STUDIES IN THE MODE OF ACTION OF ROYAL JELLY IN HONEYBEE DEVELOPMENT: II. RESPIRATION OF NEWLY EMERGED LARVAE ON VARIOUS SUBSTRATES

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Abstract
Measurements were made of oxygen uptake and carbon dioxide evolution, during the first 24 hours of life, by larvae on substrates of different age and type. These substrates included royal jelly, the pharyngeal secretion fed to larvae destined to become queens, which varied in age from 0 to 96 hours; the pharyngeal secretion fed to young larvae destined to be workers, which varied in age from 0 to 60 hours and which was termed "worker jelly"; and the food supplied to older worker larvae, composed of a pharyngeal secretion modified by an admixture of honey and pollen, and termed "modified jelly". The pattern and magnitude of oxygen uptake was similar on all substrates. Net carbon dioxide evolution by larvae on royal jelly or modified jelly was highly positive; net carbon dioxide evolution by larvae on worker jelly was slightly negative. Microchemical analyses showed that royal jelly differed in composition from worker jelly and modified jelly. The composition of royal jelly remained relatively constant with age. The addition of sugars to worker jelly produced an increase in carbon dioxide output which was nullified by the further addition of an extract of the water-soluble acids of royal jelly. The differences observed in carbon dioxide evolution by young larvae on worker jelly and royal jelly are considered to be an expression of the initiation of female dimorphism. An hypothesis of nutritional balance is advanced to account for this dimorphism.