The purpose of the present study was to evaluate if main domestic vector mosquitoes, Aedes albopictus as a diurnal species and Culex pipiens as a nocturnal species, have correlation between reflecting luminous intensity of colors and preference for blood feeding activity. Laboratory evaluations were performed and the mosquito preferences were compared to three different color brightness such as light, primary, and dark for five fundamental color series including red, yellow, green, blue, and purple. The test bodies selected for these experiments were BioGents Sentinel traps (BG traps) with 20g dry ice in each falcon tube, which covered outside of the traps attached with three different luminous intensities such as light, primary, and dark for each different color of paper sheets. In each experiment, a pair of BG traps was placed 0.6 m away from each other in a 1.8 m x 3.7 m x 1.8 m screened enclosure. The enclosure maintained at 26±2℃, 65±5% RH, and 100 lux illumination. Evaluations were performed for two hours between 10:00 and 16:00 for each 25 Ae. ablopictus females and 15 hours from 18:00 to 9:00 for each 25 Cx. pipiens females. Each experiment was replicated four times. As a result, reflecting luminous intensity (L-value) affected and correlated negatively to the preference of the two mosquito species but the fundamental colors, green-red (a-value) and blue-yellow (b-value) were not correlated significantly to the preference (p=0.05). Aedes ablopictus females were preferred for feeding activity more to lower L-values of the colors and correlated negatively between color preference of the mosquitoes and the L-values such as r = -0.584 (p=0.003) for red, r = -0.606 (p=0.002) for yellow, r = -0.620 (p=0.001) for green, and r = -0.463 (p=0.023) for blue except purple (r = -0.129; p=0.549). Similarly, Cx. pipiens females were correlated negatively such as r = -0.590 (p=0.002) for red, r = -0.564 (p=0.005) for yellow, r = -0.687 (p=0.000) for green, r = -0.623 (p=0.001) for blue, and r = -0.689 (p=0.000). In conclusion, the color brightness were negatively correlated to the feeding activity of the two vector mosquito species but not the wavelength of visible ray. Also, the mosquito females preferred significantly darker ones in the same color series (p<0.05) except purple for Ae. ablopictus females.

Imported 313 cases of Dengue fever and 16 cases of Zika virus disease were reported in the ROK during 2016. Aedesalbopictus has been reported as a major vector mosquito for Dengue and Zika virus. Various class of pesticides havebeen used locally different pesticide class. To investigate the pyrethroid and organophosphate pesticide resistance, genomicDNA was used for Allele-specific PCR (AS-PCR) genotyping of the acethylcholine esterase to detect Gly119Ser mutationsand kdr gene to detect Phe1534Cys mutations. Detoxification enzyme activities were assessed using Ae. albopictus fromYeosu and Jeju. Activities of four detoxification enzymes eg., glutathione S-transferase (GST), Non specific esterases (α-naphthylacetate and β-naphthyl acetate), and cytochrome C oxidase were determined for each Ae. albopictus strain. In our studies,Ae. albopictus showed only susceptible sequences for AchE and kdr. Activity of cytochrome P-450 and non specific esterasewas higher in a field population than a laboratory strain, except for GST. This study might be helpful to understandthe insecticidal susceptibility and resistant for effective vector mosquito control program.

Wolbachia is intra-cellular bacteria and frustrate host biology, such as parthenogenesis, feminization, male killing andsperm-egg incompatibility. It has been reported that > 90% of Aedes albopictus are infected with Wolbachia in the Republicof Korea (ROK). However any roles of the Wolbachia strains have not been reported in ROK. In this study, we infectedWolbachia to Vero cell line to investigate the cell migration which is related with the development of multi-cellular organisms,immune response and inflammation. Changes of wound healing and viability in vero cell after Wolbachia infection wereassessed. Cell migration was induced by Wolbachia after 24hr. Cell viability was not affected by Wolbachia after 24hr.This study will be helpful to understand the role of Wolbachia strain and support various information in Dengue andZika vector management programs.

