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. © 2008 The Association for the Study of Animal Behaviour.

Within a rewarding floral patch, eusocial bee foragers frequently switch sites, going from one flower to another. However, site switching between patches tends to occur with low frequency while a given patch is still rewarding, thus reducing pollen dispersal and gene flow between patches. In principle, forager switching and gene flow between patches could be higher when close patches offer similar rewards. We investigated site switching during food recruitment in the stingless bee Scaptotrigona mexicana. Thus, we trained three groups of foragers to three feeders in different locations, one group per location. These groups did not interact each other during the training phase. Next, interaction among trained foragers was allowed. We found that roughly half of the foragers switched sites, the other half remaining faithful to its training feeder. Switching is influenced by the presence of recruitment information. In the absence of recruitment information (bees visiting and recruiting for feeders), employed foragers were site specific. Foragers only switched among feeders that were being visited and recruited to. Switching was not caused by learned aversion to experimental handling. Switching in response to recruitment could provide a fitness benefit to the colony by facilitating rapid switching among exploited patches and provide a benefit of increasing plant gene flow between patches. © 2009 El Colegio de la Frontera Sur.

Several studies have examined the existence of recruitment communication mechanisms in stingless bees. However, the spatial accuracy of location-specific recruitment has not been examined. Moreover, the location-specific recruitment of reactivated foragers, i.e., foragers that have previously experienced the same food source at a different location and time, has not been explicitly examined. However, such foragers may also play a significant role in colony foraging, particularly in small colonies. Here we report that reactivated Scaptotrigona mexicana foragers can recruit with high precision to a specific food location. The recruitment precision of reactivated foragers was evaluated by placing control feeders to the left and the right of the training feeder (direction-precision tests) and between the nest and the training feeder and beyond it (distance-precision tests). Reactivated foragers arrived at the correct location with high precision: 98.44% arrived at the training feeder in the direction trials (five-feeder fan-shaped array, accuracy of at least +/-6 degrees of azimuth at 50 m from the nest), and 88.62% arrived at the training feeder in the distance trials (five-feeder linear array, accuracy of at least +/-5 m or +/-10% at 50 m from the nest). Thus, S. mexicana reactivated foragers can find the indicated food source at a specific distance and direction with high precision, higher than that shown by honeybees, Apis mellifera, which do not communicate food location at such close distances to the nest.