The honey bee is an important pollinator of wild plants and crops and provides various useful products for humans. Infestations by honey bee mites damage the honey bees’ health, decrease their lifespan, and increase their viral susceptibility. In this study, surveys were conducted throughout South Korea in 2019 to investigate the status of honey bee mite infestation. Mite samples were collected for species identification, and estimation of infestation levels from 47 apiaries in 12 regions was conducted. Mite species were identified by morphological characteristics and genetic analysis using cytochrome c oxidase subunit I (COX1). The results showed that 93.6% of the apiaries were infested by honey bee mites, of which 85.1% and 76.6% of the apiaries were infested by Varroa spp. and Tropilaelaps spp., respectively. Furthermore, 68.0% were co-infested by both honey bee mites. Additionally, 82.5% of the apiaries with Varroa spp. showed infestation rate with >3 mites per 100 bees, the infestation level could result in winter losses of honey bee colonies. Species identification revealed that all mites from the apiaries in South Korea were Varroa destructor and Tropilaelaps mercedesae. Importantly, these two mite species were determined to be vectors of one to nine honey bee pathogens in real-time polymerase chain reaction detection. The most prevalent pathogen was the deformed wing virus, followed by the Israeli acute paralysis virus and chronic bee paralysis virus. The results of the surveys are important for estimating the economic losses caused by honey bee mites and establishing a possible strategy for controlling mites and mite-borne transmissible pathogens in South Korea. Graphical Abstract

Poly(3-hydroxybutyrate) (PHB) is a versatile thermoplastic with superior biodegradability and biocompatibility that is intracellularly accumulated by numerous bacterial and archaeal species. Priestia sp. strain JY310 that was able to efficiently biotransform reducing sugars in d-xylose-rich rice husk hydrolysate (reducing sugar_RHH) to PHB was isolated from the soil of a rice paddy. Reducing sugar_RHH including 12.5% d-glucose, 75.3% d-xylose, and 12.2% d-arabinose was simply prepared using thermochemical hydrolysis of 3% H₂SO₄-treated rice husk for 15 min at 121 °C. When cultured with 20 g/L reducing sugar_RHH under optimized culture conditions in a batch bioreactor, Priestia sp. strain JY310 could produce PHB homopolymer up to 50.4% of cell dry weight (6.2 g/L). The melting temperature, heat of fusion, and thermal decomposition temperature of PHB were determined to be 167.9 °C, 92.1 J/g, and 268.1 °C, respectively. The number average and weight average molecular weights of PHB with a broad polydispersity index value (4.73) were estimated to be approximately 16.2 and 76.8 kg/mol, respectively. The findings of the present study suggest that Priestia sp. strain JY310 can be exploited as a good candidate for the low-cost production of low molecular weight PHB with improved biodegradability and reduced brittleness from inexpensive agricultural waste hydrolysates.

Background: The Japanese encephalitis virus (JEV) is transmitted by mosquitoes and circulates in Asia, the western Pacific, and other parts of the world. It is classified into five genotypes (GI–GV) based on the nucleotide sequence of the envelope (E) gene. Despite extensive surveillance, shifts in genotype distribution and mosquito species remain underreported, particularly in the Republic of Korea. Methodology/Principal findings: We conducted a nationwide mosquito collection from 2017 to 2022, capturing 1,102,031 mosquitoes from 32 sites nationwide. The predominant species were Aedes vexans (34.2%), Culex pipiens (17.9%), Cx. tritaeniorhynchus (13.4%), Ae. albopictus (4.0%), and Cx. orientalis (0.6%). JEV was detected in 49 pools, with the majority from Cx. pipiens and Cx. tritaeniorhynchus. Genetic analyses identified genotypes I, III, and V, with genotype V becoming dominant from 2020 onwards. Conclusions/Significance: The emergence of genotype V as the dominant strain of the JEV, along with its detection in mosquito species other than the previously known Cx. tritaeniorhynchus, highlights the need for ongoing surveillance. These findings underscore the importance of developing vaccines effective against all JEV genotypes to mitigate public health risks.

Background: Japanese encephalitis virus (JEV) is a major mosquito-borne pathogen, primarily transmitted by Culex tritaeniorhynchus in rural regions. In the Republic of Korea (ROK), genotype V (GV) has become the dominant JEV strain since 2010, raising suspicion about the vector competence of urban mosquitoes like Culex pipiens pallens . Methods: This study evaluated the vector competence of Cx. tritaeniorhynchus and Cx. pipiens pallens for JEV GIII and GV under laboratory conditions. Mosquitoes were orally infected, and the infection rate (IR), dissemination rate (DR), and transmission rate (TR) were assessed at days 7 and 14 post-infection. Results: Culex tritaeniorhynchus showed consistently high IR, DR, and TR for both genotypes, with over 95% of mosquitoes infected and actively transmitting the virus. In contrast, Cx. pipiens pallens exhibited a markedly lower IR, ranging from 23.1 to 39.2%; however, among infected mosquitoes, DR and TR were comparatively high. Viral load and titers were also markedly higher in Cx. tritaeniorhynchus than in Cx. pipiens pallens , particularly in the head-thorax and salivation samples. Conclusions: These findings confirm that Cx. tritaeniorhynchus is a highly competent vector for JEV GIII and GV and suggest that Cx. pipiens pallens may play a notable role in the transmission of Japanese encephalitis virus in urban areas. This study emphasizes the importance of targeted vector surveillance and control strategies for multiple mosquito species, especially given the recent urbanization of JE cases in the ROK. Graphical

권지영, 윤보람, 김기훈, 오현석, 주정원, 임진숙, 박재현, 이창준, 이욱교, 설재욱, 윤영민, 김지로, 김경록, 이태규, 이희일. Public Health Weekly Report 2025;18:1779-89. https://doi.org/10.56786/PHWR.2025.18.45.1

Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, poses a significant public health threat in Asia. Although Culex species are primary vectors, the role of Aedes albopictus in JEV transmission has gained attention under changing ecological conditions. This study evaluated the vector competence of Ae. albopictus for three JEV genotypes: I (GI), III (GIII), and V (GV). Laboratory-reared Ae. albopictus were orally challenged with each genotype, and infection rate (IR), dissemination rate (DR), head–thorax positivity rate (HTR, proxy for potential transmission), and transmission rate (defined as saliva positivity) were assessed at 7 and 14 days post-infection (dpi). Ae. albopictus showed marked genotype-specific differences. By 14 dpi, GV had the highest DR (100.0%) and HTR (71.7%), with viral RNA detected in 36.7% of TR. GIII showed moderate competence (76.9% DR, 39.3% HTR), but low TR (6.6%). In contrast, GI-infected mosquitoes exhibited minimal infection and negligible transmission, with viral RNA rarely detected beyond the midgut. These findings indicate that Ae. albopictus is highly competent for transmitting JEV genotype V and moderately for genotype III, but not genotype I, under laboratory conditions. This highlights its potential role in the transmission dynamics of emerging JEV genotypes and underscores the need for continued surveillance.