Supplementary data from: Monitoring insect biodiversity and comparison of sampling strategies using metabarcoding: a case study in the Yanshan Mountains, China

Insects are the richest and most diverse group of animals and yet there remains a lack, not only of systematic research into their distribution across some key regions of the planet, but of standardized sampling strategies for their study. The Yanshan Mountains, being the boundary range between the Inner Mongolian Plateau and the North China Plain, present an indispensable piece of the insect biodiversity puzzle: both requiring systematic study and offering opportunities for the development of standardized methodologies. This is the first use of DNA metabarcoding to survey the insect biodiversity of the Yanshan Mountains. The study focuses on differences of community composition among samples collected via different methods and from different habitat types. In total, 74 bulk samples were collected from five habitat types (scrubland, woodland, wetland, farmland, and grassland) using three collection methods (sweep netting, Malaise traps, and light traps). After DNA extraction, PCR amplification, sequencing, and diversity analysis were performed, a total of 7,427 Operational Taxonomic Units (OTUs) at ≥ 97% sequence similarity level were delimited, of which, 7,083 OTUs were identified as belonging to Insecta. Orthoptera, Diptera, Coleoptera and Hemiptera were found to be the dominant orders according to community composition analysis. Nonmetric multidimensional scaling (NMDS) analysis based on Bray-Curtis distances revealed highly divergent estimates of insect community composition among samples differentiated by collection method (R = 0.524802, p = 0.001), but nonsignificant difference among samples differentiated according to habitat (R = 0.051102, p = 0.078). The study therefore appears to indicate that the concurrent use of varied collection methods is essential to the accurate monitoring of insect biodiversity.