Scarabaeidae larvae are neglected greenhouse gas sources in soils

A precise knowledge of the sink and source distributions of greenhouse gases (GHG) in regional and global carbon and nitrogen budgets, and of the processes governing them, is a necessary prerequisite for the development and assessment of climate change adaptation and mitigation strategies1-3. Certain soil-inhabiting Arthropoda groups are known producers of GHG, namely methane (CH4), but apart from termites, their emissions have never been studied in the field and quantified at different scales4,5. Here we report the first field GHG emission data of soil-dwelling Scarabaeidae larvae, focusing on pest insects in a temperate climate region (Melolontha melolontha and M. hippocastani). Variations in larval biomass explained variations in larval field CO2 and CH4 emissions well at the individual and site level. This correlation disappeared after transferring larvae from the field to a laboratory setting. We show that GHG emissions of soil-inhabiting Scarabaeidae larvae are comparable to those from termites, thus questioning the neglect of Scarabaeidae larvae in GHG flux research, and we demonstrate the importance of field-based emission estimates for soil biota.