Shedding Light on Shining Leaf Chafers: Rutelinae MacLeay, 1819 (Coleoptera, Scarabaeoidea, Scarabaeidae) as a Neglected Group of Pollinators

The interactions between insects and angiosperms date back to millions of years ago. Among the groups of pollinating animals, it is estimated that insects are responsible for pollinating more than 70% of angiosperms. Coleoptera is one of the most studied insect groups for pollination. However, the role played by certain beetle groups as scarabs of the subfamily Rutelinae as pollinators remains poorly investigated. Some records in the literature identify Rutelinae as pollinators of angiosperms (e.g., Annonaceae, Araceae, Arecaceae, Nymphaeaceae and Magnoliaceae). However, most of these records are often generic, lacking detailed information about which angiosperm families are pollinated by these scarab beetles. In this study, we used unpublished sources and image records from an online citizen science platform (iNaturalist) to conduct a comprehensive sampling of the interactions between Rutelinae and the flowers they visit. Thus, the objectives of this study were to expand the records of geographical distribution worldwide of floral visitation by Rutelinae, using the global distribution as a case study; infer whether there is seasonality in this interaction; and determine which plant and Rutelinae species are involved in the interaction. The results reveal 281 interactions involving 32 species of Rutelinae with flowers of 54 angiosperm families; 256 records were extracted from iNaturalist and 25 were from our own data. Most of the records (90.7%) were found in the Neotropics. Of the 32 species identified, 28 species belong to Rutelini. The most frequently recorded species were Rutela lineola (Linnaeus, 1758), Macraspis morio Burmeister, 1844, and Macraspis festiva Burmeister, 1844. In the Neotropics, records were found across 40 families. Most records occurred in Fabaceae, Melastomataceae, Myrtaceae, Rosaceae, Malvaceae, Apiaceae and Asteraceae, which together account for 73.7% of all Neotropical records. Our results provide an important basis for future studies aiming at investigating the role of Rutelinae as pollinators. Furthermore, this research underscores the need for further investigation into the ecological contributions of these beetles as pollinators.