ROLE OF JUVENILE-HORMONE BIOSYNTHESIS IN DOMINANCE STATUS AND REPRODUCTION OF THE BUMBLEBEE, BOMBUS-TERRESTRIS

In Bombus terrestris females, dominant status is correlated with high levels of juvenile hormone (JH) biosynthesis and rapid oocyte maturation. Queenright workers, which are inhibited by the dominant queen, complete the cycle of oocyte maturation while exhibiting a continuous low rate of JH production, but their egg-laying is inhibited. Measurements in foundress queens suggest that the low JH titer during oogenesis is probably not responsible for the inhibition of egg-laying. Queenless workers, kept individually, are not activated either for JH production or oocyte maturation. In groups of three queenless workers, a dominance order becomes established and high rates of JH synthesis are observed in the dominant egg-laying workers, with low rates in subordinated workers. In groups of founder queens, also, a dominance order becomes established and results in a reduced rate of JH production in subordinated females.