Abstract

Since Senoo and Lincicome (1951) first have brought up for attention to the existence of malayan filariasis in Korea, several reports on the epidemiological investigations of the disease had already been made by many workers. However it is little known what kind of mosquitoes are involved as the major vectors in main endemic areas. In Cheju-Do, known as one of main endemic areas in Korea, Aedes togoi is most likely suspected as an important vector because of their abundant collections and vigorous biting attack to human. As a part of studies on filariasis in Korea, an essential preliminary is to determiine whether this mosquito, Aedes togoi collected in the above areas is receptive to the microfilariae of B. malayi. Therefore, the present paper is concerned chiefly with the development of B. malayi in A. togoi. It is also hoped that the studies on the larval morphology in the mosquito host and the structure of microfilariae will provide the base line data required for later investigation of the different vector hosts. The studies were summarized as follows: The measurements of the fixed points in percentage of the body length of microfilariae from the Giemsa stained thick films were made, and they showed that cephalic space was 8 percent,cephalic space length to width, 1.3:1, nerve ring, 21.2 percent, excretory pore, 30.8 percent, excretory cell, 36.5 percent, R1 cell, 66. 5 percent, anus 80.4 percent and body length 202 micrometer(l81-228 micrometer) maximun width 7.6 micrometer. A study on the development of microfilaria malayi in the mosquito, Aedes togoi was carried out at room temperature (24-30 C). Mosquitoes used in this experiment were reared from larvae collected from the tide water rock pool in the coastal areas of Cheju-Do and they were fed with a blood meal of carrier donors whose microfilaria densities were in the range from 0.5 to 0.7 per cmm of blood. All of the microfilariae ingested by mosquito exsheathed in stomach, penetrated into the body cavity and then migrated into the thoracic muscles of the mosquitoes within 10 hours, after two moults in the mosquito host, the length of the developing 3rd stage larvae reached in size of 1.3-1.7 mm x 23-32 microns with anal ratio, 2.6 to 3.6. The first appearance of 3rd stage larvae in the mosquito host in this experiment was in 8th day after infection. The larvae were observed in the various cavities of mosquito, such as head, thoracic cavity, abdomen, halters, eye and legs. During the larval development in larval development in the host, the shortening of body length was first observed and then elnongation was followed until becoming 3rd stage larvae. Aedes togoi was proved to be the most suitable host for this species of microfilaria malayi in the above endemic areas.