April 2012 Archives


Here's a question from a professional myrmecologist, that I'm sure has entered the minds of many in the English speaking world who are interested in ants. As the askAnt Team's "resident Latin scholar", here are the question and my response.

"I'm sure you've answered this before. Is the correct pronunciation
for Formica with the accent on the 'o' or on the 'i'? I think it
should be on the penultimate syllable, the 'i', but then it sounds
like the plastic Formica. What is the general opinion on this?"
Dr. Les Greenberg
Department of Entomology
University of California-Riverside

Thanks for the question, Les. It's true I get asked about this and similar matters fairly frequently, and here are my thoughts on your specific query.

-- If we were speaking Latin, we would say /forMEEka/ (accented like Spanish hormiga).
-- By Borror and Delong's, George and Jeanette Wheeler's, and many other biologists' published guidelines for standardized English pronunciation of Latin, the old Latin long 'i' should be pronounced as in English bite and mice, and it should be accented. Thus, they would say /forMYka/.
-- This genus got its name and was pronounced in English as /forMYka/ for probably about a century before the plastic Formica, was invented, but of course, the inventors of the plastic wouldn't have known that. See the Wikipedia article on how it got its name and more, if you like: http://en.wikipedia.org/wiki/Formica_(plastic)
-- FORmihka, accent on the 'o', is not really a Latin word, but if it were, it would be the feminine form of an adjective, formicus, meaning taking shape, shaping, forming, formative, or formic, depending on context, and agreeing with a feminine noun. Stretching this out to the realm of absurdity, but helping to make my point - Theoretically, one could have said in Latin Formica formica, i.e., /forMEEka FORmihka/, which would mean, somewhat nonsensically, "a formative ant" (a pupa?).

I personally have gone to a more Latinate, international pronunciation and prefer the first pronunciation, but sometimes slip into the old habit of the second pronunciation. I never say it with the accent on the 'o', and don't like the cognitive dissonance of it that results from my knowing too much Latin, but others whom I respect do say it that way.

So take your pick, and if you're speaking English, you'll be right no matter what.

James C. Trager of the Ask Ant TeamBiologist - Naturalist


Hello,

I have been interested in certain insects & also arachnids for many years.I happened to encounter your website today while doing a google search for images of velvet ant varieties.They have absolutely beautiful coloration so I was doing a search on those insects.I realize velvet ants are not ants & are wasps but nevertheless I thought your site was interesting.Is it true that Bull Horn acacia ants in South America have a very painful sting? Its not often insects have a mutual-beneficial relationship with plants & other insects though it does occur in a number of species.

Nick


Hi Nick,

Bullhorn acacia-ants have a sting rated as a 1.8 on the Schmidt Sting Pain Index. While not excruciatingly painful by itself, when these ants attack, they attack with the full force of the colony and will continue stinging for as long as they can. They are also incredibly aggressive and will launch themselves from their trees onto invaders with no regard for their own safety. The wisest course of action is usually to avoid these trees altogether. Once you come into contact with the ants it is easy to understand how they can so effectively protect their plants because they are so aggressive and unpleasant.

The mutualism between the acacia-ants and their host plants is rather unusual but similar behaviors have evolved convergently both within the acacia-ant genus (Pseudomyrmex) and in unrelated genera such as Crematogaster and Azteca. Mutualistic Crematogaster ants in Eastern Africa are even able to protect their acacia hosts from megaherbivores like elephants and giraffes. You can check out the citation below for more of the story.

Goheen JR, Palmer TM. 2011. Defensive plant-ants stabilize megaherbivore-driven landscape change in an African savanna. Current Biology 20: 1768-1772.

Thanks for your question and keep up the interest in arthropods!
Ben Rubin & the AntAsk Team

Hello AntWeb Associates,

My question in short is, do cockroaches eat ants?

Let me expand on this a bit. Over the last several years, I have noticed a strip of sidewalk near my home where both cockroaches and Argentine ants seem to congregate. Often times at night when the temperatures are mild, I'll go for a stroll on this particular strip of sidewalk and I'll notice a great number of cockroaches (all sizes large and small) traveling and loitering among the ant trails. What do you suspect is going on here?

Thanks,

Robert in San Jose

******

Hi Robert,

Thanks for your question!

