Aphid density, Study 1.

<p>Mean aphid numbers (± SEM) per tiller of; <b>A</b>) <i>Rhopalosiphum padi</i> in 2012, <b>C</b>) <i>R. padi</i> 2013, <b>B</b>) <i>Sitobion avenae</i> in 2012, <b>D</b>) <i>S. avenae</i> 2013, for closed (exclusion of all natural enemies), open (exposed to all natural enemies), and sham (to control for cage effect) plots in Study 1. ANOVA was used to test statistical differences. Different letters next to the treatments indicate statistically significant differences among aphids per tillers at α = 0.05.