Assessing larval rootworm behaviour after contacting maize roots: impact of germplasm, rootworm species and diapause status

Corn rootworms (Chrysomelidae: Diabrotica spp.) are widespread maize (Zea mays L.) pests that can cause economic damage by consuming plant tissues, thus negatively affecting plant physiology and function (Riedell 1990; Riedell and Reese 1999), and grain yield (Sutter et al. 1990; Spike and Tollefson 1991). The majority of plant damage is caused by the subterranean larval stages, which can also utilize roots of several alternative plant species to support their development (Branson and Ortman 1967, 1970; Moeser and Vidal 2004; Oyediran et al. 2004a; b). Soil insecticides and crop rotation are commonly used to manage rootworms (Wilson et al. 2005), although insecticide resistance has been documented (Ball and Weekman 1962; Wright et al. 2000). In addition, western corn rootworms (WCR, Diabrotica