Ants remember their enemy’s scent (By Victoria Gill)
Ant colonies - one of nature’s most ancient and efficient societies - are able to form a “collective memory” of their enemies, say scientists.
When one ant fights with an intruder from another colony it retains that enemy’s odour: passing it on to the rest of the colony. This enables any of its nest-mates to identify an ant from the offending colony. The findings are reported in the journal Naturwissenschaften.
For many ant species, chemicals are key to functioning as a society. Insects identify their nest-mates by the specific “chemical signature” that coats the body of every member of that nest. The insects are also able to sniff out any intruder that might be attempting to invade.
This study, carried out by a team from the University of Melbourne in Australia, set out to discover if ants were able to retain memories of the odours they encounter.
This poor little ants luck had run out today! A tiny rain shower, which lasted no more than 2 minutes and this little one bit the dust. Wrong place, wrong time I guess, a rain drop much have landed right on him. I think this is a Common Coastal Brown Ant.
I didn’t even nothice it was an ant in there till I took the shot, he was so small, looked like dirt. The drop is about 3mm in diameter sitting on a monster aloe-vera like plant.
A wasp looks like it is doing a daring trapeze act while being dangled from a blade of grass by four red ants. The insects lifted the wasp by his wings as they carried him back to their nest. Photographer Uda Dennie captured the team work outside his home in Batam Island, Indonesia. He said: “I love taking close-up photos of insects because it reveals things you rarely see. I went outside to look for insects and found these ants working together to carry the dead wasp back to their nest.” Picture: Uda Dennie/solent (via Pictures of the day: 17 January 2012 - Telegraph)
Where: Good specimens from Germany and Wyoming, simular wings found in eastern North America and England.
What: The genus Titanomyrma (previous name Formicium) contains the largest ants (Formicidae) known; the queens can be up to ~2.5inches (6.3cm) long. For comparison army ants are about 2 inches (5 cm) in length. Not much at all is known about how these ants lived, it’s possible they swarmed like the modern army ant. Most of the fossils are winged queens found in lake deposits (the famous fossil lagerstatten localities of Green River, Wyoming and Messel, Germany). This suggests that these poor things drowned on their first flights out to establish their colonies.
The oldest ant fossils are from the late Cretaceous, and it is thought that they did not start to achieve their modern relative abundance until the Cenozoic - the same time mammals were radiating. The fossil record for ants is pretty spotty, as is the case for most terrestrial invertebrates. Hard parts are what fossilizes, and when the only thing hard on you is a fragile exoskeleton well… the odds are not good. Thus our knowledge of fossil ants is limited to these large forms and those smaller ones that were unlucky enough to become trapped in amber.
I am also really amused that they used a humming bird for scale in the photo of the Wyoming fossil pictured above. Did they just happen to have a spare one laying around?
“Oh we need a scale bar for this picture.”
“Scale bars are old news, we’re on the dead bird standard now. Take that, metric system!”
This unique animal-plant interaction was noted by Frederick William Burbidge as early as 1880. In 1904, Odoardo Beccari suggested that the ants feed on insects found on and around the plant, but may fall prey to it themselves. In 1990, B. Hölldobler and E.O. Wilson proposed that N. bicalcarata and C. schmitzi form a mutually beneficial association. At the time, however, no experimental data existed to support such a hypothesis. A series of observations and experiments carried out in Brunei by Charles Clarke in 1992 and 1998, and by Clarke and Kitching in 1993 and 1995, strongly support the mutualism theory.
The ants feed by descending into the pitcher fluid and retrieving arthropods caught by the plant. The ants seem to ignore smaller insects and only target larger prey items. Hauling food from the pitcher fluid to the peristome, a distance of no more than 5 cm, may take up to 12 hours. In this way the contents of N. bicalcarata pitchers is controlled such that organic matter does not accumulate to the point of putrefaction, which can lead to the demise of pitcher infauna (which also appear to benefit the plant) and sometimes the pitcher itself.
