Wild About Ants » Ant Questions

Question 13. Replacing Queen Ants

Roberta — Sat, 24 Jul 2010 18:33:58 +0000

13) If a colony with only one queen ant were to die, would she be replaced with another? Or does the colony die out. If she gets replaced, then are there always alates available to replace her at any time? Or are they only produced prior for the mating season, nuptial flight, and etc.? Is there any way of the colony knowing that the queen is about to expire, like some kind of special pheromone?

Mike, you’ve taken us on quite an adventure with your questions. It’s been a fun learning experience for me to dig up the answers for the ones I didn’t know about. If you have any more questions, or you’d like clarification about anything, feel free to ask.

As for the ability of ant colonies to replace their queens, this is a topic that comes up often.

For many temperate ant species with a single queen, the answer is that once the queen dies, the colony is a goner. The worker ants will not accept one of their sisters as a new queen, workers can not become a new queen themselves, nor can they raise a new queen like honey bees do. Some worker ants can produce eggs once the queen has died, but those eggs are unfertilized and will become males.

That said, there are a number of ant species that don’t fit the norm. In species like the Argentine ant, Linepithema humile, colonies have many queens, and the males and queens mate right inside the nest. Having many queens allows the colonies to become large quickly. In fact, one problem with Argentine ants is that when they are introduced to places they have never been before, they form such large colonies that they can quickly overwhelm or drive out many native ants, even ants much bigger than themselves. Argentine ants proved to be hugely successful at spreading and are now found almost worldwide.

Another strategy is found in the ponerines that don’t have a distinct, physically different queen. In those species, the egg-laying individual is called a gamergate. When one gamergate dies, the next high-ranking worker takes over laying eggs. Hoelldobler and Wilson discuss this in detail in their book, Superorganism.

Most ants colonies have distinct periods or seasons when the reproductives are produced, but that will vary from species to species and even somewhat from year to year, due to differences in environmental triggers, amount of food, age of the queen, etc.

Finally, the queen probably won’t give off a specific signal that she is weak (it wouldn’t be to her benefit), but there might be a decrease in the pheromone(s) she produces to attract the workers and keep them from producing eggs.

By the way, you might be interested to know that researchers recently synthesized the pheromone of the queen black garden ant and were able to show that it does suppress the ovaries and egg-laying ability of worker ants. See: University of Copenhagen (2010, July 14). Elusive ant queen pheromone tracked down. ScienceDaily. Retrieved July 24, 2010, from http://www.sciencedaily.com /releases/2010/06/100630101016.htm

For more information on ant queens, see a previous post answering questions about ant queen development.

If anyone has more information about this they’d like to share, please let us know.

Do ants drink water?

Roberta — Tue, 20 Jul 2010 22:39:59 +0000

Mike wrote to the “Consult-Ant” with a number of questions about ants. I am going to try to answer each one in a separate post. For the original list of questions and links to all answers, visit here.

11) Are there some ant species that simply drink water and then other species that absorb it from the humidity of the air? Or do they all do both?

Your question reminded me of the movie Microcosmos, which contains some great footage of ants and other insects dealing with water. I’ll throw the trailer below.

The second thing I thought of was communal peeing as a flood defense, where ants drink water and then run outside to “pee,” removing excess water from their nests. You know you want to click the link and see it, so go ahead. I’ll wait for you to come back.

Ants need water. Many drink water from drops and small puddles.

Ants drinking honey

Ants can obtain moisture from a variety of sources, including food. Leafcutter ants and weaver ants obtain moisture from plant sap. Many ants tend aphids and other insects of the order Homoptera for liquid honeydew, which is full of water. Other ants visit extrafloral nectaries on plants for a source of sweet liquid.

Ants have also been shown to use “tools” to help them collect larger amounts of water and sweet liquids than they could carry in their crops. Harvester ants (Pogonomyrmex) have been known to toss sand into liquid food and then carry it back to their nest. Aphaenogaster ants use bits of plant material as sponges to soak up liquids and transport it.

Mark Moffett found Diacamma ants decorate their nests with feathers, which collect dew in the early morning. (I have seen Forelius ants carrying feathers here in Arizona.) He also suggests that the dead ants spread around the nest might also serve for dew collection.

