Any Plant Pathologists Here?

[Harry Pristis]

Any plant pathologists here? I have a piece of silicified twig with insect borings from the Early Pleistocene of Gilchrist County, Florida. The wood from the site has been dated biochronologically from the vertebrate fossils in association.

Here are some close-ups of the wood. You can see tiny cells clustered in the exposed boring. Each cell is roughly 3mm in diameter. The twig has been quartered before deposition; the borings are exposed on a sheared face. The boring is into the wood, not just under the bark.

My guess is that these are egg cells. Anyone here know what insect produced these borings?

[ashcraft]

My guess is that they are chambers from a coleopteran. It looks like the tree may have tried to grow around the invaders, forming the gall-like sacks.

Brent Ashcraft

[Harry Pristis]

My guess is that they are chambers from a coleopteran. It looks like the tree may have tried to grow around the invaders, forming the gall-like sacks.

Brent Ashcraft

That's probably correct, Brent. Under a 'scope I see evidence that the branch grew around the chambers. Whether the cells themselves are wooden, I cannot say. They do seem like discrete cells with walls differentiated from the branch wood. It may be that mother beetle altered the wood she chewed to make the cells. Dunno. I do see that there are more cells - probably intact - under a thin lip of wood.

Because this wood is only two million years old, I suspect the trees and their parasites of the time are not much different from today's. Just a supposition. Do you have any ideas about which beetle may have built egg chambers like this?

[AgrilusHunter]

Hi Harry,

These are highly unlikely to be from beetle eggs. Modern wood boring beetles generally lay their eggs on the surface of bark, once they hatch the larvae bore into the tree. A few wood wasps do drill into a tree to lay their eggs, however, they would not hollow out chambers like this, just a hole to lay an egg into. Why do you think this is insect damage? I definitely see pathological damage to the wood, but I don't see an organized boring pattern I would associate with an insect. To me this looks like a bacterial canker, these often produce a lot of bubbly sap. Could this have caused your infilled pattern?

Edited December 4, 2012 by AgrilusHunter

[ashcraft]

Now that you say that, it does resemble surface wound growths that I have seen in fruit trees, particularly peach trees. I had always assumed they were insect damage.

Brent Ashcraft

[Harry Pristis]

Hi Harry,

These are highly unlikely to be from beetle eggs. Modern wood boring beetles generally lay their eggs on the surface of bark, once they hatch the larvae bore into the tree. A few wood wasps do drill into a tree to lay their eggs, however, they would not hollow out chambers like this, just a hole to lay an egg into. Why do you think this is insect damage? I definitely see pathological damage to the wood, but I don't see an organized boring pattern I would associate with an insect. To me this looks like a bacterial canker, these often produce a lot of bubbly sap. Could this have caused your infilled pattern?

Thank you, 'AgrilusHunter,' I believe that some sort of canker - bacterial or viral - makes sense.

As I look carefully at the piece, I believe that the pathology is more extensive than I realized, affecting perhaps 80% of the length of the twig. Just a limited section is exposed as the cells-like structure.

[ashcraft]

You could argue that you have indeed found a stromatolite (I didn't say it was a good argument).

Brent Ashcraft

[Harry Pristis]

You could argue that you have indeed found a stromatolite (I didn't say it was a good argument).

Brent Ashcraft

Right!