Regulation of reproduction by dominant workers in bumblebee (Bombus terrestris) queenright colonies

摘要

Direct behavioural observations were made, and ovarian development and juvenile hormone (JH) biosynthesis rates were studied in B. terrestris workers under different social conditions. Workers in the last stage of colony development (the competitionphase) had the lowest ovarian development and JH biosynthesis rates. Callows introduced into colonies immediately after queen removal (dequeened colonies) demonstrated a significant increase in ovarian development before, but not during, the competitionphase. Reproduction of callows housed with dominant workers in small queenless groups was inhibited as in queenright colonies. Two distinct stages of inhibition of reproduction existed: (1) before the competition phase, when the queen slows down workerovarian development and prevents oviposition; (2) during the competition phase, when dominant workers inhibit ovarian development of other workers. Between these stages there was a temporal "window" of enhanced worker reproductive development. The queen's typical switch to haploid egg production was not associated with changes in worker ovarian development or JH biosynthesis rates. It is concluded that regulation of worker reproduction in B. terrestris is not determined by simple changes in the queen'sinhibition capacity or by the sex of offspring and that the worker's role is more important than previously believed.