Aim: The enemy release hypothesis (ERH) posits that exotic species suffer lower enemy damage than natives, and thus promotes their successful invasion. However, the generality of lower damage for exotics remains widely debated. A recent view proposes that enemy release (ER) could systematically change with latitude, potentially helping explain these inconsistencies. Here, we test whether exotic plant species suffer consistently lower herbivore damage relative to natives, and whether ER varies with latitude.

Location: Global.

Time Period: 1960-2018.

Major Taxa Studied: Plants.

Methods: Using leaf herbivory data for 1,098 plant species, we compared the herbivory rate between exotic and native plants across all taxa, between the introduced and native range of exotic species, and between exotic and native species co-occurring in the same community. Then, we tested the interaction effect between origin (exotic vs. native) and latitude to assess variation in ER with latitude. We also examined whether the effect of origin and its interaction with latitude changed with plant growth form (woody vs. non-woody). Finally, based on two ER effect-size datasets, two meta-regressions were performed to demonstrate the relationship between ER and latitude.

Results: Leaf herbivory rates were commonly lower for exotics than natives. However, this differential herbivory rate was only significant for woody plants. No significant interactions were found between origin and latitude, indicating that ER did not change with latitude. The meta-regressions also demonstrated that ER was not significantly correlated with latitude.

Main Conclusions: The widespread lower herbivory rate for exotic compared to native woody plant species supports the ERH for exotic woody plants. Consistent ER with latitude indicates that ER should play a similar role regardless of latitude. One future challenge is to assess to what extent ER in woody exotic plants translates to performance advantages and hence influences their invasion success.

We recommend referencing the Methods section and Supplementary Information of the corresponding paper.