A new study has shown that pollen from genetically engineered maize MON810 can have negative effects on ladybird beetle populations. Currently, MON810 is the only genetically engineered plant approved for cultivation in the EU. It produces the Cry1Ab insecticide, which is intended to combat the European corn borer. This latest study is particularly relevant as it investigates long-term effects of Bt pollen on beneficial insects not naturally expected to be adversely affected by the toxin.
The Cry1Ab insecticide occurs naturally in soil bacteria (Bacillus thuringiensis) and is only supposed to be toxic to certain species of pest moths, but not, e.g. to beetles. The toxins are called Bt toxins because they originate from bacteria. In the study, a specific ladybird beetle species (Hippodamia variegata) was fed Bt maize pollen. This is a common and important beneficial species that feeds primarily on aphids and is found in the Mediterranean region. However, ladybird beetles also feed on pollen as a food supplement, or when aphids are scarce, including pollen from maize crops. According to the authors, it is therefore very likely that under field conditions, ladybird beetles will come into contact with maize pollen, including pollen from Bt maize in areas where it is grown.
The experiment showed that the lifespan of the offspring of female ladybirds beetles that had consumed Bt pollen was reduced by 17–30 percent. This effect was partially offset by increased reproductive performance in the female insects fed with Bt pollen. Nevertheless, there was an overall negative effect on the ladybird beetle population.
Under field conditions, declines in ladybird beetle populations could limit their beneficial function, thus leading to increased aphid infestation, or even a complete disruption of the predator-prey relationship.
The study was not able to clarify the reasons for the adverse effects on the offspring of insects fed with Bt maize pollen. According to the authors, the Bt maize pollen that was examined had a significantly lower Cry1Ab content than stated in numerous other publications. The negative effects on ladybird beetles could therefore actually be even more pronounced than demonstrated in this particular study.
Neither can effects resulting from genetic modification be ruled out. Other publications have already identified changes in the nutrient content of Bt maize pollen, which means that nutrient deficiency could also play a role in the negative effects it has on ladybird beetle populations.
In the opinion of Testbiotech, this study once more highlights the lack of investigation into environmental risks associated with genetically engineered plants.
EU authorisation for the cultivation of MON810 expired in 2008. This means that it has been cultivated for the past 17 years without renewed approval. Testbiotech considers this to be a failure on the part of the European Commission, which ultimately has responsibility for authorisation procedures.
In recent years, the cultivation of genetically engineered maize in Europe has declined significantly; it is currently only cultivated in Spain and Portugal. In the past, MON810 was cultivated on about 140,000 hectares in Spain in 2014, but by 2024 this number had fallen to just 70,000 hectares. In Portugal, Bt maize is grown on a much smaller scale, and is also on a downward trend. In Germany, the cultivation of MON810 has been banned since 2009.
Contact:
Christoph Then, info@testbiotech.org, Tel + 49 151 54638040
Further information:
The current study on MON810