Sound Production and Feeding Behavior in Japanese Bumble Bees, Bombus (Diversobombus) diversus and B. (D.) ussurensis (Hymenoptera : Apidae)

Workers and queens of Bombus (Diversobombus) ussurensis and workers and probably queens of B. (D.) diversus produce rhythmical sounds when they feed larvae. Feeding bees produced sounds throughout from opening of the larval wax covering to insertion of their mouth parts into the hole in the wax covering. Sounds were produced when the bees crossed and minutely vibrated the apical parts of the folded wings. The spectrum of the feeding sounds differed between the species in the average time of burst sounds and the presence of the interruption between successive burst sounds. By contrast, species of other 4 Japanese subgenera were not detected to produce sound during feeding. At present the biological meaning of the feeding sound is unknown, but 3 conceivable assumptions were discussed.