The ants seem to favour upper pitchers and rarely colonise lower pitchers. This is likely because terrestrial traps are periodically submerged in water during heavy rains. Flooding of the ants’ nest chamber could result in the death of the developing eggs, larvae, and pupae.
C. schmitzi nests solely in the tendrils of N. bicalcarata and rarely ventures onto other plants. The species is completely dependent on N. bicalcarata for food and domicile.N. bicalcarata, on the other hand, is able to survive and reproduce without the presence of the ants; it is a facultative mutualist. This being the case, there appear to be few mature plants over 2 metres in height not colonised by C. schmitzi.
John Thompson suggests that N. bicalcarata may be the only plant species that obtains nutrients through both insect capture and ant-hosting habits. (Wikipedia)
Resource Management in Ant Colonies May Have Lessons for Politicians and Economists
Political and economic theorists could learn lessons from studying how an ant colony allocates food resources, according to the authors of a new paper recently published in the scientific journal The American Naturalist. Many political systems use regulations and legislation to curb resource overexploitation. In the new study the scientists found that ant colonies can ‘benefit’ from an external ‘parasite’ which curbs resource overexploitation by resident queens, resulting in increased production of female offspring with queen potential. This increased number of ‘potential new queens’ implies a boost to colony efficiency and ‘fitness’ (or health). The publication builds on six years of research carried out by a team from the University of Würzburg, Germany, the UK’s Centre for Ecology & Hydrology, the University of Oxford, UK , Rothamsted Research, UK, The University of Southampton, UK and Limerick University in Ireland.
The team first studied colonies of the ant Formica lemani concluding that ant colonies infested with larva of the predatory parasitic hoverfly Microdon mutabilis produced more new queens than uninfected colonies. These results were published in Ecology Letters in 2006. The next stage was to develop a theoretical model to simulate the probable mechanisms behind the increased production of potential new queens.
For potential new queens to develop successfully they need a specific level of resource. With many other worker larvae to feed food resources can be limited. Results from the 2006 study showed that the presence of the parasitic hoverfly reduces ant larvae numbers, thereby increasing the share of food available for each surviving larva including the potential new queens. Predictions from the model created for the latest study indicate that predation on the young ant brood by the hoverfly could be responsible for an increase in the production of new queens, achieved through a re-routing of food resources.
Paper co-author Dr Karsten Schönrogge, an ecologist at the Centre for Ecology & Hydrology, said, “The allocation of food resources within an ant colony has interesting parallels in the way we manage our society and environment in a sustainable manner. It is easy to visualise the ‘Tragedy of the Commons’ scenario unfolding within uninfected ant colonies, where a shared and limited resource is depleted through unregulated access resulting in over-exploitation to the detriment of society.”
In an infected colony the presence of the hoverfly ‘parasite’ has a negative effect on total larva numbers, but it ‘benefits’ the colony as a whole with the net effect being a greater number of new potential queens than in a non-infected colony.
The model also predicts that the increase occurs only at the beginning of a Microdon infection period, and a reanalysis of the original results showed that this prediction is indeed supported by real world observations.
Dr Schönrogge added, “Ant foraging behaviour has previously been modelled by computer scientists and ecologists, resulting in the ant colony optimization algorithm (ACO), a major advance in the computing sector. Ants are one of the most successful animal groups on the planet and the next questions for ecologists and political theorists is how resource management within ant colonies might affect interactions with surrounding related or unrelated competing colonies and how that would be mirrored in human societies.”
The majority of ants are wingless. However, throughout the spring and summer seasons, swarms of winged ants become a common sight. Winged ants have elbowed antennae, thin waists constricted at the thorax and hind wings smaller than their front wings.
All ant species include three castes: queens, males and workers. Female winged ants are larger than male winged ants. Worker ants, or infertile female ants, are commonly seen crawling and foraging for food. Some species of ants have winged worker ants, while other species do not. There can be thousands of winged ants in one established colony.
All ant species live in colonies established by fertile females, or queens. Winged queen ants and males typically swarm after a day of heavy rain in a particular season. Queens begin as winged ants, and usually shed their wings after mating. Reproductive males die soon afterwards.