Antixenosis in maize reduces feeding by western corn rootworm larvae (Coleoptera: Chrysomelidae)

SUM2162 is the first known example of a naturally occurring maize, Zea mays L., genotype with antixenosis (nonpreference) resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), larval feeding. Behavioral responses of neonate western corn rootworm larvae were evaluated in laboratory bioassays with seven maize genotypes selected for native resistance to rootworm feeding damage. Two susceptible maize genotypes and one transgenic (Bacillus thuringiensis) maize genotype were included as controls. In soil bioassays with cut roots, no larvae entered the roots of the resistant variety SUM2162, but at least 75% of the larvae entered the roots of every other maize type. Larvae made significantly fewer feeding holes in the roots of SUM2162 than in all the other maize genotypes, except the isoline control. In feeding bioassays, larval feeding varied significantly among maize genotypes, but there was no significant difference between the resistant varieties and the susceptible controls. There were no significant differences among any of the genotypes in host recognition (search) behavior of larvae after exposure to the roots. Little variation in feeding stimulant blends was observed among maize genotypes, indicating minimal contribution to the observed antixenosis.