Search

Adult mosquito surveillance was conducted at two sites at Gijang-gun, Busan southeastern area of the Korean peninsula, in 2004. The most frequently collected species at cow sheds were Anopheles sinensis sensu lato (s.l.) (83.4%), followed by Culex tritaeniorhynchus Giles (8.2%), Culex pipiens Coquillett (5.6%) and Aedes albopictus (Skuse) (2.4%). Adult populations of An. sinensis s.l. peaked during July (Trap Index, TI 1043.1), declining in August (TI 659.4) and September (TI 462.9) in 2004, while Cx. tritaeniorhynchus populations increased in August (TI 77.5) and September (TI 35.9). Adult Cx. tritaeniorhynchus was first collected in the second week of May (TI 4.0) and increased through August with two population peaks in the third week of July (TI 98.0) and the second week of August (TI 99.5). Armigeres subalbatus (Coquillett) was the most frequently collected mosquito at human-landing collections (30.4%) followed by An. sinensis s.l. (28.6%) and members of the Cx. pipiens complex (19.3%). Anopheles sinensis s.l. demonstrated two peaks of host-seeking activity at 22.00–23.00 hours and 02.00–03.00 hours in July, while in August the host-seeking peaks appeared at 22.00–23.00 hours and 03.00–04.00 hours. The black light trap collections of An. sinensis and Cx. tritaeniorhynchus demonstrated significant correlations to the ambient temperatures.

Adult mosquito surveillance was conducted during 2002 at 30 US military installations and training sites located in six provinces in the Republic of Korea (ROK). Adult mosquitoes were collected in New Jersey and dry ice -baited New Jersey light traps from 1 May through 15 October. Mosquito surveillance was conducted to determine threshold levels to initiate pesticide applications and identify malaria infection rates at selected Army installations and training sites. A total of 100,617 adults [82,410 (81.9%) females and 18,207 (18.1%) males] comprising 17 species and 7 genera were collected during 2002. The most common species collected were Culex tritaeniorhynchus Giles (49.5%), Anopheles sinensis Wiedemann (30.9%), Culex pipiens Coquillett(11.8%) and Aedes vexans nipponii (Theobald) (7.1%). Trap indices (TIs) varied widely for species over their range, due in part, to geographical distribution and degree of association with urban communities. Anopheles sinensis were collected at the same level while Culex tritaeniorhynchus increased by 27.2% in 2001, due in part to very high populations of Culex tritaeniorhynchus at Gunsan Air Base. The weekly population densities for some species were variable for each of the years, apparently as a result of variable annual weather conditions. None of Anopheles sp. assayed for plasmodium vivax (Pv) malaria infections by Enzyme Linked Immunosorbent Assay (ELISA) were positive.

Japanese encephalitis virus (JEV), transmitted by culicine mosquitoes, is endemic throughout much of South-East Asia, extending to the Korean Peninsula. The zoonotic cycle is from large water birds to culicine mosquitoes, with swine as an amplifying host and man as an incidental host. Culex tritaeniorhynchus, the primary JEV vector in the Republic of Korea, populations peak in late August through to early September when most cases of Japanese encephalitis (JE) are reported. Cx. tritaeniorhynchus were observed near the Demilitarized Zone in each of the years that mosquitoes were assayed for JEV. Each year that vector mosquitoes were assayed for JEV, minimum field infection rates (number of JEV positive mosquites/1000 Cx. tritaeniorhynchus assayed) ranged from 0.31 to 3.27. The epidemiology of JE has been recorded in Korea for more than half a century, from 1949 to 2005. During a major epidemic in 1949, there were 5616 cases and 2729 deaths reported, with levels persisting near epidemic levels of 1000 cases annually thereafter until 1969. Following the introduction and government mandated mass immunization in 1971, JE decreased dramatically. Since 1984, 0–6 cases of JE have been reported each year. However, continued evidence of mosquitoes positive for JEV indicates that JE continues to be a civilian and military health threat to immunocompromised persons in Korea, as well as non-immune US soldiers, civilians and their family members.

Adult mosquito surveillance was conducted during 2004 at 29 US military installations and training sites located in six provinces in the Republic of Korea. Adult mosquitoes were collected in New Jersey light traps and Magnet traps from 1 May through 15 October to determine threshold levels to initiate pesticide applications and to identify malaria infection rates at selected army installations and training sites. A total of 89 206 adults (78 454 [87.9%] females and 10 752 [12.1%] males) comprising 20 species (including five members of the Anopheles Hyrcanus Group) and belonging to seven genera were collected. The most common species collected were members of Culex tritaeniorhynchus Giles (49.4%) and Anopheles sinensis Wiedemann complex (39.1%), followed by Culex pipiens Coquillett (6.1%) and Aedes vexans nipponii (Theobald) (4.2%). Trap indices varied widely for species over their range, due in part to geographical distribution and degree of association with urban communities.

