28 May 2007
Extreme Specialization In Ants Plugs Potholes
by Kate Melville
South American army ants (Eciton burchellii) adopt some unusual tactics to conduct their predatory raids more efficiently over rough terrain. Scientists from the University of Bristol report that some ants use their bodies to plug potholes in the trail, making a flatter surface so that prey can be delivered to the developing young back at the nest at maximum speed.
Professor Franks said: "I think every road user who has ever inwardly cursed as their vehicle bounced across a pothole - jarring every bone in their body - will identify with this. When it comes to rapid road repairs, the ants have their own do-it-yourself highways agency," writes researcher Nigel Franks, in the journal Animal Behaviour.
Franks and co-researcher Scott Powell conducted experiments that showed that individuals size-match to the hole they plug and cooperate to plug larger holes. "We did this by getting the ants to literally 'walk the plank'," explained Powell. "We inserted planks drilled with different sizes of hole into the army ants' trails to see how well different sizes of ant matched different sizes of pot hole. Indeed, they fit beautifully."
Overall, the specialized behavior resulted in an increase in the average speed of prey-laden traffic. The behavior of the pothole pluggers more than compensates for them not carrying prey themselves, resulting in a clear increase in the colony's daily prey intake, noted the researchers.
"When the traffic has passed, the down-trodden ants climb out of the potholes and follow their nest-mates home," concludes Powell. "Our research demonstrates that a simple but highly specialized behavior performed by a minority of ant workers can improve the performance of the majority, resulting in a clear benefit for the society as a whole."
Source: University of Bristol