Insights into the evolution of herbivory from a leaf-mining, drosophilid fly

Abstract

AbstractHerbivorous insects and their host plants comprise most known species on Earth. Illuminating how herbivory repeatedly evolved in insects from non-herbivorous lineages is critical to understanding how this biodiversity is created and maintained. We characterized the trophic niche ofScaptomyza flava, a representative of a lineage nested within theDrosophilathat transitioned to herbivory ∼15 million years ago. We used natural history studies to determine ifS. flavais a true herbivore or a cryptic microbe-feeder. Specifically, we quantified oviposition substrate choice and larval viability across food-types, trophic-related morphological traits, and nitrogen isotope and sterol profiles across putatively herbivorous and non-herbivorous drosophilids. We confirmed thatS. flavais an obligate herbivore of living plants. Paired with its genetic model host,Arabidopsis thaliana, S. flavais a novel and powerful system for exploring mechanisms underlying the evolution of herbivory, a complex trait that enabled the exceptional diversification of insects.