Figure 1. The appropriate time lag for priming the ability of receiver plants to defend themselves against herbivores.

Maize plants were exposed to HIPVs and control volatiles (CVs) emitted from M. separata-infested and uninfested conspecific plants for three days in an open-flow tunnel. A second-instar larva was put onto HIPV- and CV-receiver plants immediately after exposure (Day 0), or after receiver plants had been maintained for 1, 5 or 10 days. The net body weight that M. separata larvae gained during 3 days after they had been applied was determined. Data represent the mean ± standard errors (n = 17–22). Asterisks indicate significant differences between HIPV- and CV-receivers based on a Student's t-test (P < 0.05).