Figure 2.
Proteinase inhibitor activity. Mean (+ SEM, n = 4 plants) proteinase inhibitor (PI) activity in leaves damaged by Tetranychus evansi (a) or Tetranychus urticae (b) and non-damaged leaves from similarly damaged plants (systemic) and leaves of non-damaged plants. The effect of treatment was significant (anova on log-transformed relative activity: F3,12 = 25.6, P < 0.0001). Within each panel, bars labelled with different letters are significantly different (Tukey HSD). The experiments with T. urticae and T. evansi were not carried out at the same time for logistical reasons. As it was impossible to maintain constant greenhouse conditions, plant quality will have varied with time. Treatments can therefore only be compared with their controls within the same experiment (i.e. within the same panel).