For the determination/confirmation of the vector species of Japanese encephalitis in Korea and for the study of their bionomics, a preliminary assessment of different collecting methods of sampling mosquito population was undertaken. Man-biting catches, cow-biting catches, pig-baited window-trap hut, light trap, dry ice trap and man-baited double net were employed. The advnntages and disadvantages of these methods are discussed. A pig-baited window-trap hut and cow-biting catches outdoors are considered the best ways of collecting large numbers of Culex tritaeniorhynchus summorosus, the most important vector of Japanese encephalitis, for virus isolation and insecticide susceptility testing. The latter method requires, however, more man-power. Light traps set in a pigsty or cowshed are the simplest and most convenient tools for studying tne mosquito population density and seasonal prevalence.
parasitology-arthropoda ; Japanese encephalitis ; vector ; mosquito ; Culex tritaeniorhynchus summorosus

In order to determine the seasonal prevalence and population density of vector mosquitoes in Kyungpook province, a survey based on average number of female mosquito per trap-night, were carried out during the period from May to November in 1984. Among the 34,571 mosquitoes collected in Kyungsan county in animal shelters and human dwellings by light traps, approximately 45.0 % were Culex tritaeniorhynchus, 34. 0 % per cent Culex pipiens pallens, and 19.0 per cent Anopheles sinensis. By comparison, distribution of mosquito species in Ankang town, in which Japanese encephalitis had been reported in the past, were quite different and A. sinensis was the most abundant species, being constituted in 75.8 per cent, followed by C. tritaeniorhynchus(23. 2 percent), and C. pipiens pallens(0. 6 per cent). In the general patten of seasonal prevalence, C. tritaeniorhynchus first appeared in mid-June, and trapped in large numbers during the periods from mid-August to early September, showing a simple sharply pointed one-peaked curve, while C. pipiens pallens was found to be active through almost the entire season showing irregular curves with several peaks. The trend of seasonal distribution of A. sinensis was similar to that of C. tritaeniorhynchus, but the earliest dates of appearance and disappearance different form that of C. tritaeniorhynchus. The results of hourly catches of mosquitoes by human baited traps have clearly shown the differences in the biting rhythm among the vector mosquitoes of this province, such as the facts that C. tritaeniorhynchus and A. sinensis are rather constantly active all through a night with more or less inconspicuous peaks twice a night, while C. pipiens pallens exhibits an irregular curve, and the numbers of A. vexans nipponii, C. vagans and Armigeres subalbatus are very small and are not sufficient for estimating the biting rhythm. Four genera and fourteen species of larval mosquitoes collected from eighteen kinds of habitats which classified according to the categories followed by Bates(1949). The main breeding sites contributing to peak C. tritaeniorhynchus adult densities in this surveyed areas were evidently ricefields, ground pools, puddles and swamps and marshes, etc. Summarizing the results, this study indicated that the highest population density of C. tritaeniorhynchus was encountered in late August and early September, showing simple sharply pointed one-peaked curve.
parasitology-arthropoda ; mosquito-epidemiology ; Culex tritaeniorhynchus ; Culex pipiens pallens ; Anopheles sinensis

During the summer season(July-August) in 1967, the insecticide tests for resistance on adult A. sinensis and C. tritaeniorhynchus were carried out in Gobu-Myun Jeongup-Gun, Chollapuk-Do, where many Japanese encephalitis cases occur every year. The mortality by 4.0% DDT in A. sinensis was 88.9% and by 4.0% dieldrin was 84.4%. Therefore the LC-50 of DDT for A. sinensis was 1.75%, while LC-50 of dieldrin was 1.1%. The mortality by 4.0% DDT in C. tritaeniorhynchus was 36.7%, and by 4.0% dieldrin was 6.0% The result indicates that A. sinensis in Korea is susceptible to DDT and resistant to dieldrin. C. tritaeniorhynchus is highly resistant to both DDT and dieldrin.
parasitology-arthropoda ; vector ; mosquito ; Culex tritaeniorhynchus ; Anopheles sinensis ; chemotherapy ; DDT ; dieldrin