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 strategies 1-3 . Certain soil-inhabiting Arthropoda groups are known producers of GHG, namely methane (CH 4 ), but apart from termites, their emissions have never been studied in the field and quantified at different scales 4,5 . 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 CO 2 and CH 4 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.