Gallers as leaf rollers: ecosystem engineering in a tropical system and its effects on arthropod biodiversity

Gall-inducers can be considered ecosystem engineers when they modify leaf morphology and create shelters for secondary users, altering properties of ecological communities. In this study, we evaluated whether shelter structures created by leaf-galling contribute to changes in the diversity and composition of the community at plant and leaf scales, the effects of leaf roll occupation on the choice of secondary colonisers and the influence of leaf shelters on herbivory levels on host plants. The arthropod abundance, richness, and biomass were higher in leaf shelters compared to intact leaves. These effects were observed at similar magnitudes at both plant and leaf scales. The composition of arthropods differed between plants with leaf-rolled galls and plants with galls removed and between unoccupied leaf rolls and intact leaves. Artificial leaf rolls increased arthropod abundance, richness, and biomass by almost 100% compared to intact leaves. However, occupied artificial leaf rolls had a decrease in abundance, richness, and biomass of arthropods by almost 60.0% compared to unoccupied leaf rolls. Finally, plants with galls removed exhibited higher levels of leaf herbivory than plants with leaf- rolled galls. Our findings demonstrated the strong and positive indirect effects of gall induction facilitating shelter creation and the indirect effects of shelters on the diversity, species composition, and on leaf herbivory, and should be replicated in other systems involving plants and their respective gallers.

Automated summary

This study found that gall-inducing plants can be considered as ecosystem engineers by modifying leaf morphology and creating shelters, which impact the diversity and composition of ecological communities at plant and leaf scales. It also explored the effects of leaf roll occupation on secondary colonizers and herbivory levels on host plants. The results demonstrated significant effects of shelters on arthropod abundance, richness, and biomass compared to intact leaves, with occupied leaf rolls showing a decrease in arthropod levels.