"In the early years of the twentieth century, South American fire ants crossed the Caribbean and invaded the shores of the south-eastern United States. These imported fire ants quickly found a niche in Gulf Coast fields and lawns, overpowered the native species, and began spreading. In the process they became a notorious pest to some, a beneficial ally to others, and a potential killer to allergy sufferers. As a result, they are among the most intensely studied insects in the world." Because the literature about Fire Ants has grown to such a massive amount, S. W. Taber decided to write a survey of what has been written about these ants.
      The first person to review this book was Mark A. Deyrup, a Fire Ant specialist in Florida. Starting with this review, the debate about the book got sometimes very angry and I decided, reading the book, to review not only the book but also M. A. Deyrup's review. If you allow, I'll start with this first and then look at the rest of the book.
      The first problem dealt with the Tropical Fire Ant (TFA) and the elaiosomes of a violet species (Viola odorata) . Both are native to the southern U.S.A. and Middle America . Taber wrote: "In Central Texas the plant "Wedelia hispida" uses fire ants to disperse its seeds. The seeds have oil-rich appendages called "elaiosomes" that the insects eat after they collect the seed and take it back to the nest. The discarded seeds germinate at a distance from the parent plant, thus perhaps avoiding competition with others of their own species. The plant's strategy is called myrmecochory. The arrowroot plant "Calathea microcephala" of tropical Mexico has similar success. But the ploy does not always work. The TFA takes the elaiosomes of the related arrowroot "C. ovandensis", leaving its seeds behind, still attached to the plant and undispersed. The ants build soil tunnels over these seeds while they do their work. At least one violet species is able to save its seeds from fire ant predation with an elaiosome. In the Dominican Republic the TFA disperses seeds of the pope's head cactus "Melocactus communis" in a similar fashion." (p. 73-74). Deyrup's remark in the review was: "The function of the elaiosome on seeds of a species of violet is not to "save its seeds from fire ant predation.""
     The quoted passage of "Fire Ants" is all that you can find in the book about the function of elaiosomes. The elaiosome is developed as an organ to attract ants (including TFA) and stimulate them to take the seed to the nest. There the ants eat the elaiosome and the seed stays in the nest or is taken to the refuse heap. In short, the seed is transported to a different place (dispersed) that gives a form of protection (from animals that eat it) and is richer in nutrients (food-products) for the seed! Also, while eating the elaiosome, the ant does not eat the seed. Thus, the plant and the ant developed together and all functions are clear. So, as a way of saying, the seeds are saved from predators, including the Fire Ants themselves!
In the original article about the violet, Beattie and Lyons wrote: "One V. arvensis seed was found destroyed and empty, while five V. odorata seeds had been gnawed, the elaiosomes removed, and returned to the surface intact. …the results of this experiment suggested that predator avoidance plus dispersal could be achieved by providing large seeds with tough seed coats but very large food bodies as bait." and "When the elaiosome is small or perhaps nonexistent the ants are more likely to eat the seed itself. When the elaiosome is present the ants were at least sometimes content with this food and did not follow through on seed destruction." (p. 717).
      The second remark of Deyrup was: "Polygyne fire ant nests that bud off daughter nests are not an example of "asexual reproduction."" This is related to two passages in Taber's book: "Queens of the polygyne social type disperse to begin nests of their own by simply leaving the colony in an overland march with a contingent of workers. This is dispersal by a kind of "budding" that calls to mind the asexual reproduction of yeasts or protozoa." (p.24) and "… ; (2) polygyne nests that bud off daughter colonies in a manner like that of a budding yeast cell, when queens simply leave with a contingent of workers; …" (p. 54).
In both cases Taber compares the budding of a colony with the asexual reproduction of yeast or protozoa (to make it visual!) but does not say that it is asexual reproduction! It is only a comparison that was misinterpreted!
      Next, Deyrup writes: "The statement that one of the now-rejected chemical controls "might have done the job" strikes me as one of those retroactive fantasies of omnipotence typical of we middle-aged males. By the time such control was begun, the red imported fire ant had dispersed widely. Even if we modern experts had been in charge, we could not have stopped a widespread, highly mobile, generalist species that reproduces rapidly, is easily relocated by commerce, and is beautifully preadapted to the habitat disturbances diagnostic of the ecological niche of our own species."
