Mosquitoes are primary medical insect pests due to their diseases transmission as vectors. In Korea, the insecticide-resistant populations of disease vector mosquito species, such as Anopheles sinensis, Culex pipiens and Culex tritaeniorhynchus, have constantly increased. Thus, management of insecticide resistance to major insecticides including pyrethroids and organophosphates is required for more efficient control of resistant populations. In this study, the quantitative sequencing (QS) protocols were established to detect the frequencies of three mutations (the L1014F on voltage sensitive sodium channel and the G119S and F331W on acetylcholinesterase 1) that are associated with either pyrethroids or organophosphates. Based on the QS protocol using newly designed non-polymorphic primers, resistance allele frequencies (RAFs) were estimated in field populations of An. sinensis, Cx. pipiens and Cx tritaeniorhynchus collected from an identical site in Korea. The dynamics of each resistance allele frequency over time in the same populations were also evaluated.

Nature conservation in the Republic of Korea (ROK), in addition the effects of global warming has increasingly changed Korea’s weather to a subtropical climate has resulted in increased populations of wild animals in association with their ectoparasites. Increased numbers of animal and bird hosts and warmer climate has resulted in higher populations of members of the Family Ixodidae (hard ticks), in addition to habitat and geographical distributions resulting from reforestation. There are; 6 Genera (Amblyomma, Boophilus, Dermacentor, Haemaphysalis, Ixodes, Rhipcephalus) in the Family Ixodidae, and with 35 species. Studies in the ROK over the past 10 years has resulted in the recognition of 3 Genera of Ixodidae (Haemaphysalis, Ixodes, Amblyomma) and 14 species (H. longicornis, H. flava, H. japonica, H. phasiana, H. ornithophila, H. formosensis, Ixodes nipponensis, I. persulcatus, I. turdus, I. pomerantzevi, I. granulatus, I. vespertilionis, I. simplex, Amblyomma testudinarium). A number of tick-borne pathogens, including severe fever with thrombocytopenia (SFTS) virus, tick-borne encephalitis (TBE) virus, Borrelia, Anaplasma, Ehrlichia, Rickettsia, Bartonella, Theileria and Babesia species, have been detected in ticks collected from the ROK. In addition to detecting these pathogens in zoonotic hosts, they have also been detected from pets, domestic animals, and humans. These pathogens often demonstrate vector and host-specificity, while affecting veterinary and medical health. The analysis of vector and pathogen distributions is crucial for the development of diseased mitigation strategies, requiring additional studies to determine the distributions of animal and bird hosts and vectors and associated pathogens.

Vector-borne diseases, including those transmitted by ticks, pose serious public health threats to US military populations, as well as military and civilian populations in the Republic of Korea. (1) From 2004-2010, a total of 54,495 ticks belonging to three genera and eight species [Haemaphysalis longicornis (33,242; 61.0%), H. flava (18,525; 34.0%), Ixodes nipponensis (2,420; 4.4%), H. phasiana (216, 0.4%), H. japonica (33; <0.1%), Amblyomma testudinarium (26; <0.1%), I. turdus (17; <0.1%), and I. persulcatus(16; <0.1%)] were collected by tick drag. (2) As part of the rodent-borne disease surveillance program, a total of 6,773 ticks belonging to two genera and four species were collected from small mammals at US military installations and training sites in Korea from 2004-2009. (3) In collaboration with Seoul National University, a total of 920 ticks, belonging to two genera and six species were collected from small-large mammals. (4) In addition, a total of 250 ticks belonging to two genera and five species were collected from migratory birds. (5) I. simplex and I. vespertilionis also were collected from limited numbers of bats. Additional collections from small-large mammals, migratory birds, bats, and other animals are needed to identify the geographical and host range of ticks and the associated pathogens they harbor. Furthermore, these data can be used to provide predictive emergence and distributions of ticks and their associated pathogens.

