Fig. 3. Response of T. basalis females in a Y-tube olfactometer to volatiles from systemically induced V. faba leaves (test) versus undamaged leaves (control). N = number of replicates. Bars represent means ± S.D. for the time spent by the wasp females in both the arms over an observation period of 600 s. Different letters indicate significant differences evaluated by t-test for paired samples.