Insect diversity in heterogeneous agro-environments of Central Europe

Abstract Insect diversity has been decreasing significantly during the past decades. A main driver causing this negative trend is agricultural intensification, which causes habitat destruction and a deterioration of habitat quality. We caught flying arthropods with 28 Malaise traps and two light traps across a heterogeneous Central European agro-environment in southern Germany over a period of four years. The arthropods captured with Malaise traps were assigned to barcode index numbers (BINs) based on metabarcoding. Lepidopterans caught with light traps and light towers were identified based on morphological characters. Within the four years study, a total of 11,984 insect operational taxonomic units (OTUs) related to unique BINs on BOLD (> 95% similarity) were recorded across this agro-environment. 7835 of them could be assigned to insect order and the vast majority of them represent different species. Different estimates of the total species richness ranged between 8188 and 11,512 OTUs (a proxy for species). This number corresponds to about 26–36% of the total German insect fauna. Light trapping also yielded a high species diversity and returned 502 Lepidoptera species (compared to 784 species captured with Malaise traps). The overlap between light and Malaise traps was less than 45%. The Malaise trap catches showed that insects are more diverse along forest edges than in the centre of meadows. Our findings underline the high value of heterogeneous agro-environments for biodiversity, and the high value when combining data collected with different sampling techniques.