Target and non-target effects on the invertebrate community of Vip cotton, a new insecticidal transgenic

Abstract

A new transgenic cotton producing the Vegetative Insecticidal Protein (Vip) is being developed to control Lepidopteran pests, especially Helicoverpa larvae. Before its introduction its efficacy against Helicoverpa larvae under field conditions needs to be confirmed, and any non-target effects it may have on the arthropod community need to be identified. We conducted field trials to compare the arthropod community in unsprayed conventional (Sicala 40) and Vip (Coker 312 Vip3A, event 102) cotton using visual searches, beatsheets, and suction samplers at 2 sites in Australia. At both sites, Vip controlled Helicoverpa larvae leading to much higher boll counts. There were no major differences in either species richness or diversity of the beneficial and non-target communities between Vip and conventional cotton, although cotton cultivar accounted for 2–7% of the variance in arthropod communities. There was no detrimental effect of Vip cotton on egg parasitoids. The number of predatory beetles and the pest mirid Creotiades dilutus (Stål) was higher in the Vip, although the increase in mirids was probably the result of more food (bolls) in the Vip crop. In a small plot experiment, we found higher numbers of whitefly in Vip, but this may be driven by differences in leaf hair between the cotton cultivars. Vip cotton appeared to have little effect on the arthropod community other than on Helicoverpa. As such it has the potential to be a useful tool in the management of Helicoverpa and may relieve resistance pressure on existing Bt cultivars (transgenic cotton containing genes for insecticidal Cry proteins), thereby increasing the durability of both technologies.