Ant biology: December 2010 Archives

Can ant colonies reproduce and sustain with no queen? And what is the role of the queen in the actions of the other ants? Has it been found to have any instruction, or only egg laying? (Angela, Baton Rouge, Lousiana, USA)


Hi Angela,

In a "typical" ant colony, there is one or several queens that have been fertilized on their mating flight before colony founding. These queens lay eggs. The queen can lay fertilized eggs, which will develop into females (workers or - when the colony is mature - workers and new founding queens). The queen can also lay unfertilized eggs, which then develop into males. If there is only one queen per colony and this queen dies, the workers can start to lay eggs. But since the workers have not been fertilized, these eggs only develop into males. Males don't contribute to maintaining the colony, they will fly off once mature to mate. So the "typical" colony cannot sustain without the queen. However, there are some ant species (e.g., Platythyrea punctata), in which workers are clonal and lay eggs that develop into females. In these colonies, the most dominant worker will lay eggs while the others maintain the colony. Once this reproductive worker gets weaker or dies, another worker will become the reproductive. A really nice review on exceptional colony structures is "The demise of the standard ant" by Jürgen Heinze.

Coming to your second question: Ants communicate with chemical signals. These can be pheromones or cuticular hydrocarbons. The queen produces a range of pheromones and by this gives instructions to her workers. One important instruction is that the workers don't lay eggs. It is in the queen's interests that she is the only egg-layer and the workers nurse her offspring, forage and defend the colony. So the queen produces pheromones that suppress the ovary development of the workers. Once the queen dies, the workers will start to develop ovaries to lay unfertilized eggs and these will develop into males. Please also read this post on ant pheromones.

All the best,
Steffi Kautz & the AntAsk Team

Specifically, I am asking if there is any record of it occurring. I imagine that the odds of it happening are extremely low, if not zero!

Thank you,
Josh


Hi Josh,

Thank you very much for contacting AntAsk! Actually, this is a really good question. At first glance ant colonies seem to be organized in a standard manner, with one queen per colony. The queen has mated once and she produces workers that are all full sisters. However, when we start taking a closer look at the organization of ant colonies, there seem to be more ant species that have some kind of exceptions than the ones that don't. A really great review on this topic is the paper "The demise of the standard ant" by Jürgen Heinze.

There are some ant species, which don't really have a distinct queen, but special workers that lay eggs and are called "reproductives". One example is Platythyrea punctata. This ant is clonal and theoretically all the workers have the potential to become the reproductive of a colony. In these cases, a single worker could leave the colony and have her own colony. But workers don't leave the colony purposely. It is really risky to found a new colony all on their own and they have a much higher chance of success when they work as a colony. However, if the old reproductive dies, the colonies of these clonal ants can live on. When a workers gets separated by her colony and she is in good health, I suspect, she would try to start her own new colony.

Another case in which ant workers would leave their colony is when they have an infection. Some ants in the tropics might catch an infection by the entomopathogenic fungus Orthocordyceps. A great YouTube video of an infected bullet ant (Paraponera clavata) is found here. At a later stage of the infection, the fungus grows into the brain and alters the infected ant's behavior. The ant leaves the colony, climbs up to the top of a plant and secures itself with its mandibles and dies. Then, fungal fruiting bodies sprout from the dead ants head and explode releasing the spores to infect other ants and complete the fungal life-cycle.

All the best,
Steffi Kautz & the AntAsk Team

Dear Ant Team,
I'm hoping you can help me with my ant query. I live in Sri Lanka, and two days ago, out of the blue, we found 14 ants of the type in the photograph on our bathroom floor. They were extremely sluggish but still alive. Having removed those ants, the next day I found about another 10 on the nearby stairs. These were in a similar state. We recently moved here from Egypt and our shipping arrived last week. We are wondering if something could have travelled in one of the many boxes we have been unpacking of late.
I would be most grateful if you could help me identify them and tell me if I should be worrying about having them in the house. I am concerned I am on the verge of a major ant infestation.
Many thanks,
Caroline


Dear Caroline,
Thanks for your question. The winged ants that you are seeing are reproductives. To learn about ant reproduction check out this post. Unfortunately, it sounds like you may have an ant colony living in your new home, and judging from the picture you sent these ants are probably some kind of carpenter ant in the genus Camponotus. Winged ants are released from their colonies in swarms at certain times of year and if a colony has a nest entrance somewhere inside your house then when they fly out to find mates they will end up in your house. I doubt that you brought that many winged ants along in your shipping. The boxes probably just happened to arrive at the same time that the ants were swarming. These ants may never bother you again but I would suggest you take a look at this post on discouraging ant pests just in case.

Good luck!
Ben Rubin & the AntAsk Team

Dear AntAsk,

I'm designing a behavioral experiment about nest-mate recognition in ants that I hope to publish in an educational journal. When I do the experiment with my class here in Oklahoma, I've been using harvester ants of the species Pogonomyrmex barbatus, but I understand this ant doesn't occur everywhere, and I'd like to offer educators from other areas suggestions for what kinds of ants might work.

Thanks!
Stephanie


Dear Stephanie,

That sounds like a really fun, educational activity! Pogonomyrmex in general are great to use, but here are some other genera that might be useful to people living outside of your region:

Formica spp. (wood ants) These ants are widespread in North America and Eurasia, and are often the most numerous large ants in boreal forests. They build mounds of vegetation (sometimes to 1m high or more) around their nest entrances.

Tetramorium caespitum (pavement ants). The most commonly seen ants on sidewalks in urban North America and Northern Europe. They often have nests with multiple entrances, so get ready to see some non-aggressive behavior, too. Ants truly from a different colony, however, will be violently rejected, and closely-spaced colonies of this species are frequently seen having all-out territorial wars (see previous post here ).

Aphaenogaster sp. and Messor sp. Also referred to has harvester ants, these ants have very similar habits and life-histories to Pogonomyrmex; all three genera co-occur, and are most common from southern California to west Texas.

The majority of ant species show some degree of internidal (between-nest) aggression, so most ants are worth a shot, with the following exceptions: most invasive ants. The Red Imported Fire Ant, Solenopsis invicta, is common and obvious from Texas to Florida. These will often not show aggression to other members of its species. The Argentine Ant, Linepithema humile, is very common in South and Central California; these ants rarely show aggression towards each other in their introduced range (there is actually a "mega-colony" that occurs in Japan, California, and the Mediterranean region in Europe; you can read more here ). Both ant species are originally from temperate South America, where they actually do often show internidal aggression. Many invasive ant species form polydomous and polygynous (multi-nest and multi-queen) colonies and show little internidal aggression in their introduced range, but have more "normal" nest structure, queen number, and levels of internidal aggression in their home ranges.

I did not really address how to identify these ant genera in this blog post, other than to direct you to some pictures. For an entry-level guide to identifying many of the relevant genera discussed above, please see this key, developed for the Bay Area Ant Survey.

For more in-depth information on ant identification, I would highly recommend checking out "The Ants of North America" by Brian Fisher and Stefan Cover.

Hope this helps!
Best,
Jesse Czekanski-Moir & the AntAsk Team