Miami Blue

John Shuey jshuey at TNC.ORG
Wed Jan 16 08:20:09 EST 2002

>Can anyone else confirm what Leroy suggests (and I was
> wondering) - is the
> >Balloon Vine an exotic and if so, what did the Miami Blue
> subsist on prior
> >to the introduction of the vine?

There are two balloon vines in the Florida Keys (aren't common names nice??)

Cardiospermum corindum, a native species and Cardiospermum halicacabum, a
non-native tropical species.  Based on a quick web search, there are similar
species (ecologically and morphologically) - and it seems likely that both
are hosts for Cyclargus thomasi bethunebakeri.

I did a quick web search for control methods for Cardiospermum halicacabum,
and there are no online resources available on the Wildland Weeds web page.
This indicates that it isn't a real problem invasive (or at least a big
enough problem that people have developed a formal element abstract for
it).. but it is a widespread exotic.  So its probably an early successional
"naturalized" species - like Queen Anne's lace in the Midwest.

This raises some questions about the actual suitability of both species as
hosts (and about plans to grow "balloon vine" as a tool to stabilize the
butterfly population).  It is possible that one of the hostplant species is
a sub-optimal host.  I know you can get perfect adults out of C. halicacabum
seed pods (I've done this), but are the adult butterflies reproductively
fit?  It seems likely that a series of quick tests looking at the
suitability of both host plants and the reproductive potential of
butterflies reared on both hosts should be assessed before any effort is
expended towards increasing the stands of balloon vine.

I seems odd to me that C. halicacabum is a common weedy plant (or at least
was when I saw the Keys in the 80's) and yet the butterfly has collapsed to
a single population.  It could well be that the exotic hostplant is acting
as a population sink - it attracts eggs and produces adults that are
physiologically impaired.

So there, you have my speculation for the day,

John A. Shuey
Director of Conservation Science
Indiana Office of The Nature Conservancy
1505 N Delaware Street, Indianapolis, IN 46202



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