Fig. 1. Preferential solubility in polar solvents and dose-dependent behavioural effects of egg foam bioactive components. (A) Effects on hatchling phase state (represented by median P_gregarious values) when water, ethanol or hexane are applied to eggs are compared to the effects of the same solvents applied to eggs following their use for either egg-washing or extraction of egg foam compounds. Asterisks indicate significant changes relative to control (see Table 2). Solitary-reared hatchlings (egg pods in parentheses): N=50 (4). Water: control, N=14 (9); wash, N=15 (9); extract, N=15 (9). Ethanol: control, N=15 (9); wash, N=13 (9); extract, N=14 (9). Hexane: control, N=14 (9); wash, N=13 (9); extract, N=11 (9). (B) Varying doses of whole extract HPLC eluent applied to eggs reveals a significant dose-dependent effect (P=0.002, one-tailed Jonckheere–Terpstra test). The median P_gregarious value for crude (unprocessed by HPLC) foam extract at a concentration of 0.1 foam plug equivalent is shown as a broken line. Individuals per treatment are shown above bars with number of contributing egg pods in parentheses.