Buzz pollination of Downingia flowers by Bombus vosnesenskii Radoszkowski (Hymenoptera: Apidae).

摘要

This paper reports the first record of buzz pollination of Downingia flowers. Field observations and sound recordings indicate that Bombus vosnesenskii workers can sonicate flowers of the vernal pool plant Downingia bella. In California, USA, B. vosnesenskii workers were observed foraging in D. bella patches on the western shore of the large vernal pool on Mesa de Colorado. Observations and sound recordings took place on 25 May and 3 June 2001 between 10.00 and 16.00 h. The buzzing and flight sounds made by foraging bumble bees were recorded. The total length of time recorded for each of three workers was 58.1, 41.4, and 27.3 seconds, respectively. A 2.5-second portion of one worker was analysed for flight and buzz frequencies. Foraging B. vosnesenskii workers were observed landing and orienting their heads towards the anthers of D. bella flowers. Shortly after, some of the bees emitted high pitched buzzing noises, followed by an outpour of yellow pollen on to their heads. On the recordings, the workers spent more time emitting flight sounds (mean duration 2.7-5.2 seconds) than pollination buzzes (mean duration 0.9-2.2 seconds). Quantitative analysis of the sound frequencies of one B. vosnesenskii worker yielded a flight frequency of 180.5+or-5.4 Hz, while the buzz pollination frequency was 369+or-5.4 Hz.