In 2005, adult and larval mosquito surveillance was conducted at selected sites in Korea to associate larval habitats with species distribution of mosquitoes of the Anopheles Hyrcanus Group (An. sinensis, An. lesteri, An. pullus, An. belenrae and An. kleini) and other mosquito species. Anopheles specimens belonging to the Anopheles Hyrcanus Group were identified to species level by molecular confirmation using the internal transcribed spacer (ITS)-2 within nuclear ribosomal (r)DNA. A total of 6644 mosquitoes from resting and light trap collections (4451; 67.0%) and larval collections (2193; 33.0%) comprising 32 species and nine genera (Culex [11], Anopheles [8], Ochlerotatus [5], Aedes [3], Armigeres [1], Coquillettidia [1], Mansonia [1], Tripteroides [1] and Lutzia [1]) were collected. Larval habitats were characterized into 14 categories. Of a total of 4534 Anopheles spp. collected (3766 resting and light trap collections and 768 larval collections), Anopheles sinensis (3194; 70.4%) was the most frequently captured, followed by An. kleini (813; 17.9%), An. pullus (299; 6.6%) and An. belenrae (129; 2.8%). Four species of Anopheles (An. lesteri, An. sineroides, An. koreicus and An. lindesayi) were infrequently collected (

Tabanid flies were surveyed using New Jersey light traps and Mosquito Magnet® traps at US Army installations and training sites in the northern part of Gyeonggi Province, Republic of Korea. A total of 344 tabanid flies, comprising 14 species and 5 genera, were collected from June to August during 2003-2004. Dominant species were Chrysops vanderwulpi (57.3%), Haematopota sinensis (29.1%), Haematopota koryoensis (4.4%) and Tabanus mandarinus (2.3%). Mosquito Magnet traps that generated CO2through the combustion of propane gas were nearly 6 times more effective in collecting tabanid flies than New Jersey light traps. Based on Mosquito Magnet trap collections, peak populations occurred from mid-June to early July.

Adult mosquito collections were conducted from 1999 through 2000 at 29 US military installations located in six provinces in the Republic of Korea (ROK). Adult mosquitoes were collected in New Jersey light traps from 15 May to 15 October each year. Adult mosquito surveillance was conducted to determine the appropriate time for pesticide applications at each of the Army installations. A total of 68,051 and 62,526 adults were collected in 1999 and 2000 respectively, comprising 53,983 (79.3%) females and 14,068 (20.7%) males in 1999, and 50,274 (80.4%) females and 12,252 (19.6%) males in 2000. A total of 19 species from 7 genera were collected. The most common species collected were Anopheles sinensis (34.2%), Culex tritaeniorhynchus (29.4%), Aedes vexans nipponii (18.2%) and Culex pipiens (16.8%). Anopheles sinensis were collected at the same level while Culex tritaeniorhynchus decreased by 6.2% in 2000. The weekly population densities for some species were variable for each of the years, apparently as a result of changing weather conditions.

A confined field experiment was conducted to investigate biological control of malaria and inland filariasis vector, Anopheles sinensis Wied. by combined use of larvivorous fishes, Aplocheilus latipes or Aphyocypris chinensis and herbivorous, Tilapia mossambicus niloticus in natural rice fields at Banwol near Suwon, Gyeonggi province from June through October, 1989. In the presence of naturally breeding Aplocheilus at the density of 0.8 fish/m2 water surface, the natural control of Anopheles larvae ranged 34.4% to 51.6% from June through August; later supplemental introduction of herbivore (Tilapia) at the release rate of 1-pair per 10 m2 resulted in 67.8% increased to 80.0% control of Anopheles sinensis in 3rd and 5th week respectively. In a combined fish release at the rate of 1.0 fish/m2 of Aphyocypris and 1-pair/10 m2 of Tilapia produced 67.3% and 82.1% mosquito larval reduction in 3rd and 5th week periods, respectively. The similar pattern of gradual but significant suppression of mosquitoes was also evident in separate rice paddy in 4-5 week period, maintaining ca. 75‘82% for the subsequent mosquito breeding season in comparison with control plot.