In all likelihood, the association you observed between the cockroaches & ants is merely coincidental rather than predatory. American cockroaches and Argentine ants alike are omnivorous scavengers that feed on a wide variety of organic matter (almost invariably dead if animal-based) and take eager advantage of the breadth of available foodstuffs in and around our homes. As with most domestic insect pests, they are more or less trophic equals, exploiting the same basic resources with similarly indiscriminate fervor. The concentration of these two opportunistic feeders in the same place says more about their overlapping diets than anything else, leading one to suspect that if you followed this particular nighttime procession, you might find some discarded fruit or an unattended waste bin or any number of other mutually appetizing treats.

While there are no known instances of cockroaches actively preying on ants, the scientific literature offers several examples of these two organisms engaging in other unexpected ways. Facultative myrmecophily (literally "ant-love", describing any meaningful association between ants and other organisms) has been documented in several species of cockroaches ranging from the miniscule Myrmecoblatta wheeleri, which has been found in the nests of both Solenopsis and Camponotus ants (Hebard, 1917; Fisk et al., 1976; Deyrup & Fisk, 1984), to the parthenogenetic Surinam cockroach, Pycnoscelus surinamensis, which exhibits a strong commensal association with the rover ant Brachymyrmex cordemoyi (Moretti et al., 2011). An earlier study describes additional, if somewhat less permanent, associations between P. surinamensis and seven other ant species, primarily the widespread tramp ant species Pheidole megacephala and Paratrechina longicornis (Deleport et al., 2002).

Perhaps the best-known cockroach myrmecophiles are those in the genus Attaphila, which maintain close host-specific associations with fungus-growing ants in the genera Atta and Acromyrmex. Most extensively studied of these is Attaphila fungicola (pictured), a minute cockroach that inhabits the fungus gardens of Atta texana and obtains nourishment by licking the exteriors of passing soldiers (Wheeler, 1910). These cockroaches will also instinctively mount the males and queen ants before a mating flight, thereby ensuring a wider dispersal than would otherwise be possible on their own.

Attaphila.jpg
Photo courtesy of LSU AgCenter

In many cases, myrmecophilous cockroaches display a marked ability to detect and orient to ant trail pheromones, especially in the more established Attaphila-Attine relationships. While it's certainly possible that the cockroaches you observed were somehow attuned to the scent trails of the scavenging Argentine ants, no functional association between these two species has ever been reported. Who knows? Maybe it's more than just a coincidence. Even without any permanent association, the Surinam cockroach was found to follow the scent trails of one of its hosts, Camponotus brutus, to a food source. Surely the enterprising American cockroach is capable of doing the same?

Thanks for your interest,

Alexandra Westrich & the AntAsk Team

Hello antweb team,

I am a huge fan of the ants and the antweb team. I have learned so much about ants from you guys, and have also taken away important life lessons from many of your eloquent responses.

My question is.. can you please tell me some things about Spechomyrma and other ant ancestors? What makes Sphecomyrma an ant and not a wasp? Also, what extant lineages of wasps are most closely related to ants? Lastly, do either ants or their wasp ancestors have free will?

Thanks so much!
-Jered

*****
Dear Jered,

Thank you for contacting AntBlog and sending in a question about ant fossils. We have asked a colleague, Dr. John LaPolla, who is currently working on some fossil ants to address your question and here is what he had to say:

"Great question about what makes Sphecomyrma an ant or not an ant. This is something ant experts have variously debated. There are a few morphological features of ants that are generally considered to define them and separate them from other hymenopterans (bees, wasps, and ants). There are two characters in particular that are important: an elongated scape (the first segment of the antenna) with an elbowed antennae and the metapleural gland (a gland found on the body of ants). While Sphecomyrma does have an elbowed antennae, it's scape is short. That being said, Sphecomyrma clearly possesses a metapleural gland (the exact function of this structure is unclear, but recent work strongly suggest it is involved in antimicrobrial functions and the secretion of various communication pheromones). The metapleural gland is particularly diagnostic for ants because no other hymenopterans possess anything remotely similar to it. Therefore, Sphecomyrma is considered an ant. It is not uncommon at all for ancient lineages of modern groups to possess some, but not all of the features we use to define them today (in this case the presence of short scape). Just so you know, there are now several known sphecomyrmines belonging to different genera (from two rather morphologically distinct tribes) that are even older (but not by much being around 95-100 million years old) than Sphecomyrma that have been discovered in French and Burmese ambers.

The next closest relatives to the ants is probably the Armaniidae which are an extinct group of large ant-like hymenopterans. We don't know much about them. Their exact placement has been hotly debated some have called them ants, some have not, and several researchers have variously flipped back and forth in their opinion. The reason is because armaniids, while being large, are only known from impressions in ancient rock (about 110 million years old) and they are very poorly preserved. Nothing resembling workers have ever been found for them (suggesting they were not eusocial), they have a wasp-like, very short scape, and they apparantly do not possess a metapleural gland.

