말라리아는 Anopheles 모기들에 의해 전파되며, 대한민국에서는 코로나 팬데믹 기간 동안(2020~2022) 약 200~300명대의 말라리아 환자가 발생하였으나, 지난 2023년에는 그 수가 폭증해 약 800명의 환자가 발생하였다. 현재까지 모기를 방제하기 위한 가장 효율적인 수단은 살충제를 사용한 방제이나, 지속적으로 이러한 화합물에 노출된 모기 개체군은 살충제에 저항성을 갖게 되는 것으로 알려져 있다. 이에 본 연구에서는 대한민국의 주요 말라리아 발생 지역인 비무장지대 부근 및 이외 지역인 용산, 평택, 오산에서 채집을 진행하였으며, 채집된 An. sinensis에 대해서 살충제 저항성과 관련되어 있다고 알려진 유전자인 acetylcholinesterase-1(ace-1)와 voltage-gated sodium channel(vgsc) 영역에 대한 저항성 돌연변이 보유 여부를 각각 확인하였다. 실험 결과 채집된 모든 지역에서 G119S(ace-1), L1014F,C(vgsc) 돌연변이가 발견되었으며, 그 빈도는 계절과 장소에 따라 차이를 나타내었다. 본 실험 결과는 향후 말라리아 감염 억제를 위한 매개체 연구에 활용될 수 있을 것으로 기대된다.

This study focused on the genomic analysis of Anopheles kleini and Anopheles pullus, both vectors of vivax malaria within the Anopheles Hyrcanus group. Using Illumina NovaSeq600 and Oxford Nanopore platforms, we identified 126 and 116 contigs, along with 40,420 and 32,749 genes from An. kleini and An. pullus, respectively. The assembled genome sizes were 282 Mb for An. kleini and 247 Mb for An. pullus, which are within a similar range to the sizes previously estimated by digital PCR (249 Mb and 226 Mb). We are currently also estimating the genome sizes of other Anopheles spp. and manually curating key genes determining vectorial capacity.

Six mosquito species in the Anopheles Hyrcanus group are known as vectors responsible for transmitting vivax malaria in South Korea. In this study, seasonal dynamics of Anopheles Hyrcanus group species and knockdown resistance (kdr) mutations in malaria-endemic sites, Paju and Gimpo, were monitored over two years. In August 2023, all six species were observed simultaneously in one of the Paju collecting sites, and kdr mutations were newly identified in all species except Anopheles kleini. Although Anopheles pullus was revealed as a relatively resistant species among five species populations without kdr mutation via bioassays, there were no critical differences in the voltage-sensitive sodium channel sequence. These findings suggest variability in pyrethroid resistance mechanisms among Anopheles Hyrcanus Group species.

Anopheles sinensis is an important vector for Plasmodium vivax and thus has been targeted with pyrethroids in Republic of Korea. Using the direct contact mortality bioassay, two field populations of An. sinensis from Ganghwa-gun and Goyang-si were characterized for their resistance to pyrethroids with RR ratio values (Resistant ratio to imidacloprid) of 125.6 to 203.8 folds and 80.0 to 120 folds, respectively. Genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the sodium channel genes to detect L1014S mutations. The homozygous susceptible Leu/Leu genotype in Ganghwa-gun and Goyang-si was 5.0% and 11.3% and the resistance genotypes were 95.0% and 88.7%, respectively. The homozygous Phe/Phe resistance genotype was the most prevalent as 35.4% in Ganghwa-gun and 44.0% in Goyang-si. Hence, this study suggests that malaria vector control programs should be prepared for the management of pyrethroid insecticide resistance.

Anopheles sinensis is an important vector for Plasmodium vivax and thus has been targeted with organophosphates in Republic of Korea. Using the direct contact mortality bioassay, two field populations of An. sinensis from Paju-si and Yeoncheon-gun were characterized for their resistance to organophosphats with RR ratio values (Resistant ratio to imidacloprid) of 446.9 to 756.3 folds and 502.1 to 861.7 folds, respectively. Genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the acethylcholine esterase to detect Gly119Ser mutations. The homozygous susceptible Ser/Ser genotype in Paju-si and Yeoncheon-gun was 20.0% and 20.9% and the resistance genotypes were 80.0% and 79.1%, respectively. The homozygous Gly/Ser resistance genotype was the most prevalent as 60.7% in Paju-si and 41.9% in Yeoncheon-gun. Hence, this study suggests that malaria vector control programs should be prepared for the management of organophosphate insecticide resistance.

