EUGENE, Ore. — Jan. 28, 2016 — Deploying multiple videos in a University of Oregon lab, scientists have documented never-before-seen views of leafcutter ants at work processing leaves and growing their food supply in their nests.
In a paper published online Jan. 27 by the journal Royal Society Open Science, Robert Schofield and colleagues detail the ants' prehensile skills and shed new insights on the various behaviors associated with gathering leaves, delivering them to their nests and processing them to grow the fungus that nourishes a colony.
Leafcutter ants are agricultural pests that range from the southern United States through much of South America. Their complex societies rely on a division of labor inside and outside their often-massive underground nests. Studying the ants, Schofield said, helps find ways to reduce the damages they and their nest cause and gather nature-based insights that could prove helpful to efforts to manufacture tiny machines and tools.
In the study, Schofield's six-member team document how leafcutters hold, lick, scrape, cut and puncture the leaves they use. The study found that the ants are selective, choosing leaf pieces that are small and easy for them to transport, and that 90 percent of this processing work takes place in their nests.
The study also links to a six-minute summary video that puts the findings together and to shorter videos that focus on individual aspects of the ants' work. The videos emerged from more than 70 hours of observations in a leafcutter colony in Schofield's lab.
The summary video is at: https://www.youtube.com/watch?v=lHXxVckY-e0
"We show that the many-jointed leg tips, or tarsi, of ants can be prehensile, like many-jointed human fingers, grasping and manipulating work pieces with precision," said Schofield, a research professor in the UO Department of Physics. "The ants are remarkably handy, often using three legs as a tripod to stand on and the other three legs to handle leaf pieces as they cut, scrape, lick, puncture and chemically treat them. When the processing is complete, the ants rock the leaf fragments into the comb, much like stonemasons building a wall."
Schofield's team also analyzed the cutting, carrying and preparation of the leaves done by the ants to understand their energy expenditure. Much of this analysis involved fieldwork at leafcutter sites in Colombia and Ecuador. The researchers also calculated estimates of leaf-cutting density based on samples of transported leaf cuttings and fungal substrate from field colonies of the leafcutter species Atta cephalotes and Atta colombica.
The task-shared processes, the researchers concluded, suggest that energy conservation and the ants' division of labor are important to the overall health and survival of the ants.
Schofield's five co-authors were former UO undergraduate students Ryan W. Garrett, Katherine A. Carlson and Christopher Shepard, all of whom have since graduated; Matthew S. Goggans, a courtesy research assistant in the UO physics department; and Michael H. Nesson of Oregon State University.
Additional videos of the ants' leaf-processing work are:
Abdominal emissions: https://www.youtube.com/watch?v=Uff7ngmWEt4
Caching fragments: https://www.youtube.com/watch?v=XW3kAphvZMY
Inserting fragments: https://www.youtube.com/watch?v=j2g15h_urZQ
Inoculating fragments: https://www.youtube.com/watch?v=A39B2m25edE
Source: Robert Schofield, research assistant professor of physics, 541-346-4783, [email protected]
Note: The UO is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. There also is video access to satellite uplink and audio access to an ISDN codec for broadcast-quality radio interviews.