Water collection by honey bees – How far will foragers fly to use water sources like guttation drops? A first distance trial using cereals and oilseed rape

Background: Depending on the location, various water sources may be available for bee colonies. These sources can be permanent, such as ponds, or incidental like dew or guttation droplets. The aim of the experiment was to investigate whether bees prefer guttation drops as a water source compared to dew or rain drops. Furthermore it was analysed if bees use these water sources up to a distance of 50m from their hives. Results: During the experiment 147 bees were observed scanning the surface of the plants without landing, 13 bees took up guttation fluid and 36 bees collected dew or rain drops. Few bees were observed collecting guttation fluid at 50m from their hives but most in close proximity of the hives. Furthermore, in some dead bees residues of the seed treatment were detected (imazalil: 0.0011 μg/bee – 0.329 μg/bee; LD50= 35.1 μg/bee). Conclusion: In the majority of observations, bees were spotted scanning the leaf area of the plants. Only single bees were observed that actually took up water from plant leaves. It seems these bees did not distinguish between dew, rain or guttation droplets. The majority of water collecting or bees resting on plants were observed in the close proximity of their hives. Keywords: guttation fluid, pesticides, seed treatment, honeybee, water source, distanc