Tolerance of Aedes aegypti larvae to synthetic sewage was investigated in 8 strains of the mosquito. First instar larvae, 4 hr after hatching, were raised in a range of concentrations of sewage, mortality being scored on day 4. There was significant heterogeneity between strains. Tolerance was particularly low in 2 longstanding laboratory strains suggesting laboratory selection for clean water breeders. Tolerance also seemed partly related to the geographical origins of strains, being consistently high in 3 from Africa. The sex ratio in survivors of exposed individuals did not differ significantly. The tests are discussed in relation to reported cases of breeding by Ae. aegypti in soakage pits, drains and similar sites.
