TEMPORAL VARIATION OF ALLOZYME FREQUENCIES IN AEDES ALBIFASCIATUS (DIPTERA, CULICIDAE) FROM ARGENTINA

Aedes albifasciatus is a floodwater mosquito widely distributed in Arg entina. It is important from economic and medical points of view. A 4- year survey of seasonal variation in allele frequencies in a populatio n of this species was undertaken to determine possible changes in the genetic structure and their correlation with environmental conditions. Significant temporal variation was detected at most of the loci, but it did not follow a cyclic or seasonal pattern. Multivariate analysis of principal components showed a remarkable homogeneity of samples col lected from December 1993 to April 1995 and a clear differentiation of the November 1991, March 1992, and November 1993 samples. This variat ion could be correlated with the magnitude of rainfall occurring in th e area. Passive transport of larvae by water streams and river freshet s produced by floods would have mined larvae from breeding sites with different allele frequencies, causing the genetic differentiation obse rved.