Figure 8.

SiHsTRPA-activating compounds repel fire ants. A, We introduced 20 fire ants at the boundary of two filter papers soaked with either compound or 10% DMSO, and then the ants were allowed to move for 40 min. The number of ants in each area was counted every 5 min for 10–40 min, and the seven recordings were summed. In the control experiments, both filter papers were soaked with 10% DMSO. We calculated the avoidance index as shown. The avoidance index is shown at the different concentrations of β-caryophyllene (B), octanoic acid (C), decanoic acid (D), β-citronellal (E; purple circle), and β-citronellol (E; blue triangle). The mean value with error bar (± SEM; n = 3) is indicated for each concentration. **, P-values at 0.06, 0.1, and 0.3 mm of β-caryophyllene are <0.0033, <0.0028, and <0.0007, respectively. P-values at 0.1, 0.3, and 1 mm of octanoic acid <0.009, <0.0001, and <0.0001. P-values at *, 0.3, and **, 0.6 mm, of decanoic acid are <0.02 and <0.004. P-values at *, 0.06, and **, 0.1, 0.3, and 1 mm of β-citronellal are <0.02, <7.3 × 10^–6, < 3.3 × 10^–6, and <1.4 × 10^–6. All of above P-values are the results of two-tailed Dunnett test compared to 0 mm.