Studies on the life budget of Aedes aegypti in Wat Samphaya, Bangkok, Thailand.

For a complete understanding of the epidemiology of a vector-borne disease, a knowledge of the bionomics of the vector is needed. The development of Aedes aegypti was studied in Wat Samphaya, Bangkok, Thailand, where work on the adult biology had been carried out the previous year (1966-67). Particular attention was given to the variation in the numbers of immature stages of the mosquito in relation to the known seasonal incidence of dengue haemorrhagic fever. Of the three types of water container in the Wat, water jars were the main source of adults, flower pot plates were less important, and the contribution of ant traps was insignificant.The variation in the numbers of emerging adults depended on changes in the mortality of the immature stages rather than on variations in the numbers of eggs laid. Both early and late larval instar mortalities are important, the former becoming more significant during the period March-August. The mortality between the eggs and second-instar larvae is density-dependent. There was no clear trend of association between mortality and season except for a fall in larval mortality in April-May preceding the increase in annual incidence of haemorrhagic fever, which usually occurs in June.