Antixenosis in Maize Reduces Feeding by Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae)

Abstract

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.

Adaptation by Western Corn Rootworm (Coleoptera: Chrysomelidae) to Bt Maize: Inheritance, Fitness Costs, and Feeding Preference

“…Results from this study indicate that western corn rootworm larvae do not exhibit behavior that leads to either reduced or increased exposure to toxins. Bernklau et al (2010) found no differences in feeding behavior of Bt-susceptible western corn rootworm neonates on mCry3A maize and non-Bt maize. Results from a study of larval feeding behavior of susceptible western corn rootworm on non-Bt and Bt maize roots producing Cry3Bb1 suggest that susceptible neonate larvae may alter feeding behavior to reduce exposure to Bt proteins (Clark et al 2006).…”

Isolation and Characterization of Host Recognition Cues in Corn Roots for Larvae of the Western Corn Rootworm (Coleoptera: Chrysomelidae)

“…In Þeld tests, these varieties had less feeding damage than susceptible control plants, and fewer and smaller larvae and fewer adults were recovered from these genotypes compared with the controls (El Khishen et al 2009). Despite their superior performance in the Þeld, behavioral bioassays showed no signiÞcant differences in larval host recognition responses between susceptible corn and any of the resistant varieties (Bernklau et al 2010). Further chemical and behavioral work should establish the speciÞc role that the host recognition factors play in rootwormÐ corn interactions, and this information may elucidate the role of these behavioral cues in host plant resistance.…”

“…We previously tested larval host recognition responses to seven corn genotypes (Bernklau et al 2010) that were selected for native resistance (El Khishen et al 2009). In Þeld tests, these varieties had less feeding damage than susceptible control plants, and fewer and smaller larvae and fewer adults were recovered from these genotypes compared with the controls (El Khishen et al 2009).…”

“…Exposure to the roots of a nonhost plant elicits a long-range search behavior that is different from the tight-turning behavior and is distinguished by a rapid rate of travel, wide turns, and minimal path crossings (Strnad and Dunn 1990). These two distinct search behaviors were used to compare rootworm (Diabrotica barberi Smith and Lawrence) responses to alternate hosts (Oyediran et al 2004) and to native sources of resistance in maize (Bernklau et al 2010).…”

Natural Variation in Maize Defense against Insect Herbivores

“…Maize antixenosis has been demonstrated in the westem corn rootworm (Bemklau et al 2010), planthoppers (Costamagna et al 2005), and European com borer (Robinson et al 1978). In some instances, trade offs in maize antixenosis have been identified, whereby the activation of a defense mechanism against one herbivore or pathogen makes the plant more attractive than another (Ballhom2011).…”