Extension of the spatially‐ and temporally‐explicit “briskaR‐NTL” model to assess potential adverse effects of Bt‐maize pollen on non‐target Lepidoptera at landscape level

Abstract

Lepidopteran-active Bt-toxins expressed in genetically modified (GM) maize events can adversely affect non-target lepidopteran (NTL) species when larvae consume harmful amounts of Bt-maize pollen deposited on their host plants. The briskaR-NTL project, as commissioned by the European Food Safety Authority, aims to: (i) further develop a spatially-explicit, generic modelling framework to estimate risks of Bt-maize pollen to NTLs at landscape scale; and (ii) offer a userfriendly tool to risk managers to inform decision-making. Using a literature map and Expert Knowledge Elicitation (EKE), the initial briskaR package was expanded to integrate: (i) a wider range of dispersal kernels for maize pollen; (ii) the variability of exposure to Bt-maize pollen over time through ToxicoKinetic-ToxicoDynamic ecotoxicological models; (iii) sublethal effects; and (iv) multi-year and cumulative effects of chronic exposure. A user-friendly and public R Shiny application was developed to run the model. Two real-life case studies were used to test the model in contrasting environmental conditions, and identify key factors that adversely affect larvae of the Common Swallowtail (Papilio machaon). These factors include: the slope of doseresponse for Bt-toxicity; cumulative effects; impact of an additional stressor (the microsporidian parasite Nosema); and host plant distribution. Overall, the case studies confirm the effect of landscape patterns and crop management practices at local level, suggesting a case-by-case approach for the assessment of risks and their possible mitigation. Several sources of uncertainty have been considered, but remaining ones as well as population processes should be considered in future (risk) assessments. While the modelling approach and EKE enabled to address the scarcity of input data by translating uncertainties into wider confidence intervals, gathering additional laboratory and field data is required to support a more robust and ecologically meaningful assessment of impacts of Bt-maize pollen on NTL and model validation.

EFSA is working to advance the environmental risk assessment of genetically modified crops to better protect butterflies and moths

“…Outlook Baudrot et al (2021b) illustrated how modelling approaches such as briskaR can inform prospective ERAs for NT Lepidoptera by providing estimates of mortality at both local/individual level and landscape scale for a wide range of different receiving environments across the EU. Such estimates would enable risk managers to implement possible risk mitigation measures that are adapted to the relevant receiving environments and specific protection goals (including for regionally protected NT lepidopteran species) under their jurisdiction.…”

“…The first spatially explicit model (briskaR) that estimated NT Lepidoptera mortality more realistically at both local/individual level and landscape scale and assessed the effectiveness of risk mitigation measures, was developed by Leclerc et al (2018) 18 (see also the EU-FP7-research project AMIGA; Walker et al, 2019;Baudrot et al, 2021a). 19,20,21 As part of the EFSA procurement, Baudrot et al (2021b) 22 extended the briskaR model to integrate: (1) a wider range of possible maize pollen dispersal curves; (2) the variability of exposure to Bt-maize pollen over time through toxicokinetictoxicodynamic models; (3) sublethal effects of Bt-proteins on the reproduction and development of NT Lepidoptera; and (4) multiannual and cumulative effects of chronic exposure.…”

“…In addition, Baudrot et al (2021b) conducted a sensitivity analysis and expert knowledge elicitations (EKE) on identified sources of uncertainty, ran the model using real-world case studies, and developed a user-friendly model interface, which are briefly described below.…”

“…As part of the EFSA procurement, Baudrot et al. (2021bb) 22 extended the briskaR model to integrate: (1) a wider range of possible maize pollen dispersal curves; (2) the variability of exposure to Bt ‐maize pollen over time through toxicokinetic–toxicodynamic models; (3) sublethal effects of Bt ‐proteins on the reproduction and development of NT Lepidoptera; and (4) multiannual and cumulative effects of chronic exposure.…”

Pressure from insect‐resistant maize on protected butterflies and moths

“…Since 2009, several models differing in complexity have been proposed for use in assessing the effects of Bt maize pollen on NTLs (Baudrot, Walker, et al., 2021; EFSA, 2015; Fahse et al., 2018; Holst et al., 2013; Perry et al., 2012; Perry et al., 2010; Walker et al., 2017). The European Food Safety Authority (EFSA) assesses GM crops and is about to replace its existing model with a more advanced solution (Baudrot, Lang, et al., 2021). Models may improve understanding of landscape biodiversity effects (Leclerc et al., 2017; Perry et al., 2012; Perry et al., 2010) or effects on local butterfly populations (Fahse et al., 2018; Holst et al., 2013).…”