DDT--susceptibility status of Anopheles philippinensis--a mosquito vector of malaria in Bangladesh.

DDT-susceptibility tests conducted on An. philippinensis Ludlow in 1979 and 1980 and several previous years of observations made during malaria programmes in different areas of Bangladesh have been reported. The LC50 value for 1980 was found to be 0.74% DDT showing 2.96 and 1.85 fold increase of tolerance level from 1961 (0.25%) and 1976 (0.4%) respectively. The tests showed that the species continues to be susceptible to DDT in Bangladesh. However, the changes in LC50 over the years may indicate a slight acquisition of "vigour tolerance."