Taber makes indeed that statement on page xv. But if you read chapter 11 ("Chemical Control and the Pesticide Issue.") you will see that there were a few good candidates to eradicate the Fire Ants! One was "Heptachlor" but it was to dangerous for humans and wildlife and stayed to long in the environment. The other was "Mirex" but this was rejected after a lot of years because they said e.g. that it caused cancer (never proven and related products were tumor-inhibitors.) and it killed and deformed rodent-embryo's (but it was originally released as a rodenticide!). So the two best candidates were rejected although they were very good against fire ants!
      The forth dispute was about Taber saying: "An unidentified substance on the TFA exoskeleton decreases the viability of narcissus pollen. This may explain why ants are not pollinators, though they would appear to be ideal candidates because they are dominant arthropods and because pollination behavior is so widespread among their wasp and bee relations." (p. 77). Deyrup's remark goes: "Ants would not make "ideal pollinators" were it not for pollen-inhibiting chemicals, because ants travel everywhere on foot, automatically making them lousy pollinators, irrespective of their body chemistry."
Now , I would restrict Taber's remark to fire ants and not to ants in general because there are ant species that pollinate flowers (e.g. Myrmecia workers in Australia that pollinate, together with a few other species, a series of Orchids. There are also a few other plants that are pollinated by worker or male ants !). For the same reason, Deyrup's remark isn't also correct. It depends on cuticular chemistry and behavior, but it doesn't exclude that there are ants that pollinate flowers!
      Now we reach critique number five. Deyrup states: "…Ernst Mayr did not actually state or imply that "the introduction of an exotic is good for all but the invader's closest competitors because the presence of an additional species increases biodiversity.""
In the attacked passage, Taber is wondering if the Fire Ants are pests or blessings and this as an introduction to the chapter "Fire Ants Pro and Con". Now here you have to read a little bit more: "Some evolutionists and even a few ecologists seem to believe that the introduction of an exotic is good for all but the invader's closest competitors because the presence of an additional species increases biodiversity (Mayr 1963; Elton 1958). This view is definitely opposed to the mainstream opinion. However, the issue has never been properly addressed in the case of the fire ants." ( p. 194 ). In a reply to Deyrup's criticism , Taber quoted from page 76 of E. Mayr's "Animal Species and Evolution" (1963): "It should be mentioned that every new arrival in an area tends to add to the total diversity and to enrich thereby the opportunities of other organisms except the most immediate competitors..."
So , Taber does not say that it is good or bad to introduce ants and he is not quoting (exactly) Mayr or Elton. He is just thinking: Is it good or bad and what are the opinions of others? He even says that most are against introductions. The problem is that nobody has looked at the case "The Fire Ants" and in the rest of the chapter he provides points pro and contra for Fire Ants. At the end of the chapter he makes the remark "…that fire ants have a beneficial side that has been largely overlooked." (p. 215) and that we don't have to see them only as big noxious pests!
    The sixth remark of Deyrup is: "One can read the entire volume and still lack answers to reasonable questions about fire ants." Taber did not have the intention to answer unsolved questions (A synthesis doesn't give answers to things that aren't looked at!), but to review all that was written about Fire Ants ("My own purpose is a synthesis of the enormous literature on the fire ants of the world.", p. xv.) and, according to me, he succeeded in it! I'm amazed how much information can be included in such a small book! You also have to remember that this book was written in 1999 and published in 2000, so don't expect scientific findings that were published after 1999 (e.g. the review of "Pseudacteon" flies.)! Also, sometimes a synthesis brings answers in the open that stayed in the dark, but not always, and this book doesn't !
