Abstract
We studied the relationship between environmental conditions of open drains and the density of Culex quinquefasciatus Say immatures in Ujung Pandang, the biggest city in Sulawesi Island. Fifty sites in the 6 drains varied in environmental conditions such as the water flow, surface-water coverage, waste water input and the presence or absence of the larvivorous fish, guppy (Poecilia reticulata Peters). The immatures of Cx. quinquefasciatus were absent in all of the sites where the surface water flowed well. Among sites with stagnant surface water, the density of the immatures was high in the sites that received waste water. The mosquito immatures were absent in the sites without waste water input where the guppy was present. Although the predation pressure of the guppy might partially prevent Cx. quinquefasciatus breeding in less polluted water, its role in controlling the entire Cx. quinquefasciatus population in Ujung Pandang was considered to be small, because the guppy was absent in the most of sites with polluted water and the majority of drains in the city received waste water from houses. Improvement of the water flow and reduction of the waste water input are considered as the effective control methods of Cx. quinquefasciatus population.
