Bumblebee workers, Bombus terrestris, store pollen in comb cells to progressively feed the developing larvae. Multiple larvae are fed by multiple workers. How do the workers keep track of who has been fed and who has not?
Pereboom and colleagues* produced clusters of starved bumblebee larvae (isolated from workers for 24 h) and fed (tended by workers) larvae. They placed these clusters into a chamber with worker bumblebees who had no experience with the larvae. The workers fed the starved larvae sooner and more often than the fed larvae. In a subsequent study** chemical extracts were made from starved Bombus terrestris, larvae. Worker bees fed larvae that were sprayed with the extract more often than larvae that had not been sprayed. This suggests the signal may bee a chemical secreted by the larvae.
*J. J. M. Pereboom, H. H. W. Velthuis & M. J. Duchateau. The organisation of larval feeding in bumblebees (Hymenoptera, Apidae) and its significance to caste differentiation. Insectes Soc. 50 (2003) 127–133.
**S.P.A. den Boer and M.J.H.M. Duchateau. A larval hunger signal in the bumblebee Bombus terrestris.