Figure 1.
Changes in EFN production and ant activity during the dry and the rainy season.
(A) EFN secretion pattern (µg g−1 dry biomass 24 h−1) and (B) the number of ants that crossed three lines along the plant branch during three minutes in A. cornigera and A. hindsii during the dry (gray bars) and the rainy season (open bars). Data represent mean and standard errors. Asterisks indicate significant differences (*** P<0.001, ** P<0.01, * P<0.05, ns = not significant, Two-way ANOVA).
Figure 2.
Effect of nectar concentration on time of course of ant recruitment on two Acacia species.
Number of ants present on branches treated with different concentrations of artificial nectar solutions, water (black circle), 5% sugar solution (white circle) and 20% sugar solution (black triangle) for (A) A. cornigera and (B) A. hindsii (Mixed model analysis).
Figure 3.
Effect of different nectar concentrations on ant activity and ant aggression on two Acacia species.
(A) Ant activity (number of ants) and (B) ant aggression against termites (number of ant bites to termites placed on the host plant over three minutes) on branches of A. cornigera and A. hindsii treated with two different sugar solutions, 5% (white bars) and 20% (gray bars) (Mixed model analysis).
Figure 4.
Herbivory levels and relative growth in two Acacia species during the dry and the rainy season.
Percentage of damaged leaflets in branches of (A) A. cornigera and (B) A. hindsii in presence (gray bars) and absence (white bars) of ants of P. ferrugineus (Mixed model analysis). Biomass (g) produced after one month for plants of (C) A. cornigera and (D) A. hindsii. Asterisks indicate significant differences (*** P<0.001, ** P<0.01, * P<0.05, ns = not significant, Two-way ANOVA).
Figure 5.
Daily time course of EFN production, ant activity and activity of EFN thieves.
(A, B) Variations in EFN production (µg g−1 dry biomass 24 h−1) and (C, D) ant activity (number of ants) across the day for plants of A. cornigera and A. hindsii. Activity of EFN thieves was quantified in presence (black circle) and absence (white circle) of ants of P. ferrugineus on (E) A. cornigera and (F) A. hindsii (Mixed model analysis).
Figure 6.
Aggression towards EFN thieves by ants of P. ferrugineus.
(A) Number of ant attacks to EFN thieves and (B) time spent per visit (sec) by EFN thieves on branches treated with 5% and 20% of sugar solutions. Asterisks indicate significant differences in the number of bee visits between branches with and without ants at a certain time (*** P<0.001, ** P<0.01, * P<0.05, ns = not significant, Wilcoxon pair test).