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Impact of oilseed rape expressing the insecticidal serine protease inhibitor, mustard trypsin inhibitor-2 on the beneficial predator Pterostichus madidus

Lookup NU author(s): Dr Natalie Ferry, Dr Evan Mulligan, Dr Kaveh Emami, Professor Angharad MR Gatehouse

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Abstract

Insect-resistant transgenic plants have been suggested to have deleterious effects on beneficial predators feeding on crop pests, through transmission of the transgene product by the pest to the predator. To test this hypothesis, effects of oilseed rape expressing the serine protease inhibitor, mustard trypsin inhibitor -2 (MTI-2), on the predatory ground beetle Pterostichus madidus were investigated, using diamondback moth, Plutella xylostella as the intermediary pest species. As expected, oilseed rape expressing MTI-2 had a deleterious effect on the development and survival of the pest However, incomplete pest mortality resulted in survivors being available to predators at the next trophic level, and inhibition studies confirmed the presence of biologically active transgene product in pest larvae. Characterization of proteolytic digestive enzymes of P. madidus demonstrated that adults utilize serine proteases with trypsin-like and chymotrypsin-like specificities; the former activity was completely inhibited by MTI-2 in vitro. When P. madidus consumed prey reared on MTI-2 expressing plants over the reproductive period in their life cycle, no significant effects upon survival were observed as a result of exposure to the inhibitor. However, there was a short-term significant inhibition of weight gain in female beetles fed unlimited prey containing MTI-2, with a concomitant reduction of prey consumption. Biochemical analyses showed that the inhibitory effects of MTI-2 delivered via prey on gut proteolysis in the carabid decreased with time of exposure, possibly resulting from up-regulation of inhibitor-insensitive proteases. Of ecological significance, consumption of MTI-2 dosed prey had no detrimental effects on reproductive fitness of adult P. madidus.


Publication metadata

Author(s): Ferry N, Jouanin L, Ceci LR, Mulligan EA, Emami K, Gatehouse JA, Gatehouse AMR

Publication type: Article

Publication status: Published

Journal: Molecular Ecology

Year: 2005

Volume: 14

Issue: 1

Pages: 337-349

ISSN (print): 0962-1083

ISSN (electronic): 1365-294X

URL: http://dx.doi.org/10.1111/j.1365-294X.2004.02381.x

DOI: 10.1111/j.1365-294X.2004.02381.x

PubMed id: 15643975


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