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Today we're featuring Kaitlin M. Baudier, PhD who is currently a post doc in the Social Insect Research Group at Arizona State University.

Dr. Baudier is the creative force behind the AntGirl YouTube Channel. Check it out, particularly the ant playlist.

To give you an idea of her content, here's her video of a Pogonomyrmex barbatus mating swarm.

Isn't that incredible? Being close to a social insect swarm is an amazing experience. I hope to see a full blown harvester ant mating swarm like this one some day.

What else does she work on?

Besides social insect swarm aggression research, she also studies tropical ecology and animal behavior. She has some great videos of tropical species, like the ants versus stingless bees.

Ever seen those odd tubercles on ponerine larvae?  (If not, the Mississippi Entomological Museum has a close up of an Ponera pensylvanica larva here.) Dr. Baudier is also interested in studying their evolution throughout the subfamily ‎Ponerinae. Take a look at her poster about "sticky fingers."

If you'd like to learn more, visit her website.

Did I mention she's also an artist?

You've probably seen the videos of people drawing circles around an ant and the ant seeming to refuse to cross the line, like this one:


Recently this question came in:

My son wants to do a science project related to a video he saw about ants not crossing a marker boundary. We assume this has to do with pheromones or rather chemicals in the markers. We have tried to find research related to this, however very little has been found by him. Wondering if you know of any research about this?

Before going into the question, first let's make sure we are clear about terminology. A pheromone is a chemical scent that animals use to communicate with other members of their species. (You can see more about ant pheromones in this previous post.) An ant repellent, on the other hand, is any chemical that keeps ants away. They are not, however, mutually exclusive. It is possible for a pheromone to repel other members of the colony, for example virgin queen honey bees produce a pheromone that tells worker honey bees to back off.

Returning to the marker problem, what could be going on?

It could be the chemicals in the marker act as an ant repellent. The ant is repelled by the line and refuses to cross it. It makes sense that ants respond to any novel or harmful chemicals by backing away or avoiding them.  In a paper in Journal of Chromatography A, scientists found all sorts of chemical compounds in pen ink that ants might want to avoid, including methylbenzene and xylene.

Another possibility that the marker has wiped away the trail pheromone trail that told the ant where to go.

Foraging ants that find food mark the surface with chemicals as they return to the nest. As more ants pass back and forth, more and more pheromone builds up. Depending on the foraging strategies of the ants, some trails can be dense with worker ants. Similarly, when ants are moving from one nest to another, they will lay and follow a pheromone trail.

You can disrupt a pheromone trail with chalk or even with your finger.

The behavior looks pretty similar doesn't it?

A third possibility is that it is a little bit of both: the marker wipes away the trail and also repels the ant.

Rather than give you all the answers, think about way you might be able to figure out which of the possibilities are likely and how to test for them. A hint: what happens if you draw a pen circle around an insect or spider that doesn't have a pheromone trail? Do they act the same way?

For more help, check out Drawing Circles Around Ants and Go and Stop? Ant Traffic at the Science Buddies Website. (Always a great resource for science fair project ideas.)

Public domain image of army ants by Alex Wild.

There's a question for the Consult-Ant this week. (The “Consult-Ant” started on the Leaping from the Box website, where I answered questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)

Question:  I have an ant question!
I have been observing common ants foraging and wonder what range their senses have to understand their foraging tactics. Presumably they are hoping to discover a food source.
Mike.

Answer:

Wouldn't it be cool to be able to slip into a creature like an ant and experience the world through their senses?

Unfortunately, we aren't quite there yet. Scientists are making some breakthroughs in understanding how ants perceive the world, but there are still many, many questions. To make things even more complicated, it appears that different species of ants have different sensory abilities, so there isn't just one answer as to how ants' senses work.

Although ants have a variety of senses, most ants probably use a combination of vision and olfaction to find their food. Let's explore those two in more detail.

1. Vision

Without even knowing how ants' eyes work, we can see there are big differences in the structure.

For example, this ant has massive eyes.

(Gigantiops destructor Photographer: Michael Branstetter Date Uploaded: 07/20/2009 Copyright: Copyright AntWeb.org, 2000-2009. Licensing: Attribution-ShareAlike 3.0 (cc-by-sa-3.0) Creative Commons License)

This huntress has normal-sized eyes.


Army ants have reduced eyes or are even blind.

(Public domain photograph of Eciton burchelli by Alex Wild)

For ants with well-developed eyes, we would expect that since they are small and close to the ground, perhaps they can't see far. In fact, (2004) found Myrmica sabuleti ants could discriminate objects 15 cm away, but only 10 cm above. On the other hand, bulldog ants in the genus Mymecia have excellent vision and have been reported to be able to see a meter away.

