Pokorny Tamara, Lunau Klaus, Eltz Thomas
Department of Animal Ecology, Evolution and Biodiversity, University of Bochum, Bochum, Germany; Institute of Sensory Ecology, University of Düsseldorf, Düsseldorf, Germany.
Institute of Sensory Ecology, University of Düsseldorf, Düsseldorf, Germany.
PLoS One. 2014 Nov 25;9(11):e113823. doi: 10.1371/journal.pone.0113823. eCollection 2014.
Unlike most other bees, the long-tongued orchid bees ingest nectar using suction feeding. Although long tongues allow exploitation of flowers with deep spurs, the energy intake rate is optimal at 10-20% lower nectar sugar concentrations compared to that of lapping bees. This constraint might be compensated by a higher digestive throughput. Additionally, orchid bees might evaporate water from regurgitated droplets of crop contents. We found male Euglossa championi (n = 10) and Euglossa dodsoni (n = 12) to regularly regurgitate droplets of crop content to the base of their proboscis, generating a fluid film between the proximal parts of the galeae, glossa and labial palps. Rhythmic movements of the proboscis may help to increase convection. There was a significant change in sugar concentration between the initially imbibed solution and the resulting crop content (P<0.05) and the time individual bees had engaged in this liquid exposure behavior was positively correlated with the resulting crop sugar concentration. Female Euglossa townsendi and Euglossa viridissima showed the same behavior. Additionally, they manipulated their nectar-enriched pollen provisions for extensive periods of time before deposition in brood cells. The deposited pollen loads (n = 14) showed a significantly higher sugar concentration than the sugar-water available to the bees (P<0.001). Thus, both male and female euglossines show behaviors that promote evaporative water loss from nectar. We suggest that the behaviors have evolved in concert with suction feeding on dilute nectar from deep floral tubes.
与大多数其他蜜蜂不同，长舌兰花蜂通过吸食来摄取花蜜。尽管长舌头能让它们利用具有深距的花朵，但与舐吸式蜜蜂相比，在花蜜糖分浓度低10 - 20%时能量摄入率最佳。这种限制可能通过更高的消化通量来弥补。此外，兰花蜂可能会使嗉囊内容物反流的液滴中的水分蒸发。我们发现雄性的尚氏兰蜂（n = 10）和多氏兰蜂（n = 12）会定期将嗉囊内容物的液滴反流到喙基部，在盖唇叶、中唇舌和唇须的近端部分之间形成一层液膜。喙的有节奏运动可能有助于增强对流。最初摄入的溶液与最终的嗉囊内容物之间的糖分浓度有显著变化（P < 0.05），且单个蜜蜂进行这种液体暴露行为的时间与最终嗉囊中的糖分浓度呈正相关。雌性的汤氏兰蜂和绿氏兰蜂也表现出相同行为。此外，它们在将富含花蜜的花粉团放入育幼室之前，会对其进行长时间处理。所放置的花粉团（n = 14）的糖分浓度显著高于蜜蜂可获取的糖水（P < 0.001）。因此，雄性和雌性的兰蜂都表现出促进花蜜水分蒸发的行为。我们认为这些行为是与从深花管中吸食稀花蜜同步进化而来的。
