Serotonin and feeding behaviour in a nectivorous ant

FALIBENE, A; JOSENS, R

Taller; I REUNION CONJUNTA DE NEUROCIENCIAS, Sociedad Argentina de Neurociencias-Taller Argentino de neurociencias.; 2009

Biogenic amines play an important role in the control and modulation of many actions and processes in both vertebrates and invertebrates. Particularly, serotonin (5-HT) is involved in behavioural and physiological feeding related processes. In insects, the regulation of feeding is governed by complex mechanisms which are controlled by external factors and also by their internal state. The ant Camponotus mus is able to modulate the nectar intake rate by changing the activity of its sucking pump, depending only on the colony requirements (J. Comp. Physiol. A 194:491, 2008; J. Insect Physiol. 55:518, 2009). Carbohydrate-starved ants reach higher intake-rates by increasing pumping frequency. Considering this modulation, the aim of this study was to determine the effect of serotonin on pumping activity and on feeding behaviour in C. mus. For this, two different groups of ants from the same colony were fed either with sucrose solution (control group) or with sucrose solution containing serotonin (5-HT group). Thereafter, the feeding behaviour and the electrical activity of the sucking pump were recorded. Serotonin promoted a decrease in sucrose-solution feeding 3:30 hours after the oral administration in a dose-dependent manner. Although the feeding time was the same for both groups, the volume of solution ingested by 5-HT treated ants was lower than the ingested by control ants, which implies a lower intake rate. This reduction was mainly due to a decrease in the volume of solution ingested per pump contraction and, when the administration of the drug was maintained for a few days, also to a decrease in the pumping frequency. Our results show a depressant effect of 5-HT on nectar feeding regulation in this insects.