Virgin queen execution in the stingless beeMelipona beecheii: The sign stimulus for worker attacks

Abstract

-Stingless bees produce considerable numbers of virgin queens over the year, most of which are superfluous and get executed by the workers. Nothing is known yet about the sign stimulus that releases the worker attacks. In the present study we investigated the queen execution process in Melipona beecheii and found in both behavioral observations and experiments with caged living virgin queens that workers are not attracted to them from a distance by means of volatile chemicals. Furthermore, worker aggression, which is obvious towards virgin queens that run through the nest excitedly with their abdomen enlarged and the wings beating, was lowered to almost zero when we made the queens "behavior-less" by experimentally killing them. Our results clearly show that the sign stimulus for releasing the execution behavior in Melipona beecheii workers is not a chemical stimulus but the virgin queens' conspicuous behavior, which, we hypothesize, could act as a direct measure of their fitness. stingless bee / Melipona beecheii / virgin queen execution / queen behavior / worker attacks

A scientific note on virgin queen acceptance in stingless bees: evidence for the importance of queen aggression

“…On the 21st day after we established an orphan condition in our observation boxes, we observed a virgin queen (marked with color the first time we saw her) that was not aggressively attacked by the workers, as is typical during queen elimination in M. beecheii (Jarau et al, 2009). Instead, she actively contacted the workers and bumped into them, often bringing herself into close lateral contact with a worker and quickly shaking her abdomen in a wagging movement, thereby pushing the workers away.…”

“…Only little is known about the mechanism that releases the execution behavior in workers or about how a particular virgin queen is chosen as a new queen. Recently, we found that in Melipona beecheii a virgin queen's conspicuous behavior, which consists of rapidly running over the brood area, thereby making spinning movements and beating her wings, triggers the worker attacks (Jarau et al, 2009). A chemical signal or cue potentially released by such queens seems not to account for her execution.…”

“…Virgin queens were never attacked as long as they sat motionless on the comb and the number of aggressive worker attacks significantly decreased from 15 to zero within 10 min when we made an active virgin queen "behaviorless" through freezing (for details see Jarau et al, 2009). During our study, in which we observed the virgin queens' behavior and interactions with workers in small observation boxes that contained a comb of approximately 200 cells and initially 25-30 adult bees (the number of which increased as further bees emerged from the cells), we registered one Corresponding author: S. Jarau, stefan.jarau@uni-ulm.de * Manuscript editor: Stan Schneider interesting case of queen acceptance, on which we report in the following.On the 21st day after we established an orphan condition in our observation boxes, we observed a virgin queen (marked with color the first time we saw her) that was not aggressively attacked by the workers, as is typical during queen elimination in M. beecheii (Jarau et al, 2009). Instead, she actively contacted the workers and bumped into them, often bringing herself into close lateral contact with a worker and quickly shaking her abdomen in a wagging movement, thereby pushing the workers away.…”

“…A chemical signal or cue potentially released by such queens seems not to account for her execution. Virgin queens were never attacked as long as they sat motionless on the comb and the number of aggressive worker attacks significantly decreased from 15 to zero within 10 min when we made an active virgin queen "behaviorless" through freezing (for details see Jarau et al, 2009). During our study, in which we observed the virgin queens' behavior and interactions with workers in small observation boxes that contained a comb of approximately 200 cells and initially 25-30 adult bees (the number of which increased as further bees emerged from the cells), we registered one Corresponding author: S. Jarau, stefan.jarau@uni-ulm.de * Manuscript editor: Stan Schneider interesting case of queen acceptance, on which we report in the following.…”

Techniques for the In Vitro Production of Queens in Stingless Bees (Apidae, Meliponini)

“…There may be other intrinsic factors related to the dominant behavior (Imperatriz-Fonseca & Zucchi 1995;Jarau et al 2009;Jarau et al 2010) such as patterns of cuticular hydrocarbons present in these bees (Nunes et al 2008) which interfere with the recognition of the individuals and are related to the process of acceptance of a new queen into the nest (Nunes et al 2009) or even group decision making regarding the choice of a new queen (Tarpy & Gilley 2004).…”