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 <i>Callipogon relictus</i> 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 <i>Quercus serrata</i> 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 <i>Q. serrata</i> 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 <i>Carpinus laxiflora</i> tree approximately 300 m away. This study constitutes the first formal field documentation of mating between released and wild <i>C. relictus</i>, indicating the onset of potential gene flow and meeting a key IUCN criterion for successful translocation (wild breeding).