A method for identifying water foraging bees by refractometer analysis: a spotlight on daily and seasonal water collecting activities of Apis mellifera L.
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The current discussion about the relevance of guttation as a water source for honey bees (Apis mellifera L.) draws attention to the activity of water foraging bees. However, due to the wide foraging range, field observations of water foraging bees are difficult to carry out. Therefore, samples of returning bees were collected in front of the entrance early in the morning as well as during the day in summer and autumn 2010. In the laboratory, honey sacs of bees without pollen or propolis were examined. Honey sac samples with a weight of ≥0.005 g were classified as successful foragers. For the determination of water or nectar foragers, the honey sac contents of successful foragers were analyzed with a refractometer. Due to the dilution and the precision of the refractometer, an accuracy of 5 % was possible. Based on the known range of sugar concentrations in nectars, the analyzed samples were divided into nectar foragers (25–65 % sugar) and water foragers (0–15 % sugar). The study reveals that nectar and water foraging bees can be discriminated by analyzing the honey sac extracts with a refractometer. In autumn, the water demand of honey bee colonies is almost exclusively covered by water collection, whereas during summer nectar is mainly used as a substitute for water. In general, water collection is not restricted to certain times of the day.
KeywordsWater foraging Apis mellifera L. Honey sac Refractometer
For funding this research on the water collecting activities of honey bees, we thank the Federal Office of Consumer Protection and Food Safety (BVL). Furthermore, we thank the staff members of the field sites for providing us experimental sites, K. Baur for helping with the preparation of the honey sacs and the reviewers for helpful comments on the manuscript.
- Casaulta G, Krieg J, Spiess W (1985) Der Schweizerische Bienenvater—Fachbuch für Imker, Chap. XXVII, 16th edn. Verlag Sauerländer, AarauGoogle Scholar
- Girolami V, Mazzon L, Squartini A, Mori N, Marzaro M, Di Bernardo A, Greatti M, Giorio C, Tapparo A (2009) Translocation of neonicotinoid insecticides from coated seeds to seedling guttation drops: a novel way of intoxication for bees. J Econ Entomol 102(5):1808–1815. doi: 10.1603/029.102.0511 PubMedCrossRefGoogle Scholar
- Maurizio A, Grafl I (1969) Das Trachtpflanzenbuch: Nektar und Pollen—die wichtigsten Nahrungsquellen der Honigbiene. Ehrenwirth Verlag, MünchenGoogle Scholar
- Park OW (1946) Activities of honeybees. In: Grout RA (ed) The hive and the honeybee, Chap. IV. Dadant & Sons, Hamilton. http://books.google.de/books?id=K84OAAAAQAAJ&pg=PA79&lpg=PA79&dq=activities+of+honeybees+park&source=bl&ots=oCS1c1uUAB&sig=RQyC5VRigJAgq9mJzs6Fw4k7VeQ&hl=de&sa=X&ei=SDhXT6CYFsTdsgaLm4GwDA&ved=0CCAQ6AEwAA#v=onepage&q=activities%20of%20honeybees%20park&f=false. Accessed 3rd May 2012
- Seeley TD (1996) The wisdom of the hive: the social physiology of honey bee colonies. Harvard University Press, Cambridge, pp 42–43. http://books.google.de/books?hl=de&lr=&id=3GvlZxWFygoC&oi=fnd&pg=PR7&dq=the+wisdom+of+the+hive&ots=-UWKXIgyDp&sig=CYpB5FI0vg2FzEfBcU8BvphUUcY#v=snippet&q=120%20kg%20nectar&f=false. Accessed 3rd May 2012
- Wykes GR (1952) The sugar content of nectars. Biochem J 53(2):294–296Google Scholar