Sensitive Environmental DNA Methods for Low-Risk Surveillance of At-Risk Bumble Bees

Area of Science:

• Ecology
• Conservation Biology
• Molecular Ecology

Background:

• Terrestrial environmental DNA (eDNA) offers potential for non-lethal pollinator monitoring.
• Previous studies lacked data comparing eDNA sensitivity to traditional pollinator surveys.

Purpose of the Study:

• To evaluate the sensitivity and effectiveness of eDNA methods for bumble bee community assessment.
• To compare eDNA detection rates with traditional netting surveys, including rare and endangered species.

Main Methods:

• Utilized a large-scale dataset comparing eDNA samples with concurrent net surveys.
• Employed COI-based metabarcoding for species-level characterization of bumble bee communities.
• Analyzed eDNA from leaf surfaces and compared detection rates with flower eDNA.

Main Results:

• eDNA methods successfully characterized entire bumble bee communities, detecting rare and endangered species like the rusty patched bumble bee (Bombus affinis).
• All species from netting surveys were detected via eDNA, except for two rare cuckoo bumble bee species.
• Leaf surface eDNA yielded lower detection rates compared to flower eDNA, potentially due to background contamination.
• eDNA detection frequency correlated strongly with net-based abundance measures.

Conclusions:

• COI-based metabarcoding is a cost-effective and scalable method for characterizing at-risk bumble bee communities using eDNA.
• eDNA techniques provide a valuable new approach for monitoring bumble bee populations and understanding their habitat associations.
• eDNA monitoring demonstrates comparable sensitivity to traditional methods for rare, non-parasitic bumble bee species.