PATTERNS OF GENETIC-VARIABILITY IN COLONIZED STRAINS OF LUTZOMYIA-LONGIPALPIS (DIPTERA, PSYCHODIDAE) AND ITS CONSEQUENCES

The genetic qualities of laboratory colonies of phlebotomine sand flie s have not been compared with field specimens despite 1) probable gene tic shifts due to the colonization process and 2) the problems associa ted with the extrapolation of experimental data derived from colonized organisms to field populations. The present study compared the geneti c profiles of five laboratory colonies of geographic strains of the Ne w World sand fly Lutzomyia longipalpis, and contrasted them with field populations. The profiles were based on the variability exhibited wit h polyacrylamide gels at 14 enzyme loci. A general pattern of a loss o f infrequent alleles and decreased heterozygosity emerged as an appare nt consequence of colonization. The average number of alleles per locu s ranged from 1.2 to 1.6, and the average heterozygosity ranged from 4 % to 11%. The field collection from Lapinha Caves (near Belo Horizonte , Brazil) averaged 2.1 alleles with a heterozygosity of 16%. In contra st, the LAPINHA laboratory colony established from that site 24 years earlier showed very low values (1.2 alleles/locus and 4% heterozygosit y) and fixation for alleles not present or rare in the field collectio n from the same site. The genetic differences between the other Brazil ian colonies and the Lapinha Caves field samples were due to presence of both different alleles and highly diverged allelic frequencies. Bio logical inferences based on colonized sand flies must be tempered by r ecognizing that the colony may represent a highly skewed genetic subsa mple of the L. longipalpis field genome.