Artificial rearing of bumble bees (Bombus terrestris) selects against heavy queens

When the bumble bee, Bombus terrestris, was reared under controlled conditi ons in the laboratory for many generations, queens with a wet weight of 1 g or more were no longer produced after several generations. At present it i s unknown what causes the disappearance of these heavier queens. In this pa per three possible explanations are given: (1) inbreeding, (2) altered ener gy allocation strategy such that more but lighter queens are produced, (3) a gradual build-up of a deficiency of scarce nutrients. No proof was found for a negative effect of inbreeding on the weight of queens, and colonies d id not produce more queens. This suggests that the disappearance of heavy q ueens is caused by a deficiency of scarce nutrients.