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Effects of Bt transgenic Plants on Parasitoids
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Chen M, Zhao JZ,
Collins HL, Earle ED, Cao J, Shelton AM. Department of Entomology, Cornell University/New York State
Agricultural Experiment Station (NYSAES), Geneva, New York, United
States of America. |
The ecological safety of transgenic insecticidal plants expressing
crystal proteins (Cry toxins) from the bacterium Bacillus
thuringiensis (Bt) continues to be debated. Much of the debate has
focused on nontarget organisms, especially predators and parasitoids
that help control populations of pest insects in many crops. Although
many studies have been conducted on predators, few reports have
examined parasitoids but some of them have reported negative impacts.
None of the previous reports were able to clearly characterize the
cause of the negative impact. In order to provide a critical
assessment, we used a novel paradigm consisting of a strain of the
insect pest, Plutella xylostella (herbivore), resistant to Cry1C and
allowed it to feed on Bt plants and then become parasitized by
Diadegma insulare, an important endoparasitoid of P. xylostella. Our
results indicated that the parasitoid was exposed to a biologically
active form of the Cy1C protein while in the host but was not harmed
by such exposure. Parallel studies conducted with several commonly
used insecticides indicated they significantly reduced parasitism
rates on strains of P. xylostella resistant to these insecticides.
These results provide the first clear evidence of the lack of hazard
to a parasitoid by a Bt plant, compared to traditional insecticides,
and describe a test to rigorously evaluate the risks Bt plants pose
to predators and parasitoids.
PMID: 18523682 [PubMed - in process]
PMCID: PMC2409141
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