Figure 7.

Bar graphs illustrating the influences of different aminergic-receptor antagonists. A, Level of aggression (circles, median; bars, i.q.r); B, fight duration (circles, median; bars, i.q.r.); C, relative frequency of level 6 fights (grappling); D, relative frequency of mandible spreading by the loser on confronting the winner of initial encounter. The crickets were first injected with vehicle (20 μl; white bars; n = 20 pairs), propranolol, (20 μl; 20 mm; lightly stippled bars; n = 19 pairs), phentolamine (20 μl; 20 mm; heavily stippled bars; n = 14 pairs), or epinastine (20 μl; 20 mm; black bars; n = 20 pairs). The animals' aggressive behavior was then evaluated in an initial fight (left) and then again 15 min after its conclusion (reengagement test; right; compare with Fig. 5). The results are also shown for a corresponding set of experiments with different crickets that were flown for 3 min before the initial fight (gray background; bars as above: vehicle, 24 pairs; propranolol, 21 pairs; phentolamine, 23 pairs; epinastine, 24 pairs). Asterisks denote statistically significant differences between the two bars indicated with square brackets (A, B, Mann-Whitney U test; C, D, χ² test; ^*p < 0.05; ^**p < 0.01; ^***p < 0.001).