Data from: Direct PCR meets high-throughput sequencing - metabarcoding of chironomid communities without DNA extraction

Abstract

Metabarcoding is a valuable tool for investigating insect community compositions. However, high-throughput applications, such as for biomonitoring, require cost-effective and user-friendly procedures. To investigate if the time-consuming and labour-intensive DNA isolation step can be omitted in metabarcoding, we studied the difference in detection rates and individual read abundance using standard DNA isolation versus direct PCR protocols. Metabarcoding with and without DNA isolation was performed on artificially created communities with known composition as well as on natural communities both of the dipteran family Chironomidae to compare detection rates, individual read abundances and presence-absence community composition. The data sets include read abundances of all artificial and natural community samples. Compositions of the samples per data set are described in the respective README files. ASVs/OTUs and their respective DNA sequences are given. R Scripts for bioinformatic processing (dada2 for ASVs, JAMP for OTUs) are provided.

Methods

Chironomidae were retrieved from artificial ponds of the Eußerthal Ecosystem Research Station (EERES) near Landau, Germany, in 2019 and 2020. Adult specimens were collected from passive emergence traps. Chironomid samples were stored in 70% ethanol and later dried at 60°C. Samples were then finely ground using a bead mill. PCR-grade water was added to each tissue sample and thoroughly vortexed. The tissue-water mixes were frozen at -20°C until further analysis. Artificial communities were created by pipetting tissue-water mixes of individual chironomids. Natural communities from eight ponds and five consecutive sampling dates were selected to assess the applicability of the dPCR approach compared to standard metabarcoding protocols on natural chironomid communities. Four of the artificial ponds were treated with the mosquito control agent Bacillus thuringiensis israelensis (Bti). Tissue-water mixes of artificial and natural communities were both directly applied to PCR and used for DNA isolation. Illumina sequencing was performed and raw data were bioinformatically prepared. For more details see "Direct PCR meets high-throughput sequencing - metabarcoding of chironomid communities without DNA extraction" (Röder & Schwenk 2023). Raw sequences are available through GenBank SRA archive (BioProject accession number PRJNA989176).