As climate change and the increase of international trade, the possibility of infectious disease inflow is increasing into Republic of Korea (ROK). Nine of total 16 cases overseas travel related Zika virus disease and 140 of 314 cases in dengue fever occurred during mosquito season throughout ROK in 2016, which increase importance on the studies of disease vectors for effective control and monitoring. However, the vector resources for the studies are not enough to support the studies by private research institutes and universities. Korea Center for Disease Control and Prevention (KCDC) has secured and maintained the disease vectors, comprised of 5 genus and 15 species in an insectarium system. KCDC has supported the disease vector resources through the system wherever to request them. In this presentation, the insectarium systems will be introduced.

The susceptibility values for field-collected (BG-BG) and laboratory (KS-BG) strains of German cockroaches, Blattella germanica (L.) to 5 synthetic pyrethroids and 3 organophosphates were assessed by topical application. Both KS-BG and BS-BG demonstrated the highest levels of susceptibility to deltamethrin. The KS-BG demonstrated the lowest susceptibility level to fenthion, while the BS-BG field population showed the lowest susceptibility to bifenthrin. The BS-BG field population showed resistance levels of 50 to 640 fold higher against the eight pesticides evaluated compared to the KS-BG. The resistance ratios (RR) of the eight pesticides were compared using populations of B. germanica that were collected from the same locality during 2007 and 2014. The field population of B. germanica collected during 2014 demonstrated significantly high resistance to an organophosphate and all pyrethroids when compared with those collected during 2007, but RR values were < 10 except for chlorpyrifos-methyl and chlorpyrifos with RR values of 74 and 104, respectively.

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.

We performed a survey for flavivirus infection and distribution of Aedes albopictus that known as Zika and Dengue virus vector using black–light trap and BG-sentinel trap around urban area in Korea. Mosquitoes were collected in 27 cities during March to November (twice a month) year 2016. Total numbers of mosquitoes collected 102,102 including 19 species 8 genera during collecting period. Total 21,467 Ae. albopictus was collected that 20,961(24.3%) by BG-sentinel trap and 506 (3.2%) by Black-light trap in urban area. Trap index(trap/night) of Ae. albopictus was showed highest in Hamyang (TI:992.3) and lowest in Taebaek (TI:0.3) there was only collected by Black-light trap. A total of 894 pools from all collecting Ae. albopictus were performed a Flavivirus detection. Flavivirus was not detected during study period. This study may provide basic information for surveillance of imported diseases (include Zika virus) and vectors in Korea.

Haemaphysalis longicornis is a major vector for Severe fever with thrombocytopenia syndrome (SFTS) throughout Republic of Korea (ROK). The ticks distribute at vast open fields and various kind of habitate. Control of the ticks with pesticides is almost impossible and personal protection such as use of commercial repellents is very critical for control. However occasional toxic effects of the commercial repellents have been reported that include central nervous system depression and urticaria. In our studies, repellency of three plant essential oils was assessed and was compared with two commercial repellents. Lavendual angustifolia demonstrated the highest repellency and higher repellency than DEET when was individually tested, but binary mixture of Cinnamomum zeylinicam and Juniperus verginiana showed significantly higher repellency with synergic effects than mixture of Lavendula angustifolia and Juniperus verginiana. Further study on repellency of the C. zelinicam in field need.

Previous laboratory repellent assessment with three plant essential oils against Haemaphysalis longicornis, a major vector for Severe fever with thrombocytopenia syndrome, revealed high repellency of Lavendual angustifolia and high synergic effects of Cinnamomum zeylinicam and Juniperus verginiana. Based on the previous laboratory repellent assessment field studies on repellency of the three plant oils were carried out with formulations such as cream type and spray type. 10% spray type of Cinnamomum zeylinicam demonstrated > 70% of repellency against H. longicornis. 10% spray type of Lavendual angustifolia showed > 80% of repellency. 10% spray type of binary mixture containing Cinnnamomum zeylinicam and Juniperus verginiana showed > 98% repellency against H. longicornis. Further studies on repellency of cream type of the plant oils might be carried out and compared with two commercial repellents.

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 Asian tiger mosquito, Aedes albopictus, is considered as potential vector of Zika virus in Republic of Korea (ROK). Vector control during mosquito season is one of critical factors for decline of viral transmission. Total 14 oversea travel-associated Zika cases by mosquito bite were reported throughout ROK from January to September 2016 and vector control and monitoring at surroundings of patient’s residences was carried out during three weeks after confirmation of the virus. Although population density rates of Ae. albopictus were remarkably various according to ecological surroundings, population density of Ae. albopictus near forest was higher than urban. All captured Aedes mosquitoes were used for detection of three flavivirus, Zika, Dengue and Chikunguya, using RT-PCR and any virus was not detected. Population density of Ae. albopictus decreased > 65% on average after vector control and in one area > 95% of population density decreased. Our data might reveal that vector monitoring and control at surroundings near residences of oversea travel-associated Zika patients might effectively prevent viral transmission by mosquito bite and naturalization of the virus in ROK.