Impacts of the invasive plant Carpobrotus edulis on herbivore communities on the Iberian Peninsula

Abstract

Human activities have facilitated the introduction of invasive plants worldwide, altering habitat structure and leading to substantial effects on biodiversity. However, the effects of plant invasions on herbivore communities are understudied. Here, we examine factors influencing the occurrence of herbivores in ten coastal sites invaded by Carpobrotus edulis in the northwestern Iberian Peninsula. The aims were to evaluate the distribution and abundance of herbivorous invertebrates in different communities (invaded vs. non-invaded), explore the structure of plant–herbivore interaction networks, and assess whether the presence of herbivores affects the performance and fitness of C. edulis. Our results show that herbivore species composition was altered by the presence of C. edulis. Non-invaded plots had a higher number of plant–herbivore interactions and more specialized herbivore species, resulting in a greater degree of specialization. We also found an increase in the number of damaged flowers (florivory) of C. edulis by the native snails Theba pisana and Cornu aspersum. We conclude that C. edulis alters herbivore communities compared with non-invaded plots by changing plant–herbivore interactions and increasing the abundance of herbivores in invaded coastal sites. Snails might reduce seed production of C. edulis, acting as a natural biological control agent. Understanding the impacts of introduced species over invertebrate species at different community levels is crucial for implementing long-term management strategies that are key to reducing the impact of C. edulis on biodiversity.