Meta-analysis on effects of Bt-maize on nontarget invertebrates – Data transportability across continents

Authors: MEISSLE, MICHAEL - Agroscope; Naranjo, Steve; ROMEIS, JOERG - Agroscope

Submitted to: Plants, People, Planet
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2025
Publication Date: 8/1/2025
Citation: Meissle, M., Naranjo, S.E., Romeis, J. 2025. Meta-analysis on effects of Bt-maize on nontarget invertebrates – Data transportability across continents. Plants, People, Planet. 8(1):365-376. https://doi.org/10.1002/ppp3.70081.
DOI: https://doi.org/10.1002/ppp3.70081

Interpretive Summary: Transgenic Bt crops are widely cultivated throughout the world and represent and important tool for integrated pest management. Before transgenic plants can be produced in a region they need to be assessed for potential negative effects on the environment by regulatory bodies. Many such assessments have been done in many parts of the world including North America, Europe and Asia. Because such processes are expensive and time consuming it has been suggested that asssessments done in one region could be transportable to other regions to make the regulatory assessment process more efficient. Here, we use a high quality global database of non-target arthropod studies for Bt maize to test if results from one region can be used for risk assessment in another. We find that many of the same taxonomic orders and families of arthropods exist and have been assessed in North America, Europe and Asia and that results from meta-analyses that found negative, neutral or positive effects on non-target organisms are generally consistent from one region to the next for given taxonomic groups. Thus, studies in North America and Europe might be useful for predicting environmental risks in novel areas such as Asia, Africa or South America, thus greatly enhancing the efficiency of environmental assessments and making these important tools for pest management more widely available. These results would be of value to regulatory authorities throughout the world and ultimately of benefit to growers and consumers.

Technical Abstract: For the regulatory approval that is mandatory before genetically engineered (GE) crops can be released, an environmental risk assessment is conducted. Maize varieties producing insecticidal proteins from Bacillus thuringiensis (Bt) have been cultivated on several continents. For insecticidal crops, adverse effects on beneficial arthropods, such as decomposers, predators, and parasitoids are of particular concern. In general, risk assessments should make use of existing information and only request additional data if necessary for a confident conclusion of acceptable risk. This work contributes to the discussion of data transportability between continents by comparing meta-analyses of non-target studies of Bt maize across continents. Most data on arthropod non-target effects of Bt maize are available for North America and Europe. The taxonomic composition of non-target arthropods in Bt maize at order or higher taxonomic level is similar across continents, which facilitates data transportability. Locally important taxa, however, need to be considered in the risk assessment. Meta-analyses of non-target field studies from North America allow the conclusion that there are few non-target effects, which has been confirmed in Europe and Asia. While effects on specialized parasitoids of target pests or species otherwise related to maize-feeding Lepidoptera are explainable, other effects are non-explainable, but were also found, through additional analyses, to be non-robust. The conclusion of no unacceptable risk of current Bt maize for non-target arthropods is generally transportable among different geographies. High quality, well-designed and well-described studies including multiple locations and years, open-access data availability (transparency), and independence of multiple studies increase trust in the data to be transportable.