As far as “absorbing humidity,” Coenen-staß (1986) suggested that the red wood ant, Formica polyctena, might be able to absorb water vapor based on sorption rates. Other scientists have investigated desiccation resistance, and suggest that, for example, some ants can reclaim their internal water through structures called “rectal pads”(Hood and Tschinkel, 1990).

Videos showing ants drinking water:

Microcosmos trailer. For a review, see my Growing With Science blog.

The bottom line is that worker ants do drink water, and give it to other members of the colony. As for humidity absorption, that is relatively unknown.

For more information:

Coenen-staß, D. (1986). Investigations on the water balance in the red wood ant, Formica polyctena (Hymenoptera, formicidae): Workers, their larvae and pupae. Comparative Biochemistry and Physiology Part A: Physiology. 83 (1): 141-147.

Hood, G. and W.R. Tschinkel. (1990). Desiccation resistance in arboreal and terrestrial ants. Physiological Entomology, 15 (1): 23-35.

Moffett, M.W. 2010. Adventures Among Ants: A Global Safari with a Cast of Trillions. University of California Press, Berkeley.

Can a worker ant become a queen?

Roberta — Fri, 16 Jul 2010 01:53:03 +0000

I have an ant question!

I have an ant farm with Little Black ants but not a queen. can one of the ants become a queen?

Thanx
Zarah

Zarah,

I’m afraid once an ant becomes an adult ant, it can no longer change form or shape. It can’t shed its skin or grow.

Adult worker black ants can not become queens, and the worker ants can not lay eggs that will become queens either.

There are a few types of ants where special workers become “queens,” but those ants are much more like wasps, and you wouldn’t want to keep them in a regular ant farm. If you’d like a more detailed explanation, check the ant queen development post.

How are your little black ants doing? I hope they are doing well.

Can ant larvae get too cold or hot?

Roberta — Fri, 16 Jul 2010 01:39:08 +0000

10) If the eggs, larvae, and pupae were placed in bad conditions, specifically temperature, for a short period of time, would they be harmed?

As you might expect, the optimal temperature for rearing larvae depends on the ant species. In his 1988 paper, Porter found that fire ant larvae (Solenopsis invicta) grew and developed between 24° C and 36° C, with optimal growth at 32 °C. Abril et al. found a range of 18°C to 32°C for larvae of the Argentine ant, Linepithema humile, with optimal development closer to 26°C. Argentine ant larvae held at temperatures above 32°C did not survive.

Of course if the temperatures are hot enough to burn or cold enough to freeze, then the larvae would be harmed even with brief exposures. But what about temperatures that are not extremely hot or cold, but just outside of the range for normal development? Once again, depending on the species, there could be critical windows of development that can be missed if the larvae aren’t reared at proper temperatures. Exposure to low temperatures could potentially stimulate larvae to enter diapause, as well.

Adult worker ants are much less susceptible to changes in temperature. Types of desert worker ants may survive soil surface temperatures of 60 to even 70° C! (Marsh 1985)

In an actual nest, the nurse workers move the larvae from chamber to chamber to ensure the larvae are exposed to the correct temperatures.

Let me know if you have more specific questions.

References:

Abril S, Oliveras J, Gómez C. 2010. Effect of temperature on the development and survival of the Argentine ant, Linepithema humile. Journal of Insect Science 10:97 available online: insectscience.org/10.97

Marsh, A.C. (1985). Thermal Responses and Temperature Tolerance in a Diurnal Desert Ant, Ocymyrmex barbiger. Physiological Zoology, Vol. 58, No. 6 (Nov. – Dec., 1985), pp. 629-636.

Porter SD. 1988. Impact of temperature on colony growth and developmental rates of the ant, Solenopsis invicta. Journal of Insect Physiology, 34(12): 1127-1133.

Can Ants Digest Chitin?

Roberta — Fri, 09 Jul 2010 01:49:13 +0000

9) Ants(obviously) eat other insects, and I probably lack observation skills but do the ants also eat the exoskeleton also? Do they (or the larvae) have some way of digesting chitin? I did see that the ants pretty much leave MOST of the exoskeleton intact, and go for soft parts.

