Insecticide resistance in adult Culex quinquefasciatus mosquitoes from Olongapo City, Philippines.
Adults of Culex quinquefasciatus Say collected in Olongapo City, Zambales Province, Philippines, were tested for levels of resistance to DDT, dieldrin and malathion, using the World Health Organization resistance test kit. High levels of resistance to 4% DDT and 4% dieldrin were detected, but the mosquitoes were susceptible to 5% malathion. DDT has not been applied in Olangapo City for malaria vector control for more than 10 years (though it is still used widely elsewhere in the Philippines), and dieldrin has never been used there. Malathion is used at a Naval Station in a bay adjacent to Olongapo.<new para>ADDITIONAL ABSTRACT:<new para>Culex quinquefasciatus (both sexes) from Olongapo City were resistant to DDT and dieldrin by WHO test methods, and 1 of 10 adults survived 1 h exposure to 5% malathion (time-expired papers), a matter of concern to the authors because malathion is used as an adulticide at the nearby US naval station of Subic Bay.newline˜J.E. Hudson