New method to stimulate the onset of Bombus terrestris (Hymenoptera: Apidae) rearing: Using worker helpers in the presence of frozen pupae

The failure of bumblebee queens to enthusiastically start a colony under laboratory conditions may be due to lack of oviposition during an experiment, a long delay in oviposition from the termination of hibernation, and failure to rear a large first brood. In the present study, the use of frozen male pupae to start the colony with the assistance of bumblebee workers rather than fresh, young, male pupae was investigated under controlled room temperature and humidity conditions. The period of initiation of the colony decreased with an increase in the number of worker helpers from one to six. The period was as short as 3.9 days in the presence of six worker helpers. Second and third broods also started earlier with the help of workers. The rate of first worker production per egg cup was double that of the normal method (i.e. without worker helpers). Egg eating behavior of the queen was not found in the first brood if more than two workers helped the development of the larvae. Four worker helpers were found to be sufficient, as they could produce 100% colony foundation and 91.46% first worker production colonies. This study showed that using frozen old pupae is a good stimulator for colony foundation in the presence of four bumblebee worker helpers.