Food-exchange by honeybee foragers (Apis mellifera L.): Trophallactic transfer-rate depends on the food source’s sucrose flow

WAINSELBOIM, ALEJANDRO JAVIER; FARINA, WALTER MARCELO

Viena, Austria

Congreso; XXV International Ethological Congress.; 1997

 Forager bees arriving at the hive after visiting a nectar source, unload the collected liquid food to recipient hive-mates through mouth to mouth contacts (trophallaxis). We tested the possibility that returning foragers represented information on the profitability of the exploited nectar source (i.e. sugar flow of nectar sources) through trophallactic contacts, analysing food exchange behaviour among pairs of foragers under controlled experimental conditions. Individual bees trained to feed at a regulated-flow artificial feeder offering sucrose solution, were captured once the foraging visit was complete, and placed in an acrylic arena with a recipient bee that had not been fed. Trophallactic time (i.e. time engaged in trophallaxis and exchanged volume (the mean difference between the initial and final weight of both bees) were recorded. From these two parameters and the sugar solution’s concentration, the trophallactic sucrose transfer rate was established, and plotted against the feeder’s sucrose flow. Two different experimental series were performed: (1) varying sucrose flow (50% w/w sucrose concentration and 0.74; 1.47; 2.95 mg of sucrose/min); (2) constant sucrose flow (20%; 36%; 64% w/w sucrose concentration and 4.8; 2.4; 1.2 µl/min solution flow respectively, obtaining a value of 1 mg of sucrose/min). Donor bees modulated the sucrose transfer rate during trophallaxis in virtue of the sucrose flow previously exploited at the feeder. Therefore recipient bees received valuable information concerning the food source profitability by means of trophallactic contacts. The possibility that this process of information transfer is involved in the social foraging strategy by honeybees will be discussed.