Recommended Further Reading
Recommended Scientific Publications
- Kranthi et al. (2020). Long-term impacts of Bt cotton in India. Nature Plants, 6(3), 188-196.
- Pott et al. (2020). Effect of Bt toxin Cry1Ab on two freshwater caddisfly shredders - an attempt to establish dose-effect relationships through food-spiking
- Latham et al. (2017). The distinct properties of natural and GM cry insecticidal proteins. Biotechnology and Genetic Engineering Reviews, 1-35.
- Santos-Amaya et al. (2017). Magnitude and allele frequency of Cry1F resistance in field populations of the fall armyworm (Lepidoptera: Noctuidae) in Brazil. Journal of Economic Entomology, 110(4), 1770-1778.
- Wang & Fok (2017). Managing pests after 15 years of Bt cotton: Farmers' practices, performance and opinions in northern China. Crop Protection, 1-10.
- Hilbeck & Otto (2015). Specificity and combinatorial effects of Bacillus thuringiensis Cry toxins in the context of GMO environmental risk assessment. Frontier in Envrionmental Sciences, 3 (71).
Bt crops are genetically modified to confer resistance against certain insect pests. The inserted genes were originally identified in the bacterial species Bacillus Thuringiensis (Bt). These bacteria exhibit insecticidal activity by producing different δ-endotoxins (Cry and Cyt toxins). For that reason, Bacillus thuringiensis spp. have long been used in biopesticides. In Bt crops, the insecticides are produced inside the plant and can, unlike traditional insecticides, kill insect pests feeding inside of plant tissues. Moreover, the toxins are not washed off or degrade by UV radiation. This caused concern that eating the crops may have adverse health effects.
The first Bt crop commercially available was Bt potato, resistant against the Colorado potato beetle, in 1995. Commercialisation of Bt cotton and maize followed in 1996. Bt maize is mainly cultivated in the USA, Brazil, Argentina and South Africa. A small quantity is also grown in Europe, mainly in Spain. Bt cotton is most common in India and China where it is the only GM crop authorised for cultivation.
Today, insect resistance is the second most common trait used in genetically modified (GM) crops, after herbicide tolerance, with 43% of all cultivated GM-crops being insect resistant.
The industry promised that Bt crops would result in higher yields and decrease insecticide applications. However, pests with resistance against certain Bt toxins have become a huge problem today. Low crop yield, high seed prices and crop loss due to resistant insect pests have been associated with farmers’ suicides in India.
Civil society organisations ask to revoke MON810 authorisation
The wild ancestor of commercial maize, teosinte, has been detected in Aragon, Catalonia and Navarra, Spain and is spreading as an invasive species in maize growing areas. In one region where growing maize is the main source of income for farmers, the teosinte population has already reached such a high density, that the local governments has issued and enacted a ban on maize cultivation to prevent teosinte from spreading further.
Since in Spain the transgenic maize MON810 is grown on more than 100’000 hectares, it is feared that teosinte could interbreed with MON810, potentially resulting in an invasive transgenic teosinte species. If the hybrids between MON810 and teosinte inherit the insect resistant trait from MON810 they are likely to show higher fitness compared to the native teosinte plants, thereby increasing the invasive potential.
The fact that maize has no wild relatives in Europe to cross and interbreed with, was an important precondition for allowing genetically modified maize to be cultivated in the EU. Thirteen civil society organisations have now asked the EU Commission and the Spanish government to ban the cultivation of MON810 in 2016.