Trophallaxis – a mechanism of information transfer

FARINA, WALTER M; GRÜTER, CHRISTOPH

Food Exploitation by Social Insects: Ecological, Behavioral, and Theoretical Approaches

CRC Press

Lugar: Boca Raton; Año: 2009; p. 183 - 197

One of the most common interactions performed by social insects are the mouth-to-mouth trophallactic contacts. Trophallaxis often involves the transfer of liquid food, the acquisition of chemical information (including taste and smell of the food transferred) and the transmission of tactile and vibratory signals. Its occurrence within an insect colony is an indication of sociability. In this sense, eusocial insect show the most frequent oral contacts within their nests compared with non-social or communal insects. Continuous trophallactic interactions amongst colony members allow the establishment of dynamic networks which allow a rapid distribution food and information along several nest mates. Honeybees are excellent models to analyse this issue through an experimental approach. The possibility to perform controlled laboratory experiments and assays at the hive level helped to understand the dynamic of food transfer during trophallaxis, the pathways of the food distribution once foragers unload the nectar collected and the propagation of information related to the flora exploited amongst nest mates. Due to nectar foraging is a partitioned task in honeybees, the coordination amongst hive members to obtain food and process it, is a challenge for the colonies since there is no hierarchical organization during nectar collecting within the worker caste. When a forager returns from a profitable nectar source has to transfer as soon as possible the collected food to receiver colony-mates. Its trophallactic behaviour is tuned with the profitability of the food source exploited. Thus, prior foraging experiences in the field affect unloading behaviour within the hive. Frequencies of contacts and the speed at which the food is transferred are some of the variables that might change with the richness of the feeding place. After receiving nectar from foragers, hive mates also adjust their behaviour according to the profitability of the food source exploited by their food-donors. Modulation in trophallaxis could be even found in second-order food donors (prior first-order receivers). Moreover, incidental cues such as floral odours could be learnt during trophallaxis and different worker subcastes (foragers, food processors and nurses) could be rapid informed about the food sources collected. This information acquisition process occurs even though hive bees have not received food directly from an active forager. Then, trophallaxis achieves other goals besides food distribution. It may help to communicate fluctuating resource opportunities, contributes to form olfactory memories of the collected resources, modulates the foraging-related tasks and promotes dynamic networks amongst different functional group of workers.