Citation

Cheng YN, Wen P, Dong SH, Tan K, Nieh JC. J. Exp. Biol. 2016; 220(Pt 4): 645-651.

Affiliation

Division of Biological Sciences, Section of Ecology, Behavior, and Evolution, University of California, San Diego, La Jolla, California, USA.

Copyright

(Copyright © 2016, Company of Biologists Limited)

DOI

10.1242/jeb.148783

PMID

27923877

Abstract

In colonial organisms, alarm pheromones can provide a key fitness advantage by enhancing colony defense and warning of danger. Learning which species use alarm pheromone and the key compounds involved therefore enhances our understanding of how this important signal has evolved. However, our knowledge of alarm pheromones is more limited in the social wasps and hornets as compared to the social bees and ants. Vespa velutina is an economically important and widespread hornet predator that attacks humans and honey bees. This species is native to Asia and has now invaded Europe. Despite growing interest in V. velutina, it was unknown if it possessed an alarm pheromone. We show that these hornets use sting venom as an alarm pheromone. Sting venom volatiles were strongly attractive to hornet workers and triggered attacks. Two major venom fractions, consisting of monoketones and diketones, also elicited attack. We used GC-EAD and identified 13 known and three unknown aliphatic ketones and alcohols in venom that elicited conspicuous hornet antennal activity. Two of the unknown compounds may be an undecen-2-one and an undecene-2,10-dinone. Three major compounds (heptan-2-one nonan-2-one, and undecan-2-one) triggered attacks, but only nonan-2-one did so at biologically relevant levels (10 hornet equivalents). Nonan-2-one thus deserves particular attention. However, the key alarm releasers for V. velutina remain to be identified. Such identification will help to illuminate the evolution and function of alarm compounds in hornets.

© 2016. Published by The Company of Biologists Ltd.

Language: en