ABSTRACT
Lepidopteran pests are among the most economically important insect pests severely impacting agricultural productivity and contributing to an estimated 25 percent loss of global annual crop production (Oerke 1994). The most common approaches for management of lepidopteran pests are application of classical chemical insecticides or the use of preprotected transgenic crops that express Bacillus thuringiensis (Bt)-derived toxins that target the midgut epithelial cells (Huang et al. 2002; Pray et al. 2002; Toenniessen, O’Toole, and DeVries 2003; Lawrence 2005). Although Bt transgenic crops are increasingly being adopted by growers, there is continued concern over the potential for development of resistance to Bt toxins, and the potential nontarget and environmental impacts (Bates et al. 2005; Heckel et al. 2007; Rosi-Marshall et al. 2007; Sisterson et al. 2007). Alternative lepidopteran-active toxin transgenes would be benecial for a number of reasons including combining toxins (so-called stacking or pyramiding) to delay the development of resistance (Cao et al. 2002), or use of new transgenes once resistance to Bt toxins has developed for maintenance of the genetically modied (GM) crop industry. The marketing of competing cultivars that express alternative toxins could also reduce the cost of seed to growers.
