Experience-based interpretation of visual and chemical information at food sources in the stingless bee Scaptotrigona mexicana

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Eusocial bee (Apidae) foragers are able to mark food sources with olfactory attractant or repellent signals. Because these bees also have an excellent ability to learn associatively, they may be able to associate forager-deposited marks either positively or negatively with food depending on reward quality. We provide the first field experiments showing such a context-based interpretation of field information (odour marks and visual local enhancement) in stingless bees. We sequentially exposed individual foragers of the stingless bee Scaptotrigona mexicana to three situations in which one feeder was marked with either the visual presence of nestmates (sealed inside clear containers to prevent odour release) or odour marks alone. In the first situation, we offered two equally rewarding sucrose feeders (unscented 2.5 M sucrose solution). In this case, experienced foragers showed no preference on their subsequent visits to any of the feeders, even though the marked feeder was made more conspicuous with odour marks or the visual presence of nestmates. In the second situation, experienced foragers significantly preferred the marked feeder when it offered a sucrose reward. In the third situation, when the marked feeder offered no carbohydrate reward (only water) and the unmarked feeder offered sucrose, the experienced foragers avoided the marked feeder and significantly preferred the unmarked one. Thus, foragers learned to associate food quality positively or negatively with chemical or visual marks at the food source. eng