RELATIONSHIP BETWEEN STREAM INSECTS’ BIOMASS AND ENVIRONMENTAL DNA DERIVED BY METABARCODING AND QUANTITATIVE PCR

Abstract

 Invertebrate species DNA of the cytochrome oxidase subunit 1 region were quantified using environmental DNA (eDNA) extracted from river water using quantitative PCR (qPCR). Subsequently, metabarcoding was conducted to obtain the proportion of stream insects of six taxonomic orders (Ephemeroptera, Plecoptera, Trichoptera, Diptera, Odonata, Coleoptera) in the community. Finally, eDNA concentrations of the six taxonomic groups were calculated by multiplying the proportion of each taxonomy and the quantified invertebrate DNA concentration. As a result, aquatic insect eDNA concentrations displayed significant positive correlations with aquatic insect individuals collected by the conventional surber net sampling (Spearman’s rank correlation = 0.74, p < 0.01). Furthermore, positive correlations were observed between the population densities and eDNA concentrations for orders Ephemeroptera, Plecoptera, and Dipetra. These results indicate that the combination of eDNA metabarcoding and qPCR can be an effective way to estimate the abundance of stream insect.