title: Reduced fitness of Daphnia magna fed a Bt-transgenic maize variety.
abstract: Genetically modified (GM) maize expressing the Bt-toxin Cry1Ab (Bt-maize) was tested for effects on survival, growth, and reproduction of the water flea Daphnia magna, a crustacean arthropod commonly used as a model organism in ecotoxicological studies. In three repeated experiments, D. magna were fed 100% ground maize in suspension, using either GM or isogenic unmodified (UM) maize. D. magna fed GM-maize showed a significantly reduced fitness performance: The mortality was higher, a lower proportion of females reached sexual maturation, and the overall egg production was lower compared to D. magna fed UM isogenic maize. We conclude that the tested variety of Bt-maize and its UM counterpart do not have the same quality as food sources for this widely used model organism. The combination of a reduced fitness performance combined with earlier onset of reproduction of D. magna fed Bt-maize indicates a toxic effect rather than a lower nutritional value of the GM-maize.
authors.affiliation: Genøk-Centre for Biosafety, The Science Park, P.O. Box 6418, Tromso, 9294, Norway. thomas@genok.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Bøhn
authors.forename: Raul
authors.initials: R
authors.lastname: Primicerio
authors.forename: Dag O
authors.initials: DO
authors.lastname: Hessen
authors.forename: Terje
authors.initials: T
authors.lastname: Traavik
mesh_terms: D000821:Animal Feed; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism / Q000633:toxicity*; D049628:Body Size / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects* / Q000502:physiology; D004731:Endotoxins / Q000378:metabolism / Q000633:toxicity*; D005260:Female; D006128:Growth / Q000187:drug effects; D006460:Hemolysin Proteins / Q000378:metabolism / Q000633:toxicity*; D007306:Insecticides / Q000378:metabolism / Q000633:toxicity*; D008136:Longevity / Q000187:drug effects; D010058:Oviposition / Q000187:drug effects; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000633:toxicity*; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis