An aphid-ant interaction: effects on different trophic levels (C. K. Renault, L. M. Buffa and M. A. Delfino; SpringerLink - Article): "The density of aphids on control plants was positively correlated with the density of attending ants, while the density of aphids on ant-excluded plants was positively correlated with the density of spiders. Plants with ants had a significantly lower quantity of viable seeds than those without ants."