Have Bt Crops Led to Changes in Insecticide Use Patterns and Impacted IPM?

Abstract

GM crops have now been commercialised for over ten years and currently over 114 million hectares are grown in 23 countries (James, 2007). By incorporating a powerful pest management tactic within the plant these Bt crops overcome some, but not all of the problems with timing and variable rates of application of insecticides, which reduce efficacy and often result in higher than necessary concentrations being applied than is necessary. The aim of this chapter is to gather the current evidence for impacts of Bt crops, largely Bt cotton and Bt maize, on insecticide use and to reflect on their role in IPM. Analyses of Bt crop performance across a range from large-scale intensive production to smallholder production systems of varying levels of sophistica- tion indicate significant reductions in insecticide input and in some systems, highly significant improvements in yield. However, economic performance is highly variable and seems dependent more on the market characteristics, support structures and culture of the systems in which Bt crops are deployed than on the Bt crops themselves. Given their specificity for key target pests and well demonstrated lack of impact on beneficial insects, Bt crops provide an important new platform for sustainable IPM systems, one that is compatible with a full range of other tactics. However, achieving that IPM out- come will often require ongoing education and extension support for farmers, particu- larly in smallholder systems, to ensure they can build confidence and gain sustainable benefit from a mix of new and established technologies in pest management. 11.1 Introduction GM crops have now been grown commercially for over ten years. Currently over 114 million hectares are grown to GM crops in 23 countries (James, 2007). This first generation of GM crops has focussed exclusively on so-called input traits associated with pest, disease and weed management and thereby provide direct benefits to producers, but are perceived to provide little direct benefit to consumers. CSIRO Entomology, Brisbane, Queensland, Australia * To whom correspondence should be addressed. E-mail: gary.fitt@csiro.au J. Romeis, A.M. Shelton, G.G. Kennedy (eds.), Integration of Insect-Resistant Genetically Modified Crops within IPM Programs. © Springer Science + Business Media B.V. 2008 303