Among living groups of wasps it remains unclear who is most closely related to the ants. Some have suggested vespids, others have suggested scoliids, and still other some of the more obscure wasp families, but I would say the jury is still out on this question. As for free will, I don't think ants have this - the concept of free will is very much a human construct. Ant colonies are more or less units that respond to their environment through chemical communication among nestmates."

Thanks again,
John LaPolla (guest expert), Corrie Moreau & the AntAsk Team


Hello,

Are ant social parasites and host ants examples of sympatric speciation?


Best,
Andrew

Andrew,

Whew, this is quite the question!

The short answer is: I don't know, but probably not.

To give a longer and somewhat more complete answer (though still not one that might completely satisfy you) I'm going to back up a little bit and get our other readers up to speed on some of the different strategies ants use to exploit each other--the different flavors of nest parasitism. I also think it might be useful to define sympatric speciation.

There are many species of ants, such as the members of the (Diploroptrum group within the genus Solenopsis, aka 'thief ants') that are thought to make their living from living very close to larger ant nests and stealing stored food and/or eggs and other brood. At the nest level, these ants are technically parasites (I've heard myrmecologists refer to them as kleptoparasites, although this term is usually reserved for organisms that steal food or other resources from other organisms, not baby-eaters). The exact behavioral ecology and the extent to which these relationships are specific is not known for many of these groups, but the hosts of thief ants tend to be larger ants from different genera, so it's unlikely that members of this variety of nest parasitism are examples of sympatric speciation.

While "thief ants" tend to build their nests just on the outskirts of a host nest, there are other ants that actually live inside ant nests. Animals (ants and otherwise) that live in other social insect nests are said to be "inquiline." There are many kinds of arthropods and other organisms that have observed to be inquilines in different types of ant nests, and there are ants that are inquiline in termite nests (for example, members of the genus Metapone). Either case could, I suppose, be considered an "ant social parasite," but for the purposes of this blog post, I'll focus on ants that are inquiline within other ant nests. Much more detail about the many flavors of inquilinism can be found in this excellent review (Buschinger 2009), but rather than summarize that article, I'm going to emphasize that inquilines are the category of parasites that might be most promising group in which to look for examples of sympatric speciation. I will return to this idea (finally!) in just a few more paragraphs.

Another parasitic strategy that some ants employ is stealing pupae from another nest, bringing them back to their own nests, and making those ants do all the work. These ants have sometimes been referred to as slave-raiders (see a great discussion here as to whether or not to refer to use this terminology); Polyergus is the textbook example. This genus is exclusively comprised of ants that steal pupae from members of the genus Formica. There are several species of Polyergus, but some of them seem to have non-overlapping geographic ranges. For example, Polyergus samurai is found in Japan, whereas other species are found in Mongolia, Northwestern Europe, or the American Southwest. These distinct geographic ranges suggest that allopatric speciation might be most likely mechanism of diversification in this genus, Although it is intriguing that they come out sister to their host ant, Formica, in the ant phylogeny by Moreau et al. (2006).

Speaking of allopatric speciation: what is that? And what is sympatric speciation?

Saying that speciation is allopatric is basically just saying that a pair of populations speciated because they were geographically isolated. Speciation is said to be sympatric if reproductive isolation occurs in populations whose ranges overlap substantially (it doesn't count if the populations speciate while they're separated and then later come back into contact, which can make distinguishing between these two modes tricky). The classic examples of sympatric speciation involve host shifts in parasites: if the ranges of the hosts overlap, and speciation occurs because of a host-shift, then many would argue that this is an example of sympatric speciation. Others would actually classify this as "micro-allopatric," because at small scales, the ranges of the new species never overlap, i.e., they're "never" on the same plant. I think this distinction is a little silly, though. To me, allopatric speciation implies the existence of a (usually geologic) barrier to dispersal between populations, like a river or a mountain range. To say populations are in allopatry because they are behaviorally inclined to eat different plants is just...silly. Stephen Stearns at Yale has a great lecture on speciation here if you want more depth on this somewhat daunting subject.

