Assessment of the genetic base of Tasmanian bumble bees (Bombus terrestris) for development as pollination agents

The bumble bee Bombus terrestris has spread over much of the island state of Tasmania since it was first found there in 1992. Horticulturists in Tasmania are hoping to use local, commercially raised colonies for use as pollinators in glasshouses. In this experiment 100 field-captured queens were confined under conditions suitable for colony establishment to check for the prevalence of diploid male production, an indication of inbreeding. The ratio of males to workers at the beginning of colony development was used as an indicator. Results of this experiment show that the Tasmanian bumble bee population is presently very inbred. About 50% of the adult-producing colonies produced initial sex ratios consistent with male diploidy, which suggests that the entire Tasmanian population may be descended from one inseminated queen. The importation of new genetic material may be necessary to sustain commercial breeding of B. terrestris in Tasmania.