The Relationship of Weight and Ovarian Development in Bombus terrestris L. Workers under Different Social Conditions

Egg-laying behaviour of bumblebee workers is highly flexible and influenced by the bees’ social status and social environment. In this study, the dependence of the starting time of ovarian development in Bombus terrestris workers was determined under four different social conditions. The purpose was to test the effect of group stimulation and the presence of a queen on ovarian development. The relationship between weight and the commencement of ovarian development in workers was also investigated. We created four test groups: (1) 8 callow workers with a queen, (2) 8 callow workers without a queen, (3) 1 callow worker with a queen, and (4) 1 callow worker without a queen. Mated and hibernated (freshly awoken) B. terrestris queens made up Group 1 and 3. There was no significant difference between the starting times of ovarian development in the experimental groups composed of 8 callow workers in queenright (9.81 ± 2.44 days) and queenless (9.53 ± 2.53 days) conditions. However, ovaries of workers confined singly with a queen started to develop significantly earlier (11.77 ± 3.30 days) than workers confined singly without a queen (14.70 ± 3.56 days). The observations indicate that the presence of a queen does not inhibit the ovarian development of workers. The Point-Biserial Correlation Coefficient between the starting of ovarian development in workers and their weight was −0.013. However, there was a positive correlation between the weight and the ovarian developmental status of workers in groups containing 8 workers.