Regulation of queen-worker conflict in bumble-bee (Bombus terrestris) colonies

In annual colonies of bumble-bees overt queen-worker conflict is limited to a distinct 'competition phase' (CPh). In unmanipulated Bombus terrestris c olonies, the queen's switch to male production (the 'switch point', SP) acc ounted for only 22% of the variation in the onset of the CPh. In some colon ies, the CPh even began before the SP. The CPh was more strongly correlated with the transition in queen production (r=0.79). Replacing the queen eggs with male eggs or doubling the number of workers in young colonies resulte d in a significantly earlier onset of the CPh and a significantly earlier t ransition to queen production. Replacing queen eggs with female eggs did no t have this effect. These manipulations did not affect the timing of the qu een's switch from female to male production. These findings show that the m echanism underlying the queen-worker conflict in insect societies is more c omplex than previously appreciated. The onset of queen-worker conflict cann ot be attributed simply to a single factor such as the queen's switch to ma le production or a decrease in queen inhibition. Rather, multiple cues are important.