Transgenic insect-resistant crops have been commercially cultivated on a surface of around 9 mio. hectares worldwide in 1999. The main target of growing pest-resistant plants is to reduce crop losses due to insect pests and to reduce insecticide applications and thus to minimize negative impacts on the environment. Potentially negative effects are discussed for Bacillus thuringiensis toxin expressing corn (Bt-corn), Bt-potatoes and Protease-inhibitor expressing oilseed rape (PI-oilseed rape).<br><br>A reduction in insecticide use in Switzerland is only possible for Bt-potatoes and PI-oilseed rape, in Switzerland no insecticides are registered nor used against the corn borer. As the three main pests of the crops discussed (corn borer, Colorado potato beetle, pollen beetle) have already developed resistance against several insecticides in the lab, it is possible that transgenic pest-resistant crops will loose their efficiency on the long term. Several laboratory studies on side-effects of transgenic crops on non-target insects indicate negative impacts of the toxin-expressing plants. Such effects are not demonstrated so far in the few existing field studies. Final conclusions on this subject are not possible yet. Vertical gene transfer is possible from all three transgenic crops on non-transgenic varieties within the maximum distance of pollen dispersal. From the many plants (manly widespread weeds) closely related to oilseed rape, vertical gene transfer has only been observed on turnip (Brassica campestris=Brassica rapa).
Those wishing to promote biodiversity in agriculture by means of result-based schemes need meaningful indicators. An overview of proposed and used indicators highlights developments and challenges.
Foods of animal origin – friend or foe? It all depends on the needs of consumers and on local production conditions, as shown by a major review in which Agroscope took part.
In vegetable production it is usual to leave crop residues on the field. Measurements carried out by Agroscope researchers show that removing these residues significantly reduces nitrate leaching.