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Proc Biol Sci

Title:		Reproductive competition in the bumble-bee Bombus terrestris: do workers advertise sterility?
Author(s):		Amsalem E; Twele R; Francke W; Hefetz A;
Address:		"Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel. amsaleme@post.tau.ac.il"
Journal Title:		Proc Biol Sci
Year:		2009
Volume:		20090106
Issue:		1660
Page Number:		1295 - 1304
DOI:		10.1098/rspb.2008.1688
ISSN/ISBN:		0962-8452 (Print) 1471-2954 (Electronic) 0962-8452 (Linking)
Abstract:		"Reproductive competition in social insects is generally mediated through specific fertility pheromones. By analysing Dufour's gland secretion in queens and workers of Bombus terrestris under varying social conditions, we demonstrate here that the volatile constituents of the secretion exhibit a context-dependent composition. The secretion of egg-laying queens is composed of a series of aliphatic hydrocarbons (alkanes and alkenes), while that of sterile workers contains in addition octyl esters, dominated by octyl hexadecanoate and octyl oleate. These esters disappear in workers with developed ovaries, whether queenright (QR) or queenless (QL), rendering their secretion queen-like. This constitutes an unusual case in which the sterile caste, rather than the fertile one, possesses extra components. Individually isolated (socially deprived) workers developed ovaries successfully, but failed to oviposit, and still possessed the octyl esters. Thus, whereas social interactions are not needed in order to develop ovaries, they appear essential for oviposition and compositional changes in Dufour's gland secretion (ester disappearance). The apparent link between high ester levels and an inability to lay eggs lends credence to the hypothesis that these esters signal functional sterility. We hypothesize that by producing a sterility-specific secretion, workers signal that 'I am out of the competition', and therefore are not attacked, either by the queen or by the reproductive workers. This enables proper colony function and brood care, in particular sexual brood, even under the chaotic conditions of the competition phase"
Keywords:		"Animals Bees/*physiology Behavior, Animal/*physiology Female Ovary/physiology Pheromones/physiology Reproduction/physiology Social Behavior;"
Notes:		"MedlineAmsalem, Etya Twele, Robert Francke, Wittko Hefetz, Abraham eng Research Support, Non-U.S. Gov't England 2009/01/09 Proc Biol Sci. 2009 Apr 7; 276(1660):1295-304. doi: 10.1098/rspb.2008.1688. Epub 2009 Jan 6"