The Extended Microbiota: How Microbes Shape Plant-Insect Interactions

Microorganisms were the first forms of life on Earth and are now part of all living organisms, but the role they played during the evolution of multicellular species is still a mystery. Among other biotic interactions, plants and their herbivorous insects have always occurred under a microbial milieu. During the past 20 years, our understanding of how microorganisms shape the ecology and evolution of plant-insect interactions has increased rapidly. However, the extent to which plant-associated microbes influence insect performance and how insect-associated microbes influence plant defenses remains largely unexplored. Here, we will highlight the potential reciprocal feedbacks between the microbiotas of plants and insects that could affect their interaction. We also bring attention to how network theory can help us understand the potential interactions within and between microbiotas. Finally, we will point out some promising directions for future experimental studies in order to better understand microbe-insect-plant interactions.