Suppression of ovarian development of Bombus terrestris workers by B. terrestris queens, Psithyrus vestalis and Psithyrus bohemicus females

Abstract

Ovarian development was studied in workers of Bombus terrestris under four different treatments, which produced different levels of ovarian development. Psythirus females of both specific (P. vestalis) and non-specific (P. bohemicus, which is the specific parasite of B. lucorum) species were able to inhibit worker ovarian development and to reproduce in B. terrestris colonies. The effect of P. vestalis females on ovarian development of workers was statistically not different from the effect of A terrestris queens (positive control) and significantly different from ovarian development inhibition measured in groups of workers alone (negative control). Ovarian development inhibition by P. bohemicus was not statistically different both from the positive and the negative control, indicating that this non-specific parasite is able to affect the ovarian development of workers, but not to the same extent as the queens of the same species or the females of the specific parasite.