Effects on Insecticidal Selection and Treatment on Reproductive Potential of Resistant, Susceptible, and Heterozygous Strains of the Southern House Mosquito1

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Abstract
The effects of the organophosphate insecticide temephos on the reproductive potential of Culex quinquefasciatus Say was investigated on a resistant (RR) strain, a susceptible (SS) strain, and a heterozygous (RS) strain synthesized from them. Strains were treated as larvae at two to four mortality levels, and daily fertility and fecundity estimates were made on a sample of the adult survivors. From these data, the intrinsic rate of increase, r, was calculated. This measure was found to be a more useful estimate of reproductive potential than fecundity or fertility alone. The RR strain that had been maintained under strong selection pressure before the study exhibited several classical effects of strong directional selection; it was less fecund, took longer to develop, and had poorer viability than a similar strain that had been maintained without selection. In addition, the reproductive potential of this strain was adversely affected at all three treatment levels investigated. The SS strain also was affected adversely by treatment, but the RS strain showed no apparent biotic effect.