The effect of chemical diversity on insect resistance
We found that across all plant species, only the specialist caterpillar grew worst on high chemical diversity (H) plants, while the generalist sap-feeder grew more on plants with the lowest FDiv values (Table 1). Specifically, within group analyses of insect resistance showed that, the growth of all of the herbivore insects differed among different plant groups. The specialist P. brassicae performed the worst on species of group 1 (Fig. 4a; F1, 126 = 9.81, p < 0.0001), while the generalist S. littoralis performed best on species within group 4 (Fig. 4b; F1, 126 = 8.19, p < 0.0001). The growth of aphids was generally highest on plants from group 2. While the growth of specialist B. brassicaeaphids differed only between group 2 and 4 (Fig. 4c; F1, 126 = 3.75, p = 0.01), the generalist M. persicae grew best on species of group 2 (Fig. 4d; F1, 126 = 5.68, p = 0.001).