Aedes albopictus is an important vector for yellow fever, dengue fever, chikungunya fever and Zika virus. This mosquitohas been exposed to organophosphates and pyrethroids in Republic of Korea for a long time. Using the direct contactmortality bioassay, susceptibility strain and two field populations of Ae. albopictus from Busan, and Damyang. Insecticidalproperty were indicated to RR ratio values (Resistant ratio to strain of susceptibility) of LC50 (Midian Lethal concentration)to organophosphats and pyrethroids. Genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the acethylcholineesterase to detect Gly119Ser mutations and kdr gene to detect Phe1534Cys mutations. Detoxification enzyme activitiesof Ae. albopictus from Busan and Damyang were assessed using microplate enzyme activity assays. Activities of fourdetoxification enzymes eg., glutathione S-transferase(GST), Non specific esterases (α-naphthyl acetate and β-naphthyl acetate),and cytochrome C oxidase were determined for each Ae. albopictus strain. This study might suggest that Ae. albopictuscontrol programs should be prepared for the management of organophosphate and pyrethroid insecticide resistance.

The intracellular endosymbiont bacterium Wolbachia is currently known to be the most common in arthropods. It mayleads to male-killing, cytoplasmic incompatibility, parthenogenesis and feminization of genetic males with large impacton host ecology and evolution in mosquitoes. Mosquitoes was collected in four areas with various ecological conditionsusing black light traps and Wolbachia detection from the collected mosquitoes was carried out by PCR using WSP andFtsZ genes primers. A total of 385 individual mosquitoes were screened. 213 mosquitoes (55.3%) belonging to four specieswere positive for Wolbachia infections. Aedes albopictus showed the highest infection rate (100%). Wolbachia infectionand type were firstly reported in Aedes in Korea.

The activities of three class, five acaricides (Permethrin, Deltamethrin, Fenitrothion, Chlorpyrifos, Imidacloprid) againstHaemaphysalis longicornis nymph, a major vector for Severe Fever with Thrombo cytopenia Syndrome (SFTS) and Lymedisease. The ticks distribute at vast open fields and various kind of habitats. Five acaricides were applied to ticks collectedform four areas(Gapyeong, Paju, Chuncheon, Wonju) to confirm the effect of acaricide. This areas was the area whereSFTS disease occurred and a large nember of ticks were collected. As a result, All areas is the most acaricidal effectto Deltamethrin. And two areas(Gapyeong, Paju) has the lowest acaricidal effect to Imidacloprid and two area(Chuncheon,Wonju) has the lowest acaricidal effect to Permethrin. Futher study will need to compare the acaricidal efficacy of theremaining seven province.

A climate change has been reported as the most important issue related with vector borne diseases eg. Zika and Denguemainly transmitted by Aedes mosquitoes. In 2016, 24 imported Zika virus disease cases and > 300 cases of Dengue feverwere reported in the Republic of Korea (ROK). In the ROK, the control of disease vectors has been mainly carried outusing chemicals, which resulted in high insecticide resistance. Many studies and projects in Korea Center for DiseaseControl & Preventionfor overcoming the insecticide resistance of disease vectors have been carried out and some nationaldisease vector management systems for effective vector control are established throughout the ROK. In this presentation,the national vector management systems and studies will be addressed.Key words : Disease vectors, National management, the Republic of Korea, climate change

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.

