Transfer of the Cry1Ab Toxin in Tritrophic Bioassays Involving Transgenic Maize MON810, the Herbivore TetranychusurticaeKoch and the Predatory Ladybird Beetle Adaliabipunctata L. (Coleoptera: Coccinelidae)

Laboratory bioassays of tritrophic were conducted to determine whether Adalia bipunctata L. (Coleoptera: Coccinelidae) larvae might accumulate and/ or degrade Cry1Ab toxin in relation to different exposure time with Bt-loaded prey. The spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) was used as herbivore. The concentration of Cry1Ab toxin through the trophic chain decreased from Bt maize plants (60.49 mu g/g(-1) FW) to spider mites (0.12 mu g/g(-1) FW). The third trophic level, predatory larvae of A. bipunctata, showed different mean concentration of Bt toxin between feeding periods. In first repetition significant difference of Bt content (0.128 mu g/g(-1) FW) was obtained only during 72 hours feeding. The second repetition of bioassay showed higher mean contents of Cry1Ab toxin than the first. The highest concentration of Bt toxin content as was indicated in the first repetition during the 72 hours feeding time. The analysis in both bioassays showed predominantly similar pattern of Cry1Ab degradation through the tritrophic system (Bt maize plants-herbivorous prey-predatory ladybeetle larvae).