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Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae)

Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae)
Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae)
Recent studies have shown that transgenic insect resistant plants can have negative effects on non-target herbivores as well as on beneficial insects. The studyof tritrophic interactions gives insight into the complex mechanisms of food webs in the field and can easily be incorporated into a tiered risk assessment framework. We investigated the effects of transgenic maize (Zea mays) expressing insecticidal proteins derived from Bacillus thuringiensis (Bt maize) on Spodoptera littoralis, a non-target herbivore, and on the hymenopteran parasitoid Cotesia marginiventris. In a laboratory study, S. littoralis larvae were reared for their whole lifespan on a mixture of leaves and stems from 2–4-week old Bt maize plants. S. littoralis survival, developmental times and larval weights were significantly affected by Bt maize diet. However, adult moths, which survived development on Bt maize, were the same size as the adults from the control group. C. marginiventris survival, developmental times and cocoon weights were significantly negatively affected if their S. littoralis host larva had been fed Bt maize. ELISA tests confirmed that S. littoralis larvae ingest high amounts of Cry1A(b) toxin while feeding on Bt maize. In S. littoralis pupae and in C. marginiventris cocoon silk, only traces of the toxin could be detected. No toxin was found in S. littoralis and C. marginiventris adults. Thus the toxin is not accumulating in the trophic levels and in fact appears to be excreted. Our results suggest that the effects on C. marginiventris when developing in susceptible S. littoralis larvae are indirect (host mediated). The biological relevance of those results and the significance of this study in risk assessment are discussed.
bacillus thuringiensis, Cry1A(b), ELISA, natural enemies, transgenic maize, tritrophic interactions
0962-8819
133-144
Vojtech, E.
5527d763-9610-4305-bdfb-82da7c50d206
Meissle, M.
d2730263-8748-4a1a-bff5-0d446fc0a22e
Poppy, G.M.
e18524cf-10ae-4ab4-b50c-e73e7d841389
Vojtech, E.
5527d763-9610-4305-bdfb-82da7c50d206
Meissle, M.
d2730263-8748-4a1a-bff5-0d446fc0a22e
Poppy, G.M.
e18524cf-10ae-4ab4-b50c-e73e7d841389

Vojtech, E., Meissle, M. and Poppy, G.M. (2005) Effects of Bt maize on the herbivore Spodoptera littoralis (Lepidoptera: Noctuidae) and the parasitoid Cotesia marginiventris (Hymenoptera: Braconidae). Transgenic Research, 14 (2), 133-144. (doi:10.1007/s11248-005-2736-z).

Record type: Article

Abstract

Recent studies have shown that transgenic insect resistant plants can have negative effects on non-target herbivores as well as on beneficial insects. The studyof tritrophic interactions gives insight into the complex mechanisms of food webs in the field and can easily be incorporated into a tiered risk assessment framework. We investigated the effects of transgenic maize (Zea mays) expressing insecticidal proteins derived from Bacillus thuringiensis (Bt maize) on Spodoptera littoralis, a non-target herbivore, and on the hymenopteran parasitoid Cotesia marginiventris. In a laboratory study, S. littoralis larvae were reared for their whole lifespan on a mixture of leaves and stems from 2–4-week old Bt maize plants. S. littoralis survival, developmental times and larval weights were significantly affected by Bt maize diet. However, adult moths, which survived development on Bt maize, were the same size as the adults from the control group. C. marginiventris survival, developmental times and cocoon weights were significantly negatively affected if their S. littoralis host larva had been fed Bt maize. ELISA tests confirmed that S. littoralis larvae ingest high amounts of Cry1A(b) toxin while feeding on Bt maize. In S. littoralis pupae and in C. marginiventris cocoon silk, only traces of the toxin could be detected. No toxin was found in S. littoralis and C. marginiventris adults. Thus the toxin is not accumulating in the trophic levels and in fact appears to be excreted. Our results suggest that the effects on C. marginiventris when developing in susceptible S. littoralis larvae are indirect (host mediated). The biological relevance of those results and the significance of this study in risk assessment are discussed.

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Submitted date: 5 February 2004
Published date: April 2005
Keywords: bacillus thuringiensis, Cry1A(b), ELISA, natural enemies, transgenic maize, tritrophic interactions

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Local EPrints ID: 24050
URI: https://eprints.soton.ac.uk/id/eprint/24050
ISSN: 0962-8819
PURE UUID: cdf91ecc-26c0-4aab-bb7b-382a29a70dda

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Date deposited: 20 Mar 2006
Last modified: 17 Jul 2017 16:15

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