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Ants As Geochemists

Ants have been known to have a positive impact on soils by mixing different layers and by adding nutrients, etc. Now a researcher from Arizona State University, Dr. Ronald Dorn, has found that ants are enhancing the breakdown of certain minerals and the movement of carbon dioxide into calcium carbonate (limestone). The bottom line:  ants might be helping to remove greenhouse gases from the atmosphere.

Dr. Dorn did not start out to study ants. He actually began the study 25 years ago to look at weathering of olivine and plagioclase minerals from Hawaiian basalt. He placed samples in various sites in Arizona and Texas, and then went back every five years to see what was happening to them.

Other researchers have shown that weathering of calcium and magnesium silicates by living things is important in removing atmospheric carbon dioxide gases. A simplified reaction is shown here:


Over the 25 year period of this study, Dorn found the ant colonies of eight different ant species (Pogonomyrmex rugosus, Pogonomyrmex barbatus, Dorymyrmex bicolor, Forelius pruinosus, Liometopum luctuosum, Tapinoma sessile, Formica neogagates, and Camponotus vicinus), enhanced the weathering of the minerals some 50x-300x over that of the bare ground control. At the same time he found the percent carbonate increased substantially in the nests of all the different species.


Pogonomyrmex worker ant moving soil from its nest.

Of all the factors he studied, Dorn found that ants were by far the most important weathering agents. Given the amount of material a given ant colony moves around, that is not surprising.

What was a bit more surprising was that all the ant nests accumulated calcium carbonate over time, at levels well above what was happening in bare soil nearby. Perhaps it is time to investigate what exactly ants are doing in those underground galleries.

What do you think? Are ants an answer to removing excessive carbon dioxide from the atmosphere?

Dorn, R.I. (July 14, 2014) Ants as a powerful biotic agent of olivine and plagioclase dissolution. Geology.

Interested in learning more about the impact of ants on soils? Try this excerpt from the Encyclopedia of Soil Science Vol. 1

Pogonomyrmex Mystery: What Are Those Spots? Follow Up

Remember that  Pogonomyrmex nest with the shiny black spots around the nest entrances from a few weeks back?



This one?

Upon revisiting a few weeks later, the ants are looking better.


They seem to have cleaned up nicely.


Maybe there are a few spots left, but nothing like before.


What are they harvesting today? You probably recognize the beetle elytra, but what is the gray cylinder?


You might need to be from Arizona to recognize it. That is part of a seed pod from a tree with the common name “screwbean mesquite.”

Wonder what they will be up to next time I visit.

What kind of ants do you visit regularly?

Pogonomyrmex Mystery: What Are Those Spots?

While visiting a local park this week, I stopped by to visit a Pogonomyrmex nest I have been watching over the years.


I almost immediately noticed the black spots around the nest entrances.


Here’s another entrance about 20 inches from the first two. There was a noticeable blackening around the hole in comparison to the surroundings. Otherwise, the ants seemed to be active and doing fine.


This is a closer view.


Looks kind of shiny.

My first thought was ant feces. Studies have shown that some ants mark their nest areas with feces, for example a study by Grasso et al. (2005).


My other guess is that someone tried pouring something into the nest (as it is a public place.)

What do you think? Have you seen this before?

Grasso, D. A., Sledge, M. F., LE Moli, F., Mori, A., and Turillazzi, S. 2005. Nest-area marking with faeces: a chemical
signature that allows colony-level recognition in seed harvesting ants (Hymenoptera, Formicidae). Insectes Sociaux 52:36–44. (.pdf available for viewing)

First-Rate New Book: Beetles of Eastern North America

Look what came out this week: Beetles of Eastern North Americaby Arthur V. Evans.

What’s a myremecologist like me doing talking about a book about beetles? Ants and beetles actually get along well.

This book has something for everyone, in fact, hard-core coleopterist to lightly-interested amateur. If you are new to beetles, it is a fabulous place to start learning. There is an extensive introduction covering anatomy, natural history, where to look for beetles, how to observe and collect them, etc. On page 52, Evans discusses how to become involved in beetle research, encouraging students and amateur naturalists to participate.

The majority of the book, however, is devoted to the beetles themselves. It covers a “goliath” number of species: 1,406 with representatives from all 115 families of Coleoptera. Even better, each species description is accompanied by a full-color photograph. Most of the photographs are of live specimens, showing the shape and posture as no drawing can. The photographs are by a number of different photographers, but care was obviously taken that the images are of uniform composition and quality. This is not a lightweight field guide, but a desk top reference you will go back to again and again.

Let’s do a test run and see if the book describes some beetles I’ve chosen at random.


Does the book have the thistle tortoise beetle, Cassida rubiginosa? Check, listed on page 435.


What about the lady beetle, Coleomegilla maculata? It is described on page 315.


How about the spotted asparagus beetle, Crioceris duodecimpunctata? On page 433 there is another Crioceris species, but not this one.

How about these?


The tumbling flower beetles were easy enough to key to family Mordellidae, even from this photograph. With only 17 species shown out of a possible 149, I couldn’t identify them any further.

I’m pretty familiar with beetle families, so it probably took only a few minutes to find the first three beetles and less than 5 minutes to key out the last one to verify my guess. The photographs add a lot of information and make searching easy for the visually-oriented. With the Glossary, family classification list in the Appendix, and a full Index, the book is a breeze to use. The page numbers are even easy to read and find.

If you are interested in beetles, then this is a must have. Are you still using those two old volumes of Dillion and Dillion? Are still thinking of bark beetles as Scolytidae? Get up to date with Beetles of Eastern North America!

Paperback: 560 pages
Publisher: Princeton University Press (June 8, 2014)
Language: English
ISBN-10: 0691133042
ISBN-13: 978-0691133041

Disclosures:  This book was supplied by the publisher for review purposes. Also, I am an affiliate for Amazon, and if you click through the linked titles or ads and make a purchase, I will receive a small commission at no extra charge to you. Proceeds will be used to maintain this self-hosted blog.