Navigation Links
When their tools get dull, leaf-cutters switch jobs
Date:12/9/2010

EUGENE, Ore. -- (Dec. 9, 2010) -- When their razor-sharp mandibles wear out, leaf-cutter ants change jobs, remaining productive while letting their more efficient sisters take over cutting, say researchers from two Oregon universities.

Their study -- appearing online ahead of regular publication in the journal Behavioral Ecology and Sociobiology -- provides a glimpse of nature's way of providing for its displaced workers.

"This study demonstrates an advantage of social living that we are familiar with -- humans that can no longer do certain tasks can still make very worthwhile contributions to society, even if they could not live on their own," said the paper's lead author Robert Schofield, a scientist at the University of Oregon. "While division of labor is well documented in social insects, this is the first suggestion that some social insects stop performing certain tasks because they are no longer as good at them as they used to be. As social organisms, these ants have the luxury of being able to leave the cutting task to their more efficient sisters."

Leaf-cutter ants slice leaves, carry pieces back to the underground nest for further processing and, like tiny mushroom farmers, grow an edible fungus on the resulting substrate. The ants doing the cutting are usually members of the generalized forager caste, one of four size-based behavioral castes of workers. The foragers are second in size to the majors, the large workers that protect the colony and do heavy clearing work on the trails constructed to connect the nest to the leaf sources. In addition to cutting, the foragers transport the cuttings, scout for new resources and also help protect the colony.

"Cutting leaves is hard work. Much of the cutting is done with a V-shaped blade between teeth on their mandibles that they use like a tailor who holds a pair of scissors in a fixed V shape to slice through cloth," Schofield said. "This blade starts out as sharp as the sharpest razor blade that humans have developed."

Over time, though, their mandibles slowly dull. It takes longer and requires more energy to get the job done. When it takes an ant about three times as much time and energy to cut out a leaf disc than it would have taken when her blades were sharp, behavior changes, the researchers reported. The cutting ants rest their blades and join the delivery staff, carrying the discs cut from the leaves into their nest.

"Imagine having only two tiny knives to use for your entire life, with no sharpening allowed," Schofield said. "You would want them to be made of the best material possible. You would use them very carefully, but cutting would still get harder and harder as they dulled until you had to rely on others to cut for you. That's what it is like to be a leaf-cutter ant."

The composition of the cutting blades is of particular interest to researchers. The findings support the idea that wear and fracture are big problems for smaller animals. The researchers estimate that, because of wear, the colony spends twice as much energy cutting leaves as it would if all ants had sharp mandibles. This cost should have resulted in an evolutionary pressure to develop materials that resist dulling, the research team noted. The cutting blades are indeed made of a zinc-rich biomaterial that the researchers suspect is wear resistant.

Schofield was lead author of a study published in 2001 that had identified a family of biomaterials present in mandibular teeth, tarsal claws, stings and other such tools of small organisms. In 2009, a team led by Schofield reported that a similar type of substance empowers the claw tips of striped shore crab and is present on the walking legs of Dungeness crabs.

"Humans are just starting to try to engineer tiny machines and tools, and we have a lot still to learn from organisms that have coped with being small for millions of years," Schofield said. "And in addition, it's good to know how important wear is to these ants, because they are agricultural pests, and this research hints that crops that produce high levels of wear might discourage them."


'/>"/>

Contact: Jim Barlow
jebarlow@uoregon.edu
541-346-3481
University of Oregon
Source:Eurekalert  

Related biology news :

1. Bird-brained? Birds personalities are correlated with their hormone levels
2. Listening for ocean spills and their ecological effects
3. Play with your kid, for their mental healths sake
4. How some plants spread their seeds: Ready, set, catapult
5. Successful mothers get help from their friends: Dolphin study
6. Study of tiny magnets may advance their use in microelectronics
7. Team of chemists produces biodiesel at their university, using used cooking oil as a basis
8. Unlike us, honeybees naturally make quick switch in their biological clocks, says Hebrew University researcher
9. Stem cells shape up to their surroundings
10. Fighting cancers by tagging their triggers
11. Fungal spores travel farther by surfing their own wind
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
When their tools get dull, leaf-cutters switch jobs
(Date:4/28/2016)... , April 28, 2016 First quarter 2016: ... up 966% compared with the first quarter of 2015 ... SEK 589.1 M (loss: 18.8) and the operating margin was 40% ... 0.32) Cash flow from operations was SEK 249.9 M ... revenue guidance is unchanged, SEK 7,000-8,500 M. The operating ...
(Date:4/15/2016)... Research and Markets has announced ... 2016-2020,"  report to their offering.  , ... global gait biometrics market is expected to grow ... 2016-2020. Gait analysis generates multiple variables ... to compute factors that are not or cannot ...
(Date:3/29/2016)... , March 29, 2016 LegacyXChange, ... LegacyXChange "LEGX" and SelectaDNA/CSI Protect are pleased to announce ... used in a variety of writing instruments, ensuring athletes ... originally created collectibles from athletes on LegacyXChange will be ... of the DNA. Bill Bollander , ...
Breaking Biology News(10 mins):
(Date:5/3/2016)... , ... May 03, 2016 , ... According to world ... for definitive prostate cancer treatment, patients traditionally had two main treatment options: surgery or ... would be made. , New technology has enabled doctors to administer higher doses ...
(Date:5/2/2016)... , May 2, 2016 ... that its technology partner Mannin Research Inc. will be ... (ARVO), which takes place from May 1-5, 2016 in ... will be meeting with its vendors and research partners. ... business development goals and other collaborative opportunities for the ...
(Date:5/2/2016)... ... 02, 2016 , ... StarNet Communications Corp, ( http://www.starnet.com/ ) a leading publisher ... Remote Desktop modules to its flagship X-Win32 PC X server. The new modules ... the user’s PC over encrypted SSH. , Traditionally, users of PC X servers deploy ...
(Date:4/29/2016)... ... April 30, 2016 , ... The MIT bioLogic design team has won multiple ... how bacterial properties can be applied to fabric and formed into living interfaces between ... response to humidity change. The team harvested Natto cells and applied them to fabric ...
Breaking Biology Technology: