The effects of box stocking density on the reproduction of female Bombus terrestris (Hymenoptera: Apidae: Bombini).

Bumblebees (Bombus spp.) are important pollinators that are widely used for greenhouse crop pollination and are produced annually by commercial breeding facilities. In this study, we used the commercially important bumblebee species Bombus terrestris Linnaeus (Hymenoptera: Apidae: Bombini) to evaluate the effects of artificial box stocking density on the reproductive performance of newly eclosed females under commercial rearing conditions. Newly eclosed gynes and workers were artificially held in separate wooden boxes at different stocking densities (1 to 150 individuals per box for gynes and 1 to 50 individuals per box for workers) before mating tests, ovarian development assessments, or oviposition observations. Higher box stocking density reduced mating success in both gynes and workers, whereas worker ovarian development and oviposition occurred earlier as worker box stocking density increased. At worker stocking densities of 30 individuals per box or higher, workers began to lay eggs on day 6, and oviposition was concentrated between days 6 and 9. These findings show that artificial box stocking density is an important management factor during commercial bumblebee rearing and can be adjusted according to whether the production goal is to maximize female mating success or promote earlier worker-derived male production.