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

Area of Science:

• Evolutionary Biology
• Ecology
• Entomology

Background:

• Herbivorous insects and host plants represent the majority of Earth's species.
• Understanding the evolution of insect herbivory is key to explaining biodiversity.
• The Drosophilidae family, including Drosophila, ancestrally feeds on microbes.

Purpose of the Study:

• To determine the trophic niche of Scaptomyza flava, a fly lineage that evolved herbivory.
• To investigate if S. flava is a true plant-feeder or a microbe-feeder.
• To establish S. flava as a model system for studying the evolution of herbivory.

Main Methods:

• Natural history observations and experiments.
• Quantification of oviposition substrate choice and larval viability across diets.
• Analysis of trophic-related morphology, nitrogen isotopes, and sterol profiles in drosophilids.

Main Results:

• Scaptomyza flava exclusively feeds on living plants, confirming it as an obligate herbivore.
• Evidence supports a transition to herbivory in S. flava approximately 10-15 million years ago.
• Comparative analyses differentiated herbivorous from non-herbivorous drosophilids.

Conclusions:

• Scaptomyza flava is a true herbivore, challenging assumptions about its ancestral lineage.
• This species, alongside Arabidopsis thaliana, offers a novel system for investigating herbivory evolution.
• The evolution of herbivory is a significant driver of insect diversification.