Tachinidae (Diptera) as Floral Visitors and Pollinators in Natural and Managed Systems

ABSTRACT Awareness of the roles of flies as pollinators in natural and agricultural ecosystems has increased considerably in recent years, and there is growing consensus that globally they rank second in importance as floral pollinators after the Hymenoptera. The bristle flies (Tachinidae) are among the most important and ubiquitous flower‐visiting flies, yet relatively few studies have focused on the pollination services of tachinids and there have been no comprehensive studies of the frequency of flower visitation across the family. The goal of this paper is to review the pervasiveness and importance of bristle flies as floral visitors and pollinators. We provide an overview of the prevalence of Tachinidae as floral visitors, highlighting their importance in high elevation (and high latitude) environments, and as visitors of a broad array of plant families, most notably those with relatively short corollas and compound inflorescences. Using information from the iNaturalist database, we find that most tachinid genera visit flowers at least occasionally and many taxa are major floral visitors. The likelihood of floral visitation is found to vary significantly among subfamilies and tribes, with genera in the Phasiinae exhibiting the highest probability of floral visitation. We explore the phylogenetic distribution of floral adapted elongated mouthparts in tachinids, finding that these adaptations have evolved independently well over 20 times across the family and in multiple lineages in every subfamily. We further review patterns and examples of floral specificity within the family and assess the efficacy of tachinids as pollinators with case studies. Finally, we consider the roles of Tachinidae as pollinators in agricultural systems and their potential dual ecological services as both biocontrol agents and pollinators.