A Test of Bombus terrestris Cocoon and other Common Methods for Nest Initiation in B. lapidarius and B. hortorum

Several methods for stimulating nest initiation (particularly the use of the Bombus terrestris cocoon) in queen bumblebees of the species B. lapidarius and B. hortorum were compared. For B. lapidarius, it was determined that the percentage success rate for establishing the first egg cell on a cocoon of B. terrestris is similar to that on a conspecific cocoon. Nest establishment, however, was significantly slower on the cocoon of B. terrestris. Moreover, it was determined that queens of B. lapidarius are able to initiate a nest without hibernation. Queens hibernated in the laboratory displayed a similar percentage success rate in establishing an egg cell during stimulation with the cocoon of B. terrestris as did the outdoor queens, but the lab queens established it significantly more slowly. Queens of B. hortorum did not incubate the cocoon of B. terrestris, nor did they establish an egg cell on it.