Dussutour explains that when an individual regulates its nutritional intake, all it has to do is listen to its own stomach. But it is a completely different matter for a colony where only 10% of the population supplies everyone's needs. The foragers must listen not only to their own needs but also the needs of the entire colony. So how does the colony regulate its nutritional intake and communicate its needs to the small number of foragers that keep it supplied?
Focusing on how ants regulate their sugar intake in good and bad times, Dussutour and Simpson offered individual ants concentrated and dilute sugar solutions to find out how they responded when they only had themselves to think of. 'Adult ants can survive without food' explains Dussutour, and having tested out the sugar solutions, the ants tucked into the concentrated sugar solution while ignoring the weaker solution: they would prefer to go without rather than eat a poor quality sugar solution.
But what happened when the foragers had to start thinking of their entire community? Starting out with 18 adult-only colonies, Dussutour offered them either a dilute, medium strength or concentrated sugar solution diet. Over the first few weeks, the colonies regulated their sugar intake to some extent, with the colony on the strongest sugar solution gorging until it was full, while the colony on the dilute sugar diet preferred to starve at first rather than consume the unpalatable 'nectar'.
However, things changed when larvae started coming along. All three colonies started regulating their sugar intake much more precisely, with the 'dilute sugar' colony sending out more foragers and doubling the amount of sugar they took home, even though they would have preferred to starve if left to their own devices.
|Contact: Kathryn Phillips|
The Company of Biologists