a1 Plant and Invertebrate Ecology Division, Rothamsted Research, Harpenden, AL5 2JQ, UK
a2 Biomathematics Unit, Rothamsted Research, Harpenden, AL5 2JQ, UK
a3 Division of Biodiversity and Ecology, School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, UK
a4 Department of Plant Sciences, The University of Tennessee, Knoxville, TN 37996, USA
Crops transformed to express Bacillus thuringiensis (Bt) toxins can cause close to 100% mortality of certain target pest species. This study assessed the effect of target pest reduction on the predatory insect Chrysoperla carnea (Stephens) in the presence of alternative prey. Numbers of lacewings recovered from Bt oilseed rape (cultivar Oscar, event O52) did not differ significantly from numbers of lacewings recovered from conventional oilseed rape in cage experiments with the target pest Plutella xylostella (Linnaeus) and the non-target pest Myzus persicae (Sulzer) when aphid densities were high. However, significantly fewer lacewings were recovered from Bt plants as aphid densities were lowered. Lacewing weights were not affected by plant type.
(Accepted December 22 2004)