Asterid Ray Floret Traits Predict the Likelihood of Florivory by the Polyphagous Katydid, Phaneroptera brevis (Orthoptera: Phaneropterinae)

Abstract

Insect-flower visitation is crucial for many angiosperms because insects can facilitate pollination. Floral traits can attract pollinators so studying how they correlate with insect-flower visitation can elucidate how insects and plants interact and coevolve. However, there are few studies on how floral traits correlate with florivory. Not all floral traits that predict attractiveness of flowers to pollinators are applicable for florivory because they may not necessarily reflect the palatability of the flower parts. Leaf functional traits have been studied extensively to predict herbivory, but we are not aware of studies that adopt such leaf traits in florivory. We addressed these limitations by investigating the research questions: 1) How do floral traits differ among different species? 2) How do the floral traits predict the likelihood of florivory? We measured 10 floral traits, including adopting common leaf traits associated with herbivory (e.g., specific leaf area and leaf dry matter content), among three Asteraceae species: Bidens pilosa L., Sphagneticola trilobata (L.) Pruski, and Tridax procumbens L. We then performed the cafeteria assay using a polyphagous floriphilic katydid, Phaneroptera brevis (Serville 1838). We found that ray floret dry matter content correlates negatively with the likelihood of florivory of the asterid ray floret, whereas the total biomass of the ray floret correlates positively with the likelihood of florivory of the entire capitulum. The specific ray floret area also correlates nonlinearly with the likelihood of florivory of the asterid ray florets. We believe that these florivory traits can be applied to the flowers of other species.