Dual Detection of the Chytrid Fungi Batrachochytrium spp. with an Enhanced Environmental DNA Approach.

David Lastra González,Jiří Vojar,Vojtech Baláž,Petr Chajma

doi:10.3390/jof7040258

Abstract

Environmental DNA (eDNA) is becoming an indispensable tool in biodiversity monitoring, including the monitoring of invasive species and pathogens. Aquatic chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are major threats to amphibians. However, the use of eDNA for detecting these pathogens has not yet become widespread, due to technological and economic obstacles. Using the enhanced eDNA approach (a simple and cheap sampling protocol) and the universally accepted qPCR assay, we confirmed the presence of Bsal and Bd in previously identified sites in Spain, including four sites that were new for Bsal. The new approach was successfully tested in laboratory conditions using manufactured gene fragments (gBlocks) of the targeted DNA sequence. A comparison of storage methods showed that samples kept in ethanol had the best DNA yield. Our results showed that the number of DNA copies in the Internal Transcribed Spacer region was 120 copies per Bsal cell. Eradication of emerging diseases requires quick and cost-effective solutions. We therefore performed cost-efficiency analyses of standard animal swabbing, a previous eDNA approach, and our own approach. The procedure presented here was evaluated as the most cost-efficient. Our findings will help to disseminate information about efforts to prevent the spread of chytrid fungi.

Highlights

This disease is caused by two chytrid fungal species: Batrachochytrium dendrobatidis (Bd) [13] and B. salamandrivorans (Bsal) [14]
These filters were from nine different localities, in four of which this was the first case of Bsal detection
Just in three of the localities, both Environmental DNA (eDNA) and swabs tested positive for Bsal

Summary

Introduction

Multiple infectious diseases with a detrimental impact on biodiversity have emerged and have been recognized on a global scale [7,8,9,10]. Amphibians have become the canaries in the coal mine in this pathogen-mediated crisis [11], with chytridiomycosis being the main culprit in their decline [12]. This disease is caused by two chytrid fungal species: Batrachochytrium dendrobatidis (Bd) [13] and B. salamandrivorans (Bsal) [14]

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Methods

Results

Conclusion