Fig. 2: iNext species accumulation curves for Malaise-trap samples and temporal turnover.

a Species richness (MOTUs) per sampling unit recovered through metabarcoding of Malaise-trap samples (solid lines). Incidence frequency-based species richness extrapolations (dashed lines) were performed over the total sampling period (from May 15 to September 15, 2017) (green curve) as well as for the following 4-weeks temporal sampling categories: May, June, July, August to assess the potential variations in both sampling effort and species richness (pink, yellow, cyan and violet curves, respectively). Sampling units are the total number of Malaise-trap samples available per temporal category. Shaded area represents 95% confidence interval. b Sample coverage (sampling efficiency of sampling units to recover the expected biodiversity) per number of sampling units. c Species diversity (MOTUs) per sample coverage. Accumulation curves indicated that the 211 sampling units used in the present study allowed a 90% sampling coverage of the given area and sampling period and allowed us to recover nearly 75% of the total Malaise-trappable diversity. Estimations gave around 4000 trappable species and the need of more than 400 sampling units on-site to recover them. d Venn diagram showing the species (MOTUs) turnover in the French Pyrenees across the 4-month sampling period of the study. Total number of MOTUs found every four weeks is given under the name of each starting month. Number of MOTUs shared between months is given within the diagrams. The high MOTU numbers specific to each month and the comparatively low number of shared MOTUs throughout the entire sampling period (highlighted in red) indicated an important temporal turnover of insect species.