Genetic Attributes and Conservation of an Endangered Giant Water Bug Species, Diplonychus esakii Miyamoto and Lee, 1966 (Hemiptera: Belostomatidae).

Simple Summary: An endangered giant water bug species, Diplonychus esakii, is one of the top predators in Korean freshwater ecosystems. This study investigates D. esakii populations in South Korea, a species potentially endemic to this region, and identifies 11 haplotypes with a haplotype diversity value of 0.623 out of 318 individuals across 27 sites. Through AMOVA (analysis of molecular variance) and FST analyses, we discovered significant genetic differentiation among populations and limited gene flow, indicating potential vulnerability to environmental changes. Consequently, we emphasize the need for conservation efforts to protect D. esakii. We also highlight the value of the Upo Wetland and Jeju Island populations as important conservation units to conserve the genetic diversity of Korean D. esakii. We also suggest an evaluation of the conservation status of D. esakii compared to the level of genetic diversity known from other endangered insect species. The genetic information in this study will provide valuable data for developing effective conservation strategies. Diplonychus esakii, a water bug from the family Belostomatidae, plays an important role in freshwater ecosystems as one of the top predators. In this study, we investigated the genetic diversity and population structure of D. esakii by analyzing 318 specimens across 27 sites in South Korea. We found that the populations of D. esakii possess 11 haplotypes with a haplotype diversity of 0.623. This represents a relatively low level of genetic diversity compared to other known belostomatids and endangered species. AMOVA and FST analyses revealed significant genetic differentiation among populations, with most populations harboring only 1–2 haplotypes, suggesting restricted gene flow between populations and a low level of genetic diversity. This low genetic diversity and limited gene flow suggest a potential vulnerability to environmental changes and an increased risk of extinction, indicating that D. esakii should be designated as a protected species in South Korea as part of future conservation efforts. Based on the results of this study, Upo Wetland, which maintains relatively high levels of genetic diversity and Jeju Island, which, despite its lower genetic diversity compared to the mainland, does not share haplotypes with other regions, should be considered key conservation units for this species. This study highlights the importance of incorporating genetic information into conservation status assessments under the Red List Categories and Criteria and also emphasizes the need to evaluate this species on the Korean Red List. The data provided here will serve as essential baseline information and valuable resources for the development of effective conservation strategies. [ABSTRACT FROM AUTHOR]