MALATE-DEHYDROGENASE PHENOTYPE, TEMPERATURE AND COLONY EFFECTS ON FLIGHT METABOLIC-RATE IN THE HONEYBEE, APIS-MELLIFERA

1. The 'fast' and 'medium' alleles of malate dehydrogenase (MDH-1) exh ibit dines on three continents in Honey-bees (Nielsen, Page & Crosland 1994), suggesting that MDH-1 phenotype may have functional consequenc es. 2. To test the effect of MDH-1 phenotype on a relatively constant genetic and environmental background in Honey-bees, we compared slow-f ast (SF) and slow-medium (SM) workers within two colonies containing m edium-fast (MF) queens singly inseminated with semen from an (S) drone , Within each colony, all genes not tightly linked to MDH-1 should be randomly distributed among SM and SF workers. 3. SF bees had higher fl ight metabolic rates (MR) than SM bees at ambient temperatures of 21 d egrees C and 38 degrees C, and higher wing-beat frequencies (WBF) at 2 1 degrees C. 4. There were also highly significant differences in MR o f foragers from adjacent, similarly sized, related colonies, suggestin g that there are other strong unexplained effects on flight MR. Flight MR and WBF decreased while thorax temperatures (T-th) increased as am bient temperature increased. 5. The data suggest that during high-inte nsity flight, Honey-bees reduce motor behaviour, either as a behaviour al mechanism to prevent overheating or owing to direct inhibition of f light muscle metabolism by high T-th. 6. Our data and a previous study (Coelho & Mitten 1988) indicate a link between MDH-1 allozymes and fl ight metabolism in Honey-bees, supporting the contention that MDH-1 ph enotype has functional metabolic consequences which may be subject to selection.