Are carpenter ants only spectators to a tree's demise.

[fpyontek]

Do Carpenter Ants Damage Trees.

I've started this new thread because this topic isn't about filling holes in ash trees. It is a response to Tree Machine's question and, as I feel, a topic for Commercial Tree Care.

I'd say there is a much better sense about the relationship of Ants and Trees. What I'm intrigued by is the relationship between the Ants and the Fungus.


That's not really the topic of this thread, though.

Or is it?

It is.

Mike, first of all thanks for posting those links, some of which I have visited in the past.

I would like to clarify my position on tree compartmentalization and carpenter ant activity.

It seems the Department of Entomology at Iowa State University, would disagree with you:

"Carpenter ants in trees are not directly harmful to the tree. Control is not essential for the tree's health, as the ants are only taking advantage of an existing situation of soft, weak wood in which to establish their colony.

What I gather from the majority of the entomology, university, and extension publications is not that carpenter ants do no damage to trees, but that they are not the primary cause, carpenter ants need some type of tree injury through which to gain access into the wood.

Consider this analogy. Elm bark beetles are not directly harmful to elm trees. The elm bark beetle does not cause Dutch Elm Disease it only carries the disease on it's body where it infects a healthy tree. Were it not for that shipment of elm logs from Europe in the 1920's, or some subsequent entry into the U.S., the elm bark beetle would just be another minor pest.

My first question is: How does a fungus gain entry to a tree wound? Not all wounds have a fungal infestation. What causes some wounds to acquire a fungal infection while other wounds evade infection? I doubt it's random, there must be a vector involved. If it is common knowledge that carpenter ants live in fungal infected wood, and it is also common knowledge that as the ant colonies expand carpenter ants will search for other suitable sites in trees where damage has occurred, it is possible then that carpenter ants carry the wood decay fungus on their bodies and transmit the fungal infection to a new host.


I agree with the theory that the tree compartmentalizes itself from injury.

My second question is: Why then does a fungal infection continue to expand in the host tree, through the compartmentalized barrier that the tree has erected. What good is an evolutionary adaption,(compartmentalization) if it doesn't protect the tree from the primary cause of it's demise(fungus)?
A tree cannot protect or compartmentalize itself from mechanical injury, and the mandibles of the carpenter ant cause that type of injury. The possibility exists that it is the action of carpenter ants expanding their nests through the compartmentalized barrier that allows the fungus to expand it's range within the tree.


Working with specimens from outside a controlled environment, a determination cannot be made that a fungal infection in tree species, that are known to compartmentalize, will continue to expand while unaided by carpenter ant activity.

Fred

 

[Lumberjacked]

A fungus can enter in a number of ways, any wound which can include; dead branch tip, dead top, or any other open wound. Not all wounds have a fungal infection because of the vigor of the tree and its ability to compartmentalize the fungi. Shigo's concept of decay is that the wound initiates that process, succession of microbes invade and condition the wood for conlonization of the wood decay fungi and the trees response is the compartmentalization. There are four ways that a tree can compartmentalize; 1) Wall 1(up and down): gums or tyloses acts like a wall, by "plugging" up the vessel elements (conifers) or the trachieds (hardwoods) which can transmit the fungi. 2) Wall 2: the latewood rings nearest the wound protect the tree from inward movement of the fungi 3) Wall 3: Radial ray parenchyma, protects the tree from radial movement by producing chemical extractions. 4) Wall 4: Barrier zone, the cambium layer of the tree grows over the wound and creates clear fungus free wood. As for the question about if the ants can carry the decay fungi I am not 100% sure, I know some species of beetles do have specialized sacks on their legs that allow them to transmit the fungi as the the ants not sure. If the tree cannot compartmentalize the wound it is either due to the lack of vigor of the tree or the intensity of the wood decay fungi. You typically never see a highly vigorous tree with a compartmentalization problem, likewise that is why we do not prune large branchs off old trees. Hope that helps.

