Genetic variability among populations of Lutzomyia (Psathyromyia) shannoni(Dyar 1929) (Diptera : Psychodidae : Phlebotominae) in Colombia

Polyacrylamide gel electrophoresis was used to elucidate genetic variation at 13 isozyme loci among forest populations of Lutzomyia shannoni from thre e widely separated locations in Colombia: Palambi (Narino Department), Cimi tarra (Santander Department) and Chinacota (Norte de Santander Department). These samples were compared with a laboratory colony originating from le M agdalena Valley in Central Colombia. The mean heterozygosity ranged from 16 to 22%, with 2.1 to 2.6 alleles detected per locus. Nei's genetic distance s among populations were low, ranging from 0.011 to 0.049. The estimated nu mber of migrants (Nm=3.8) based on Wright's F-Statistic, F-ST, indicated lo w levels of gene flow among Lu. shannoni forest populations. This low level of migration indicates that the spread of stomatitis virus occurs via infe cted host, not by infected insect. In the colony sample of 79 individuals, the Gpi locus was homozygotic ((0.62)/(0.62)) in all females and heterozygo tic ((0.62)/(0.72)) in all males. Although this phenomenon is probably a co nsequence of colonization, it indicates that Gpi is linked to a sex determi ning locus.