Pierie virginiensis - host plants and threats from exotic mustards

Pavulaan at aol.com Pavulaan at aol.com
Thu May 8 19:55:30 EDT 1997


In a message dated 97-05-06 10:31:51 EDT, Shuey writes:

<< If Garlic mustard is indeed toxic to P. virginiensis larvae, and presents
a
 super-attractive oviposition substrate (both visually and chemically) to
 females, could garlic mustard invasion into forest systems effectively
 wipe-out populations of this localized butterfly?
  >>


This is definitely the case in the first few mountain ridges just west of
Washington, D.C.  A former colony of P. virginiensis used to occur on a
wooded hillside in an place known as Pleasantville, MD. (Washington Co.).  A.
midea used to be common there too.  The forest floor at this location is
carpeted with Dentaria.  In the late 1980's, Garlic Mustard took over these
woods, becoming the dominant plant on the forest floor, though Dentaria hides
underneath, and P. virginiensis and A. midea both dissappeared.  Same for the
Catoctin Ridge where Krizek took his photo of virginiensis, for the book with
Opler.  Pieris rapae, which can feed on the plant, has now become the typical
spring woodland white at former virginiensis sites such as this one.

Several years ago, I found virginiensis ovipositing on Garlic Mustard over in
Page Co., VA. and took several eggs back to try to rear the larva on the
plant.  All died within days.  Unfortunately, virginiensis prefers
ovipositing on Garlic Mustard, probably because the plant is taller and
probably because it has more mustard oils to attract the ovipositing females.
 Unless evolution quickly selects larvae that can digest Garlic Mustard,
virginiensis colonies will dissappear everywhere that Garlic Mustard shows
up.  

Harry Pavulaan



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