Assessing the impact of Bt maize on non-target arthropods Michael Meissle, Yunhe Li & Jörg Romeis Zurich, Switzerland Agroscope Reckenholz-Tänikon Research Station ART Innovation Promotion Agency CTI Contact: [email protected] [email protected] Introduction Research on Bt maize and non-targets started at Reckenholz more than 10 years ago 2 PhD thesis on Diabrotica-resistant Bt maize and non-targets just completed Mainly laboratory studies, field collections in collaboration with German BMBF Project Non-target risk assessment Work on Chrysomelids • Testing biological activity of Cry3Bb1 • Effects on the cereal leaf beetle Oulema melanopus Work on non-targets (other than Chrysomelids) •Ladybird Stethorus punctillum • Lacewing Chrysoperla carnea •Spider Theridion impressum • Interaction with EP fungus Metarhizium anisopliae Literature review Risk assessment Exposure to Cry3Bb1 Ingestion of the Bt protein Risk Hazard Adverse effects after ingestion of the Bt protein (toxicity) Risk assessment Laboratory Extended lab / semi field Field Low Realism of assessment high Low Ecological complexity high High Generalization Low Power in Power in evaluation of evaluation of hazard consequences of hazard Risk assessment Analyze available data Sufficient data? Laboratory studies Sufficient data? Stop testing Semi-field studies Sufficient data? Field studies Nature Biotechnol. 26, 2008 Biological activity of Cry3Bb1 ELISA / Western blot: Sensitive insect assay: Presence of toxin Biological activity Maize Colorado potato beetle • leaves Lower activity (Leptinotarsa decemlineata, • silk than expected Coleoptera: Chrysomelidae) • roots from ELISA • pollen >100 times more sensitive to Cry3Bb1 than western corn rootworm Litter Arthropods (feeding on maize) •spider mites • D. v. virgifera adults Meissle & Romeis 2009 Entomol Exp Appl (in press) Cereal leaf beetle Oulema melanopus • Non-target Chrysomelid • Pest of wheat • Adults also found in maize • Larvae on MON88017 (expressing Cry3Bb1) showed higher mortality after 4 days feeding than larvae on 5 other maize varieties • No effects on adults Meissle et al. (in preparation) Ladybird Stethorus punctillum Specifically feeding on spider mites, which contain High high toxin levels when feeding on Bt maize exposure Coleoptera: same order as target pest of Toxicity Cry3Bb1-expressing maize likely Positive effect of Bt maize: No effect: Daily fecundity Larval survival Pre-oviposition Development time Egg hatching rate Pupation rate Adult fresh weight Conclusion: no hazard for the beetle when feeding on toxin-containing spider mites Li & Romeis (in preparation) Lacewing Chrysoperla carnea Predatory larvae Low exposure, no toxicity intensively tested Indirect, prey quality mediated effects Pollen • Adults consume high amounts of maize pollen in the lab and the field • Pollen is digested by lacewings Faeces • 60-80% less Cry protein in faeces than in pollen grains Exposure to Cry proteins given Li et al. (in preparation) Lacewing Chrysoperla carnea Number of eggs 40 Cry3Bb1 Cry1Ab GNA 30 Artificial diet Control 20 Pollen Mon88017 DKc5143 10 Event176 Dracma 0 0 51015 20 25 510152025 Days after emergence No effect of Bt maize pollen or purified Cry protein (10x concentration in pollen) on oviposition, fertility and survival Negligible hazard and consequently risk Li et al. (2008) PLoS ONE 3(8) Spider Theridion impressum Prey species and Cry3Bb1 content Laboratory feeding studies • Juveniles pollen maize fed spider mites •Adults maize fed adult lacewings and adult D. v. virgifera 8 weeks No effects on growth, survival and reproduction Negligible hazard and consequently risk Exposure given & highly variable Meissle & Romeis (in review) Interaction with fungus Metarhizium anisopliae • Entomopathogenic fungus • Naturally occurring in soil • Commercially used for biocontrol of various pests • Can be effective against corn rootworms Results: • L2 larvae on Bt maize Slower growth on Bt maize • After 4 days dipping in Higher mortality with higher dose spore suspension of spores • Back on Bt maize No difference in mortality between Bt and control maize- fed larvae Effects additive rather than synergistic or antagonistic Meissle et al. (in review) Literature review Effects of Cry3Bb1-producing Bt maize on non-target species Lab: Data on 28 species from 16 publications Most studies on predators: (6) (3) (1) (2) Most studies demonstrate no effect of Bt maize or purified Cry3Bb1 on non-target species Meissle & Romeis (2008) In Mason et al. Proceedings of the 3rd International Symposium on Biological Control of Arthropods. Christchurch, New Zealand, United States Department of Agriculture, Forest Service, Morgantown, WV, FHTET-2008-06, pp.145-160. Literature review Effects of Cry3Bb1-producing Bt maize on non-target species Field: 11 publications No adverse effect of Bt maize on plant- and ground- dwelling arthropods and on soil fauna Side effects of chemical insecticides: • foliage application: yes • soil application: sometimes • seed coating: no Meissle & Romeis (2008) In Mason et al. Proceedings of the 3rd International Symposium on Biological Control of Arthropods. Christchurch, New Zealand, United States Department of Agriculture, Forest Service, Morgantown, WV, FHTET-2008-06, pp.145-160. Conclusions 1. Biological activity of Cry3Bb1 can be demonstrated in Colorado potato beetle bioassays in maize and arthropods 2. Our work on non-target species and the published literature indicates that Cry3Bb1-expressing Bt maize is specific to Chrysomelids 3. Similar to other commercialized Bt crops, rootworm- resistant Bt maize maintains biological control and can contribute to sustainable agriculture..