Towards red listing understudied tropical insects: A case study of the dung beetles of Sabah, Malaysian Borneo

The IUCN Red List is the most authoritative framework for assessing species' extinction risk and is widely used in conservation policies and decision‐making. Yet for tropical insects, the IUCN Red List Criteria are rarely implemented, partly due to the misconception that all five Red List Criteria must be used. As most tropical insect taxa only have occurrence data and lack information on population demographics, among the five Criteria, only Criterion B (i.e. geographic range) can usually be applied. As a case study, we performed a regional (within Sabah, Malaysian Borneo) and global Red List assessment using Criterion B on a dataset of over 30,000 occurrence records of 159 dung beetle species from Sabah. At the regional level, we assessed 10 Endangered, 7 Vulnerable, 33 Near Threatened, 24 Least Concern, 84 Data Deficient and 1 Not Applicable species. At the global level, we assessed 7 Endangered, 10 Vulnerable, 23 Near Threatened, 41 Least Concern and 78 Data Deficient species. We found that incorporating expert validation, particularly regarding species' rarity in field surveys, ecology and habitat associations, was critical to performing and finalising these assessments. While increased sampling, species descriptions and data mobilisation efforts are essential for documenting patterns in insect declines, we show that Red List assessments of tropical insects are feasible, and necessary, to increase their representation in conservation priorities.