Colony development of two bumblebees, Bombus eximius and B. sonani, reared in captivity in a subtropical area of Taiwan (Hymenoptera, Apidae, Bombini).

摘要

Two bumblebee species, Bombus eximius and B. sonani, were reared artificially to investigate the characteristics of colony development under laboratory conditions in Taiwan. A total of 53 queens of B. eximius and 37 queens of B. sonani were collected in the field during 2007 and 2008. B. eximius has a longer period for colony initiation, immature stages in each caste, and a larger colony size (63-271 workers) than B. sonani (21-68 workers). Under the laboratory conditions, queens of B. eximius laid 4-6 eggs in each eggcup, while B. sonani laid 2-3 eggs. The queen production point (QP) of B. eximius started before the switch point (SP), and the queen production eggs were laid in Phase 3. However, queen production eggs of B. sonani were probably laid during the Phase 2 and Phase 3. It was found that B. eximius has a longer period of colony development than B. sonani, and the main difference between the two species was the number of third worker brood during Phase 3. In the field, the endemic species B. sonani is considered to adapt to the temperate climate, while B. eximius is adapted to the subtropical climate in Taiwan. The colony development and seasonal occurrence of B. eximius is expected to be from September-/October to April or later, and from April to August or later in B. sonani. The results showed no differences between the two species in the queen nesting rate, successful colonization rate, successful mating rate of laboratory-reared queens, and egg laying rate of laboratory-reared queens. We strongly suggest that B. eximius has great merit for pollination programs of commercial utilization, while B. sonani can only serve as a substitute species for pollinations in Taiwan.