3. Results
3.1. Insecticide bioassays
Results of the adult insecticide bioassays conducted with the
discriminating dosages of DDT, malathion, permethrin and propoxur
for Ae. aegypti and Ae. albopictus populations from different districts
are presented in Table 1. Populations of both species were
resistant to DDT in all the districts. However the lowest DDT resistance
(40% resistance) was from Ae. aegypti from Jaffna district and
the highest resistance was from Kandy and Gampaha districts
(about 87–91% survivals). All the populations were more or less
susceptible to malathion except for Jaffna Ae. aegypti population
(48% survivals). A possible resistance to propoxur was shown only
by Kandy Ae. aegypti population while all the others were susceptible
to propoxur. Resistance to permethrin (40–75%) was shown
by all the populations except Jaffna Ae. aegypti, which showed only
8% permethrin resistance (Table 1).