The Comparative Viability of some Insecticide Susceptible and Resistance Strain of Lucilia cuprina (Wied) and Musca domestica (Linn.) (Dipteria Cyclorrhapha)

Abstract

The comparative viability of eight strains of flies, comprising susceptible and insecticide resistant lines of Lucilia cuprina (Wied.) and Musca domestica (Linn.) was investigated, in terms of their longevity, reproductive potential, and their capacity for increased resistance. Based on survival records, mean longevity for the resistant flies was greater than that of the susceptible flies, although the measure of increased survival did not reflect the degree of resistance. Egg out-put by the resistant flies was significantly less than that of the susceptible strain; but hatch and pupation rates were about the same. Also the emergence rates of the adult flies from pupae were identical for both the resistant and the susceptible strains. Using diagnostic doses of gamma BHC and diazinon, increased tolerance of insecticides was noted in both adults and larvae of all the resistant strains with persisting selection pressure. The increase in resistance was much more in the larvae than in the adult flies; and more so in the organo-phosphorus resistant strains than in the organochlorine resistant strains. Reasons for the differences in longevity and oviposition rates of the susceptible and resistant flies are discussed, and the possible implications for fly control of the higher rates of resistance increase in the larvae are indicated.