In the first decade of 'Bt' insecticidal GM maize growing, it was noted that aphids unexpectedly thrived on them. Aphids are sap-sucking insects which can reproduce prodigiously under the right conditions, but don't usually cause economic damage to maize crops. It was suggested that these overwhelmingly 'right conditions' in the Bt maize plants might be their slight, but significantly, increased levels of amino acids*, dismissed by regulators as of 'no biological significance'.
*Amino acids are the building blocks of proteins
In 2014, Brazilian scientists in collaboration with Monsanto published a study on how well its latest Bt GM soya, 'Intacta', coped with a known problematic pest. The pest studied was 'Spodoptera', or 'southern armyworms', a moth known not to be susceptible to the Bt insecticide which Intacta produces.
It was found that, when fed on Intacta, Spodoptera larvae ('worms') not only survived but developed faster, and that the adult males lived longer than on non-GM comparator soya.
This was treated as "an alert that (Spodoptera) populations may increase in Bt soybean". Clearly not what growers would expect. Rather than suggest spraying with an insecticide which would defeat the purpose of growing a Bt crop, Monsanto recommended releasing other predator insects, such as wasps, that act as natural enemies of southern armyworms if Intacta soybeans are grown.
So, Intacta isn't just failing to poison Spodoptera, as expected, but is promoting the pest. The paper points out that the Spodoptera-friendly nature of Intacta isn't likely to come from the presence of the GM traits engineered into the crop, but rather some unintended changes in plant characteristics caused by the whole GM procedure. It is explained that the composition, and therefore nutritional content, of a transgenic Bt plant will differ from its nearest non-GM relative due to the extensive breeding needed to arrive at the final, marketable product*. For example, information from Monsanto reported that one of its Bt maize strains (MEB 307Bt) shared only 97.5% of its genes with its closest, non-GM, relative. This leaves a lot of wiggle-space for 'unintended changes'.
*The original genetically transformed plant created in the laboratory must be cross-bred with the desired commercial variety of the crop after which back-crossing is needed to purify the strain.
Indeed, when the two parent GM soyabeans (one herbicide-tolerant and one Bt) were bred together to create Intacta, the hybrid GM plants had higher levels of sugars and lower levels of protein than their ancestors. Is this the food that Spodoptera like best?
Most new GM crops now coming to market are stacked with multiple artificial genes bred into them from multiple GM parents. The safety of the stacked GM crop is assumed if all the simpler GM strains which went into its creation are deemed safe. If each parent is contributing its own little bit of any kind of problem on top of all that breeding, this could stack up into a great big food safety and crop sustainability problem.
However, there's more going on in a Bt plant than small nutrient changes. A year before the Monsanto/Brazilian paper was published, scientists elsewhere had identified some very complex interactions between pests, the damage they cause, and the plants' immune system. These can result in an impaired production of natural protective substances in a Bt crop and increased vulnerability to attack by unusual pests [1].
A few more Bt/pest problems are featured in WEAK-SKINNED Bt PLANTS WITH Bt-UNFRIENDLY VIRUSES - May 2022
Don't let regulators get away with taking the lazy path of unsupported assumptions about the safety of your food: each and every new GM hybrid should be thoroughly tested for safety as the unique new plant it obviously is.
Background:
[1] Bt INSPIRED PESTS - September 2013
SOURCES
In 2014, Brazilian scientists in collaboration with Monsanto published a study on how well its latest Bt GM soya, 'Intacta', coped with a known problematic pest. The pest studied was 'Spodoptera', or 'southern armyworms', a moth known not to be susceptible to the Bt insecticide which Intacta produces.
It was found that, when fed on Intacta, Spodoptera larvae ('worms') not only survived but developed faster, and that the adult males lived longer than on non-GM comparator soya.
This was treated as "an alert that (Spodoptera) populations may increase in Bt soybean". Clearly not what growers would expect. Rather than suggest spraying with an insecticide which would defeat the purpose of growing a Bt crop, Monsanto recommended releasing other predator insects, such as wasps, that act as natural enemies of southern armyworms if Intacta soybeans are grown.
So, Intacta isn't just failing to poison Spodoptera, as expected, but is promoting the pest. The paper points out that the Spodoptera-friendly nature of Intacta isn't likely to come from the presence of the GM traits engineered into the crop, but rather some unintended changes in plant characteristics caused by the whole GM procedure. It is explained that the composition, and therefore nutritional content, of a transgenic Bt plant will differ from its nearest non-GM relative due to the extensive breeding needed to arrive at the final, marketable product*. For example, information from Monsanto reported that one of its Bt maize strains (MEB 307Bt) shared only 97.5% of its genes with its closest, non-GM, relative. This leaves a lot of wiggle-space for 'unintended changes'.
*The original genetically transformed plant created in the laboratory must be cross-bred with the desired commercial variety of the crop after which back-crossing is needed to purify the strain.
Indeed, when the two parent GM soyabeans (one herbicide-tolerant and one Bt) were bred together to create Intacta, the hybrid GM plants had higher levels of sugars and lower levels of protein than their ancestors. Is this the food that Spodoptera like best?
Most new GM crops now coming to market are stacked with multiple artificial genes bred into them from multiple GM parents. The safety of the stacked GM crop is assumed if all the simpler GM strains which went into its creation are deemed safe. If each parent is contributing its own little bit of any kind of problem on top of all that breeding, this could stack up into a great big food safety and crop sustainability problem.
However, there's more going on in a Bt plant than small nutrient changes. A year before the Monsanto/Brazilian paper was published, scientists elsewhere had identified some very complex interactions between pests, the damage they cause, and the plants' immune system. These can result in an impaired production of natural protective substances in a Bt crop and increased vulnerability to attack by unusual pests [1].
A few more Bt/pest problems are featured in WEAK-SKINNED Bt PLANTS WITH Bt-UNFRIENDLY VIRUSES - May 2022
OUR COMMENT
It looks like those small non-biologically-significant nutrient changes in Bt plants could be both biologically and environmentally significant after all. If a Bt crop is not only pest-promoting but also unable to defend itself against any pest not targeted by its GM insecticide, it is not fit-for-purpose and shouldn't be approved by regulators.Don't let regulators get away with taking the lazy path of unsupported assumptions about the safety of your food: each and every new GM hybrid should be thoroughly tested for safety as the unique new plant it obviously is.
Background:
[1] Bt INSPIRED PESTS - September 2013
SOURCES
- Cristina
A. Faria, et al., 2007, High Susceptibility of Bt Maize to
Aphids Enhances the Performance of Parasitoids of Lepidopteran Pests,
PLoS ONE 7
- O.C.
Bortolotto, et al., 2014, Development and reproduction of Spodoptera
eridania (Lepidoptera: Noctuidae) and its egg parasitoid Telenomus remus
(Hymenoptera: Platygastridae on the genetically modified soybean (Bt) MON
87701.MON89788, Bulletin of Entomological research 104
- Monsanto
warning on negative effects of growing its genetically engineered soybean
"Intacta", TestBiotech, 2.10 14
- Steffan Hagenbucher, et al., 2018, Pest trade-offs in technology: reduced damage by caterpillars in Bt cotton benefits aphids, Proceedings of the Royal Society
Photo Creative Commons
No comments:
Post a Comment
Thanks for your comment. All comments are moderated before they are published.