The decision for a forager to launch recruitment is governed by an internal response threshold. If foragers are given the opportunity to ingest a desired volume of their own (V), they lay a trail and recruit nestmates. If they cannot reach this volume V, they go back to nest without recruiting. Therefore, the desired volume V acts as a response threshold that determines the proportion of trail-layers among returning ants that will spread information about food volume through the ant colony (Mailleux A.-C. et al 2003. Proc. R. Soc. Lond. 270:1609-1616).

Here, we investigate whether this rule of thumb remains valid when colonies are food deprived for different durations (1, 4 or 8 days) and are offered different food volumes (a 3 or a 0.3 microliter droplet volumes).

When food volume exceeds ants’ crop capacity (a 3 microliter droplet), the desired volume V increases with starvation. Indeed, the volume V that satisfied 50% of ants equals 0.64 microliter after one day of starvation, 0.86 microliter after 4ds and 0.90 microliter after 8ds. The percentage of trail-layers does not change with starvation.

Under food availability below crop capacity (a 0.3 microliter droplet), the percentage of trail-layers decreases with starvation: 37% after 1day, 17% after 4ds, 12% after 8ds. This percentage decrease is a consequence of the starvation-dependent increase of the thresholdV.

The threshold V triggering trail-laying increases under starvation. As a consequence, highly starved foragers will bring back higher quantities of food to nest from large unlimited resources. In contrast, when the food volume is under their crop capacities, the percentage of trail-layers will be lower after a prolonged starvation. Such starvation-dependent changes in the threshold V explain how ants optimize recruitment and select liquid food sources in order to prevent collective exploitation of low profitability resources.