Ant biology: December 2011 Archives


Dear AntAsk,

I am doing a hands on report/experiment on ants for 6th grade. I will need to test my theories and answer questions. My Hypothesis is, ants will only eat sweets. My investigative question is, are ants picky about their food? My mom and I have read info from www.live-ants.com. We found info of types of ants and foods they eat. I am supposed to mention who discovered this? Further investigation led me to Dr. Brian Fisher. He was identified as discovering the 12,000. different species. Can you help me to answer who discovered what ants eat, when, where, and how did they make this discovery or point out a resource I may be missing. Not able to search to get my answers. Also is there a specific ant farm I can purchase to test my hypothesis?
Thank You so much for your help.
Stephanie

Dear Stephanie,
Thanks so much for your question! Like you saw, there are many species of ants. In fact, if you include the species that haven't been described yet, the number may even be closer to 24-28,000! It would take a long time to watch all of those different ants, so for the majority of ants, we don't have any clue of what they eat.

For many of the ants that live around our houses, observations of their preferences are so easy that very few people have published in-depth studies of their diets. Asking who was the first to observe an ant eating something sweet is sort of like asking who was the first to observe rabbits eating vegetables. Even if I did find out who the first person was to write about rabbits eating vegetables, I would be reluctant to give them credit for "discovering" that! Also, as you found out, there are many, many species of ants, more than the number of species of birds! Ants live in many different places and eat many different things. According to evolutionary biologists, the last common ancestor of all ants may have actually been back in the age of the dinosaurs, aroud the same time modern birds may have started to diversity (give or take 50 million years), and perhaps before the origin of modern mammals (there are more than twice as many ant species as mammal species!) so asking who discovered what ants eat is a little like asking who discovered what birds or mammals eat. Without being more specific, you're going to have a hard time!

That being said, several researchers have been doing very interesting research on specific diet preferences of ants. In another blog post we put up today, Dr. Mike Kaspari explains why some ants might be more attracted to salt than to sweet bait (read more here). In some older studies, Dr. James Brown (no relation to the funk/rock singer) showed how important competition was between ants and rodents for seeds in desert communities in the American Southwest (overview of his experiments here and here). Dr Corrie Moreau and Jacob Russell and their colleagues discovered how important it might be for certain kinds of bacteria to live inside of certain ants, so that the ants can get all the nitrogen they need just from the bacteria turning nitrogen in the air into food the ants can use (read more here)! Other authors have researched what the best ratio of food is to feed to ants. For example, Dussutour and Simpson published the recipe for a diet that they claimed made their ants the happiest (click here for link).

Those four studies show how the environment might change what ants need to eat (Kaspari), how ants might change the environment for other animals by competing with them for food (brown), how ants and bacteria can work together to make food for each other (Russell and Moreau), and what the basic nutrients ants might need are (Dussutour and Simpson). The important thing to remember about ants and the food they want to eat is that just like us, they need carbohydrates, fats, proteins, and lots of vitamins and minerals. Ants definitely need salt, for example, and calcium. Some ants usually get by with mostly sugary water they drink from different parts of plants, but most of those ants will also eat fatty, protein-rich foods like peanut butter and dead insects. It all depends on what nutrients they need most at the moment. Some ants are strict predators, and will pretty much ignore anything that doesn't move. Leaf-cutter ants actually chew the leaves they cut into something like paper mache, and use that material to grow fungus garden (They are the worlds first gardeners--they discovered agriculture millions of years before we did!).

If you give us some more information about where you live, we might be able to help you out with diets of specific ants you might be able to find around your house. Many of the best Ant Farm ants are the "Seed Harvester" ants, in the genera Pogonomyrmex, Messor, and Aphaenogaster. These ants will sip sugar, but they need to gather seeds as well, to feed to their larvae. In terms of ants that you might already have around your house, Structure-infesting Ants (or any of Stoy Hedges books) has a number of good notes on dietary preferences of ants that are commonly found in and around houses in North America. If you don't live in North America, let us know, and we might be able to point you towards some other general references.

So, to summarize, if you have a certain type of ant, you might be able to discover who best characterized the different foods that ant eat. You might want to check out some other blog posts here about specifics for ant foods here, here, here, here, and here. About specific ant farms, it might be easiest to just place some bait out in an open jar and try to catch some ants! If you know of some place that there are ants around, you could get a bunch of small jars. I've used baby-food jars before, but I'm sure anything would do as long as it has steep, smooth sides. Just put a bunch of them with different kinds of food out in a place where you know there are ants (for example, every 5 paces along a wall), and pick them up three or four hours later! Then you can see which kind of food got more ants. My favorite food to use is peanut butter, but other people think tuna fish works really well, or some kind of nutty, shortbread cookie. For sweets, you could use honey, jelly, or any kind of sugar-water solution.

Hope this helps!
best,
Jesse

ps., just for the record, Brian Fisher is an amazing guy, and he's described quite a few species of ants. However, he did not describe all of them. You can read more about people who have described some of the 11,000 or so ants Brian hasn't had time for here. In fact, I'm pretty sure Dr. Fisher himself has a number of heros in the ant world, including Dr. Barry Bolton. There are lots of great qualities that make Dr. Fisher special, even amidst the hundreds of talented myrmecologists (people who study ants), but personally one the things I'm most grateful for is his passion and persistence at pulling together this great website. Pretty much everyone who studies ants would have a much harder time doing our jobs without it!

Hi,
For my specialist study in the UK I am studying the food preference of Lasius niger by feeding them 3 cotton buds soaked in different solutions (sugar+water, salt+water, and just water). So far, I have found that they prefer the salt solution over the suger solution and I am wondering whether this is possible as Lasius niger are knwon to prefer sweet foods over others. I believe the food preference is seasonal and is related to colony needs (althought my colony does not have a queen).

Kind regards,
Christina
*****

Dear Christina,

Your ant feeding experiments sound interesting. We contacted an expert on the salt preference of ants, Dr. Michael Kaspari, to help us with this question. Here is what Mike had to say:

"Christina,
It is indeed possible. A diet rich in plant exudates like nectar is typically poor in sodium, the Na in NaCl, or table salt. We have found that ants that are more herbivorous are likely to take advantage of NaCl baits, especially if those baits are presented to ecosystems that are far from an ocean source of sodium. Check out KASPARI, M., YANOVIAK, S. & DUDLEY, R. 2008. On the biogeography of salt limitation: a study of ant communities. Proceedings of the National Academy of Science USA, 105: 17848-17851."

Mike also suggested Googling "ants" and "salt" to find other relevant resources.

Best of luck with your research!
Mike Kaspari (guest expert), Corrie Moreau & the AntAsk Team

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