Effects of Insecticide Resistance on Biotic Potential of the House Fly (Diptera: Muscidae)1

Abstract

Biotic potential (length of developmental period and fecundity) was measured for one susceptible (S) and four organophosphate insecticide-resistant (R) strains of Musca domestica L. and for RS heterozygotes. The R strains showed an 11 to 43% decrease in biotic potential relative to the S strain. The decrease was associated with reduced fecundity in all R strains and an increase in developmental time in two of them. In contrast, the biotic potential of RS heterozygotes, which are resistant, was seldom different from the S strain. Therefore, the R gene is dominant for expression of resistance but recessive for adverse effects on biotic potential. This may result in the occurrence of a balanced polymorphism in field situations. The implications of these findings for resistance managment are discussed.