First field documentation of interbreeding between released and wild Callipogon relictus (Coleoptera, Cerambycidae) signals in situ reinforcement progress in Korea

Background The relict longhorned beetle Callipogon relictus is protected in Korea as Natural Monument No. 218 and listed as an Endangered Species, Class I. Recent conservation measures include captive breeding and releases to bolster wild populations; however, empirical evidence of integration between released and wild individuals remains limited. New Information During daytime routine surveys in Gwangneung Forest, a radio-tagged female released on 10 July 2023 (LOTEK’s Pip4, model Ag337) was video-recorded copulating with an unmarked wild male on a Quercus serrata at 37°44′56.3″N, 127°09′04.3″E, at an elevation of 213 m. Copulation was first observed on 19 July and continued intermittently over 2 days, with repeated bouts lasting 10–20 minutes. This event occurred approximately 12 m aboveground on the leeward side of the Q. serrata trunk. The female radio-tracking tag was visible and did not appear to impede mating. Oviposition by the released female was later documented on a dead Carpinus laxiflora tree approximately 300 m away. This study constitutes the first formal field documentation of mating between released and wild C. relictus , indicating the onset of potential gene flow and meeting a key IUCN criterion for successful translocation (wild breeding).