Effects of Bt transgenic Chinese cabbage on the herbivore Mamestra brassicae (Lepidoptera : Noctuidae) and its parasitoid Microplitis mediator (Hymenoptera : Braconidae)

摘要

We investigated the effects of a diamondback moth-resistant Chinese cabbage (Brassica campestris subsp. napus variety pekinensis Makino), expressing the insecticidal protein Cry1A (c) toxin Noctuidae) and its parasitoid wasp Microplitis mediator (Haliday) (Hymenoptera: Braconidae). A decreased survival rate at neonate stage was observed ill M. brassicae when reared oil Bt cabbage, although overall development was not significantly affected. According to enzyme-linked immunosorbent assay test using Cry1A (c) antibody, the Cry toxin was only detected ill the alimentary canal, not ill the hemolymph or remaining body parts of M. brassicae, indicating that the ingested Cry toxin is neither distributed inside the body nor transferred through the trophic level. As expected, no Cry toxin was found ill the larvae and cocoons of M. mediator. Ill addition, no significant changes were observed ill the parasitization rate, larval period, pupal period, cocoon weight, or adult emergence rate when M. mediator wasps were reared oil the M. brassicae larvae fed with transgenic Chinese cabbage. In summary, no direct or indirect adverse effects of transgenic Chinese cabbage oil the two nontarget insect species were observed, suggestive of low risk in herbivore-parasitoid food chain.