Pierie virginiensis - host plants and threats from exotic mustards

[Anne Kilmer]

Shueyi at AOL.COM wrote:
> 
> Leppers---
> 
> Last week I the oppurtunity to to hike several state-owned and Nature
> Conservancy preserves in southern Indiana.  Two of the sites were deeply
> entrenched valleys through mesic decidious forest .  Not  surprisingly, P.
> virginiensis was pretty common at these sites, as both communities supported
> abundant stands of Dentaria in the creek bottoms, the typical host.  However,
> both sites also supported sparce stands or Arabis lavigata on the drier
> slopes.  Knowing that we found P. virginiensis using this host on a
> preferential basis at one site in Ohio, I checked out the Arabis.  Almost
> every stem had 1 or more eggs on it, while I could not find any eggs on
> Dentaria (but keep in mind that there were thousands of stems of Dentaria at
> each site and I checked 20 or so plants at the most).
> 
> Thus it would appear that using Arabis is more widespread than previously
> thought, and that Arabis (which is about 5X taller than Dentaria) is a very
> attractive target for ovipositing females.
> 
> I also spotted a single garlic mustard plant at one of the sites (an
> agressive exotic which we always remove when we find it in a preserve), and
> it had over 10 eggs on it!  Most reports say that this European mustard
> species has too much mustard oil in it for North American Pieris, and is
> toxic to larvae.  Garlic mustard is a huge visual target for ovipositing
> females, Standing taller than Arabis and with broad leaves (very slender
> grass-like leaves on Arabis).
> 
> 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?
> 
> Just a question to ponder from,
> 
> John Shuey

What a horrid thought. Think of this as an ecological opportunity and 
plant milkweed, why don't you :?  
I fantasize a nice little laser gun with which I can wipe out trees, 
shrubs and vines that annoy me. The weeder's delight. Nobody's given me 
one yet. 
You'll need to muster a roll of kids to slay this nuisance. Child-power 
is wonderful when it comes to killing stuff. 
Anne Kilmer
Florida