You have definitely got some challenging questions here. I’m going to give this one a try, but if anyone knows more about this, please jump in.

You probably have seen bug bits (discarded exoskeletons) littering the trash heaps around ant nests.

Many arthropods, including insects, have long chain polysaccharides in their cuticle known as chitin. (Chitin is also found in fungi, which was one of the lines of evidence that moved fungi into their own Kingdom.) The exoskeleton of insects is also made up of various proteins and waxes.

Chitin is known to be difficult to digest. It’s long chain polysaccharide structure is similar to cellulose, which is also difficult for animals to use as food. The digestion of chitin requires special enzymes, chitinases, to break the strong bonds between the molecules. For a time it was thought that chitinases only occurred in a few bacteria, but evidence is showing up that certain animals have chitinases in their digestive systems, too.

It turns out that insects have chitinases able to break down chitin, but they aren’t where you might expect them. The chitinases in insects are in the cuticle and are used to move chitin during molting.

We know that adult worker ants can’t digest solids, so they can’t digest chitin. What about larvae? It is highly unlikely, because the larval digestive system is also lined with chitin. When insects molt, they also shed most of their digestive tract, which is derived from the same tissues as the exoskeleton. Therefore, it seems larval ants probably couldn’t digest chitin without digesting their own alimentary canal.

Many arthropod predators of insects suck out the insects fluid insides. Think about spiders, assassin bugs, lacewing larvae, etc. They are all feeding on fluids.

If it is true that insects can’t digest chitin as a food source, this leads to some other questions. Leafcutter ants feed on special fungi, which they grow in their nests. Do the fungi they grow have chitin? Do the leafcutters have gut symbionts or some other means to digest that chitin?

If there are any chitin experts out there, it would be great to have some clarification.

Feeding Ant Queens

Roberta — Wed, 07 Jul 2010 18:17:50 +0000

Question 8. If I were to catch a queen ant, would it be recommended to feed her some protein as well as sugary foods like honey? I was thinking about this because I’ve read that the eggs and larvae would need protein to grow properly (I’m guessing for muscle development and such). So is peanut butter a good protein choice, in substitute of other insects? I’m worried that peanut butter wouldn’t have all the essential amino acids because peanut butter is an incomplete protein. But I’m not sure about ant development and physiology, so I’m curious.

The answer to this question depends on what kind of ant queen you find. In many temperate ant species, the queen starts a colony via what is called “claustral” founding. In this case, she seals herself off from the world as much as possible, often forming a special chamber. Then the queen lays her first batch of eggs. Until those eggs complete development and eclose into worker ants, it is likely the queen will not feed at all. Usually a queen in this case is surviving on the fat reserves she stored while in her natal colony, as well as the breakdown products from the deterioration of her flight muscles. The queen has no further use for her flight muscles once she has removed her wings, so the muscles break down.

Carpenter ant queens have claustral founding.

You might want to give new queens a bit of honey- or sugar-water solution absorbed into a piece of cotton ball or paper towel wad. Just so you know, adding any food always increases the chance of introducing unwanted molds or bacteria.

Once the little colony is underway, you can start feeding. To figure out the best foods, do some research on your particular species. Many scientists prepare a general diet useful for a variety of species. One of the earliest is known as the Bhatkar diet, named for the scientist who developed it. Hoelldobler and Wilson have a section on culturing ants in the back of their book, The Ants. It gives the recipe for Bhatkar diet. (Try Google Books). The Myrmecology Forum also has a link to a .pdf file of the original paper with the recipe. Basically it is honey, an egg, vitamins and agar (available online). You mix it up, cook it to get the agar to thicken, and then cool.

Supplement the diet of predator or scavenger ants with small amounts of freshly killed insects, such as mealworms or crickets, both available at many pet stores. You can also maintain mealworm/cricket cultures of your own. I have used tuna in a pinch. I’ve never tried peanut butter. It might be a bit sticky and the ants could get stuck in it, depending again on what kind of ants you have.

The maker of this video has some good ideas, such as putting the food on a bit of foil, to help with clean up. I would also soak it into cotton or paper towel to prevent workers getting stuck and drowning, but this person didn’t find that necessary.

