Illustrating the challenges of creating a pollinator reference collection using skipper butterflies and carpenter bees.

Pollinators support crucial ecosystem services and are essential to sustain life on Earth, so their monitoring and conservation are a top priority. However, many pollinating insects are difficult to identify for non-experts, potentially hampering participation in monitoring and data reliability. Development of reference collections represents one strategy to support pollinator identification and monitoring, but is undermined by a lack of accessible digitized and taxonomically validated insect specimens. INC-STEP (Instigating a National Reference Collection for Spain’s Threatened Pollinators) was launched for six pollinator taxa as part of the EU TETTRIs project. Here we demonstrate for skipper butterflies (Hesperiidae) and carpenter bees (Xylocopa) as a case study, the challenges and investment of resources needed to create a validated and accessible reference collection. In Spain there are 33 Hesperiidae species and 6 Xylocopa. Neither group in the Museo Nacional de Ciencias Naturales (MNCN) had been recently reviewed, necessitating a full process of identification and digitization that included specimen location, expert identification, genetic confirmation of cryptic species, and uploading of data regarding each specimen. After reviewing all specimens, we have validated 559 Xylocopa and 5,741 Hesperiidae, with all Spanish species present except one skipper. The digitized specimens provide information to be made accessible to assist pollinator identification, and for studying the distribution, trends, and habitat needs of these species. The results obtained show the crucial role of taxonomically validated collections in supporting accurate identification of pollinators, while paving the way for extending this approach to other taxonomic groups and regions in the future.