Leaf Cutter Ants - How Do You Deal with Them?

[agroventuresperu]

Here we


use chlorpyrifos in a powdered form, which doesn't work very well. You powder their entrances and lines, and hope for the best. I even get on hands and knees and blow some of the powder down the entrance. Inevitably in a week or so, they will be back, rinse and repeat for weeks on end.
 
A biological agent would work better.

Edit: Here's a nice article from Brazil where scientists conducted an experiment with some sort of processed orange pulp as a carrier bait into which they infused sulfluramid at 0.3% concentration. Apparently the ants incorporated more of the sulfluramid pellets into their nest than even the control group (the processed orange pulp without any insecticide). That might have just been a coincidence, but the mechanism of action sounds very convincing to me.
The sulfluramid is very slow acting, so the worker ants don't perceive the compound. The ants feed this bait to their fungus and only after the bait has been incorporated into the fungus, does the sulfluramid start to affect the worker ants. The workers are not able to associate the bait as being the source of toxicity as they are able to do with more acute toxins from their environment. The article states that after three or four days the ants stop harvesting plant material from the landscape, and all individuals die 16-22 days following the treatment.
https://www.sciencedirect.com/science/article/pii/S0085562619300755

Sounds promising to me. Now I just have to see if I can find a product with this chemical composition.

[Epicatt2]

You will need a chemical product (bait) that decimates the fungus that the ants are growing from all those cut leaves that they carry back to the nest which they use to farm more fungus with. 

That farmed fungus is the colony's main food source and once their food source is destroyed then the colony will either die or relocate.

There are several of these sorts of bait product on the market to control leaf-cutters' fungal food.  You will need to ask around to see what is available where you are.  Check with your local agricultural offices or with plant nurseries in that area.

OK — HTH

Regards,

Paul M.
==

[Finca La Isla]

Myrex is what is used most commonly. When the ants are working you place about 3 tablespoons near the entrance of the holes where they are taking fresh leaf pieces. They will carry the Myrex in and not do well. It’s important that you get every active hole in the nest. Don’t worry about the holes they use to remove spent leaf bits. An organic product we get that works as well is called Omitox.
Peter

[agroventuresperu]

Myrex is what is used most commonly. When the ants are working you place about 3 tablespoons near the entrance of the holes where they are taking fresh leaf pieces. They will carry the Myrex in and not do well. It’s important that you get every active hole in the nest. Don’t worry about the holes they use to remove spent leaf bits. An organic product we get that works as well is called Omitox.
Peter

Do you happen to know what the active ingredient is in those products?

[Finca La Isla]

The active product was changed a couple of years ago it seems. But you can find that information on line.

[agroventuresperu]

The active product was changed a couple of years ago it seems. But you can find that information on line.

Looks like it contains sulfluramid. That was what I was leaning towards using, but I did a little reading and discovered that it breaks down into a Persistent Organic Pollutant, which gives me pause. I came across a short article that gives some alternative suggestions for biologicals on page six. Not sure which formulations would be best. There are so many. Of course, I'll have to investigate if any of them are available in Peru. 

https://ipen.org/sites/default/files/documents/en_ipen-sulfuramide-factsheet-v1_10a-en.pdf

[Finca La Isla]

So that concern would bring us back to Omitox (sp?) might be Omnitox,which is also granules applied the same way and seems to work as well..
Peter

[agroventuresperu]

So that concern would bring us back to Omitox (sp?) might be Omnitox,which is also granules applied the same way and seems to work as well..
Peter

They don't have that here. We've been looking into biologicals. They don't have any products of those here either, but the government phytosanitary department published some info suggesting they have a lab producing entomopathogenic fungi now, so we contacted them and they referred us to a lab. I'm guessing they're a goverment contractor. It wasn't clear to me. Sounds like they have Beauveria bassiana, Metarhizium, and maybe even some sort of Trichoderma. We will call them soon. Hopefully they don't charge an arm and a leg. One hill on our property that measures about three hectares has sixteen different nests, so we will need a lot. The weird thing is that we have another adjacent 3-hectare hill that has zero nests. Wonder why.

I read an article too that says you can use moldy oranges (Penicillium) and wash them in water. You use the wash water applied to the entrance to the nest as well as the line of ants. Not sure the mechanism of action as Penicillium is known to produce antibiotics, but at least some Penicillium species also produce anti-fungal proteins, so I'm guessing the mechanism of action is to disrupt the Pseudonocardia bacteria on the ant cuticle, which makes the ants unable to prevent infections of their Leucoagaricus gardens. Perhaps the Penicillium also competes against the Leucoagaricus to some degree as well. Either way, it doesn't sound extremely effective (40-45% reduction of ant population over two months).

[Finca La Isla]

Unless you are relying on organic certification I think I would use myrex. It’s very simple and effective to use and I don’t see that it’s current form causes much harm.
Peter