Anyway, this definition suggests two intriguing ways in which sympatric speciation might be important for the diversification of ant social parasites: new species might arise in lineages that are already parasitic because of a host switch, and parasitism might arise within a population of non-parasitic ants. The former case is straightforward in principle: in order to better dominate/fool their hosts, parasitic ants need to adjust their smell (cuticular hydrocarbon profile), which is also important in mate recognition; thus, if you've been parasitizing different species, you might not recognize each other as mates. There are several species of ants that are known to parasitize a few different hosts, and these might be interesting candidates to look for cryptic, sympatric speciation within (cryptic species are genetically isolated, but difficult or impossible to tell apart under the microscope). I don't know of any documented examples of this speciation-by-host-shift mode, however, which may be due in part to how risky the nest-raiding lifestyle is. It may also be due to my incomplete knowledge of this subject, and the generally incomplete state of natural history and genetic knowledge of ants. In general, though, the inquiline lifestyle is risky, and host ants are patchily distributed across landscapes. Host specialization is a good strategy for herbivores with abundant food sources (whose only defenses are chemicals; plants won't try to bite your body in half), but if there are examples of speciation-by-host-switching in ants, I suspect those species would have a very high extinction probability, so at any given time they would be exceedingly rare.

Sympatric speciation due to a shift from a free-living lifestyle to parasitizing your relatives is difficult to rule out. There are many instances of social insect parasites that seem to be closely related to their hosts (this pattern actually has a name: Emery's rule). There are numerous documented examples of intra-specific parasitism: newly mated queens attempting (and sometimes succeeding) in joining pre-existing colonies (so: intra-specific inquilines), and of same-species raids in which pupae are stolen and made to work in the new colony. It seems like a simple logical sequence to move from within-species parasitism to sister-species parasitism in a perfectly sympatric way. There is some unpublished evidence of multiple origins of inquilinism in the genus Tapinoma in North America, which is consistent with sympatric speciation, but these data are very preliminary, and cannot rule out allopatric speciation, as I'll discuss below.

The difficulty I have with the sympatric scenario is that there is still no mechanism for reproductive isolation: what prevents the "parasites" from mating with the "hosts" if they haven't already speciated? To me, it seems more likely that Emery's rule arises from the fact that sister species are pre-adapted to foiling each other's nestmate recognition abilities. The smells ants use to recognize each other have a hereditary component, and so closely-related species are more likely to stumble upon the perfect disguise, as it were. My scenario requires that:
1) Populations of a single species were isolated,
2) These populations speciate allopatrically,
3) They return to contact with one another, and
4) One evolves the ability to exploit the other.

This may seem like an unlikely scenario, but the first three stages are thought to have happened repeatedly in insect species, especially over the past few million years following the glaciation cycles in the northern hemisphere. (Siepielski et al. describe the ecological repercussions of this process in damselfly communities in the Northeastern United States here. A pattern that would be consistent with my scenario would be a higher proportion of close-relative parasitisms in areas that are thought to have undergone more recent, repeated range shifts and expansions, such as the Northern Eurasia and North America, and the continental islands of Indonesia, as opposed to areas that have been more stable, like the Amazon Rainforest and perhaps some of the Southern hemisphere temperate areas.

To me, this seems like a more likely scenario than either the host-switching or the rise of parasitism scenarios discussed above (note that Buschinger 2009, linked above, definitely disagrees with me). Some evolutionary biologists believe that, in general, we should assume speciation has been allopatric unless there is compelling evidence otherwise (for a more full discussion, see a 2002 review of sypatric speciation by Berlocher and Feder here). While my scenario is essentially a "just so story," I think these scenarios are important to consider when evaluating the likelihood of different mechanisms in ecology and evolution.

However, there are many areas of the world where new ants have been introduced, and it would be theoretically possible to catch a host-switch sympatric speciation event in action. Just as the most clear-cut example of sympatric speciation occurred during a host-switch from one plant to an introduced one (Rhagoletis flies switching from native hawthorn trees to introduced apple trees in North America), it might be very advantageous for inquiline ants in Europe or Japan to be able to exploit, say, the invasive Argentine ant (Linepithema humile). This might require a specialized smell disguise, which in turn could lead to a mutual lack of attraction between otherwise compatible mates.

This and many other areas of social insect parasitism are completely fascinating to me, but these ants are so rare that much of our knowledge is very fragmentary. When you look for ants, keep your eyes out for inquilines, but don't be disappointed if you don't find any!

