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Important Info RE OE Spores & Monarchs

11 years ago
Important Info RE OE & Monarchs! Posted by tdogmom on Tue, May 2, 2006

Okay folks, I got a response from Dr. Sonia Altizer, an expert on Monarchs, from U of Georgia.

Several people have asked questions about using a 2% bleach solution to cleanse OE spores when working with Monarchs. I asked her some of those key questions and here is what she said. I paraphrased and summarized her reply to each question.

1. Is it possible to clean Milkweed plants while they are in the ground (planted MW plants)?

This is NOT recommended. Spraying wild plants growing out in the field with 2% Chlorox is not very effective against the tough OE spore walls.

An alternative is the following:
Take Milkweed cuttings (clip the stalks) and soak them in a basin in 10-15% Chlorox for 20 minutes. Then, soak them in regular tap water for the same amount of time and rinse well. The cuttings can then be placed in florist tubes (plant picks) and fed to the caterpillars.

Dr. Altizer has found that if the leaves are rinsed well in tap water, they can be fed safely to Monarch larvae.

2. If you find a lot of OE in the Monarchs raised, it is possible that the spores are on your plants. What is another way you can eliminate or reduce the OE on the Milkweed?

To reduce spore loads on plants, cut the stalks (or mow these down) to within a few inches of the ground. New material that grows back should have fewer spores on it, especially if kept away from infected adult butterflies. If necessary, use netting to keep the butterflies off the plants. Presumably a heavy rain or a strong hosing with water can also wash off a large portion (but not all) of the parasite spores.

Dr. Altizer also recommends growing native milkweed species as opposed to the tropical species, as most of the native species naturally die back during the winter months, and hence would accumulate fewer parasite spores.

3. Can you use a bleach solution to cleanse Monarch eggs of OE? How safe is this and is it effective?

This approach is NOT recommended as bleaching the eggs has NOT been found to be a satisfactory method of elminating OE. The concentration of bleach needed to kill the OE spores can also damage the egg chorion. A method to try to rescue some potentially contaminated eggs is to remove them from the Milkweed they're on (the contaminated Milkweed) and transfer them to a clean Milkweed leaf. This will reduce the potential number of spores the caterpillar might ingest.

4. What about the use of the commercially prepared OE spore spray?

She was not familiar with the Educational Sciences product. Her exact words, "I'm not familiar with this product so cannot make an educated comment, except to say that there are probably cheaper, easier, safer and more effective methods available than using a commercial spray -- and definitely would not advocate widespread dissemination of a product such as this into the environment.

5. Is there a way to test the Milkweed plant itself for OE spore contamination?

She felt this was a good question and thought that perhaps this could be done similarly to the way OE is tested on the Monarch butterflywith a swab, tape, etc.

I think that her answers were very clear. I also felt good because personally, I have always been concerned when reading about people using bleach to clean their butterfly eggs. It is reassuring that someone who does a lot of research corroborates my own thinking and methods. :) So, take it for what its worth--CalSherry aka tdogmom.


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