Rearing of Honeybee Larvae in Vitro: Effect of Yeast Extract on Queen Differentiation

Abstract

SummaryFirst instar honeybee larvae (60 per test) were reared in vitro under controlled conditions. The yield of adults was 70–80%, and 10% were queens if royal jelly was used, diluted 1:1 with water and supplemented with D-glucose and D-fructose (2·5 g in 40 g test food). Difco bacto-yeast extract (0·5 g) or charcoal-treated extract (1 g) were added to this basic food. At the same rate of survival, larval growth and queen determination were considerably increased (30% and 50% queens). The charcoal-treated yeast extract was separated by gel chromatography into a salt and an amino acid fraction. The salt component reduced the yield of adults to about 50%, but it increased larval growth rate and differentiation (20% queens). The amino acid fraction reduced the rate of survival to about 30%; growth rate and caste differentiation were below those with the basic food. Addition of both fractions gave the same result as addition of charcoal-treated yeast extract. The average gain in weight of 4th to 5th instar larvae was related to the degree of caste differentiation. For routine tests, use of a mixture of royal jelly, water, sugar and yeast extract yields more than 30% queens, at a survival rate from 1st instar worker larvae near 80%, under controlled in vitro conditions.