Biting midges of the genus Culicoides Latreille are important pests of humans and livestock and many species act as vectors of important medical and veterinary pathogens. Culicoides and other biting flies were collected using black light traps set near nine cowsheds, as described by Kim et al., and New Jersey light traps set at 10 US army installations and one military training site from May to October, 2010– 2011 as part of the Animal and Plant Quarantine Agency and 65th Medical Brigade (Eighth US Army, Korea) arthropod-borne disease surveillance program. Culicoides spp. were separated and identified to species using the keys and descriptions of Arnaud, Wada and Yu et al. and checklist of Cho and Chong. Kim et al. provided a brief summary of the history of research into the Culicoides fauna of the ROK noting the presence of several species of medical and veterinary importance. There are currently 28 species of Culicoides reported from the ROK and the presence of additional species has been reported by Cho & Chong, Kang & Yu and Lee, suggesting that the fauna has not yet been fully documented. Additionally, recent uses of DNA barcoding, by Bellis et al. have clarified the status of several species of Culicoides elsewhere and if applied more fully to Korean material, will likely reveal more records and perhaps new species. Surveys of adult biting midges from the ROK resulted in the discovery of three species previously not known from the ROK. So a total of 31 species of Culicoides are now known from the ROK. This study reports the presence of C. nasuensis Kitaoka, C. pallidulus Yu and C. jacobsoni Macfie from the ROK and an updated checklist of the Culicoides fauna of the ROK.

Ecological changes, both man-made and natural, have changed the landscape of the Republic of Korea following the end of Japanese occupation at the end of World War II (1939-1945). During the Japanese occupation, forested hillsides were cleared and wood products shipped to Japan, leaving the hills and mountains largely covered by grasses and other shrub vegetation. Following WWII, the country of Korea was divided into North and South Koreas, with North Korea under communist powers, while South Korea was established as a democratic government. In South Korea poverty was rampant and local populations scavenged for wood for cooking and heating during the cold winters. Just as economic conditions were increasing, South Korea was attached by North Korea, beginning a long drawn-out conflict from 1950 to the summer of 1953, whereby an armistice was signed and an often uneasy peace between the two countries continues today. Again, the Republic of Korea emerged from a War as an impoverished country with treeless country sides, hills, and mountains. In the 1960’s, president Chung-Hee Park established a tree planting policy to reestablish long-ago lavish forested mountains and hillsides that make up more than 70% of the South Korean landscape. Today, mountains and hillsides are generally not used for agriculture and are completely forested, with planted groves and volunteer trees ranging in age from 10-50 years. These forested areas have led to increased protection for large and small mammals and birds, increasing the potential for zoonotic pathogens that there ectoparasites harbor to be transmitted to man during work and leisure activities. While forested areas provided an expanded habitat for some animals, agriculture expanded and modernized, resulting in short-cut grasses on banks separating much of the rice paddies, orchards, ditches, and dry-land farming that increased competition for small mammal habitat. As a result of increased surveillance of small and large animals and their ectoparasites, the increased prevalence of known pathogens and identification of new pathogens, especially those harbored by ticks, has demonstrated the presence of tick-borne encephalitis, several species of spotted fever group Rickettsia, and a host of other zoonotic diseases in wild animals, their ectoparasites, and man. As tick-borne diseases are not reportable diseases in Korea, the extent and impact on civilian and military populations is unknown as diagnoses are often likely sought for the wrong pathogen. While agriculture modernized, military training sites largely consist of unmanaged lands with tall grasses that are conducive to large and small mammal populations, which are host to a number of zoonotic diseases, e.g., hantaviruses, scrub typhus, murine typhus, leptospirosis, tick-borne encephalitis, spotted fever group rickettsial pathogens, Lyme disease, bartonellosis, etc. that impact on military populations training in those areas. The impact of training sites habitat modification has not been assessed, but for many sites is impractical. To reduce health risks of vectorborne diseases, the US Army has established better housing (tents to barracks with screened windows and air conditioning) at some field training sites, reducing the potential for the transmission of mosquito-borne pathogens (malaria and Japanese encephalitis virus). The increased use of permethrin-treated all climate uniforms (ACUs) and repellents, also reduce the potential for transmission of mosquito-, tick-, mite-, and flea-borne pathogens. However, training conditions at some field training sites remain largely unchanged, with personnel working and sleeping in tents that abut to forested areas where animals and their ectoparasites are present. While some training and maneuver sites are well planned for weapons qualifications of wheeled and tracked vehicles, others sites are in areas of unmanaged lands which are rodent infested. Increased surveillance by the 65th Medical Brigade not only provides a baseline and relative distribution for vector-borne diseases in Korea, but also provides disease trends and risk assessments that are necessary for protecting US military personnel training in Korea.