Individual study: A review of methods for rearing five species of bumblebee Bombus spp. in captivity
Velthuis H.H.W. & van Doorn A. (2006) A century of advances in bumblebee domestication and the economic and environmental aspects of its commercialization for pollination. Apidologie, 37, 421-451
Some bumblebee species Bombus spp. have declined dramatically, including the western bumblebee B. occidentalis of North America. Captive rearing could be used to augment or re-establish populations. This paper reviews methods for rearing artificial colonies of bumblebees.
This review covers published papers, reports and conference proceedings from 1912 - 2006 relating to bumblebee rearing techniques. It also draws on the personal experience of the authors, who have connections to the commercial bumblebee-rearing industry.
Rearing conditions: The climate in the rearing room should be 27-29°C and 65% relative humidity (not less than 50%).
Hibernation: mated queens should be allowed to dig themselves into soil, peat or moss, or placed in small containers with damp compost or similar, and stored at 1- 4°C. Some authors have found lower survival below 0°C. Raising the temperature and light intensity can break hibernation, but CO2 anaesthetization for 30 minutes is used commercially.
Colony initiation: Confining queens with one or more newly emerged bumblebee workers, including those of closely related bumblebee species, helps initiate colony formation. Using newly emerged honey bee workers Apis mellifera can induce colony formation in Bombus terrestris but not as effectively as using bumblebee workers, and not in some other Bombus species. Male cocoons or artificial cocoons made of Styrofoam plastic are sometimes also added to encourage colony formation.
Feeding: Colonies should be fed sugar syrup (50% sucrose by weight) and pollen collected by honey bees that is freshly frozen (not dried). The pollen lump should be replaced at least every other day. Rearing success is higher when colonies are fed pollen with high protein content, such as from Brassica or Prunus species. Two litres of sugar syrup with preservative will support a colony for 8 – 12 weeks.
Parasite control: The internal parasites Nosema bombi (protozoan) and Locustacarus buchneri (tracheal mite) can be problematic in rearing facilities. The only treatment is to destroy all infected colonies. Wax moths Vitula edmandsii and Plodia interpunctella are common pests, feeding on pollen or bumblebee brood. They can be controlled using Bacillus thuringiensis spray (causes 99.8% mortality in larvae) without harming the bumblebees.
Five bumblebee species are reared commercially using these methods – B. terrestris (Eurasia), B. impatiens (N America), B. lucorum and B. ignitis (China and East Asia) and B. occidentalis (western North America). All these species are in the group of bumblebees called ‘pollen-storers’, whose workers accept pollen placed anywhere near the brood.