     Related to this is the next thing Deyrup says: "The vision, complete with map, of future distribution shows the red imported fire ant sweeping up the West Coast to Canada. This seems highly unlikely: the extremes of temperature in Seattle might not be too cold for fire ants, but the northern west coast marine climate is unfavorable to a broad spectrum of ants for other reasons." Now this is something I don't like so much either, predictions about the distribution of an animal in the future. There are so much variables that influence these distributions that speculations and predictions are unreliable! Also, probably most of the interfering factors aren't known yet or aren't quantifiable at this moment! So I don't like these computer-simulations because they are limited in their predictive powers! Taber gives them for the RIFA (p. 219-221) and makes remarks about these simulations (e.g. cold tolerance and global warming problems, p. 223 + p.225.). All this between information on the distributional history of the RIFA. But indeed, these simulations are all unreliable but Taber included them, according to me, to make his literature review complete!
      And finally, Deyrup's last remark is: "In the key to species one must check the "dorsolateral junction of the propodeum", a hitherto unknown feature, which is absent from the glossary." This will lead me to the part of the book I didn't like to much ("Appendix 2") and into my own review of "Fire Ants".
If you read the revision of fire ants by J. C. Trager (1991, A revision of the fire ants, Solenopsis geminata group [Hymenoptera: Formicidae: Myrmicinae], J. New York Entomol. Soc. 99: 141-198.), you notice that Fire Ants are not an easy group (Some specimens are, at the moment, not determinable to species!). So I would like to see the following points considered or included in the next edition of the book. First, if you work, for a part, with coloration differences between species in the determination keys and you give pictures to show these differences, don't give the pictures in black and white but in color. I would suggest that at least figs. 1.8, 1.9, 1.10, 1.11, 1.12, 1.13, 1.14 and all the photographs of "Appendix 2. How to Identify U.S. Fire Ants" should be in color . Second, the terminology in the determination keys is not so clear as in Trager's revision (e.g. the feature mentioned above by Deyrup takes, in Trager, 2 to 3 lines of explanation, starting with "…propodeal carinae originating…", in each lug of couplet 3!), but it is still detectable what is meant ! The third point is about the determination keys. Why dividing them in two parts, one for imported species and one for natives? You must get the chance to determine them with the keys even if you don't know if it's introduced or not! Yes, the division is explained on page 231 (If you need a quick determination, you take automatically the keys and not the text 3 pages earlier to start the determination of the specimen!), but I would have liked to see it in the keys! And lastly, the key I prefer is the more elaborated one of Trager! Why not asking Trager if it is possible to include his determination key (couplets 2-7/7c !) in the book. This key is more elaborate and, according to me, it is the best at this moment!

The rest of my review is about some small remarks I have about "Fire Ants".

      The first remark is about the sex ratio's mentioned in the book. On page 32 Taber says "…total sex ratio is 1:1 sexual female to male,…" and on page 109 he says "…do produce approximately three times as many sexual females as males." Both quotes are about RIFA! These are contradicting results! But in the field of social evolution, these are important differences. In one case (a monogyne colony with a queen who mated only once!) it is known that females prefer a sex ratio of 1:1 and workers of 3:1 (This has to do with the asymmetric relatedness between mother and son/daughter at one side and sister and brother/sister at the other side respectively.). Later on, in the discussion about his book, Taber said "For example, I think we'll find that there is no contradiction regarding sex ratio. If one investigator finds and reports one thing, and another finds and reports a second thing. They don't have to agree at all. This isn't math, it's the variation of nature and the variation of investigators we're confronted with. I'll have to look. In any event, it probably won't be MY contradiction. For example, the sterile females are of the female sex, sterile or not, and I was merely drawing attention to what the numbers would be like IF the calculations were done differently. And remember, please don't curse the messenger..." This last remark of Taber is about the following phrase on page 32 were he says "The sex ratio would be enormously biased in favor of females if the hordes of sterile workers were included in the calculations." This is never done! Only the possible future reproductive individuals are counted.
      Second, on page 43, when talking about polygyne colonies, Taber says "…, the recognition pheromone of one appears to be more attractive to workers than that of any other queen,…". In that case the other queens loses in the end and, after execution of these "losers", one queen remains and the colony becomes monogynous! This can't be the outcome in nature where a polygynous colony stays polygynous.
