Reader Questions

Recently a follower on our FaceBook page asked an interesting question,  "Will ants die if they eat chocolate?"

The question is an intriguing one. As many of you probably already know, consuming chocolate can be fatal to dogs and cats. A friend of mine recently had to rush her dog to the vet because he ate most of a large cake with chocolate in it.

The compound that is toxic to dogs and cats is an alkaloid called theobromine. Chocolate also contains small amounts of another, related alkaloid: caffeine. In fact, theobromine is a chemical precursor to making caffeine in plants. (Some of the older literature suggests chocolate does not contain caffeine, but newer, more sophisticated chemical tests have shown that caffeine is indeed present in chocolate). See the Hershey website for a discussion of theobromine and caffeine in chocolate.

Caffeine is known to kill insects. Nathanson (1984) suggested that it was a naturally occurring pesticide, and showed that it can inhibit growth in tomato hornworm larvae. More recently, scientists have been looking at genetically modifying tobacco plants to make caffeine. Their thinking is that the caffeine would repel or kill insects that feed on the tobacco. In their experiments, the caterpillars of the tobacco cutworm and small white avoided eating plants treated with caffeine. It was a repellent (Kim, et al.).

What about in ants?

As personal experience, I had once used a chocolate-covered peanut butter candy as a bait for some ants.

The sidewalk ants seem to prefer the peanut butter, although possibly a couple are trying the chocolate. It isn't clear.

This fire ant also seems to be feeding on the peanut butter part. This highly-limited evidence might suggest ants might also be repelled by certain ingredients in chocolate.

Miyashira, et. al. recently looked at the effect of caffeine on leaf-cutter ants. They found that although there was "no conclusive effect" on the ants, the higher doses of caffeine did kill the mutualistic fungus that the ants use for food.

Back to our central question, can chocolate kill ants? Obviously caffeine can be a repellent and potentially have adverse effects on on insects. Caffeine is only a minor ingredient in chocolate, however. Chocolate is a conglomeration of some 300 different chemicals, any one of which could have an adverse effect on ants. Obviously more research needs to be done.

I was intrigued by this problem enough to set up a small experiment. I let you know more about that in an upcoming post.

What do you think? Do you know if chocolate has an effect on ants?

References:

Kim YS, Uefuji H, Ogita S, Sano, H. (2006). Transgenic tobacco plants producing caffeine: a potential new strategy for insect pest control. Transgenic Res. 15(6):  667-72. (Abstract at PubMed) (Google the title for a free .pdf version)

Carlos H Miyashira, Daniel G Tanigushi, Adriana M Gugliotta, Déborah YAC Santos. (2012). Influence of caffeine on the survival of leaf-cutting ants Atta sexdens rubropilosa and in vitro growth of their mutualistic fungus. Pest Management Science. 68 (6): 935–940.

Nathanson, James A. (1984). Caffeine and related methylxanthines: possible naturally occurring pesticides. Science 226: 184-187.

For more about chocolate and how it is made:

Ask-a-Scientist at Binghamton has general information about how chocolate is made

For more depth try The Science of Chocolate by S.T. Beckett (link goes to an excerpt at Google Books)

Recently a reader had a question about ant anatomy. "I want to know the division of the ant's body where the head, chest and abdomen and what is from the antennae and legs and wings, eyes, etc."

In general, insects have three body parts: the head, thorax, and abdomen.

In ants, however, the main body parts are not as easy to tell apart.

When adult ants are developing their lovely thin “waists” within the pupa, a bit of the true abdomen gets pressed up against the thorax, and the rest of the abdomen becomes the "waist" and the hind section. When ant biologists realized this problem, they thought,  “Hum, we can’t really call that middle section a thorax, if it’s really a thorax and a bit of abdomen pushed together. And we can’t call the back section an abdomen if it’s only part of the abdomen… so we’ll call the middle part a mesosoma (in older literature an alitrunk) and the back part a gaster (or metasoma)." The thin part between the mesosoma and gaster is called the petiole. The head is still a head.

In some ant species, the "waist" is longer and consists of two segments, which are called the petiole and postpetiole.

Roberto Keller has an excellent illustration of the segments that make up the true abdomen.

Scanning Electron Micrograph, Roberto Keller/AMNH)

The bit of abdomen that joins with the thorax is labelled as I in this diagram. It is called the propodeum. The segments labelled II and III are the petiole and postpetiole. The rest form the gaster.

If the ant is a queen rather than a worker, you will see either the wings attached to the mesosoma (labelled as trunk), or wing scars where the wings were attached.

Hopefully that helps answer your question.

If you have anything to add, please leave a comment.

2 Comments

We have a question for the Consult-Ant today:

Hello

I wanted to ask you if wild Harvester ants, will learn to eat the gel in a antworks gel farm.

I have an empty one and put about 30 wild, I'm pretty sure they are harvester ants, same size same color, but I am guessing of course. But my main concern is if they will learn to eat the gel or will I have to feed them. Its real nice of you to answer ? from us newbies.
Thank you very much.

Ron

Dear Ron,

I am glad to hear about your interest in ants. You are correct to be concerned about whether your harvester ants will eat the gel supplied with your ant farm.

The blue gel used in ant farms was originally put together for a short science experiment designed by students. The students were sending ants up on the Space Shuttle for a few days and they needed something that they could see the ants through and that would stay in place with no gravity. Obviously, sand would not work.  They came up with the blue gel and it worked well for their experiment.

The problem is, it was never meant to be used to keep ants for a long time. Although it will keep the ants alive and they will tunnel in it, it isn't the best food for them. However, if you put a bunch of food into the gel habitat, there is a good chance you will get mold and bacteria growth, which will harm the ants.

In the video below, you can see how the person places the food on a small bit of aluminum foil. That would be a helpful way to feed your ants in the gel ant farm. Try to keep the food on the foil and replace it once a day.

Also, your harvester ants can eat the same sorts of things as shown in the video. They will accept a bit of dead insect, such as a small cricket and/or a few drops of honey and water mixed together. You can soak the honey and water into a bit of cotton or paper towel so it won't drip as much.

Here's an excellent video that shows some basic information about how to feed and keep ants:

I know it isn't as cool to look at as the gel, but people who are serious about raising ants use a test tube nest (the link shows you how to make one).

This link has a lot information about how to build/make several different kinds of ant farms, in case you want to try another kind.

It's great that you have decided to find out more about keeping ants. It can be a very interesting hobby. Let me know if you have any other questions.

(Note: As I mentioned previously, I have been the “Consult-Ant” on the Leaping from the Box website. I answer questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)

5 Comments

Just had a question come in from a young ant enthusiast (edited):

If you have heard of an Ant-O-Sphere(eight pods) I’m trying to make a colony in there but so far the bulldog ants are too big and the Argentine ants are too small.

I don’t know what other ants I can find in Australia (where I live) Victoria Mornington.

I wonder is there an ant shop in Victoria?

I'm not familar with Australian ants at all, so I'm going to put this out to you the reader. Do you have any helpful suggestions?

It is easy to imagine that neither bull ants nor Argentine ants would be really the best choices for an ant farm. It also seems likely the Argentine ants are probably chasing out the local species of ants (see reference below), like they have done in California.

Does anyone out there have any ideas of suitable Australian ants that might be available and good for use in an ant farm?

References:

Argentine ants give weeds a boost at ABC Science

Ants of Australia