Fig. 2. Response of T. basalis females in a Y-tube olfactometer to volatiles from N. viridula egg masses offered (A) alone or (B) combined with V. faba leaves damaged by feeding activity (test) versus undamaged leaves offered in the control arm. 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 determined by t-tests for paired samples.