Interactive effects of plant defense and predation risk on M. sexta digestive physiology (mean ± SE) as measured via (a) frass nitrogen, and whole-body composition (μg/mg caterpillar dry weight) – (b) glycogen, (c) sugars, and (d) lipids.
Plant defense was manipulated using three plant types varying in their jasmonate signaling pathway with ‘jasmonate insensitive’ expressing low resistance, ‘wild-type’ the intermediate phenotype, and ‘jasmonate overexpress’ displaying high resistance. White bars are the predator-free control, and grey bars are labeled ‘PR’ to denote the ‘predation risk’ treatment (i.e., presence of a non-lethal stink bug). Statistical outcome for the main factors, covariate (weight), and interaction term are displayed in the upper right corner of each panel; asterisks correspond to the level of significance: * = P<0.05, ** = P<0.01, *** = P<0.001. Bolded asterisks above bar pairs indicate significant differences between the predator-free and predation risk treatments at each level of plant resistance in cases where the resource-risk interaction was significant. N = 17–21 replicates per treatment combination.