Of the 2 species of human filaria found in China Filaria bancrofti is transmitted by Anopheles hyrcanus var. sinensis, Culex pipiens and Culex fatigans according to the researches of Feng,
1
Hu
2
and Manson.
3
Microfilaria malayi has only recently been found in China (Feng
4
). It is therefore interesting to find out which species of mosquito is the intermediate host of this parasite. In the summer of 1933 (July to August), experiments have been carried out in Huchow, Chekiang Province, with the local species of mosquitoes and Microfilaria malayi.
Ten species of mosquitoes were found in Huchow, but only 5 species have been used for the experimental purposes because the remaining, namely, Culex pallidothorax, C. vichnui, C. mimeticus, C. (Lutzia) vorax, and C. (Lutzia) fuscana were either uncommon or did not suck human blood. All mosquitoes, except M. (Mansonioides) uniformis, were bred from larvae or pupae in the laboratory. The results of these experiments are given in Table I.
From the table it will be seen that Anopheles hyrcanus var. sinensis is an excellent intermediate host for Microfilaria malayi. Under the room temperature of 29–32°C. (July to August) the microfilariae developed in this species of mosquito quite normally and they reached maturity from the 6th day after the infective meal. Labial infection has been found very frequently beginning from the 6th day. Out of 30 mosquitoes in which mature microfilariae were found, 14 harbored microfilariae in the labium.
Microfilariae reached maturity also in M. (Mansonioides) uniformis. But this species of mosquito is probably not as good an intermediate host as A. hyrcanus var. sinensis since only a small number of the ingested microfilariae completed development. Majority of the microfilariae stopped development from the 5th day and became granular and degenerated.
