Fig. 8. Frequency histograms showing the distribution of P_sol values obtained in the behavioural assay after locusts were stimulated at 1 min intervals with either (A) 5 cm³ air, (B) 0.5 cm³ acetic acid odour mixed with 4.5 cm³ air, (C) 5 cm³ acetic acid odour drawn from the headspace of a bottle of glacial acetic acid, (D) stroking with a small paintbrush or (E) simultaneously stroking with a paintbrush whilst 5 cm³ acetic acid odour was applied. Median P_sol values for each distribution are indicated next to each graph; significance is indicated with asterisks (Dunnet's post-hoc of ANOVA analyses): ^*, P<0.05; ^**, P<0.01, N=8 locusts for all groups.