EFSA updates advice to protect butterflies and moths in protected habitats

EFSA has updated its previous risk management recommendations to reduce the risk of exposure to Bt-maize pollen for the larvae of non-target butterflies and moths (Lepidoptera) in protected habitats.

The genetic modification in Bt-maize – including in maize 1507, Bt11 and MON810 – relates to an insecticidal protein that protects the plant from being eaten by the larvae of certain butterflies and moths. Non-target butterfly and moth larvae could also be exposed and affected by Bt-maize pollen unless appropriate mitigation measures are in place for their protection.

Same model – new information

EFSA uses a mathematical model to quantify the risk of exposure to Bt-maize pollen for the larvae of non-target butterflies and moths. New information on maize pollen dispersal over long distances led EFSA’s Panel on Genetically Modified Organisms (GMO) to run new simulations on mortality estimates, applying the same model as before.

Data previously used in the model to estimate the mortality of non-target butterflies and moths in protected habitats considered maize pollen dispersal over tens of metres from Bt maize fields. Using new information from a survey by Hofmann et al (2014) has led to revised mortality estimates for non-target butterfly and moth larvae in protected habitats up to hundreds or thousands of metres from Bt-maize fields.

Adjusted exposure estimates

EFSA also refined its previous conservative exposure estimates of non-target butterflies and moth larvae to Bt-maize pollen. More realistic exposure estimates were derived by considering how factors such as wind, rain, and the structure of leaves affect the deposition of Bt-maize pollen on plants. These adjusted exposure estimates result in more appropriate mortality estimates for non-target butterfly and moth larvae. 

Tool provided for risk managers

EFSA found that the new calculations using the same model - fed with new information and applying a more realistic level of exposure - have little impact on their previous risk management recommendations for the protection of the currently known sensitive non-target butterfly and moth species.

These recommendations consist of a set of isolation distances between Bt-maize fields and protected habitats. They provide risk managers with a tool to estimate and mitigate the risk of exposure of non-target butterfly and moth larvae in protected habitats to Bt-maize pollen. This tool will allow risk managers to select risk management measures that are in accordance with their respective protection goals. 

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