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

Salt preferences of honey bee water foragers.

Author information

1
University of California San Diego, Section of Ecology, Behavior, and Evolution, Division of Biological Sciences, 9500 Gilman Drive, MC0116, La Jolla, CA 92093-0116, USA plau0168@tamu.edu.
2
University of California San Diego, Section of Ecology, Behavior, and Evolution, Division of Biological Sciences, 9500 Gilman Drive, MC0116, La Jolla, CA 92093-0116, USA.

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

PMID:
26823100
DOI:
10.1242/jeb.132019
[Indexed for MEDLINE]
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