Impact of insect herbivory on plant stress volatile emissions from trees: A synthesis of quantitative measurements and recommendations for future research

Plants, and particularly trees, are the largest source of atmospheric volatile organic compounds globally. Insect herbivory alters plant volatile emission rates and the types of compounds that are emitted. These stress volatiles are a major contribution to total plant volatile emissions during active herbivore feeding, with important implications for atmospheric chemistry processes. However, emission models do not currently have a quantitative description of plant volatile emission rates during and after insect herbivore feeding. This review provides a brief background on plant volatile organic compounds, the urgency of including biotic stress emissions in models, and a summary of plant volatile emission models and steps they have taken to incorporate stress emissions into their framework. The review ends with a synthesis of volatile emissions from trees during insect herbivory. This synthesis highlights key gaps in studied systems and measurement approaches. We provide a summary of recommendations for future work to address these gaps, improve comparability between studies, and generate the data-sets we need to develop a descriptive model of these plant stress volatile emissions.