Bt Cotton Does not Affect Cotton Aphids

Jörg Romeis from Agroscope ART in Zurich, Switzerland, and colleagues assessed the performance of cotton aphids, Aphis gossypii, when grown on three Indian Bt (Cry1Ac) cotton varieties and their corresponding non-transformed near isolines. While plant transformation did not influence a range of aphid life-table parameters, some variation was observed among the three cotton varieties. Furthermore, the authors examined whether aphids pick up the Bt protein and analyzed the sugar composition of aphid honeydew to evaluate its suitability for honeydew-feeders. None of the aphid samples contained Bt protein. As a consequence, natural enemies that feed on aphids are not exposed to the Cry protein. A significant difference in the sugar composition of aphid honeydew was detected among cotton varieties as well as between transformed and non-transformed plants. However, it is questionable if this variation is of ecological relevance, especially as honeydew is not the only sugar source parasitoids feed on in cotton fields.

The study allows the conclusion that Bt cotton poses a negligible risk for aphid antagonists and that aphids should remain under natural control in Bt cotton fields.

The article is published online by PLoS ONE. For the full article, visit http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0004804;jsessionid=FC4FF3BE190D1B36FEBF697EC09312E1