Data for Lu et al.

Latitudinal patterns of plant defense are usually attributed to stronger selection by herbivores at lower latitudes or near the host’s range center. However, empirical researches examining the influence of herbivory specialization and multiple defense strategies on these patterns remain limited. Here, we examined latitudinal patterns in Alternanthera philoxeroidesusing 28 genotypes sampled along a 13.5°latitudinal gradient in native and introduced ranges, conducting bioassay experiments to compare constitutive resistance, induced resistance, and tolerance against one generalist (Spodoptera litura) and one specialist (Agasicles hygrophila) herbivore. We found that for native genotypes, constitutive resistance against a specialist decreased linearly with latitude, while induced resistance increased. For introduced genotypes, constitutive resistance against a specialist peaked at mid-latitudes, and induced resistance showed an inverse pattern. Both genotypes showed a trade-off between constitutive and induced resistance against specialist rather than generalist. Additionally, no latitudinal patterns were observed for tolerance. Thus, our results provide the first experimental evidence that the trade-off between constitutive and induced resistance was driven by specialist and was not evident for generalist, which shapes latitudinal defense patterns in a worldwide invasive plant. This highlights the importance of considering herbivore specialization and defense strategies when studying latitudinal patterns of invasive plant defense.