Study of honey bee (Apis mellifera) water preferences: do bees really like dirty water?

Abstract Honey bees collect water primarily for thermoregulation and larval food production. For these purposes, honey bees can collect water from a wide range of sources, raising concerns among beekeepers about the risks this may pose to colony health if these waters are polluted or contaminated. However, honey bee preferences for different water sources are poorly understood, except that bees prefer to collect mineral-rich water to achieve colony nutritional homeostasis. Therefore, we investigated honey bee water preferences and how ambient temperatures, which influence thermoregulation, affect these preferences. To this end, we tested, under semi-field conditions and multiple-choice conditions, waters sampled from different environmental sources (rainwater, swimming pool water, pond water and farm puddle water) likely to be collected by bees, and slurry waters (mixture of livestock feces and urine), a reported but controversial source of water and nutrients, diluted at different rates. Unexpectedly, our results showed that honey bees expressed a strong preference for distilled water and the least mineralized waters (i.e., rainwater and 0.1% dilution of slurry water). Visits to the waterers decreased with increasing mineralization of environmental waters or with increasing concentration of slurry waters. Finally, we found that, as expected, the number of bees foraging at the waterers increased with temperature, but the bees’ water preferences remained unchanged. Our study provides a better understanding of honey bee water collection as a function of temperature and sheds light on the influence of water quality on bee’s water preferences.