Anopheles sinensis is an important vector for Plasmodium vivax and thus has been targeted with pyrethroids in Republic of Korea. Using the direct contact mortality bioassay, two field populations of An. sinensis from Paju-si and Yeoncheon-gun were characterized for their resistance to pyrethroids with RR ratio values (Resistant ratio to imidacloprid) of 96.8 to 167.2 folds and 34.2 to 98.4 folds, respectively. Genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the sodium channel genes to detect L1014S mutations. The homozygous susceptible Leu/Leu genotype in Paju-si and Yeoncheon-gun was 3.3% and 37.1% and the resistance genotypes were 96.7% and 62.9%, respectively. The homozygous Phe/Phe resistance genotype was the most prevalent as 45.0% in Paju-si and 31.5% in Yeoncheon-gun. Hence, this study suggests that malaria vector control programs should be prepared for the management of pyrethroid insecticide resistance.

한해 약 2억 명 이상의 감염 보고와 40만 명 이상을 사망하게 하는 것으로 알려진 말라리아는 Anopheles속에 속하는 약 60여종의 모기에 의해서 Plasmodium속의 원충을 인간에게 매개하여 발생하는 질병이다. 특히, 사망자의 대부분을 차지하는 아프리카 지역의 말라리아는 P. falciparum으로 이들을 매개하는 주요 모기 종은 An. gambiae, An. coluzzii, An. arabiensis, An. funestus이다. 이 네 종 중 An. gambiae, An. coluzzii, An. arabiensis는 An. gambiae complex에 속하는 종으로 이 complex에 속하는 8종의 경우 외형적 분류가 힘들기 때문에 ribosomal DNA(rDNA)에서의 염기서열 분석을 통한 분자생물학적 방법을 이용하여 이들을 분류하고 있다. 또한 최근 An. gambiae에서 두 종으로 분화된 An. gambiae와 An. coluzzii의 분자생물학적 차이를 알아보고 토론해 보고자 한다.

Control of the vector mosquitoes is critical for implementation of patient’s decrease. Vector mosquito control has been mainly carried out using pesticides in Republic of Korea (ROK), which has developed the resistance against selected insecticides. Voltage-gated sodium channel (VGSC) and Acethylcholine esterase (AchE) are the target of several classes of insecticides. Genetic mutations of VGSC and AchE have been documented to confer resistances to pyrethroids and organophosphates in mosquitoes, respectively. In our studies, the insecticidal resistable level of An. sinensis from four malaria risk areas near Demilitarized Zone (DMZ) was measured. The partial sequence of An. sinensis voltage gated sodium channel (VGSC) IIS6 domain for Kdr gene and ace1 gene for AchE was sequenced. An. sinensis from two areas demonstrated significantly higher resistance to pyrethroids and mutation rates of Kdr gene were comparatively higher. In all tested areas An. sinensis showed high insecticidal resistance to organophosphates and > 70% of mutation rates of ace1 gene ware higher. Understanding the mechanisms of insecticide resistance among vector mosquitoes populations is very important to efficient and effective vector control.

The insecticidal activities of materialsderived from Dryopteris crassirhizoma Nakai against third instar larvae of three species mosquitoes (Culex pipiens, Aedes albopictus and Anopheles sinnensis) were evaluated using a direct contact mortality bioassay. The methanol extracts of D. crassirhizoma showed 100%, 87.8% and 100% larvicidal activity at 1,000 ppm against Cx. pipiens, Ae. albopictus and An. sinensis, respectively. Hexane fraction showed 100% larvicidal activity three species mosquitoes at 500 ppm after 24 hrs. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 and H3 fractions gave 100% mortality to Cx. pipiens, Ae. albopictus and An. sinensis at 100 ppm. H1 fraction separated with methanol to give a H111 through centrifugation. Fraction of the biologically active constituents from the H3 fraction with larvicidal activity was done using methanol. H31 fraction was determined 100% mortality to Cx. Pipiens, Ae. albopictus and An. sinensis at 50 ppm, respectively. Two fractions were analyzed C14H22O (H111, MW206.0) and C11H14O4 (H31, MW210.08) by GC and GC-MS. D. crassirhizoma derived compounds described herein could be useful for managing filed populations as larvicide of Cx. pipiens, Ae. albopictus and An. sinensis.