title: Uptake and bioaccumulation of Cry toxins by an aphidophagous predator.
abstract: Uptake of Cry toxins by insect natural enemies has rarely been considered and bioaccumulation has not yet been demonstrated. Uptake can be demonstrated by the continued presence of Cry toxin after exposure has stopped and gut contents eliminated. Bioaccumulation can be demonstrated by showing uptake and that the concentration of Cry toxin in the natural enemy exceeds that in its food. We exposed larvae of the aphidophagous predator, Harmonia axyridis, to Cry1Ac and Cry1F through uniform and constant tritrophic exposure via an aphid, Myzus persicae, and looked for toxin presence in the pupae. We repeated the experiment using only Cry1F and tested newly emerged adults. Both Cry toxins were detected in pupae, and Cry1F was detected in recently emerged, unfed adults. Cry1Ac was present 2.05 times and Cry1F 3.09 times higher in predator pupae than in the aphid prey. Uptake and bioaccumulation in the third trophic level might increase the persistence of Cry toxins in the food web and mediate new exposure routes to natural enemies.
authors.affiliation: Embrapa Genetic Resources and Biotechnology, Parque Estação Biológica, W5 Norte, P.O. Box 02372, Brasília, DF, 70770-917, Brazil. Electronic address: debora.pires@embrapa.br.
authors.forename: Débora P
authors.initials: DP
authors.lastname: Paula
authors.affiliation: Department of Entomology, University of Minnesota, 219 Hodson Hall, 1980 Folwell Ave., St. Paul, MN, 55108, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Andow
mesh_terms: D000818:Animals; D001042:Aphids / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism* / Q000633:toxicity; D001517:Coleoptera / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D004731:Endotoxins / Q000378:metabolism* / Q000633:toxicity; D020387:Food Chain; D006460:Hemolysin Proteins / Q000378:metabolism* / Q000633:toxicity; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bt toxin; Coccinellid; Persistence; Tritrophic exposure