SANCHEZ, F.*; KORINE, C.; PINSHOW, B.; DUDLEY, R.; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; University of California, Berkeley: Is ethanol used as an odor cue to find and assess fruit quality by Egyptian fruit bats?

Ethanol is present in all fleshy fruits consumed by vertebrate frugivores. It has been hypothized that fruit-eating animals use ethanol as an odor cue to find fruits and assess their palatability. We examined this hypothesis with Egyptian fruit bats (Rousettus aegyptiacus) and tested the predictions that concentrations of ethanol similar to those in ripe, palatable, fruit would attract the bats, whereas higher concentrations, as might be found in overripe, unpalatable fruit, would be deterrent. R. aegyptiacus is able to discern between feeders with and without fruit juice by odor. The odor of aqueous ethanol solutions (0.001%, 0.01%. 0.1%, and 1%, v/v) were not attractive to the bats compared to plain fruit juice or water. Solutions of ethanol in mango juice with concentrations from 0% to less than 1% were equally preferred, and those above 1% were avoided. Egyptian fruit bats are able to use ethanol vapor as a cue to choose food, avoiding those ethanol concentrations higher than 1%. Since the percentage of ethanol in ripe wild fruits varies from ~0.01% to ~1%, these results suggest that the ethanol emitted from fruits may be used by R. aegyptiacus to recognize unpalatable fruit.