LARVAL GROWTH IN BUMBLE BEES (HYMENOPTERA: APIDAE)

Abstract

Larval growth in B. terricola Kirby was measured from daily photographs of the combs of colonies. The growth rate of well-fed larvae was exponential until the commencement of cocoon spinning. No difference between the instantaneous growth rates of physiologically determined workers and queens developing in the same larval clump could be detected. Queen morphogenesis consisted principally of an extended stadial duration as compared with workers. Larvae which were starved regained their former growth rates once they were again fed plentifully. As a general feature of larval growth in Bombus it is suggested that the capacity to resume growth at an invariant maximal rate is retained under widely varying trophic regimes. Thus larval growth in bumble bees is interpreted as a succession of bursts of maximum proportional increase separated by periods of temporary starvation induced both by irregularities in colony food intake and the inherent stochasticity of worker feeding behaviour.