CONSERVING GENETIC-VARIABILITY OF A WILD INSECT POPULATION UNDER LABORATORY CONDITIONS

Drosophila melanogaster (Meigen) was used to test the power of isofema le lines in preserving genetic variability. We performed experiments i n two ways. One series consisted of measuring the genetic variability for three enzymatic loci in 32 isofemale lines, in the first and 23rd generations of culture. In the second series, we tested the capacity o f the larvae to eliminate a parasitoid by encapsulation after eight ye ars of laboratory breeding. In general, individual isofemale lines app eared to change during the 23 generations of the study, but the global frequency of these alleles among the 32 isofemale lines stayed relati vely unchanged. The only rare allele observed was also conserved. Chan ges in allozyme frequencies at any one locus were independent of those at other loci. Genetic variation of a biological trait, the capacity of the larvae to encapsulate a parasitoid, also changed, but it could be restored to a level close to that of the starting population by mas s hybridizing together individuals of each line.