The pear pest, Cacopsylla jukyungi (Hemiptera: Psyllidae), is one of the most damaging insect to commercial pears in South Korea. In this 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. 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 sources 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.

Ceriagrion nipponicum (Odonata: Coenagrionidae) is listed as climate-sensitive indicator species in Korea and now expands its range northward. In this study, we sequenced complete mitochondrial genome (mitogenome) of the species collected from South Korea for comparatively analysis in damselflies and to detect the genes suitable for subsequent population genetic study. Comparison of the mitogenomes from two geographic samples of C. nipponicum showed the highest variation in ND4 and ND1, whereas no variation was detected in COI, warranting usefulness of the two genes for subsequent population-level study. Phylogenetic analysis using 13 PCGs and 2 rRNAs in Zygoptera showed non-monophyletic Coenagrionidae, forming two groups.

Bombyx mandarina (Lepidoptera: Bombycidae), the presumed ancestor of B. mori, has long been a subject of study to illustrate the geographic relationships in connection with origin of B. mori. We report 97 mitochondrial genome (mitogenome) sequences of B. mandarina collected from Korea and Japan. Phylogenetic and population genetic analyses showed that all individuals of B. mandarina collected in Korean localities formed a strong group together with all individuals originated from northern China (mainly north of the Qinling-Huaihe line) and some of southern China. This group was placed as the sister group to B. mori strians suggesting that this group had been served as an immediate progenitor for B. mori.

In Korea, both Sympetrum depressiusculum Sélys, 1841 (Odonata: Libellulidae) and Sympetrum frequens Sélys, 1883 are recorded. However, the identity of Korean populations and the validity of listing the two species have not yet been settled. In this study, we collected 74 individuals from Kroea, Russia, the Netherlands, and Japan. These were sequenced for COI, 16S rRNA, and ITS region. Major morphological characters and phylogenetic, network, and structure analyses all consistently suggest that Korean populations form a single species. Consequently, it could be valid to treat Korean populations as one species, S. depressiusculum, by applying the senior name.