Impact of Bt crops on non-target organisms – 3 systematic reviews

Authors: MEISSLE, MICHAEL - Agroscope; ROMEIS, JOERG - Agroscope; RIEDEL, JUDITH - Agroscope; Naranjo, Steven; KOSTOV, KALOYAN - Agrobioinstitute; CHRISTOVA, PETYA - Agrobioinstitute; ASSENOV, BORISLAV - Agrobioinstitute; TSVETKOV, IVAN - Agrobioinstitute; SLAVOV, SLAVTCHO - Agrobioinstitute; DAMGAARD, CHRISTIAN - Aarhus University; KROGH, PAUL - Aarhus University; HENDRIKSEN, NIELS - Aarhus University; SWEET, JEREMY - Cambridge University

Submitted to: IOBC/WPRS Bulletin (Abstract for Conference Proceedings)
Publication Type: Proceedings
Publication Acceptance Date: 6/14/2016
Publication Date: 6/16/2016
Citation: Meissle, M., Romeis, J., Riedel, J., Naranjo, S.E., Kostov, K., Christova, P., Assenov, B., Tsvetkov, I., Slavov, S., Damgaard, C.F., Krogh, P.H., Hendriksen, N.B., Sweet, J. 2016. Impact of Bt crops on non-target organisms – 3 systematic reviews. IOBC/WPRS Bulletin. 114:37-38.

Interpretive Summary: Maize that has been genetically engineered (GE) to produce Cry toxins originating from the bacterium Bacillus thuringiensis (Bt) is cultivated widely in 17 countries. This GE crop and several others has continued to raise environmental concerns over their sustainable use and consequences for biodiversity and ecosystem services in agricultural land such as biological control, decomposition and pollination. An European Union funded project called GRACE (GMO Risk Assessment and Communication of Evidence) has gathered and reviewed available field studies focuses on comparing biotic communities in Bt and non-Bt maize. The projects have strictly followed a predefined and transparent systematic review process that was developed in part from input and feedback from multiple stakeholder groups. Three systematic reviews covering Bt maize have been completed including one examining non-target animals (mainly invertebrates), a second comparing the abundance and diversity of soil inhabiting invertebrates, such as Protozoa, Nematoda, Collembola, mites, enchytraeids and earthworms, and a third evaluated the abundance, activity and functional and genetic diversity of microorganisms, including bacteria and fungi, in Bt and conventional crops. Narrative summeries and quantitative meta-analyses of these data have shown that Bt maize had invertebrate communities that were similar to those in non-insecticide treated conventional maize. In contrast, treatments with broad spectrum insecticides caused several significant effects on invertebrate populations, in particular foliar applications of pyrethroids. Similarly, there were no significant effects of Bt crops in general on soil invertebrates, neither when all crops expressing different Cry proteins were combined, nor when data for different Cry proteins were analysed separately. Finally, Bt crops did not have major effects on soil microbial endpoints as compared to conventional crops. Minor short term effects on the microbial communities were recorded but they were unlikely to have functional significance, in contrast to other factors, such as plant species and growth stage, soil type, and season. The results are of interest to regulatory bodies that oversee the approval of GE crops, agricultural producers, and to many other stakeholder groups including the general public concerned with environmental and food safety.

Technical Abstract: The cultivation of genetically modified (GM) crops producing Cry toxins, originating from the bacterium Bacillus thuringiensis (Bt), has raised environmental concerns over their sustainable use and consequences for biodiversity and ecosystem services in agricultural land. During the last two decades, a range of biosafety research programmes in Europe and elsewhere conducted experimental field studies to investigate potential effects of GM crops on non-target organisms. In the EU project GRACE (GMO Risk Assessment and Communication of Evidence) available evidence from those field studies was reviewed following a predefined and transparent systematic review process that sought input and feedback from multiple stakeholder groups. Three systematic reviews covering Bt maize have been completed including one examining non-target animals (mainly invertebrates), a second comparing the abundance and diversity of soil inhabiting invertebrates, such as Protozoa, Nematoda, Collembola, mites, enchytraeids and earthworms, and a third evaluated the abundance, activity and functional and genetic diversity of microorganisms, including bacteria and fungi, in Bt and conventional crops. The meta-analyses and narrative summaries revealed that Bt maize had invertebrate communities that were similar to those in non-insecticide treated conventional maize. Only few significant differences were observed and those were usually traceable to individual studies. In contrast, treatments with broad spectrum insecticides caused several significant effects on invertebrate populations, in particular foliar applications of pyrethroids. Similarly, there were no significant effects of Bt crops in general on soil invertebrates, neither when all crops expressing different Cry proteins were combined, nor when data for different Cry proteins were analysed separately. Finally, Bt crops did not have major effects on soil microbial endpoints as compared to conventional crops. Minor short term effects on the microbial communities were recorded but they were unlikely to have functional significance, in contrast to other factors, such as plant species and growth stage, soil type, and season.