For more information:

BHATKAR, A. P., AND W. H. WHITCOMB. (1970). Artiﬁcial diet for rearing various species of ants. Florida Entomol. 53: 229-232.

COHEN, A. C., AND L. K. SMITH. (1998). A new concept in artiﬁcial diets for Chrysoperla ruﬁlabris: The efﬁcacy of solid diets. Biol. Control. 13: 49-54. This diet has been used for fire ants successfully.

Ant Cam website has many FAQ’s useful for ant farms. Try What is good food for ants in my ant farm? for two different diets and advice.

Does anyone have any other great websites or papers with useful information on feeding queen ants and new colonies?

Ant Trophallaxis

Roberta — Sun, 04 Jul 2010 00:35:29 +0000

7) I’ve read a little about trophallaxis (I hope I spelled that right, because Microsoft Word does not help in scientific terminology), but I don’t see ants perform trophallaxis much. I was observing pavement ants though, so perhaps it has to do with the species. But my question is, do they perform it more underground, as in their colony? Or is it all because these ants weren’t hungry at the time? And what does an ant have to do induce another ant to perform trophallaxis? Some kind of touch communication by antennae?

Yes, you did spell trophallaxis correctly.

When ants feed on liquid food, it goes to the crop, an organ inside the gaster. The crop can be called the ant’s “social stomach” because food collected there may be given to other ants via regurgitation. Ants pass food from mouth to mouth via a process called trophallaxis, which may look like kissing to the untrained observer. Any food the ant doesn’t share with other ants is passed to the ant’s own midgut where it is digested.

Most of the ants you see at the surface are foraging ants intent on getting food back to the nest as soon as possible. Outside the nest is a dangerous place. Thus, it is more common for the ants to engage in trophallaxis underground, as you surmised.

Dr. Bert Hoelldobler studied how certain beetles are able to trick ants into giving them food this way. He was able to show that tapping an ant lightly with the antennae and/or forelegs (tarsi) in the right parts of the body, usually the labium, is enough to trigger an ant to regurgitate food. He was then able to use a human hair to touch an ant and get it to regurgitate.

Dr. Alex Wild from Myrmecos blog, has an absolutely fabulous video of ants performing trophallaxis, which due to the wonders of YouTube, I can show you here. Thanks Dr. Wild! He also has some awesome photos of trophallaxis.

Memory in Ants

Roberta — Sat, 03 Jul 2010 15:36:49 +0000

6) So ants have pheromones they lay to provide trails to sources of food, but I’ve read somewhere that ants have memory. Can you explain more about that? A ‘leader’ ant would teach a ‘follower’ ant towards a food source. Is that true? with only certain species?

Although their brains are obviously very different from ours, we do have some evidence that worker ants do have memories. For example, James Hare and Thomas Eisner showed that workers ants that had been exposed to moth eggs (Utetheisa ornatrix) full of nasty alkaloids would still avoid moth eggs days later. But not just avoid toxic eggs. In an elegant study, Hare and Eisner were able to rear moths that did not contain the alkaloids, producing eggs that were perfectly edible. Ants with no previous exposure to the alkaloid-laden eggs would eat the alkaloid-free ones readily. It was the workers with previous experience (up to 33 days prior!) that would avoid both kinds of moth eggs.

In a paper in Myrmecological News, Dornhous and Franks give an overview of cognition in ants, and other insects. They report that foraging ants use memory to find food sources, and can even remember times of day the food sources are available. Ants can also remember where they have looked for new nests. Wood ants apparently memorize visual “snapshots” of landmarks as they travel about. Although chemical cues are important, if an ant is dropped into its environment in a place with no chemical trails, it might be able to orient back to the nest using visual cues. Ants have been known to be able to learn to move through mazes since Schneirla’s work in the early 1940’s, so are able to improve their performance of certain tasks.

Ant running a maze.

Dornhous and Franks point out that most of the studies of cognition in insects have been carried out with honey bees and fruit flies, for various reasons. There is still a lot of work to be done on ants.

As for the leader and follower ants, would you believe that ants could be teachers? When researchers looked at how ants lead their nest mates to new sources of food or a better nest, they found that the experienced ants actually taught the others where to find the target during a process known as “tandem-running.” Tandem running is when one ant follows another closely while running.

