Ants: Ranchers

Summary: We know ants are farmers, but are they also ranchers? Join Kiersten to find out!

For my hearing impaired followers, a complete transcript of this podcast follows the show notes on Podbean

Show Notes: 

“Adventures Among Ants” by Mark W. Moffett

“Trophobiosis is a tropical rainforest on Borneo: Giant ants Camponotus gigs (Hymenoptera: Formicidae) herd wax cicadas Bythopsyrna circulate (Auchenorrhyncha: Flatidae),” by Martin Pfeiffer and Karl Eduard Linsenmair

“Aphid-farming ants,” by Annie B. F. Ivens and Daniel J. C. Kronauer

“Ecological consequences of interactions between ants and honeydew-producing insects,” by John D Styrsky and Micky D. Eubanks

Music written and performed by Katherine Camp

Transcript

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Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Kiersten - Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

Two episodes ago we found out that ants are farmers, at least some species of ants are farmers and they are amazingly well organized and productive farmers. The other side of sustained food production is ranching. Ranching is a form of agriculture focused on raising livestock for various uses. Are ants ranchers? Let’s find out! The eighth thing I like about ants is their ranching activities.

For those of you listening in order, last episode we learned about the Weaver ants of Africa that live in trees. They are some of the coolest ants out there with special physical adaptations  and behavioral adaptations that help them survive in the tree. One of the activities I didn’t talk about, because I was saving it for this episode, is their ranching. The weaver ants, Oecophylla longinoda, use other insects as a form of food resources. Now they do hunt other insects and tear them apart and eat the bits, but they also corral certain insects and use the honeydew that those insects produce as food. Mealy bugs, plant hoppers, and scale insects are some of the “cattle” that Weaver ants utilize. These insects are all sap-sucking species that tap a plant for it’s sap and drink it. The ants love the honeydew, or doo-doo, that comes out the other end of these insects. Yes, that’s correct, the ants are eating their excrement which is actually more nutritious than nectar. 

The Weaver ants are protective of their livestock keeping them from harm and moving them to fresher pastures, just like human cowboys. They often build leaf tents over and around their charges keeping them hidden from predators and controlling their movements so they can gather the honeydew for as long as the insect lives. 

Who knew ants were ranchers? It’s not only Weaver ants that exhibit this behavior. 

Some species of Formica ants are also ranchers. They will tend similar insects as the Weavers including Mealy bugs, plant hoppers, scale insects as well as whiteflies and aphids. I found several papers talking about the relationship between Formica ants and aphids. They really treat these aphids like humans treat cattle. The ants tend them, watching them to protect them from predators, they will pick them up and remove them from a plant when danger arises (okay humans can’t pick up cattle, but we can escort them to another area when needed), and when the part of the plant that the aphids are eating from begins to run dry the ants will take them to greener pastures. The ants are after the honeydew, of course, the excrement from the aphids, just like the Weaver ants. It is high in concentrated sugars and carbohydrates that keep the ants running.  

Giant ants, Camponotus gigas, from the tropical forests of Borneo herd wax cicadas. They are incredibly well organized in their herding and perform three behaviors to help gather as much honeydew from these cicadas as possible. Some of the ants are collectors and spend about 80% of their time sitting below the cicadas to collect the honeydew as it comes out. Ants that spend their time collecting often focus on one cicada, returning to the same individual after each collection. There are also secondary gatherers that collect honeydew from the body parts of the primary collectors and receive honeydew via trophallaxis, or passing of regurgitated liquids to another insect. This allows the primary collectors to spend more time collecting directly from the cicadas. The secondary gatherers take the collected food back to the nest. A third worker might sometimes stand in front of the cicada and perform what the researchers called “antennating from ahead”. One or more ants will sit in front of the cicada or next to it and gently tap it with its antenna. At times this seems to encourage the cicadas to pass honeydew more frequently, but sometimes it didn’t do anything, except possibly annoy the cicada. It’s so interesting that these Giant ants of Borneo have adapted such specialized behaviors to collect excrement from another insect.

It may seem like the ants may be controlling the aphids or cicadas and taking advantage of their production, which is not entirely false. Many ant colonies restrict the movement of their insects just like humans do with cattle, allowing them to go only where they want them to go, but its not always bad for the cattle. Aphids are not the most cleanly insects and they congregate in large groups, as any gardener listening to this episode will tell you. A group of aphids can suck a plant dry! Anyways, the ants retrieve the honeydew almost immediately once it is excreted. This is an advantage to the aphids, because it cuts down on fungus that can grow on the excrement and sicken the aphids. The ants are also protecting them from predators. Some ants remove Ladybugs, their larvae, and pupae from the plants that the aphids have chosen to feed upon. Ladybugs love a juicy aphid! Parasitic wasps that feed on aphids are also on the ants’ radar.

One of the questions that researchers have about this mutualistic relationship is whether it’s obligate or facultative. Turns out it can be both. Facultative mutualism is a relationship where both parties benefit from each other’s company but do not rely on each other. The previous discussion is an example of this. The Formica ants tending these aphids can walk away and find food elsewhere and the aphids can also go about their business without the ant ranchers.

Obligate mutualism is when one or both parties is reliant on the other for survival. Some ants and aphids have evolved to rely on the other for survival. Some species of aphids and other insects have lost their ability to protect themselves without the help of ants. Some ants rely on the aphids and other sects to provide honeydew, they have lost the ability to go out and look for other food. Certain aphids live inside the ant colony and have lost the ability to grow wings and fly to find a mate. They just reproduce asexually throughout their entire lives and never the the ant colony at all. If these aphids left the ant nest, they would not survive.

I guess we have proven that ants can be ranchers, as well as farmers. Thanks for joining me for this episode of ants as ranching is my eighth favorite thing about them.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change. 

Join me next week for another exciting episode about ants.  

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This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, my very own piano playing hero.