Cinderella Biodiversity: Three Decades of Monitoring Reveal Earlier Emergence and Increasing Abundance in Undervalued and Sparsely Recorded Flying Insects and Ballooning Spiders

Abstract

ABSTRACT Arthropod declines have been reported widely, and yet the spotlight has fallen on relatively large, colourful insects, rarely considering the abundant, small‐sized, yet charismatic flying insects and ballooning spiders we class as neglected and undervalued ‘Cinderella species’. This diverse set of arthropods contributes important ecosystem services, such as decomposition, pollination, pest regulation and nutrient cycling. We sampled a 30 year long archived arthropod collection, preserved in ethanol from the daily 12.2 m suction‐trap catches at four sites in the UK, to provide new data on more than 600,000 previously unidentified insects and spiders. Group or family‐level trends for the Coleoptera (beetles), Diptera (true flies), Hemiptera (true bugs) and Hymenoptera (bees, ants and wasps) as well as trends for seemingly less well‐known orders including the Psocoptera (barkflies), Dermaptera (earwigs) and Araneae (spiders) are provided. Our aim is to produce 30 year explainable trends in abundance and phenology for 71 Cinderella arthropod groups, and explore their functional trophic guild and habitat use during the immature stage. We trained random forest models to predict log abundance and phenology (Day of 5% catch) using a set of landscape, topography, weather‐related drivers. We show that the majority of arthropod taxa, as well as most trophic and habitat‐use groups, report either stable or increasing abundances, and stable or earlier phenologies. We also found that across taxa, earlier phenologies (54%–70% of taxa) and more abundant catches (55%–77%) are significantly related. These trends are mostly explained by temperature‐related drivers and secondarily by landcover, of which the strongest signal is improved grassland. Our study establishes a quantitative baseline for an undervalued, forgotten and often sparsely recorded segment of Britain's biodiversity.