[LEPS-L:8036] Re: diapause in midea

[Mark Walker]

Neil Jones wrote (regarding Ron's discussion of Anthocharis):

> I'd be interested to see a scientific referrence for this.
> My understanding of this in Orange Tips is that emergence is triggered
> by warmer temperatures after a colder spell. I have had Anthocharis
> cardamines lie over like this when kept indoors. I have also had
> Pieris napi emerge in February on a windowsill in a cool room
> after the frost had got at them for a while a few weeks before due to
> poor heating. We don't suffer from low humidity here. It rains a lot.
> It hasn't rained today yet but its only one o'clock.

There could be an interesting behavioral difference between the continental
species (or within species according to local humidity).  Down in the
southwestern part of the U.S., I am convinced that the Anthocharis species
emergence is linked to rainfall.  I'm sure there is also a temperature
component - these are often among the first spring leps to emerge (just as
soon as daytime temperatures begin to rise).  Because we go through more
drought years than we do wet ones, the well documented mass emergences
following heavy (and early) spring rainfall would suggest that such a
trigger does exist.  This is especially true with the desert species A.
cethura.

I have enjoyed chasing A. midea on the east coast and in Texas where
hundreds of individuals were flying during early spring.  I don't know how
much fluctuation there is with this species based on rainfall - but then the
east coast is generally wetter than we are out west anyway.  They have had
drought years recently - but long term (multi-year) droughts would likely
have a significant impact on population dynamics beyond delayed emergence.

Anyway, discuss on - this topic interests me as well.

Mark Walker.

"When I consider your heavens,
   the work of your fingers,
the moon and the stars,
   which you have set in place,
what is man that you are mindful of him,
   the son of man that you care for him?
You made him a little lower than the heavenly beings
   and crowned him with glory and honor."

Psalm 8:3-5
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> --
> Neil Jones- Neil at nwjones.demon.co.uk http://www.nwjones.demon.co.uk/
> "At some point I had to stand up and be counted. Who speaks for the
> butterflies?" Andrew Lees - The quotation on his memorial at 
> Crymlyn Bog
> National Nature Reserve
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