Ant Behavior

Looking for ants? Sometimes it is only a matter of finding the right plant.

Most people know ants come to the extrafloral nectaries on peony buds and we've talked about sandmat before, but are there any other plants that regularly attract ants?

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The umbel flowers of wild parsnip (Pastinaca sativa) might be a good place to look for different kinds of ants.

wild parsnip leaf

Wild parsnip grows in wet areas, such as along creeks or streams.  It can also be found growing on roadsides. At four to five feet tall, the flowers are right at eye level for many people. Be careful when visiting the plant, however, because contact with the sap can cause burns to the skin when exposed to sunlight.

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Ants, flies, wasps and other insects can be readily found visiting the large nectaries of open flowers.

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Although these particular ants were fairly small, large ants such as Formica and Camponotus were also seen on wild parsnip flowers.

What are the ants doing on the plants besides collecting nectar? Wild parsnips are considered to be invasive weeds in many areas. Therefore, ants feeding on nectar might considered to be favorable if they interfere with the plants' success or might be unfavorable if the ants protect the plants from herbivores. Jing Yang and Dana Dudle from the Biology Department at DePauw University studied the effects of ants on the reproductive success of wild parsnip by excluding flying versus crawling insects from certain flowers. In their limited investigation they found no differences in plant fitness whether ants were present or not, but suggested further studies needed to be done.

Regardless, if you are interested in watching ants you should keep your eye out for wild parsnip flowers.

Ave you ever seen ants on wild parsnip?

When you are searching for ants, what plants do you look for?

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Last time we discussed how certain species of ants can swim. Even if they can't swim, some species are able to withstand temporary floods by grouping together to form living rafts to float on the water.

Although there has been a rash of papers about the ability of fire ants to form rafts, Jessica Purcell, assistant professor of entomology at The University of California, Riverside, has been studying the ability to float by Alpine silver ants, Forica selysi.

 

Formica_selysi-worker(Photograph by Estella Ortega / © AntWeb.orgCC-BY-SA-3.0)

After marking some of the worker ants, the researchers subjected the ants to flooding. They discovered that when the same ants were subjected to flooding a second time, many of them assumed the same positions in the rafts. Rather than coming together randomly, as might be expected during a flooding crisis, the ants were apparently assembling in a somewhat organized fashion.

This video shows the experimental protocol. Note: You probably will want to turn down your computer's sound or hit mute before you click on the play button.

Based solely on this video, I'm going to suggest that painted ants tend to be towards the outside of the raft. Is it possible that damaged ants (painted ants) can assess their health and position themselves at the rim?  Of course, that may have happened at random, too. What do you think?

References:

All ants on deck, EurekAlert, AAAS

Purcell J, Avril A, Jaffuel G, Bates S, Chapuisat M (2014) Ant Brood Function as Life Preservers during Floods. PLoS ONE 9(2): e89211. doi:10.1371/journal.pone.0089211

If you have a pool, you know that most insects don't have a chance if they fall into the water. Here at Wild About Ants, however, we know ants often do the seemingly impossible. To prove it, let's look at the ability of certain species of ants to swim.

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In a recent article in Myrmecological News, Gora et. al. reported on their investigation into swimming by the carpenter ant, Camponotus pennsylvanicus. They found carpenter ants use vision to find escape platforms from the water. One hundred percent of the control ants placed in the water of the test apparatus were able to swim to the edge and get out of the water successfully. Ants with their vision occluded, on the other hand, failed to exit the water.

Although this study focused on ants swimming as a method to escape from water if they fall in accidentally, some Camponotus ants in pitcher plants are able to actively swim to capture mosquito pupae for food. In this video you can see how they move all six of their relatively short legs to push through the liquid.

As you might expect, ants that live in areas that are regularly flooded by tides, such as ants living in mangrove swamps, are particularly good at swimming.

This video from Life in the Undergrowth shows mangrove ants running across shallow water and then at about 1:02 minutes actively swimming in the water. Notice how the swimming ant holds its hind legs out behind it like a rudder.

Yanoviak and Frederick tested 35 species of tropical forest ants to see how many had the ability to move through water in a directed way. Of those, ten species were able to show rapid directed movements and ten more exhibited slower, but directed movements. The remaining species apparently needed tiny life jackets.

The bottom line is that although different species of ants vary in their ability to swim, some are quite adept at it.

Previous Posts at Wild About Ants:

References:

Gora, E.M., Gripshover, N. & Yanoviak, S.P. (2016) Orientation at the water surface by the carpenter ant Camponotus pennsylvanicus (De Geer, 1773) (Hymenoptera: Formicidae)  Myrmecol. News 23: 33-39. (Let me know if the link doesn't work and I'll find it for you.)

S. P. Yanoviak, D. N. Frederick (2014) Water surface locomotion in tropical canopy ants. Journal of Experimental Biology 217: 2163-2170; doi: 10.1242/jeb.101600

It has been too long since I've posted here, so let's jump in with two discussions about battles and weaponry in the insect world. Today we'll look at battles among acacia ants. Tomorrow let's take a look at animal weapons in general.

Acacia ants, Crematogaster mimosae, live on and fiercely defend Africa's whistling thorn acacia trees, Acacia drepanolobium.

Crematogaster_mimosae_casent0904507_p_1_highCrematogaster mimosae photograph by Will Ericson / © AntWeb.orgCC-BY-SA-3.0

Scientists have found they can induce battles between ant colonies on separate trees by bringing the branches of the trees into contact. The worker ants begin to fiercely defend their home tree when overlap occurs. The ants both bite and release a venom. When in defensive mode, Crematogaster ants hold their metasomas over their backs in a characteristic way, which has given them the common name "acrobat ants." Unlike some ants that have more ritualistic confrontations, Acacia ants actually battle causing significant losses in the number of workers. Before one colony is completely wiped out, however, the battle ceases and one colony is the apparent winner.

Recently Kathleen P. Rudolph and Jay P. McEntee studied Crematogaster mimosae colony battles in Kenya. They examined the genetic makeup of workers of the colony before and after the battles and discovered the winning colony became more genetically diverse afterwards. In other words, worker ants from the losing colony were joining forces with those of the winning colony. In fact, when two colonies fought to a draw, they actually ended up fusing together, including their queens.

From an ant biology conventional wisdom, this is startling finding because it is generally thought ant colonies reject workers that are not their sisters. However, the fact that even the winning colony is weakened and can't defend the trees against large herbivores makes the ability to recruit workers from a losing colony a distinct advantage.

Of course, there are ants that raid other colonies for pupae. Other ants eat the bodies of their fallen victims. Do you know of any other ant species that recruit or allow the losing workers to join the colony?

Literature:

Kathleen P. Rudolph, Jay P. McEntee. Spoils of war and peace: enemy adoption and queen-right colony fusion follow costly intraspecific conflict in acacia ants. Behavioral Ecology, 2015

Mack, Aileen. "Turn mortal enemies into allies? Ants can. UF News. 17 March 2016. .