Oviposition in DDT-resistant and susceptible strains of Aedes aegypti (L.): egg-laying on open-water surfaces

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Abstract
Oviposition was investigated in five strains of Aedes aegypti (L.), two being DDT-resistant (from Trinidad (STR) and Haiti) and three susceptible (two from West Africa and one (AS) from U.S.A.). Strains were compared with respect to their oviposition at sites illuminated at two levels (0·02 and 6·5 lumens per sq. ft.), each site being composed of a strip of moist white paper and an approximately equal area of open water set against a dark background.Oviposition on the water surface was consistently less at the lower level of illumination. Generally the moist white paper was preferred by all strains, but oviposition on the water surface was practised more readily by strain AS than by the others, and differences between certain strains (including AS and STR) were significant.Mass crosses and back-crosses were performed between strains AS and STR. The results were in close agreement with the hypothesis that laying on open-water surfaces is controlled by a genetic system in which there is no dominance.The frequency of oviposition on an open-water surface was not correlated with two other characteristics (oviposition time and oviposition light preference) that have been investigated in these five strains, nor with DDT resistance.