A list of mosquitoes collected from Lao People's Democratic Republic (Lao PDR) from May 2002 to August 2004 is presented. A total of 8,945 mosquitoes belonging to 14 genera and 57 species was collected. The genera recorded were Aedes, Anopheles, Armigeres, Coquillettidia, Culex, Diceromyia, Downsiomyia, Fredwardsius, Mansonia, Neomelaniconion, Ochlerotatus, Paraedes, Stegomyia, and Verrallina. Seventeen species are first reports for LAO PDR.
Resistance to insecticides in Culex pipiens fatigans has already been reported from two areas in Malaya. In Penang two years' use of BHC as a larvicide resulted in the development of a strain which was found to have acquired a tenfold resistance to BHC, and also to dieldrin to which it had not been exposed. In Singapore, when larval control became unsatisfactory after 6 months' use of a dieldrin emulsion, laboratory experiments confirmed that active resistance to dieldrin had developed. The present observations report the finding of two further dieldrin-BHC resistant strains of C. p. fatigans in Malaya, but differ from the previous reports in that resistance, in one strain at least, was developed as a result of house-spraying with dieldrin against adult mosquitos. In this strain resistance to dieldrin was about 100 times in both adults and larvae, resistance to gamma-BHC in larvae was about 20 times, while resistance to DDT was slight.