      The third remark is about the location of the metapleural gland on the "…front part of the abdomen…" (p.44) and on "…the anterior abdomen." (p.77). On page 77 Taber also uses the terms head, thorax and gaster (The correct and accepted terms in Myrmecology!) so I would have preferred that he said "…at the lower hind corner of the thorax."
      On page 48, for my remark number four, you can read "…, but because the vast majority of males in polygyne nests are sterile for some reason,…". These males are from inseminated eggs (diploid) but the information on the corresponding genes is identical (mostly as a result of inbreeding!). Because of that, these males have problems with the production of sperm cells and that is the reason why these males are sterile! These results are from research done by Ross and Fletcher .
      The fifth remark is a very small one about "Chapter 10. Medical Importance of Fire Ants." (It starts on page128.). This is a very good review of fire ant venom and it's effect on humans! The only remark I can make about this chapter is that I would have liked some figures of the alkaloids and the allergenic proteins mentioned in this chapter.
      Then, on page 148, I read about "the Mrak report of 1969." But I would appreciate it if I could find the reference for it in the "Bibliography."
      Remark number seven goes about a passage you can find on page 151. Talking about virgin egg laying females in polygyne colonies, Taber writes that they "…will probably be limited to the production of male offspring, which are commonly sterile in polygyne colonies anyway." Now, this is the combination of two different things, first that virgin queens lay eggs that aren't inseminated and these are producing males (haploid and fertile!) and, second those males I referred to in my remark number four.
      The next, number eight, is about the "Bibliography" that starts on page 243. On page xvi of the "Preface" Taber says a few times that he used "Biological Abstracts" for compiling a big part of the bibliography . Why didn't he also used the "Fire Ant Literature Database" (FALD) or "FORMIS" (In this the FALD is included as one of the foundations.). I know that "FORMIS" doesn't include all ant related articles and books (That's why they keep expanding the old references in it while they make updates!) but these are already vast resources to find scientific Fire Ant literature!
      And lastly, there are some typographic errors, not to many and not disturbing ones, but these are not mistakes made by the author and they aren't included here.
      Now, in this concluding section, I want, before my closing remark, to mention two paragraphs that I found confusing. Their contents is correct but, to be clear and bright, they needed more space in the book to explain them!
      The first one is this: "Tropical fire ant queens do not seem to produce the diploid variety of the male sex, though the RIFA can. Diploid males have twice as many gene-bearing chromosomes as the more common haploid variety of male ant. Nor are the winged TFA virgin queens likely to shed their wings and begin laying eggs when the mated mother queen is removed from her nest. The tendency to do so seems to be unique to one or a very few fire ant species and perhaps evolved when recently mated queens attempted to usurp the reproductive role after joining established colonies." (p. 81). Just don't let you be distracted when you read this passage and everything is o.k.!
      For confusion number two, we go to page 114: "It is often found that hybrids are superior in some ways to both parental species, a condition known variously as hybrid superiority or hybrid vigor. An increase in genetic variation is considered an indication of the phenomenon, and although this increase is apparent in the case of the RIFA x BIFA hybrid, the supposed superiority over the parental types does not seem to hold because hybrid fire ants which resemble a given parent more than the other are inferior in competition with that same parent. Yet the hybrid is encroaching upon the BIFA's range and may eliminate the original import with the help of the red imported fire ant. In fact, the range of the hybrid now exceeds that of the BIFA. This trend would seem to conflict with the generalization that hybrids are inferior to the parental types that surround them, and with the generalization that hybrids more like one parent than the other suffer in competition with that parent." It is correct, this passage, but a little bit mind-buzzing like it is written here! I had to read it a few times on a quit place before it sank in and got clear to me! This is the darkest passage in this book!
     
      And now my closing remark to end this long and enduring review: I didn't "find cause to cringe and twitch on almost every page.", no, I enjoyed reading it and did find things I didn't know (e.g. "It is now possible to culture fire ant ovaries in the laboratory for a period of at least eight months. This…" you can find on page 54!). For me this was a very good review of Fire Ant literature (except the determination-key.)!

E-mail: marc.stappen@pandora.be