EFFECTS OF RICE CULTURE PRACTICES ON THE ABUNDANCE OF CULEX MOSQUITOS(DIPTERA, CULICIDAE) IN NORTHERN THAILAND

In 1991-1993, the density (numbers per 10 dips) and abundance (density x flooded area) of mosquitoes were studied in 3 areas of northern Tha iland with different environmental conditions. Culex tritaeniorhynchus Giles, Cx. vishnui Theobald, and Cx. gelidus Theobald were predominan t among the 8 Culex species collected. Abundance of these 3 species va ried significantly among the 3 areas. Type of habitat classified accor ding to agricultural practices in rainy and dry season significantly i nfluenced larval abundance of Cx. tritaeniorhynchus and Cs. vishnui. S easonal variation in lan al abundance was significant only in Cx. vish nui. The response of the 3 vector mosquitoes to environmental heteroge neity is discussed.