 

[Kneejerk Bombas]

The ant don't need to carry the fungal spores to the wood, the spores are floating around everywhere.
If you wanted a piece of wood to decay, you wouldn't hunt around for wood decay fungus and sprinkle them on the wood, you'd just take the wood outside, maybe find a cool shady spot, wet it down a bit, and wait.
As Lumberjacked pointed out in his excellent post is the main factors are the age and health of the tree, and how big the injury is. There are other factors too, like species of tree, what type of injury, how the injury was made, and things like that.
As far as ants go, I've looked into what damage they do by excavating thousands of nests (splitting firewood), reading any information I can get my hands on, listening to expert speakers at arborist shows, and talking personally to several etymologists. There is one common theme, ants, except in rare cases, don't hurt trees.
From Treedictionary.com:
"Ants - Ants live in trees and eat elsewhere. Ants control the environment inside the tree. If ants in their present form grew to the size of elephants, their bodies would be crushed by gravity. More on the topic: Ants are social insects that live in colonies, live in the soil, or in trees and timber, have 3 distinct body parts and a strong constriction or "waist" between the thorax and abdomen, and when wings form, they are of unequal size. The castes include females, males, and workers. Females are generally winged, but the wings fall off after mating. Males are usually smaller than females and generally retain their wings until death. Workers are wingless and usually smaller than the males and females. Ants eat other small animals, plant sweet fluids such as sap from wounds, nectar, and honeydew produced by other insects. Ants and aphids are often seen together on plants. Three types of ants are potential problems for trees. The leaf cutting ants such as the Texas leaf-cutting ant can remove many leaves from a tree, especially young pine seedlings, and young orchard trees. The Allegheny mound ant can injure or even aid to the death of the symplast of young pines by wounding the trunks and by injecting formic acid into them. The ants aid to the death of the symplast of trees that shade their nests, but they do not remove the wood out of the forest. (See "Kill and Die") The carpenter ants receive the most attention because they are seen commonly in trees and poles. Many trees and utility poles that had carpenter ants and other species have been dissected, and we doubt very much that the ants were causing the decay columns to increase. (See NEW TREE BIOLOGY DICTIONARY, SHIGO, 1986) Instead, we believe they regulate the development of the column, and if anything, decrease its rate of development. Ants live in the tree; the galleries are their homes. They keep the galleries clear of debris and allow air to circulate. Such conditions are not best for the growth of decay-causing fungi. Do not blame the decay on the ants. In other words - The ants in the tree are there because the wood is in an optimal condition for their establishment. Most likely an old wound or injury. If you have carpenter ants in your house than you have wood in a condition in which they are attracted. Some call it rotten wood but that's a poor term to represent the highly ordered succession of microorganisms with wood. If you remove the tree, you do not remove the similar wood from your house. An example, what if we made 2x4’s out of the wood in the tree you speak of and put it in your house? The ants will know its there and they will be there. Don’t believe because I said, but because you see it for yourself."

 

[a_lopa]

with out a doubt ants make trees less stable in high winds

 

[TheTreeSpyder]

From their bodyweight distribution?

 

[Kneejerk Bombas]

The problem with determining whether or not ants damage trees is that it is confused by the cause and effect fallacy.
We see a broken tree with hollow full of ants, and determine the ants caused the hollow and subsequent failure simply because they happen to be there together.
Using the same logic, hollows up in trees are caused by Great Horned Owls, because I often see Owls in tree hollows.
Last time we discussed ants, a_lopa showed some pictures of ants on a log and I don't know anything about AU ants. This thread is about Carpenter Ants in the US, and there has been a lot of studies done that show "ant cause hollows" to be a fallacy.

 

[Ax-man]

I'm not an entomology expert, but I was told or should say taught that ants lack chewing mouth parts, so they can't tunnel into live wood like the larvae of the boring insects that have chewing mouth parts. Ants can only excavate soft decayed wood with their powerful mandables or jaws to build a colony or nest in a tree.

Larry

 

[TheTreeSpyder]

The problem with determining whether or not ants damage trees is that it is confused by the cause and effect fallacy.
We see a broken tree with hollow full of ants, and determine the ants caused the hollow and subsequent failure simply because they happen to be there together.
Using the same logic, hollows up in trees are caused by Great Horned Owls, because I often see Owls in tree hollows.

So you are saying that my buddy is wrong about marriage being the leading cause of divorce in this country?:monkey:

 

[John Paul Sanborn]

So you are saying that my buddy is wrong about marriage being the leading cause of divorce in this country?

I thought it was lawyers!



Great thread!

Carpenter ants use decayed wood for thier colonies, only fungus causes deacy.

What good is an evolutionary adaption,(compartmentalization) if it doesn't protect the tree from the primary cause of it's demise(fungus)?

Fungus have adapted to overcome the compartmentalization startigies of trees. Some will actually form wedges that delamintate the growth increments.

Different organisms feed on different parts of the wood, so there is a sucession of feeding, if a barrier is overcome then it starts all over.

Or do i over simplify too much?