Miami Blue

[John Calhoun]

John,

Thanks for the response.  You are correct, there are two species of
balloon-vine in the Keys. However, C. corindum was never all that common and
has never been known to support populations of C. thomasi (that's not to say
it can't).  Also, the exotic C. halicacabum has suffered a decline recently
(even botanists have noticed). I think that as the butterfly became more
fragmented, C. halicacabum offered a suitable and readily available
alternative in southern Florida.

I don't know about the suitability, or unsuitability, of C. halicacabum as a
host.  It deserves a look.  It appeared to support healthy populations of C.
thomasi for at least twenty years.  However, Hurricane Andrew hit and
destroyed a number of sites in 1992, further fragmenting the species.  This,
combined with the continued development of coastal south Florida, has likely
contributed to a rapid downward spiral.  I believe it simply reached a
critical level and could no longer locate distant habitats and hosts.  As
populations sites disappeared, they were not replaced.  In fact, the
surviving populations on Bahia Honda utilize both balloon-vine and
nickerbean.  The Bahia population is quite isolated from other potential
sites. The Big Pine Key population is the dilemma.  It simply disappeared
from there, despite an abundance of native hosts and lack of balloon-vine
where it once occurred (in other words, it likely used something other than
balloon-vine as a primary host, but it still disappeared from there).

Cardiospermum halicacabum has been removed from a number of areas by the
State of Florida during habitat restoration projects.  This removal has been
both intentional and accidental.  A large patch that supported C. thomasi on
northern Key Largo was removed during the development of the Key Largo
Hammocks State Botanical Site.  In 1996, thomasi was observed there.  After
removal of the plants, none were seen until last year when a probable
sighting of a single adult was reported in the area.

John


-----Original Message-----
From: John Shuey [mailto:jshuey at TNC.ORG]
Sent: Wednesday, January 16, 2002 8:20 AM
To: leps-l at lists.yale.edu
Cc: 'Don Stillwaugh'; 'Judith Buhrman'; 'Cornelius(Neil) Cosentino';
'Ron Gatrelle'; 'John Calhoun'; goodpat at tampabay.rr.com; Kurt Johnson
(E-mail); Mark Salvato (E-mail); Linda and Buck Cooper (E-mail);
Leptraps at aol.com; John Heppner (E-mail); 'Bob Parcelles,Jr.'; 'Lynn
Marshall'; 'Director Stephen Garrett Komlos'; 'Jack Alvord'; 'Katy
Anderson'; John.Calhoun at sempermedusa.com
Subject: RE: Miami Blue



>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
_____________
John A. Shuey
Director of Conservation Science
Indiana Office of The Nature Conservancy
1505 N Delaware Street, Indianapolis, IN 46202
317.951.8818


>


 
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