In the course of entomologic studies conducted on Koh Samui during 1966 both Aedes aegypti and Aedes albopictus were implicated in the transmission of dengue viruses on that island. Both species were widely distributed and abundant during the 1966 epidemic of dengue hemorrhagic fever on the island. Eight isolations of dengue type 2 virus were obtained from wild female A. aegypti, and four strains of the same virus were isolated from A. albopictus collected during the epidemic. Both mosquito species appeared to coexist on Koh Samui in distinct but overlapping ecologic habitats, but the distribution of A. aegypti was more restricted than that of A. albopictus, which exhibited greater versatility in the utilization of oviposition sites on Koh Samui. Varying levels of resistance to DDT were detected in four strains of A. aegypti and one strain of A. albopictus from this area.
Alternate address: SEATO Medical Project, U. S. Component, APO San Francisco 96346.