Tributes to Scientists


Did I see Dr. Bert Hölldobler at the Ants: Nature's Secret Power film screening Saturday night? Let me give you a hint:

The event was a golden opportunity to meet Dr. Hölldobler because the crowd was small (Arizona State University was having a lot of competing activities for Night of the Open Door.)

He started the evening with a brief overview of how the movie came about. It all started when director and cinematographer Wolfgang Thaler had the idea for a movie about ants and contacted Dr. Hölldobler. It was about the same time he was retiring from the University of Würzburg, so he wasn't sure about the project. Once he had seen a copy of Thaler's Bees - Tales From the Hive, however, he said he realized the idea had potential. (By the way, Dr. Hölldobler said that Tales from the Hive is the best movie about honey bees he has ever seen).

The final product of their collaboration is the award-winning documentary, Ants: Nature's Secret Power. It is a complex story that offers both glimpses into the "alien" world of ants for the layperson and peeks into the intriguing experimental techniques used in a high-powered ant research facility for the myrmecologist.

The visuals are outstanding for the most part, as you would expect from an experienced director. Dr. Hölldobler said he was particularly impressed that Thaler had the patience to wait for the ants to do what he wanted them to. He didn't rush shots. After the movie was shown, Dr. Hölldobler answered questions. His discussion of the part of the movie about the ants tending mealybugs was particularly intriguing. If you have seen the movie (or watch it below), you might remember the dark-colored Dolichodorus cuspidatus (with the golden hairs on their gaster) that were moving around Malaicoccus mealybugs like humans tend to domesticated cattle. He said Ulrich Maschwitz found that D. cuspidatus not only move around the mealybugs to find the best resources for them, but also cart their own colonies along, too. The ants do not build permanent nests, but are essentially nomadic, following their mealybug herds (See Journey to the Ants: A Story of Scientific Exploration by Bert Hölldobler, Edward O. Wilson pp. 149-150 for more information).

He also talked about the scene of the excavation of the leafcutter ants' nest, which reveals an extraordinary and massive underground structure. He said some of the trails underground extend 90 m or more from the nest. He also mentioned the conflicts that occur in that part of Argentina because the leafcutter ants and agriculture are at odds.

Listening to the passion in his voice, you can tell that Bert Hölldobler is still as excited about ants as he was when he started studying them as a young boy. It was definitely an informative and enjoyable evening. Have you seen Ants:  Nature's Secret Power? If not, I was able to find it on YouTube. Not the same as the big screen, but it is still pretty awesome, don't you think?



For more information, try:

As Ossein correctly commented, the naturalist who first realized that leafcutter ants were feeding on fungi rather than leaves (trivia question in the Fungus Gardener post) was Thomas Belt.

I first ran across Thomas Belt in the selection of essays about insects, Insect Lives edited by Erich Hoyt and Ted Schultz. In this collection the editors included two essays from Belt's book The Naturalist in Nicaragua (1874):  "Army Ants," and "The Ant and the Acacia Tree."

Thomas Belt (1832-1878) was a mining engineer by profession, but he was also a superb naturalist. When his work took him to places like Nicaragua he was able to put his keen interest and observation skills to good use. When examining leafcutter ants, Belt discussed the likelihood that many local trees and plants were probably less suitable for leafcutter ant gardens than undefended crop plants brought in from other areas. In addition to noting the leafcutters' use of fungal gardens, Belt also first recognized the nature of the relationship between "bull's-horn" acacias and ants, and that Cecropia stems provided homes for ants.

The electronic versions of his book The Naturalist in Nicaragua available for free at Project Gutenberg have a wonderful introduction from the Life and Letters of Charles Darwin. If you are interested in the "history" aspect of natural history, then you might want to take a look.

The Naturalist in Nicaragua is also available on Amazon for the Kindle

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While in Fort Collins, Colorado last month I spent a few minutes peering into small holes in the ground.

Why? This hole was not made by ants.

Instead, the hole was constructed by a digger wasp. By looking for wasps in action, I was paying tribute to Dr. Howard Ensign Evans, who spent most of his life studying digger wasps. Dr. Evans was a professor at Colorado State University in Fort Collins for many years, after working at Kansas State University and Harvard. Dr. Evans passed away this month (July 18) in 2002. I'd like to think that perhaps this wasp was the descendant of a wasp that he had once watched.

In general, digger wasps, such as this one, build burrows under ground as a place to raise their young. The female wasps capture various arthropods to feed to their offspring, and the type of prey taken depends on the species of wasp. Potential prey ranges from bees to spiders.

One she has captured a prey item, the wasp carries it into the burrow. There she lays an egg on the paralyzed arthropod. The larval wasp hatches out and consumes the arthropod meal over a period of days. When it is finished, it pupates and later emerges as an adult wasp.

You can see a digger wasp constructing the start of her nest in this video.

Over the years Howard Evans studied many, many different species of these wasps and carefully recorded all the different variations in their behavior. Some species only brought in one prey item and left it. Others brought in a series of prey over time. Some closed their burrows each time they went hunting, others left the entrances open. Some had simple tunnels for nests, others had more complex branching structures.

Most of these solitary wasps carry their prey under their bodies with their legs. Evans studied the wasps of the genus Clypeadon that grab worker harvester ants as their prey, sting the ants and then carry them back to their burrow attached to the end of their abdomen. As you would imagine, that looks quite unusual. Previous workers had thought the ant was carried on the sting, but Evans showed the wasp actually has a structure on the tip of its abdomen that is used for transporting the ant.

Over time, Evans put together a careful map of how all these behaviors were related, and how they had become modified. He produced a great body of work that is still being used and cited today.

In addition to being an accomplished scientist, Howard Evans was also a prolific nature writer. I discovered some of his more popular works, such as Wasp Farm and Life on a Little Known Planet, early in my career and they definitely influenced my interest in the family Hymenoptera. I'm sure many other budding entomologists have had a similar experience.

So, it seemed fitting to spend a few minutes watching a digger wasp and remembering, as a tribute to Dr. Evans.

See a more extensive biography at Howard E. Evans (February 23, 1919–July 18, 2002) by Mary Jane West-Eberhard

Alexander, B.A. 1985. Predator-prey interactions between the digger wasp Clypeadon laticinctus and the harvester ant Pogonomyrmex occidentalis. Journal of Natural History. 19:1139-1154.

Have you read any of Howard Ensign Evans books?

The Sand Wasps: Natural History and Behavior by Howard Ensign Evans and Kevin M. O'Neill, published by Harvard University Press, 2007.