ESTERASE-2 POLYMORPHISM IN APIS-MELLIFERA

Starch gel electrophoresis of abdomen extracts from adult drones revea led the occurrence of electrophoretic variants of esterase-2 in Apis m ellifera. We demonstrated an enzyme preference for 4-methylumbellifery l butyrate as a substrate and a pattern of enzyme inhibition which sug gests that it is an arylesterase. Tests demonstrated that esterase-2 h as the highest heat stability among all A. mellifera esterases. The me an frequency of the Est-2(s) allele estimated for the five populations investigated was 9.22%. Electrophoretic analysis of worker pupae demo nstrated that the heterozygous phenotype only presents an intermediate band between the fast and slow variants of this enzyme, suggesting a probable preferential association of the monomers for the formation of the dimer. Five new tests of two-point genetic linkage involving este rase-2 and other known markers permitted us tb demonstrate the occurre nce of gene linkage between the loci Est-2 and Est-1 a, with a map dis tance estimated at 26.5 units.