Updating risk management recommendations to limit exposure of non-target Lepidoptera of conservation concern in protected habitats to Bt-maize pollen

Abstract

Using mathematical model ling , the EFSA GMO Panel ha s previously quantified the risk to non - target (NT) Lepidoptera of conservation concern, potentially occurring within protected habitats, associated with the ingestion of Bt - maize pollen deposited on their host plants. To reduce the estimated larval mortality to a negligible level, an isolation distance of 20 and 30 m was recommended between protected habitats and the nearest fields of maize MON 810/Bt11 and 1507, respectively. Here , the EFSA GMO Panel refines its model predictions , accounting for new ly reported information on maize pollen deposition over long distances . For its calculations , the EFSA GMO Panel considered three exposure scenarios at a range of isolation distances, at two protection levels and for a range of lepidopteran species, including hypothetical ones, with a wide spectrum of sensitivities to Bt toxins . An analysis of various sources of uncertainties affecting the exposure of NT Lepidoptera to Bt - maize pollen was conducted, in order to provide quantitative estimates of realistic exposure levels. The EFSA GMO Panel therefore provides risk managers with a tool to estimate and mitigate the risk for NT Lepidoptera of conservation concern. In contrast to its previous o utcomes obtained for unrealistically large levels of exposure that would not be expected in practice, the EFSA GMO Panel reports here mortality estimates for a more realistic level of exposure. The EFSA GMO Panel concludes that its previous recommendation for a 20 m isolation distance around protected habitats, within which maize MON810/Bt11 should not be cultivated, remains valid. New calculations show that the previously recommended isolation distance of 30 m from the nearest maize 1507 field would still protect NT Lepidoptera with known levels of sensitivity, including the ‘highly - sensitive’ Plutella xylostella . Should hypothetical species with greater sensitivities exist, larger isolation distances would be needed to ensure the desired level of protection.