To discover whether or not the ants were actually teaching each other, first the investigators needed a solid definition of what it means to be a teacher. They decided that to be a true teacher, the ant must change its behavior when it encounters an inexperienced ant. At a cost to its own ability to perform the task, it must set an example so that the untrained ant can learn more quickly than it could have without training.

Sure enough, teacher ants approached uninformed nest mates and literally showed them the way to the food or new nest by running ahead. The follower gives feedback to the leader by continuous touching with her antennae. By teaching others the path to take, the teacher ant ran slower than it would have without a follower, but the pupil ant found the target in two-thirds the time it would have taken without help.

To learn more:

Dornhous, A. and N. R. Franks. (2008). Individual and collective cognition in ants and other insects (Hymenoptera: Formicidae). Myrmecological News. 11: 215-226.

Franks, N.R. and T. Richardson. (2006). Teaching in tandem-running ants. Nature. 439: 153.

Hare, J.F. and T. Eisner. (1993). Pyrrolizidine alkaloid deters ant predators of Utetheisia ornatrix eggs: effects of the alkaloid concentation, oxidation state, and prior exposure of ants to alkaloid-laden prey. Oecologia. 96: 9-18.

R. Josens, C. Eschbach, and M. Giurfa. (2009). Differential conditioning and long-term olfactory memory in individual Camponotus fellah ants. J. Exp. Biol. 212:1904-1911 Retrieved from http://jeb.biologists.org/cgi/content/abstract/212/12/1904

Nowbahari, E. (2007). Learning of colonial odor in the ant Cataglyphis niger (Hymenoptera; Formicidae). Learning & Behavior, 35: 87-94. Retrieved from http://lb.psychonomic-journals.org/content/35/2/87.abstract ( free .pdf available)

Y. Provecho and R. Josens. (2009).Olfactory memory established during trophallaxis affects food search behaviour in ants. Journal of Experimental Biology. 212: 3221-3227. Retrieved from http://jeb.biologists.org/cgi/content/abstract/212/20/3221 (.pdf available)

Schneirla, T.C. (1943). The nature of ant learning II. The intermediate stage of segmental maze adjustment. Journal of Comparative Psychology. 35: 149-176.

What is she thinking?

Questions About Ant Pheromones

Roberta — Sun, 27 Jun 2010 13:16:45 +0000

4) Besides making trails and setting alarms, are there any other kinds of unique pheromones? Such as, attracting the queen ant or inducing certain behaviors like digging.

Sure, there are a lot of different pheromones in ants. Ants use pheromones to

recruit to food sources,
mark the way to new nest sites during emigration
aggregate
mark territories
recognize nestmates
“call”- the release of pheromones by reproductive females to attract males
induce nestmates to defend the nest (alarm)

to name a few. Some queens release pheromones that induce workers to kill larval forms that would become reproductives, or that prevent virgin queens from shedding their wings. In carpenter ants, the males release a pheromone from their mandibular glands that signals to the female reproductives that it is time to fly from the nest and join the mating swarm. (Holldobler and Maschwitz 1965, as cited in LD Hansen and JH Klotz, Carpenter Ants of The United States and Canada).

Behaviors like digging can also be stimulated by non-chemical signals, such as stridulation (making sounds) by buried worker ants trying to get nestmates to dig them out.

Knowledge of ant pheromones a bit rusty? Let me explain what we are talking about. Ants produce chemicals, in fact they are walking chemical factories. Bert Holldobler and E.O. Wilson wrote extensively about how ants use chemicals for communication in Chapter 7 of their book, The Ants (starting on page 227).

The term “pheromone” is defined as a substance released by an organism to the outside that causes a specific behavioral or physiological reaction in a receiving organism of the same species. [Nordlund, D. A. and W. J. Lewis. (1976). Terminology of chemical releasing stimuli in intraspecific and interspecific interactions. J. Chem. Ecol. 2: 211-220.]

For example, this video shows an ant laying trail pheromones. Other ants will detect the chemical in the trail and follow it back to the food.

All of these chemicals are made in exocrine glands found throughout the ant’s body.

