Decrease in faeces removal and soil bioturbation by dung beetles in genetically modified maize plantations in southern Brazil

Abstract

Ecosystem functions are the product of the interaction between living and non‐living components, providing goods and services that satisfy the needs of humans and other organisms, directly or indirectly. Dung beetles (Coleoptera: Scarabaeidae, Scarabaeinae) contribute to soil improvement through their feeding and reproductive behaviour by removing and burying faeces and thus participating in processes associated with nutrient cycling. Our aim was to investigate the structure of the community of beetles, biomass, and the ecosystem functions performed by them in maize plantations on five farms with GM maize, five with unmodified hybrids, and five with landrace (traditional) maize. We measured faecal removal, soil bioturbation, richness, abundance, and biomass of the dung beetle community. Arenas to quantify functions were installed to measure faeces' burial and the soil turned over by dung beetles. After measuring the functions, beetles were sampled with baited pitfall traps installed at the same sampling points. Ground cover was measured at all sites. Further, nesting houses were installed on each field to check for nesting inside the plantations. We recorded a total of 198 dung beetles belonging to 18 species. The lowest abundance occurred in GM maize plantations, and the highest abundance was found in conventional maize plantations. Dung beetle nesting activity was higher in landrace maize crops. Faeces removal and soil bioturbation had lower values in GM maize fields, mainly due to a decrease in large paracoprids (tunnelers), which are responsible for most ecosystem functions.