The state of the science of flower-derived environmental DNA for pollinator biodiversity monitoring and conservation

Declines in insect pollinator abundances and ranges have been observed around the world, threatening possible collapse of natural and agricultural ecosystems. In response to this threat, pollinator conservation has risen in priority, but shortages in taxonomic expertise, the expense of time-consuming abundance-based surveys, and limited knowledge of species’ life-history characteristics impede successful monitoring and conservation actions. In 2019, Philip Thomsen and Eva Sigsgaard proved the feasibility of applying environmental DNA (eDNA) methods to detect insect pollinator DNA from the flowers where they forage. The potential applications for this method are extensive for monitoring rare or cryptic species, and researchers and managers quickly championed them as a possible solution to the overwhelming task of monitoring insect populations. However, in studies following the seminal paper, primer assay development, sampling design, and analysis methods have been unevenly developed, and experts have called for standardization of best practices. In May 2024, a cohort of leading researchers in terrestrial arthropod eDNA gathered at the Field Museum in Chicago, Illinois, USA to hold the first workshop on the current state of the science of terrestrial pollinator eDNA. The workshop connected academic, agency, and museum experts to identify opportunities and challenges to wider application of eDNA to insect pollinator conservation. Here, we present the products of this workshop, including (i) a review of the current state of the science, (ii) recommendations for best practices for assay design, sample collection and sample processing, and (iii) discussions of developing analytical methods that could expand on current applications.