title: Dissipation of insecticidal Cry1Ac protein and its toxicity to nontarget aquatic organisms.
abstract: The widespread cultivation of Bacillus thuringiensis crops has raised public concerns on their risk to nontarget organisms. Persistence of Cry1Ac protein in soil, sediment and water and its toxicity to nontarget aquatic organisms were determined. The dissipation of Cry1Ac toxin was well described using first order kinetics, with the half-lives (DT50) ranging from 0.8 to 3.2, 2.1 to 7.6 and 11.0 to 15.8 d in soil, sediment and water, respectively. Microbial degradation played a key role in the dissipation of Cry1Ac toxin and high temperature accelerated the processes. Cry1Ac toxin was more toxic to the midge Chironomus dilutus than the amphipod Hyalella azteca, with the median lethal concentration (LC50) of C. dilutus being 155 ng/g dry weight and 201 ng/mL in 10-d sediment and 4-d water bioassays, respectively. While Cry1Ac toxin showed toxicity to the midges, risk of Bt proteins to aquatic nontarget organisms was limited because their environmentally relevant concentrations were much lower than the LC50s.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences , Guangzhou 510640, People's Republic of China.
authors.forename: Yan-Liang
authors.initials: YL
authors.lastname: Li
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.forename: Zhi-Xiang
authors.initials: ZX
authors.lastname: Fang
authors.forename: Jing
authors.initials: J
authors.lastname: You
mesh_terms: D033304:Amphipoda / Q000187:drug effects*; D000818:Animals; D059001:Aquatic Organisms / Q000187:drug effects*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000633:toxicity*; D002683:Chironomidae / Q000187:drug effects*; D004731:Endotoxins / Q000737:chemistry / Q000633:toxicity*; D019015:Geologic Sediments / Q000737:chemistry; D003368:Gossypium / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006207:Half-Life; D006460:Hemolysin Proteins / Q000737:chemistry / Q000633:toxicity*; D030821:Plants, Genetically Modified / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012989:Soil Pollutants / Q000737:chemistry / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C030956:insecticidal crystal protein, Bacillus Thuringiensis