I hope this helps!
best,
Jesse Czekanski-Moir & the AntAsk Team




Dear Ajay,

As it turns out, your question was a very interesting one. After a bit of digging, we discovered that most citations on the vestigial traits of Eciton eyes trace back to Schneirla's seminal book "Army Ants: A Study in Social Organization" (1971). The most pertinent parts of the book that deal with eyes as vestigial structures are quoted below:

"Although often spoken of as blind, all army ants are sensitive to light, and many of them have eyes. New World species nearly all have two tiny degenerate compound eyes called "lateral ocelli," equipped with single lenses (Werringloer, 1932). Even the workers and queens of Old World species, which lack eyes, have a subdermal sensitivity to light." [pp. 28-29]

"By contrast, foraging army ants utilize light only in minor ways as by withdrawing in groups from bright light in a fallen tree area or at the forest edge. Light, although forcing changes in their local movements, affects the main direction of the raid very little." [pg.75]

As you can probably see, the reference you were looking for is the only real citation in Schneirla's book on the material. The rest is assumed to be observational by Schneirla himself. Although we could not locate an electronic copy, we did manage to find a hard copy of the journal in the Field Museum library, and it looks to be heavily morphological.

Why is this so interesting? It appears that there have been no direct studies targeting the neurobiology of Eciton, indicating that the evaluation of worker and queen eyes as vestigial is based on morphology alone. Males, which need functional eyes to navigate during their mating flights, have eyes of distinctly different morphology in addition to the triad of ocelli on the top of their head, which you have probably already seen on AntWeb.

Hope this helps!

Best,

Max Winston & the AntAsk Team


--------------------

Hi

I was looking for information on eye structures of Eciton and discovered a comment made on the ant blog:

"Other vestigial traits are the absence of functional eyes in army ant species (see photo of Eciton burchellii below). These ants are blind, but show remains of the eyes."
http://www.antweb.org/antblog/2012/01/vestigial-features-in-ants-haley.html

Would you happen to have a reference for this? I have only got an old german reference which I have not found a pdf for!
Werringloer, A. 1932. Die Sehorgane und Sehzentren der Dorylinen nebst Untersuchungen ├╝ber die Facettenaugen der Formiciden. Z. Wiss. Zool. 141,432-524.

Any help would be greatly appreciated.

You guys are doing a fantastic job on the ant blog - keep it going!!

best wishes,
Ajay

====
Ajay Narendra
Bldg 46
ARC Centre of Excellence in Vision Science
Research School of Biology
The Australian National University
Canberra, Australia
http://antvisions.wordpress.com/ajay/

Polar ants?



Is there anywhere that ants do not live, such as Iceland, Antarctica, Alaska or Greenland? It is hard to find an answer to these questions on the web.

Thanks,
Jinho Lee


Dear Jinho

Thanks for another interesting question on ants. And thanks for your permission to post this at the antweb blog, as I did with your earlier set of questions.

There are a few ants that live in southern Alaska and neighboring northwestern Canada. One of these, Lasius neoniger, also known as the cornfield ant, is thought to be a relatively recent arrival from the south. It lives in the relatively warm and well-drained habitat of raised road beds, along highways. There are no resident ants in Iceland, Greenland or Antarctica.

It is a bit difficult to find information on your question, because people usually don't put up negative information, i.e., there are no ants in a particular location, so no one mentions ants from there. Here is a link to an article on ants of the Yukon: http://www.biology.ualberta.ca/bsc/pdf/francoeur.pdf.

It may surprise you to learn that there are also no native ants on the remote tropical islands of Polynesia or Hawaii. However, these all now have numerous "tramp" ant species brought in (accidentally) by human trade and commerce - a synthetic ant fauna, if you will.

James C. Trager of the Askant Team



To whom it my concern,

Hi, I live around Ozark, Missouri, and heard that their were some nice orchids and morells in this little wooded patch across from the Walmart over by 65. Anyway, I wanted to try to photograph some of them with my new macro lens, when I saw these strange ants, I mean they just looked really wierd. I read a few of you're blog posts, and thought maybe they were those velvet ant things?

Thanks a bunch!
Rick

strangeAnts1.jpg

strangeAnts3.jpg

Dear Rick,

These ants almost certainly belong to the genus Polyrhachis. There is a species that is fairly common in Southeast Asia that closely resembles the ants in your photographs, Polyrhachis bellicosa.


It is very strange that these ants have ended up in Missouri. If it weren't for the date, and the fact that you have the same name as a one-hit-wonder from the 80s, I might ask you to take some voucher specimens. As it stands, I'll just advise you that being funny and being cool with the lines is actually not the way love is supposed to be. That's why my girl doesn't like you. You're shallow and narcissistic.
http://www.youtube.com/watch?v=tMPB56KiQX8

Best,
Jesse Czekanski-Moir & the AntAsk Team