used “on many hectares where they do not deliver an economic return and cannot be considered part of an IPM approach”.



Douglas and Tooker warned, “This pattern of use may have unintended consequences, namely resistance in target pests, outbreaks of nontarget pests, and pollution with detrimental effects cascading to wildlife… some of these effects have already emerged.”



Douglas and Tooker’s warning is supported by another timely new study, which found that one neonicotinoid insecticide, clothianidin, has been found in milkweed, the food of the monarch butterfly, at levels harmful to monarch larvae (abstract below). The authors of the second study concluded that the neonicotinoid could be another “stressor” on monarch populations, in addition to the mass wipe-out of milkweed by the herbicides sprayed on GM herbicide-tolerant crops.



As a solution, Douglas and Tooker recommended a reduction in neonicotinoid seed treatment use, along with proper implementation of IPM. In case anyone doubts that such methods will work in controlling pests, Prof Robert Van Den Bosch’s book The Pesticide Conspiracy explains that they are the only thing that does work – pesticide use, in contrast, actively creates pest attacks by wiping out the natural pest predators. A more recent book, Poison Spring, by former US EPA staffer Evaggelos Vallianatos, demolishes the notion that pesticide use is based on any kind of sound science at all.



Douglas and Tooker’s study is another piece of evidence showing that GM crops are simply an extension of the pesticide-reliant model of agriculture that is destroying our world and that claims of their environmental benefits are unreliable. A move towards organic and low-input agriculture is urgently required.



Notes



* In neonicotinoid seed treatments, the insecticides are coated onto the seed before planting. As the plant grows, it contains the pesticide in its foliage, seeds, and pollen. Neonicotinoids spread and persist in the environment. Even in the relatively small amounts used as seed treatments, they have proven toxic to bees and other important pollinators, leading to the EU limiting their use.

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Large-Scale Deployment of Seed Treatments Has Driven Rapid Increase in Use of Neonicotinoid Insecticides and Preemptive Pest Management in U.S. Field Crops

Margaret R. Douglas and John F. Tooker

Environ. Sci. Technol, March 20, 2015

http://pubs.acs.org/doi/abs/10.1021/es506141g



Abstract

Neonicotinoids are the most widely used class of insecticides worldwide, but patterns of their use in the U.S. are poorly documented, constraining attempts to understand their role in pest management and potential nontarget effects. We synthesized publicly available data to estimate and interpret trends in neonicotinoid use since their introduction in 1994, with a special focus on seed treatments, a major use not captured by the national pesticide-use survey. Neonicotinoid use increased rapidly between 2003 and 2011, as seed-applied products were introduced in field crops, marking an unprecedented shift toward large-scale, preemptive insecticide use: 34–44% of soybeans and 79–100% of maize hectares were treated in 2011. This finding contradicts recent analyses, which concluded that insecticides are used today on fewer maize hectares than a decade or two ago. If current trends continue, neonicotinoid use will increase further through application to more hectares of soybean and other crop species and escalation of per-seed rates. Alternatively, our results, and other recent analyses, suggest that carefully targeted efforts could considerably reduce neonicotinoid use in field crops without yield declines or economic harm to farmers, reducing the potential for pest resistance, nontarget pest outbreaks, environmental contamination, and harm to wildlife, including pollinator species.

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Non-target effects of clothianidin on monarch butterflies

Jacob R. Pecenka and Jonathan G. Lundgren

Sci Nat (2015) 102:19



Abstract

Monarch butterflies (Danaus plexippus) frequently consume milkweed in and near agroecosystems and consequently may be exposed to pesticides like neonicotinoids. We conducted a dose response study to determine lethal and sublethal doses of clothianidin using a 36-h exposure scenario. We then quantified clothianidin levels found in milkweed leaves adjacent to maize fields. Toxicity assays revealed LC10, LC50, and LC90 values of 7.72, 15.63, and 30.70 ppb, respectively. Sublethal effects (larval size) were observed at 1 ppb. Contaminated milkweed plants had an average of 1.14 ±0.10 ppb clothianidin, with a maximum of 4 ppb in a single plant. This research suggests that clothianidin could function as a stressor to monarch populations.