Notes on the laboratory rearing of the Japanese endangered bumblebee, Bombus cryptarum florilegus (Hymenoptera: Apidae)

Bombus cryptarum florilegus is a rare bumblebee in Japan. We tried to rear this bumblebee under laboratory conditions to investigate its nesting habits and colony development. Five queens out of 15 were successful in establishing colonies, and new queens and males were produced from these colonies. In the laboratory colonies, the average numbers of workers, males, and new queens per colony of B. cryptarum florilegus were 15.2 +/- 4.7, 26.0 +/- 8.0, and 2.0 +/- 2.1, respectively. Although a feral colony producing five hundred cocoons has been reported, B. cryptarum florilegus established small colonies under laboratory conditions. Further study suggests that the improvement of rearing technique is required to produce the large colony of B. cryptarum florilegus.