Oxygen consumption during hovering is associated with genetic variation of enzymes in honey-bees

Despite a general paucity of genetic variation, colonies of honey-bees, Apis mellifera L., usually contain genetic variation for the soluble form of the enzyme malate dehydrogenase (s-MDH). To determine whether this genetic variation influenced the physiology of honey-bees, we examined the maximal metabolic rate ((V) over dotO(2)max) during hovering flight of the common s-MDH genotypes. Among workers, heterozygotes and slow homozygotes had similar, low (V) over dotO(2)maxs and the fast homozygote had the highest. In drones, the pattern was reversed: the (V) over dotO(2)max of the slow haplotype exceeded that of the fast haplotype. In both males and females, the variances of (V) over dotO(2)max were heteroscedastic among s-MDH genotypes and the genotype with the highest (V) over dotO(2)max also had the highest variance. The data suggest that there may be kinetic differences among s-MDH allozymes. Drones had significantly higher thoracic temperatures than workers. The reversal of favoured genotypes in workers and drones may be related to the difference in thoracic temperature between them.