Floral resource availability declines and florivory increases along an elevation gradient in a highly biodiverse...

Flower-visitor interactions comprise a continuum of behaviours, from mutualistic partners to antagonistic visitors. Despite being relatively frequent in natural communities, florivory remains unexplored, especially when comprising abiotic factors, spatio-temporal variations and global environmental changes. Here, we addressed the variation of florivory driven by changes in elevation and temporal flower availability. We expect decreased floral resources as elevation increases - due to environmental constraints - which may affect plant-florivore interactions. Yet if floral resources decrease but florivores remain constant, then we may expect an increase in florivory with increasing elevation in the community.

The flowering phenology of plant individuals was recorded in the Neotropical campo rupestre vegetation, in southeastern Brazil. Damage by florivores was recorded in plots at elevations ranging from 823 to 1411 m using two response variables as a proxy for florivory: the proportion of attacked flowers per plant and the proportion of petal removal on single flowers.

Flower attack increased with elevation and damage was intensified in species with longer flowering periods. Conversely, longer flowering periods resulted in higher levels of petal removal with decreasing elevation. The temporal availability of flowers affected florivory, with the proportion of attacked flowers being more intense when there were fewer flowered individuals in the community. Petal removal on single flowers was intensified in plots with a larger number of individuals flowering, and with more species co-flowering.

This study provides one of the broadest records of a commonly neglected interaction of insects feeding on floral structures, quantifying the combined effect of floral display and availability along an elevation gradient in a highly biodiverse mountaintop community. These findings contribute to filling the gap in the understanding of florivory dynamics, focusing on a tropical mountaintop scenario facing imminent environmental changes and excessive natural resource exploitation.