Lost insect species: Challenges and methods in detection and reporting

The lost species concept is a relatively new addition to the discussion around species conservation status that has until recently been used only for major groups of vertebrates. A species is considered lost if it has not been detected in the wild by different lines of evidence within the last 10 years. The designation of lost reflects a confluence of biological and observational processes. It can be indicative of rarity and decline, but can also be explained by low detection probability, lack of information, or other non-mutually exclusive factors. Insects are well known for data deficiency, thus it can be expected that most insect species will be labelled as lost following consultation with experts and interrogation of public databases. This does not, however, preclude the utility of the lost species concept in insects. In fact, it might make it an especially compelling framework for organizing how we search for data-poor insect species. Expanding this framework in meaningful ways outside of vertebrates, including insects, is a critical frontier to facilitate species rediscovery, engage the public, and launch conservation efforts for rediscovered species. We discuss methodological approaches and unique challenges for assessing and publishing lost status in insects, with empirical examples based on ongoing work with Anthophila and Lepidoptera.