The neglected pollinators: settling moths are keystone floral visitors essential to network connectivity and tropical forest recovery

The underrepresentation of nocturnal taxa in ecological research constitutes the 'nocturnal problem'. A significant example is settling (i.e. non-sphingid) moths, coined as 'needles in a haystack' given the uncertainty of their role as pollinators. Using high-throughput pollen metabarcoding, we compiled interactions from 24 400 individuals from 504 species of tropical diurnal and nocturnal pollinators. We investigated the role of different functional groups in a comprehensive pollen transfer network, employing tiger moths (Erebidae: Arctiinae) as a model to disentangle the effect of settling moths on network connectivity along a recovery chronosequence. Tiger moths were central generalists, amassing more interactions with plants than any other pollinator group, and were the main connecting agents between network modules. Moreover, they served as network hubs alongside pioneer plant genera, which were their primary resources. Tiger moth dominance was maintained throughout four decades of passive restoration but increased in the canopies of older forests. Dominance was primarily driven by their high abundance and diversity, which resulted in more interactions per unit of sampling effort. Moreover, moth functional morphology drove specialization and centrality patterns. Our results underline a largely neglected functional group of nocturnal pollinators as prominent floral visitors, key to ecosystem stability and recovery.