Effect of insecticide-free rearing on the reproductive potential of organophosphorus-resistant African strains of Aedes aegypti (L.)

Abstract

Insecticide-free rearing of organophosphorus-resistant African strains of Aedes aegypti results in approximately a threefold enhancement of follicular development, a fourfold increase in fecundity, and over twice increased fertility and viability within five to six generations. Although the level of oviposition tended to stabilize within 5 to 6 generations, the level of susceptibility to malathion and parathion steadily decreased for 10 generations, indicating that an increase in the number of recombinant types was probably responsible. A molecular basis for reversal of insecticide-resistance has been postulated. It involves a release of the inhibitory effects of selection on protein biosynthesis; this results in increased fecundity and thus increased variation in the population. The increase in recombinant types due to a higher fecundity must inevitably bring about a relative increase in the number of susceptible genotypes.