What we have learnt on impacts of <i>Bt</i> cotton on non-target organisms in China.
2003
Wu KongMing | Peng YuFa | Jia ShiRong
<i>Bt</i> transgenic cotton, containing a <i>Bacillus thuringiensis</i> toxin gene, has been widely planted in cotton growing areas in China since 1997. One of the major concerns of environmental risk is the impact on non-target organisms in the agriculture ecosystem. Results obtained in recent years indicate that the predator levels in <i>Bt</i> cotton fields are significantly higher than those in conventional cotton fields where insecticide has been used for control of the cotton bollworm, <i>Helicoverpa armigera</i>. However, the population density of parasitic wasps which parasitize on <i>H. armigera</i> larvae decreases dramatically due to the lower density and poor quality of <i>H. armigera</i> larvae in <i>Bt</i> cotton fields. As the predator population increases, the outbreak of cotton aphid [<i>Aphis gossypii</i>] in mid-season is effectively controlled, while the mirids become key insect pests in <i>Bt</i> cotton fields because of a reduced number of insecticides used against <i>H. armigera</i>. The diversity of the arthropod community in <i>Bt</i> cotton fields is higher than that in conventional cotton, suggesting that <i>Bt</i> cotton is highly favourable for integrated management of cotton pests. An assessment on the impact of <i>Bt</i> cotton pollen on two important economic insects, the Chinese tussah silkworm, <i>Antnaea perngicuerin</i> [<i>Antheraea pernyi</i>] and the silkworm, <i>Bombyx mori</i>, was conducted, from which it was concluded that the adverse effect is negligible.
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