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Q's re: Monarch toxins and non-native milkweeds

15 years ago

Hi all,

Murray recently brought up this question about whether there is a problem letting Monarch cats feed on non-native species of milkweed-- or, more specifically, milkweed that is not native to the migration path through which the butterflies go.

For example, I live in CA, and I have some a. curvassica "gold" (I thought it was a. tuberosa, murray, but I'm now pretty sure otherwise). According to the Las Palitas Nursery website, this is a bad plant to use for CA butterflies because it only produces toxins appropriate to protect butterflies living and migrating in the Eastern US. I was also re-reading a section of Judith Lowry's "Gardening with a Wild Heart" in which she suggests very similar things about needing to use natives to build up toxins against "native" animals, although without the specifics re: which plants one should exactly use. The point isn't that you shouldn't be planting a. curvassica anywhere-- only that you shouldn't be planting it in CA. or other parts of that migration path. Same would go for other "exotic" non-native milkweeds.

Here's what Las Palitas has to say-- "The alkaloids associated with (Milkweed) give the butterflies that feed on it protection. Alkaloids from the wrong milkweed(South American, Mexican, etc.) can expose the butterflies to predation. If the monarch or other butterfly has not evolved with the milkweed they have no tolerance for the particular alkaloid of the species. The California flyway runs from Baja to Canada, it does not include Mexico proper nor Central America. If you live in Chicago you can plant Mexican species (Asclepias mexicana) or Asclepias tuberosa, don't plant our species."

So, here I am now. Does anyone else know anything about this? Is this pure hearsay? Is there any real research that's been done on this? Are there any other places that corroborate this sort of opinion??

Experienced butterfly gardeners, come to rescue!!

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