Longevity of Bombus terrestris workers (Hymenoptera: Apidae) in relation to pollen availability, in the absence of foragingPaul Smeets and Marie José Duchateau
Utrecht University, Faculty of Biology, Behavioural Biology, PO Box 80.086, 3508 TB Utrecht, The Netherlands
(Received 17 June 2002; revised 8 November 2002; accepted 26 November 2002)
The need for protein of Bombus terrestris workers was investigated by examining the effect of pollen availability on their longevity. Workers were kept under three conditions: provided with sugar solution only, with sugar solution and pollen ad libitum, and with sugar solution and pollen for 6 hours. Worker survival curves differed significantly among all conditions. Pollen deprivation led to a strong decline in survivorship whereas access to pollen for 6 hours only had a small and transient positive effect. This indicates that adult bumblebees have an ongoing need for protein food throughout their lives and confirms the observation that workers that eat pollen without subsequently feeding larvae do so for their own needs. There was no correlation between worker size and longevity, indicating that the reported higher mortality of foragers is not due to their bigger size. Our results show that, when environmental variables are excluded, workers die of senescence after about two months.
Key words: Bombus terrestris / longevity / pollen availability / protein / social insect
Correspondence and reprints: Marie José Duchateau
© INRA, EDP Sciences, DIB, AGIB 2003