Alphamethrin is an important type II pyrethroid, a cyano-derivative that exhibits toxic response in the mutants of Drosophila melanogaster which has been adjudged on the basis of LC50 values. The concentrations to assess LC50 value of alphamethrin were the same for double mutants (sepia ebony and sepia vestigial) and single mutants (ebony, sepia, vestigial). Double mutant (sepia vestigial) have been adjudged most resistant whereas single mutant (sepia), the most susceptible. The observed difference in LC50 among single and double mutants are due to some genetic consequences which include single chromosome with mutation on one arm, two chromosome with mutation on both the arms, distance of mutation site from centromere, nucleotide bases, pigmentation, wing pattern and rate of mutation, effect of pesticide toxicity on cell survival and metabolism.