Salt preferences of honey bee water foragers

J Exp Biol. 2016 Mar;219(Pt 6):790-6. doi: 10.1242/jeb.132019. Epub 2016 Jan 28.

Abstract

The importance of dietary salt may explain why bees are often observed collecting brackish water, a habit that may expose them to harmful xenobiotics. However, the individual salt preferences of water-collecting bees were not known. We measured the proboscis extension reflex (PER) response of Apis mellifera water foragers to 0-10% w/w solutions of Na, Mg and K, ions that provide essential nutrients. We also tested phosphate, which can deter foraging. Bees exhibited significant preferences, with the most PER responses for 1.5-3% Na and 1.5% Mg. However, K and phosphate were largely aversive and elicited PER responses only for the lowest concentrations, suggesting a way to deter bees from visiting contaminated water. We then analyzed the salt content of water sources that bees collected in urban and semi-urban environments. Bees collected water with a wide range of salt concentrations, but most collected water sources had relatively low salt concentrations, with the exception of seawater and swimming pools, which had >0.6% Na. The high levels of PER responsiveness elicited by 1.5-3% Na may explain why bees are willing to collect such salty water. Interestingly, bees exhibited high individual variation in salt preferences: individual identity accounted for 32% of variation in PER responses. Salt specialization may therefore occur in water foragers.

Keywords: Apis mellifera; PER; Salt concentration; Sodium preference; Water foraging.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Appetitive Behavior
  • Bees / physiology*
  • Feeding Behavior
  • Magnesium
  • Phosphates
  • Potassium
  • Reflex
  • Salinity
  • Seawater
  • Sodium
  • Water / chemistry*

Substances

  • Phosphates
  • Water
  • Sodium
  • Magnesium
  • Potassium