Resume: Important food components for brood rearing: water, vitamins of the B group, serine, glycine, proline, cholesterol, pyridoxine, inositol, heteroauxins, oil growth factor, antibiotics, cobalt, or giberellic acid.

The food of adult worker bees consists of pollen and nectar or honey. The most widely used substitute consists of a mixture of soybean flour, dried brewers' yeast, and dry skim milk. When commercial casein and dried egg yolk are added, the nutritive value approaches that of mixed pollens brought fresh to the hive by bees. After emerging, some worker bees begin consuming pollen during the first 1 to 2 hours of their presence in the colony. At 12 hours after emergence, 50 per cent or more of the workers have started eating pollen in small amounts (13, 26) . However, mass consumption begins when bees are 42 to 52 hours old (26) and reaches a maximum when they are five days old. When bees are 8 to 10 days old, their pollen consumption diminishes. Workers may also obtain food from the queen.  Apparently, wintering queens are fed larval food by workers, and neither feed themselves on honey nor are fed honey.  Isolated queens kept in cages and offered sugar candy and water are known to live on an average of two weeks or more; kept without water they survive only three or four days. Bees utilizes large amounts of water during the active season to dilute honey. 

Protein requirement - Under natural conditions, pollen supplies the necessary proteins for bees. As mentioned earlier, growth begins when emerging bees start eating pollen. Within five days the N content increases by 93 per cent in the head, by 76 per cent in the abdomen, and by 37 per cent in the thorax. Older bees have considerably smaller amounts of vitamins of the B group in muscular tissues than do emerging bees-a condition similar to that found in other animals. The intestines of emerging bees produced by nurses 50 days old and older are very fragile and the longevity of such bees diminishes as the age of the nurse bees increases (44). The weight and N content of queens produced under similar conditions is considerably lower than that of queens reared by young bees. Serine, glycine, and proline, though not essential for growth, exert a stimulating effect at suboptimal growth levels. There are some indications that cobalt added to sugar solution fed to colonies of bees increases the growth rate of the larvae reared. When the B vitamins and cholesterol are added to diet, four 10-day cycles of normal brood are produced. The development of the hypopharyngeal glands alone cannot serve as an indication of suitability of any food for brood rearing, since such well-developed glands may secrete a product that is deficient in a factor or factors essential for normal development of growing individuals. Of those vitamins studied pyridoxine and inositol appear to be definitely required for normal brood rearing.  There are also indications of improved brood rearing when the food of nurse bees contains heteroauxins, oil growth factor, antibiotics, cobalt, or giberellic acid. 

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