In the head are the

mandibular gland – often produces alarm and defense compounds, extends all the way to the gaster in certain Camponotus
maxillary gland -source of digestive enzymes
propharyngeal gland – source of digestive enzymes
postpharyngeal gland – source of cuticular hydrocarbons (colony odor) and also food for larvae
antennal glands – found in Solenopsis fire ants

In the alitrunk are the

labial gland – equated with a salivary gland
metapleural gland (labeled in illustration) – source of antibiotic compounds, occasionally alarm pheromones/repellents

(Archetype has an awesome post about the structure and function of the metapleural gland.)

In the gaster, we find the

poison gland – source of defensive formic acid in Formicinae, recruitment to food in some myrmecines
rectal gland
sternal gland (Pavan’s gland) – trail pheromones
Dufour’s gland – often the source of trail pheromones
pygidial gland
etc.

The presence or absence of these glands, their structure and their contents varies between ant species, and even within individual caste members of a given species. The pheromones used and the message they contain are species specific by definition. That means what scientists learn about the pheromones of one species may not have general application to any other species, although some have been found to overlap.

To learn more about the chemistry of ant pheromones, try The Pherobase, a website of known pheromones, attractants, etc. You can search the database by animal taxon, or go directly to the Formicidae page.

There you can find out, for example, that the trail pheromone for Atta texana is me-4me-pyrrole-2-carboxylate, and what it’s structure looks like. Or the mandibular gland components of the exploding carpenter ants of Camponotis cylindricus group. Solenopsis invicta queens apparently produce (E)-6-(1-Pentenyl)-2-pyranone for recognition, that is so that the workers know she is their queen. This site is really cool if you are an ant geek.

5) The ant uses their antennae to pick up ant pheromones, so if that’s the case, then do ants necessarily ’smell’ food if the pheromone is blown towards the ant’s way? Essentially speaking, can ants smell their way to food?

Oh, definitely yes. In a recent post I discussed how certain ants can even use odors as a type of chemical map to find their way around. Their way of orienting can be called a “topochemical” map. Of course ants may use a variety of cues to find food, including sight, but it makes sense that they can detect plant chemicals and even those of sources of honeydew like aphids and scales.

If anyone has posts or references that might be helpful to Mike, please let us know.

Question 3 Ant Queens and Pheromones

Roberta — Thu, 24 Jun 2010 22:33:48 +0000

3) I’ve been meaning to catch an ant queen, but I’ve been curious about other methods of catching one. Are there ant pheromones that can basically attract queen ants to come out of the colony? I assume that each ant species would probably have their own type of pheromones, so I’ll have to find out which species I’m planning to catch, which leads me to the next question: Where can I get these pheromones? Can I synthetically make them on my own? What differentiates certain pheromones from another? Subtleties in molecular structure?

That’s an interesting idea, Mike, but it actually works in reverse. The queen produces pheromones to attract males during the mating flight (although some species have other signals, like harvester ant queens stridulate). Once she has started a colony, usually the pheromones she produces regulate the behavior of the workers, attracting them to her. She is the most important member of the colony after all. I guess it is possible that wafting an alarm pheromone into a nest might drive out the queen, but your chances of finding her amidst the other ants? I’m not sure.

Chemists have definitely synthesized pheromones for insects, usually for those with economic importance, for example gypsy moths. The chemistry is often quite complex. The chemical structure may vary by something as simple as chirality or as complex as being a totally different molecule.

If you want to catch a queen, nothing beats learning all you can about the life history of the species you are interested in and then going out when at the time of year when swarms occur (often depends on the weather) and look for mated queens. I find queens all the time because I’m looking for ants, and queens start their colonies where other ants are successful.

Anyone else out there have any ideas for Mike?

Edit: In researching your next question I did find evidence that in carpenter ants, the males release a pheromone from their mandibular glands that signals to the female reproductives that it is time to fly from the nest and join the mating swarm. (Holldobler and Maschwitz 1965, as cited in LD Hansen and JH Klotz, Carpenter Ants of The United States and Canada). Although they would be unmated, that might be a way to entice them from the nest. The other problem I foresee is that the unmated queens would need to be physiologically ready to go on their mating flight or the pheromone wouldn’t work.

See the next post for more information on pheromones.