Recruitment in a scent trail laying stingless bee (Scaptotrigona aff. depilis): Changes with reduction but not with increase of the energy gain

Abstract

How does the sugar concentration of the food source affect the recruitment of Scaptotrigona aff. depilis? We offered sugar water of either constant, increasing, or decreasing concentrations. Simultaneously, we recorded the number of recruits and the recruiters' running speed, jostling contacts, and vibrations inside the nest. Neither the number of recruits nor the behavioral parameters depended on the actual sugar concentration but rather on the changes experienced over time. Concentration increases neither led to increased numbers of recruits nor to increased recruitment activity. Concentration decreases resulted in significantly decreased numbers of recruits. However, most parameters of intranidal activity changed significantly only when the concentration was reduced from 40% to 20% w/w and recruitment to the food source nearly ceased. These findings support the idea of a feedback mechanism reducing the colony's effort to exploit food sources of decreasing profitability. © INRA/DIB-AGIB/ EDP Sciences, 2006.