How do ants use vision for foraging? Not only can they spot prey, but also according to Hölldobler and Wilson (1990) foraging worker ants can learn/remember to return to places where they found food in the past using visual cues. Researchers have found some species of ants can orient to food sources using the the skyline (Graham and Cheng, 2009), or polarized light (for example Krapp 2007, Wehner et al. 2014). So, they may see farther than we might expect.

Related:

2. Sense of smell - Olfaction

Blind ants -- or those that forage at night -- may use their sense of smell to find food. Insects detect odors largely with their antennae.

How do the antennae work? Within the antennae are odor receptors that can bind with specific free-floating molecules. When the correct molecule bumps into and binds with the receptor, a nerve associated with it sends a signal to the mushroom bodies in the insect's brain, where it is processed or identified.

From how far away can ants detect smells? It really depends on how far the odor molecules can travel. I wasn't able to find much about detection distances for ant antennae, but male moth antennae can detect female moth pheromones from 300 feet away.

What kinds of things can they smell? Zwiebel at al. (2012) found over 400 different odor receptors in each of two species of ants: a carpenter ant, Camponotus floridanus, and the Indian jumping ant, Harpegnathos saltator. Using an unusual bio-assay involving frog eggs they discovered that although the receptors were equally numerous in both species, the odors detected by the receptors were not the same. For example, the jumping ant could detect a component of anise (a spice), whereas the carpenter ant could detect an odor from cooked pork. Presumably those differences reflect differences in their biology or environment.

According to the same article, ants also have gustatory receptors, which distinguish taste (among other things). In addition, they have ionotropic glutamate receptors that can detect toxins and poisons. This can be important for seed-harvesting ants and leaf cutter ants because plants may contain toxins that will either harm the ant larvae, or the fungus that leaf cutter ants garden for food.

3. Scouting for Food?

"Presumably they are hoping to discover a food source."

Yes, when they are outside the nest, by-and-large foraging ants are looking and smelling for food. (Although a few may be scoping out potential enemies as well.)

Again, the process varies depending on what kind of ant you have. Some ants are solitary hunters. Each ant hunts and brings food back on its own, whether seeds or insect prey. In some species, special scouts search for food and return to the nest once they find it. They recruit other foragers to retrieve the food. Often the strategy will be intermediary, and depend on the size or quantity of food on a given day.

Although most ants are omnivores, what constitutes food will also vary and those differences will change how ants detect it. For example, ants that tend aphids or leafhoppers may locate potential food by smelling honeydew that has dropped to the ground under the plant where the insects are feeding.

Conclusion

The bottom line is that how an ant finds food will be limited by the range of its senses, but right now we don't have a complete picture of what those limits are. Personally, I would not be surprised if we discover that certain ants have some amazing abilities that we haven't even thought to look for yet.

_________

Hopefully, that answers your question at least in part.

Does anyone else have anything to add to help Mike?

A few ant nests dot the sides of a walking pathway at a nearby park, so of course I have to check them out.

For the most part the nests are small colonies of southern fire ants, Solenopsis xyloni.

There are also seemingly endless streams of Forelius mccooki workers traveling along the concrete edgers and sidewalks.

While taking photographs of the fire ant middens, I noticed the fire ants had a few visitors standing by an entrance hole.

Millimeters away from the fire ant workers stood two Forelius workers.

 

Curious, I watched for some minutes. The fire ants did not approach the Forelius, and the Forelius remained relatively still. They didn't appear to be investigating the middens.

The Forelius had a nest entrance not too far away. Perhaps they were just nosy neighbors? (I did notice there weren't any Solenopsis visiting them.)

Wayne Armstrong suggests perhaps the relationship isn't entirely benign. In this video, Solenopsis xyloni workers flag their gasters in response to Forelius pruinosus workers encountered at an artificial feeding site. (You will notice the coloration difference between our local S. xyloni compared to his California ones.)

Interestingly, the soldiers don't seem to respond. According to his notes (scroll down to Southern fire ant), the Forelius were ultimately successful in overtaking the food.

Ants of the Southwest has a photograph of a Forelius worker spraying a S. xyloni worker. He reports S. xyloni exoskeletons piled in Forelius middens, which is also reported here.

Even though southern fire ants are chemically well defended, perhaps they are no match for Forelius.

Have you ever encountered these two species?

References:

Obin, Martin & Vander Meer, Robert. (1985). Gaster flagging by fire ants (Solenopsis spp.): Functional significance of venom dispersal behavior. Journal of chemical ecology. 11. 1757-68. 10.1007/BF01012125.