TY - JOUR
T1 - The appeasement effect of sterility signaling in dominance contests among Bombus terrestris workers
AU - Amsalem, Etya
AU - Hefetz, Abraham
N1 - Funding Information:
Acknowledgment This research was supported by a grant from The Israel Science Foundation founded by the Israel Academy of Sciences (ISF grant no. 535/08). We thank Naomi Paz for editorial assistance.
PY - 2010
Y1 - 2010
N2 - The establishment of dominance hierarchies through aggressive interactions is very common in insect societies. In many cases, it is also mediated through pheromone emissions that enable individuals to evaluate the reproductive quality and level of aggressiveness of the dominant individual, thereby reducing the number and intensity of costly fights. Here, we studied these processes in the primitively eusocial bee Bombus terrestris, using a paired bee system. Specifically, we investigated the behavioral, reproductive, and pheromonal correlates of dominance establishment. Workers were shown to establish dominance hierarchies using overt aggression within 3-4 days. Thereafter, the aggression drastically decreased, and dominance was maintained mostly by ritualized agonistic behavior. The behaviorally dominant bee lost the ester compounds that workers produce in their Dufour's gland (the so-called "sterility signal") concomitantly with the development of her ovaries. The other bee announced as subordinate by continuously producing high amounts of those esters. The hypothesis that sterility signaling serves as an appeasement signal to pacify the dominant bees is supported by the negative correlation found between the proportion of these esters and the level of aggression that the subordinate received from the dominant worker. Physical interactions, and presumably also the ensuing overt aggression between the bees, were essential for the above pheromonal change to take place and enabled the dominant workers to develop their ovaries and to lay eggs. The subordinate bee's signaling of non-reproductive status may minimize energy expenditure in costly fights and help stabilize the reproductive division of labor among workers.
AB - The establishment of dominance hierarchies through aggressive interactions is very common in insect societies. In many cases, it is also mediated through pheromone emissions that enable individuals to evaluate the reproductive quality and level of aggressiveness of the dominant individual, thereby reducing the number and intensity of costly fights. Here, we studied these processes in the primitively eusocial bee Bombus terrestris, using a paired bee system. Specifically, we investigated the behavioral, reproductive, and pheromonal correlates of dominance establishment. Workers were shown to establish dominance hierarchies using overt aggression within 3-4 days. Thereafter, the aggression drastically decreased, and dominance was maintained mostly by ritualized agonistic behavior. The behaviorally dominant bee lost the ester compounds that workers produce in their Dufour's gland (the so-called "sterility signal") concomitantly with the development of her ovaries. The other bee announced as subordinate by continuously producing high amounts of those esters. The hypothesis that sterility signaling serves as an appeasement signal to pacify the dominant bees is supported by the negative correlation found between the proportion of these esters and the level of aggression that the subordinate received from the dominant worker. Physical interactions, and presumably also the ensuing overt aggression between the bees, were essential for the above pheromonal change to take place and enabled the dominant workers to develop their ovaries and to lay eggs. The subordinate bee's signaling of non-reproductive status may minimize energy expenditure in costly fights and help stabilize the reproductive division of labor among workers.
KW - Aggression
KW - Bombus terrestris
KW - Dufour's gland
KW - Reproductive competition
KW - Sterility signal
UR - http://www.scopus.com/inward/record.url?scp=77956781944&partnerID=8YFLogxK
U2 - 10.1007/s00265-010-0982-4
DO - 10.1007/s00265-010-0982-4
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AN - SCOPUS:77956781944
SN - 0340-5443
VL - 64
SP - 1685
EP - 1694
JO - Behavioral Ecology and Sociobiology
JF - Behavioral Ecology and Sociobiology
IS - 10
ER -