Listening to orthoptera in agroforestry: methodological and management insights for conservation

Biodiversity, particularly insects, faces considerable threats in intensively managed agricultural landscapes. Agroforestry systems (AFS), which integrate woody elements into agricultural land, can enhance biodiversity. This study aims to identify management factors influencing orthopteran richness and abundance in AFS. Additionally, it evaluates the utility of passive acoustic monitoring (PAM) for orthopteran detection by comparing it to field monitoring. Orthopteran monitoring was conducted at 20 silvoarable AFS in western Switzerland. Orthopteran richness was recorded using transects and PAM, while abundance was obtained only from transects. Both methods yielded similar species numbers. Daytime PAM detected cryptic or low-abundance species missed by daytime transects but failed to record one non-stridulating and some nocturnal species. Consequently, data from both methods were combined to provide a more comprehensive analysis of factors influencing orthopteran richness. The analysis revealed that increasing plant species diversity within the understory vegetation strips (UVS) had a positive, though not statistically significant, effect on orthopteran species richness. Furthermore, a non-significant reduction trend in orthopteran abundance was observed in conventionally managed agroforestry systems compared to organically managed ones. Implications for insect conservation Our study shows that PAM can effectively monitor orthopteran richness in AFS. By increasing plant diversity in UVS and through organic management, farmers can enhance orthopteran richness and abundance in AFS and support biodiversity conservation.