Comparing modern identification methods for wild bees: Metabarcoding and image-based morphological taxonomic...

Area of Science:

• Ecology
• Entomology
• Conservation Biology

Background:

• Wild bee populations are declining globally, necessitating accurate distribution and diversity assessments.
• Traditional wild bee identification relies on expert taxonomy or genetic analysis, each with distinct advantages and limitations.

Purpose of the Study:

• To compare the efficacy of image-based morphological identification versus DNA metabarcoding for identifying wild bees.
• To evaluate the combined potential of these methods for advancing wild bee research and conservation.

Main Methods:

• Wild bees were collected from Iowa conservation grasslands and identified using morphological analysis of images and DNA metabarcoding of composite legs.
• Sanger sequencing of individual bee legs served as a positive control for metabarcoding accuracy.

Main Results:

• Morphological identification yielded 36 taxa across 22 genera, with high species-level accuracy for Bombus.
• Metabarcoding provided genus-level assignments for 18 genera, resolving some morphologically similar taxa but missing some genera, including kleptoparasitic bees.
• Sanger sequencing confirmed metabarcoding presence/absence data and identified cryptic species, while morphological methods were limited by image quality and genetic methods by database completeness.

Conclusions:

• Image-based and DNA metabarcoding methods for wild bee identification have complementary strengths and weaknesses.
• Combining morphological and genetic approaches can provide comprehensive genus- and species-level data, crucial for effective wild bee conservation and distribution studies.
• Further refinement of these methods could facilitate field applications, accelerating ecological research and conservation efforts for declining bee populations.