In South Korea, both Sympetrum depressiusculum Sélys, 1841 (Odonata: Libellulidae), which is distributed throughout Europe and from Russia to the Korean Peninsula, and Sympetrum frequens Sélys, 1883, which is endemic to Japan, are recorded. However, the identity of South Korean populations and the validity of listing the two species have not yet been settled. In this study, we collected seventy-four individuals of Sympetrum species from South Korea (five localities), Russia, The Netherlands, and Japan. These samples were examined for morphology and sequenced for partial COI, 16S rRNA, and a nuclear internal spacer (ITS) region, after which these molecular data were combined with available public data from Russia, Japan, and The Netherlands. Major morphological characters that have been used to distinguish the two species and phylogenetic, network, and structure analyses all consistently suggest that South Korean populations form a single species. Consequently, it could be valid to treat South Korean populations as one species, S. depressiusculum, by applying the senior name. Nevertheless, the validity of maintaining each as an independent species in other countries may need additional study considering that our samples were focused more on South Korea and limited for Europe, Russia, and Japan.

Understanding the genetic basis of growth and moltism in silkworm (Bombyx mori) is essential for improving silk production efficiency and elucidating the mechanisms underlying developmental plasticity. Thus, this study aimed to establish a collection of 20 representative B. mori core strains and perform integrative genomic analyses combining genome-wide association studies (GWASs) and population-specific variant detection. A total of 5,293,831 high-confidence single-nucleotide variants (SNVs) were identified across the population, and GWAS revealed significant associations between specific genetic loci and four growth-related traits: larval weight at day 7 of the fifth instar, pupal weight, cocoon weight, and cocoon layer weight. Among these, two missense variants within the Cycb gene were significantly correlated with increased body weight at the late fifth instar stage, suggesting a potential role for this isoform in regulating cell-cycle-driven tissue expansion during rapid larval growth. Moreover, a population-based comparison identified 2803 trimolter-specific missense SNVs in 1440 genes, of which 109 were functionally annotated. Notably, homozygous variants were detected in key developmental regulators, such as MET1 and TOR1, implying potential alterations in juvenile hormone signaling and nutrient-dependent growth pathways that may contribute to the dominant trimolter phenotype. Although experimental validation remains necessary, these findings provide a genomic framework for understanding the molecular mechanisms underlying moltism variation and offer valuable resources for future silkworm genetic improvement.

The pear pest, Cacopsylla jukyungi (Hemiptera: Psyllidae), is the most damaging insect to commercial pears in South Korea. An assessment of the population genetic characteristics of the species will raise the potential of effective control. In the present study, we developed eight microsatellite markers specific to C. jukyungi and genotyped 132 individuals collected from 11 localities throughout South Korea. Populations showed lower observed heterozygosity than expected heterozygosity and slightly or highly positive values of inbreeding coefficients, suggesting that C. jukyungi is subjected to inbreeding. A strong dependence on commercial pear trees throughout the whole life cycle, even during overwintering, and a nationwide targeting of the overwintered adults are likely contributors to such heterozygosity deficiency. On the other hand, population analyses consistently indicated strong gene flow among populations, implying the presence of persistent factors that have facilitated this process. The nationwide expansion of pear orchards and the replacement with a popular new cultivar during the last 50 years, which may have accompanied the spread of C. jukyungi-bearing pear grafts and scions, are likely causes of such facilitated dispersal. Thus, a management strategy against unintended anthropogenic dispersal of the pear psyllid will be required for better control of C. jukyungi.