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EC-sponsored Research on Safety of Genetically Modified Organisms - A Review of Results
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image Effects and mechanisms of BT transgenes on biodiversity of non-target insects: pollinators, herbivores and their natural enemies

Background and objectives

Bacillus thuringiensis (Bt) is bacterium that occurs in various environments, often in association with insects. At a particular stage in its life cycle it produces crystals composed of proteins that are highly toxic to insects, and different strains of the bacterium are toxic to different species of insects, including various pest species. Thus, the genes for these toxic proteins, naturally produced by Bt have enormous agricultural potential. The genes introduced into crop plants can make crops resistant to its pests, thereby decreasing the need for chemical insecticides. One of the advantages of Bt toxins is that they are specific for particular insect species, whereas chemical pesticides can be environmentally harmful and often kill innocuous and even beneficial insects (pollinators for example). This project will investigate the effects of transgenic, insect-resistant (Bt-) crops on the biodiversity of non-target herbivorous insects and their natural enemies, and pollinators. The project will deliver contributions to a solid scientific foundation for EU policies and regulations for release of transgenic crops. It will also use the most state-of-the-art technology to develop tools for monitoring effects on biodiversity.

Approach and methodology

The effects of Bacillus thuringiensis insecticidal proteins in trangenic crop plants on the biodiversity of associated non-target and beneficial insects (insect predators, parasitoids, and pollinators) will be assessed at different organisational levels, including the cell, the whole organism, and the ecosystem. The underlying mechanisms of observed effects on beneficial insects will be investigated at the molecular level. Four toxin/crop combinations will be used for testing effects of insecticidal proteins. These combinations will be tested by laboratory feeding experiments, in greenhouse and field cage experiments. Field sampling will be used to evaluate the effects of the transgenes on the biodiversity of the associated insect community. The mode of action of Bt toxins in a beneficial insect will be studied in more detail. Molecular tools involving the use of cDNA micro-arrays will be developed for fast and efficient observation of effects, based on changes in gene expression patterns.

Main findings and outcome

This project is at a very early stage. The work underway includes the following. The mode of action of Bt toxins on the important predatory insect, the green lacewing, will be elucidated. Transgenic Cry1Ab-corn exerts an effect on this species through a herbivore. cDNA micro-arrays are being developed as tools for monitoring any adverse effects of plant-expressed toxins on beneficial insects, in this case lacewings. The utility of these micro-arrays will be tested with lacewings collected from Bt and non-Bt crop fields. Laboratory feeding studies will be used to study further the effects of Bt transgenes on non-target herbivores and, through these herbivores, on insect predators such as lacewings, ladybirds and spiders, in a tritrophic system. The effects of 4 gene/crop combinations on parasitoids of herbivorous insects will also be studied in a tritrophic system. Effects on parasitoid behaviour and fecundity and on behaviour-mediating plant volatiles will be determined. Similarly, the effects of the Bt crops on pollinator behaviour and biodiversity will be considered. Field sampling will be used to assess effects on pollinator biodiversity. Feeding studies of bumblebees will determine effects of transgenic pollen, and the effects of transgenes on pollen and nectar composition will be determined. Finally, non-target herbivores and beneficial insects will be sampled in field experiments with the four crops and non-Bt fields. Caged field plant experiments will study population dynamics of non-target herbivores and their prey in more detail.


This thorough analysis will greatly improve our knowledge on how non-target insect biodiversity might be affected by the use of Bt-crops. Possible hazards from Bt-plants for the biodiversity of non-target insects will be identified. The study of the action of a Bt toxin on a beneficial insect should give cues for ways to prevent negative effects. The project also involves developing a high-technology tool to be used in monitoring for effects of Bt transgenes in field insects. These various studies will contribute to a solid scientific basis for establishing European policy and regulations concerning the release of transgenic, insect-resistant crop plants.

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Contract number

October 2000 – September 2003

R. de Maagd
Plant Research International
Wageningen (NL)



P. Edwards
Swiss Federal Institute of Technology
Zurich (CH)

S. Arpaia
Metapontum Agrobios s.r.l.
Metaponto (IT)

S. Vidal
Georg-August-Universität Göttingen (DE)

J. Kiss
Szent Istvan University
Gödöllö (HU)

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