Determines the Malate Dehydrogenase (MDH-1) genotype and a mitochondrial DNA haplotype for feral honeybees. Molecular markers used to distinguish groups of honeybees; Hypotheses of selection at the MDH-1 locus and hybridization between populations with differing allele frequencies; Temperature-associated cline in MDH-1 allele frequencies over a distance of less than 300 kilometers.