Behavioural and physiological aspects of nurse bees in relation to the composition of larval food during caste differentiation in the honeybee
E. V. M. Brouwers, R. Ebert And J. Beetsma
The behaviour of nurse bees provisioning honeybee (Apis mellifera) brood cells was studied by using video equipment 10 make long-term recorings of individual queen and worker larvae from hatching until the brood cell was sealed. The contents of water, sugars, proteins, lipids and free amino acids were determined for larval food collected from brood cells containing drone, worker or queen larvae. The feeding pattern of queen larvae hardly altered during their development: most feedings occurred during relatively short (<50 s) visits of nurse bees and the composition of the royal jelly remained nearly constant. In worker larvae short feedings were regularly observed during the first 48 h of development but in the subsequent period of 36 h almost all feedings were of long (>50 s) duration. In this period a marked decline was observed in the glucose/fructose ratio for worker jelly. After 84 h of larval age, feedings of long duration were interspersed with feedings of short duration. At this stage the total sugar content of worker jelly increased and the contents of proteins and lipids decreased simultaneously. Hypopharyngeal glands isolated from bees feeding younger worker larvae (making long visits) displayed high rates of in vitro protein synthesis. Most glands from bees feeding queen larvae (brief visits) demonstrated reduced synthetic activity. It is suggested that the duration of the larval feedings is related to the origin and consequently to the composition of the food secreted by the nurse bees.
Nurse bees, caste differentiation, larval food composition