GM crops adding to ecosystem collapse

June 2022

A key selling-point for 'Bt' insecticide-generating GM crops is that they reduce the need to spray chemical pesticides on the crop. It is claimed this makes them 'environmentally-friendly'.

Indeed, a study published in 2014, which combined data from 147 studies world-wide, showed a significant 42% reduction in the quantity of pesticide applied on Bt crops compared to conventional ones. This was much hyped as proof of the benefits of GM in agriculture by the pro-GM lobby and by the UK government committee which reported it. The study was, however, narrowly focused on comparisons of the weight of pesticide applied in kilograms per hectare or per year. Pre-emptive systemic insecticides, put on the seed but not sprayed onto the crop in the field, were not factored in.

Besides the questionable omission from the 'weight of pesticide' calculation of the Bt protein itself which is present in most plant parts for most of the GM crop's life, there's a second systemic toxin routinely present in these GM crops.

A few years after the launch of Bt crops, another agrichemical fashion took hold. This was the coating of seeds before planting with 'neonicotinoid' insecticides. As the plant grows, the pesticide disperses throughout the plant tissues where it provides protection for several weeks and persists at low levels for several months. There's plenty of opportunity for non-target insects, including pollinators, to come into contact with the toxin and to suffer adverse effects.

Note that, by 2011, 100% of US corn hectares were planted with neonicotinoid-coated seeds. This routine use of the insecticide is being re-enforced by the seed market in which there's limited availability of neonicotinoid-free seed.

Bt and neonicotinoids, both systemic pesticides which are present whether they're needed or not, share a number of other undesirable features. For example, both endanger wildlife either by direct toxic effects or by decimating the food supply needed further up the food chain. Both promote the evolution of target pest-resistance and the emergence of new pests which weren't previously a bother. The latter tendency means that both, inevitably, lead to increased pesticide applications over time [1].

It's difficult to see the reality of Bt crops as anything other than the replacement of one group of chemicals used only intermittently and as-needed with another set of chemicals which are constantly-present and may not be needed at all.

It's also been pointed out that neither Bt nor neonicotinoids are compatible with US pest management policy which, since the 1970s, has supported Integrated Pest Management (IPM). In IPM, insecticide use is reserved for situations where pest damage reaches a level of economic concern.

A more recent study carried out by a German University has highlighted another ominous trend in pesticide application.

Modern insecticides have made a politically-expedient shift to chemicals with an environmentally-friendly lower toxicity to birds and mammals. At the same time, they have become increasingly toxic to target insects so that they can be applied in proportionately lower amounts than their predecessors.

The German scientists gathered US data on 381 pesticides used over the 25 years to 2016, including their effects on eight groups of non-target species*. Then, instead of using the weight of the chemical formulations, they calculated the 'toxic potential' of the applied chemicals for different animals using the regulatory-defined threshold levels for harm. These toxic potentials can be combined to derive a total applied toxicity (TAT) for each substance, each species group, and year. The TAT is predictive of potential pesticide impact on the environment.

*Note that American data were used because this is the only area where pesticide use information is made publicly available.

Based on this more refined metric, they confirmed that pesticide toxicity for mammals and birds has decreased by a factor of 9. In sharp contrast, pesticide toxicity to aquatic invertebrates and pollinators has more than doubled, with clear negative effects on biodiversity. In fact, using this metric, the toxicity of the insecticides applied to Bt maize was equal to that for conventional maize.

The authors suggest that the increases in the toxicity of pesticides to non-target species may be even more pronounced on a global scale than they are in the US.

These studies present 

"... yet more evidence showing GM crops are simply an extension of the pesticide-reliant model of agriculture that is destroying our world and that the claims for their environmental benefits are unreliable. A move towards organic and low-input agriculture is urgently required" (GM Watch 2015)

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Background

[1] NON-GM COTTON TO THE RESCUE - June 2019


SOURCES:

• Wilhelm Klümper and Matin Qaim, November 2014, A Meta-Analysis of the Impacts of Genetically Modified Crops, PLoS ONE
• Pesticide toxicity to invertebrates and pollinators increasing in GM crops, GM Watch, 2.04.21
• Damian Carrington, Toxic impact of pesticides on bees has doubled, study shows, The Guardian, 1.04.21
• Ralf Schultz, et al., April 2021, Applied pesticide toxicity shifts toward plants and invertebrates, even in GM crops, Science 372
• Claims of reduced pesticide use with GM crops are baseless, new study shows, GM Watch 4.04.15
• Margaret R. Douglas and John F Tooker, 2015, Large-Scale Deployment of Seed Treatments Has Driven Rapid Increase in Use of Neonicotinoid Insecticides and Pre-emptive Pest Management in U.S. field Crops, Environmental Science & Technology

CC photo by Greensefa on Flickr