monarch butterfly study

[bridget1964]

Study finds monarch butterflies use medicinal plants to treat offspring for disease | Bioscience Technology Online

Monarch butterflies appear to use medicinal plants to treat their offspring for disease, research by biologists at Emory University shows. Their findings were published online Oct. 6 in the journal Ecology Letters.

[swamp thing]

This is amazing - most of us have seen dogs eat grass to settle their stomach, but for an insect do something like this for offspring is a whole different story.

[will-o-wisp]

I wonder what is the toxic species of milkweed they seek?

[Gloria]

The cardenolides (toxin)that can kill off the Ophryocystis elektroscirrha (monarch parasite) is found within tissue and milksap of all asclepias species in various levels.
In the following pdf a chart listing findings for several Asclepias/milkweed is on page 11.
http://www.eeb.cornell.edu/agrawal/p...-Evolution.pdf

But sometimes levels can vary a within a variety and even segments of an individual plant.The Monarch seems able to do its own field testing. A sick monarch will look for a plant with high levels of specific cardenolides to kill off the parasite it can not help passing on to its larvae. Hand raising monarches may supersede this ability and help unintentionally to keep the parasite viable.

Field Test for Screening Milkweed Latex for Cardenolides - Journal of Natural Products (ACS Publications and Am. Soc. of Pharmacognosy)
Field Test for Screening Milkweed Latex for Cardenolides
Michael B. Sady, James N. Seiber
J. Nat. Prod., 1991, 54 (4), pp 1105–1107
DOI: 10.1021/np50076a031
Publication Date: July 1991

http://www.monarchsacrossga.org/Less...j=95190&mode=1 pdf file

[will-o-wisp]

Thanks Gloria. The last link at 7th grade level was at my level of understanding.
Who knew in High school it was Latin and Biology instead of Literature and Art that were the subjects I needed to pay more attention to? I need a do over.

[NEWisc]

Great info Bridget1964 and Gloria! I also found the oviposition stimulants circles in the diagram on page 4 (666) interesting.

[erictjohnson]

I have noticed that female monarchs tend to prefer our Asclepias incarnata, aka swamp milkweed, for laying eggs. We have two other species of milkweed in our yard, Asclepias syriaca, aka common milkweed, and Asclepias tuberosa, aka butterfly milkweed. When I bring in a leaf with an egg, for hand rearing, I always end up feeding the caterpillar leaves from A. incarnata, because I know the cats do well on this variety, from experience. Also, this variety seems to do well in our yard, and we usually have young and fresh leaves that look like high quality food to my eye. I was not aware that the plant had medicinal properties useful to monarch caterpillars.

[ButterflyLinda]

With that first article, I just found it strange that it gives the impression that only adult butterflies are seriously impacted by Oe...and other scientific info I've seen on Oe indicates otherwise. I knew that A. asperula (which grows in this area) is high in cardenolides. In general, it's picked for egg-laying by relatively few butterfly mothers. A. curassavica and A. texana seem to be more preferred. Unfortunately, I have no idea on cardenolide levels in A. texana. I do try to keep the caterpillars on the milkweed they start on. But that just isn't always possible. If the foliage is used up, well, I give them something else. And these days with milkweeds disappearing in the wild exponentially more and more over time, the butterflies may not have many choices. Oh...and that one particular article that was so excessively wordy...my BS in Biology helps a bit...but it's still pretty bad...I would say practically useless...some scientists go overboard with their "tech speak" and leave readability behind!

[bridget1964]

In my experiences, I too have noticed the monarchs prefer incarnata over syriaca. But, this year I grew exaltata and that was by far their favorite this summer! If a female would show up in the yard, she'd lay first on that, then the incarnata, syriaca and occasionally on the tuberosa and verticillata. At the end of the summer when most of the milkweeds were stripped, they'd lay on the tuberosa. I don't grow curassivica since it is not native to the US.

Before I became more of a native gardener, I'd grow curassivica in pots and in the school garden. I was told it would grow like an annual and that it would not spread or come up yearly. I was told wrong. Even after two years of not planting it and a very harsh, cold, snowy NJ winter, it still came up again this year.

[bridget1964]

Btw, Oe is a horrible disease to see caterpillars/pupa/butterflies die from. I had a bad 'infection' of it last summer and lost at least 100 monarchs.

If you want to learn more about Oe, go to http://www.monarchparasites.org/ and click on the link labeled: What is Oe? There are photos showing what an infected chrysalis/adult looks like. If you get one that is infected, it should be euthanized.