RESUMEN
The effects of sublethal concentrations of a synthetic pyrethroid, beta-cyfluthrin (Bulldock 025 SC) were investigated in the F1 generations of white and sepia mutants of Drosophila melanogaster after various cross combinations of the parents which were exposed separately to the insecticide mixed diet for 24 hours. The experiment was carried out under the laboratory conditions at a temperature of 25+/-5 degrees C and 60+/-5% relative humidity. The insecticide had deleterious effect on the growth and development of both the mutant flies. Larval, pupal and total developmental periods were found to be increased as compared to controls, whereas the number of adult emerged decreased in all the treatment sets. Larval period index (LPI), pupal period index (PPI) and growth index (GI) were observed to be decreased in the entire cross combinations. Maximum effects were observed in those sets where both the sexes were treated, crossed and F1 generation was studied on the treated food having sublethal concentration of the insecticide, followed by similar treatment sets but on the fresh untreated food. Females were found to be resistant as compared to the males, whereas white mutant files were more susceptible to the test insecticide beta-cyfluthrin as compared to sepia mutant flies.