The purpose of this monitoring is to survey the geographical distribution of tick species using dry ice bait traps and flagging methods at each ten provinces (GangwonⅠ,GangwonⅡ, Gyeonggi, Chungbuk, Chungnam, Gyeongbuk, Gyeongnam, Jeonbuk, Jeonnam and Jeju area) and one Metropolitan area in the Republic of Korea for eight months from April through November, 2016. A total of 65,339 ixodid ticks (8,200 females, 1,988 males, 31,453 nymphs and 23,698 larvae) was collected, belonging to three genera (Haemaphysalis, Ixodes and Amblyomma). Haemaphysalis longicornis was the most commonly collected species, which is represented for 96.88% of all the collected ticks and followed by H. flava (2.69%), I. nipponensis (0.35%), A. testudinarium (0.05%) and H. japonica (0.03%) in the Republic of Korea for the study period. Haemaphysalis longicornis was a dominant species observed in these eleven areas.

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.

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.

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.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonosis and SFTS virus is transmitted to humans by tick bites. The aim of this study was to monitor tick population and its SFTS virus infection. During March 2014 to October 2015, ticks were monthly sampled using dry-ice bait trap and flag method from 4 collecting points in Boeun-gun. A total of 16,500 ticks, including 14,646 Haemaphysalis longicornis (88.7%), 1,825 H. flava (11.1%), and 29 Ixodes nipponensis (0.2%), were collected. Ticks were pooled (5,156 ticks in 456 pools) and tested by RT-PCR and nested PCR and the minimum infection rate of ticks was 0.27% (14 pools) consisting of 0.13% H. longicornis (6 pools), 1.19% H. flava (8 pools). This annual surveillance study will be needed for long-term monitoring of ixodid ticks in Korea.

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.

Population density of Culex tritaeniorhynchus was annually monitored to predict the possibility of a Japanese encephalitis (JE) outbreak at 10 collection sites throughout Republic of Korea (ROK) during mosquito season from 2011 to 2015. Prevalence of Cx. tritaeniorhynchus in ROK was spatially and timely very variable and was significantly highest at Busan city during August. Monthly average population density of Cx. tritaeniorhychus showed high correlation to the monthly average daily average temperature and monthly average precipitation. Two models for the estimation of occurrence of Cx. tritaeniorhynchus based on annual monthly daily average temperature and monthly precipitation are shown with linear regression equations of exp(0.413×temperature-0.949) and exp(0.01258×precipitation+3.777). JE vector surveillance and vector control is warranted as part of an effective JE management program at ROK.

The geographical distribution of ixodid ticks in were surveyed at 10 areas from April to November 2015. We investigated tick distribution using dry ice bait trap and flagging method as a part of disease vector monitoring in Korea. As a result, ticks collected 29,992 ixodid ticks with 3 genera, 7 species. Among them, Genus Haemaphysalis, Ixodes and Amblyomma accounted for 29,751 (99.2%), 223 (0.7%) and 18 (0.1%). Haemaphysalis longicornis was accounted for 88.9%, which has become the dominant species. Some species, such as H. japonica and Ixodes persulcatus were only collected Gangwon area. Metropolitan area had the highest population of ticks 6,540 (21.8%), Chungbuk area was next 5,049 (16.8%). In environmental distribution, Genus Haemaphysalis was highly collected in grassland site (32.1%) and Genus Ixodes was highly collected in coniferous forest site (43.5%). Upon analysis of the monthly distribution, H. longicornis, the dominant species, was highly collected at nymph stage in May, and its larva was highly collected in September. These studies may provide important information for control and management of tick in Korea.

As the malaria surveillance agency, the Korean Center for Control and Prevention (KCDC) has been monitoring malaria vector mosquito density and Plasmodium vivax infection since 2009. Anopheline mosquitoes were collected at 35 sites in Incheon, northern Gyeonggi and northern Gangwon Province using black light trap daily from April to October 2015. P. vivax infection of malaria vector mosquitoes tested by polymerase chain reaction (PCR). In 2015, a total of 57,926 malaria vector mosquitoes were collected among 138,119 mosquitoes. Three P. vivax positive pools were detected among 1,556 pools (13,745 individuals) and its minimum infection rate was 0.22. According to the monitoring result of malaria vector mosquitoes, early summer (June-July) could be an appropriate time for a malaria elimination campaign until September.