FWD: Re: larval & pupal exuviae

[Doug Yanega]

This is a message I received from James Adams, and he agreed to let me put
it on the list so other people could benefit from the info:

> I'm curious as to whether these things
> (larval & pupal exuviae, cocoons) are (1) regularly saved and kept with
> reared adults, and (2) regularly *described* in detail sufficient for use
> in taxonomic revisions? If the answer to either is "NO", then I'm really
> curious as to why not, and whether it's a trivial thing to encourage the
> practice.

The answer to the first is "yes".  I regularly send exuviae to the
Carnegie, (under the auspices of John Rawlins) which is building an
immatures collection to exceed any other.  The answer is a "lesser"
yes to your second question.  Several studies I have read have used
pupal, and, of course, larval characteristics in phylogenetic
analyses, and, at least a couple of papers I've read have used
comparative analysis of the weave of the cocoons as a phylogenetic
character.  Just as an example, it is not readily apparent looking at
the adults of Rothschildia and Eupackardia calleta that they are
quite close.  Larval characteristics are more telling, but the most
striking similarity one that leaves the species almost
indistinguishable, is the cocoon shape/attachment to the plant/weave,
etc.  Marc Epstein has done a lot of stuff with larvae, pupae, and
cocoon shape of limacodids.

> Just for example, with all those large,
> flashy, commonly raised and traded N American Saturniids, are there keys or
> phylogenies using diagnostic features of the pupae? Other publications,
> like DeVries' book on Costa Rican butterflies, give features and
> illustrations of larvae and pupae (where known), but this is by no means
> exhaustive coverage or presentation, nor arranged such that one could take
> a Costa Rican butterfly larva/pupa and easily ID it. But of any insect
> group, leps would have to be the prime candidate for immature-centered
> studies and publications.

Ric Peigler has used larval/pupal information for numerous Saturniid
groups, and also has an extensive publication on the parasitoids of
Saturniids and cross-phylogenetic relationships.  The MONA series has
as part of most fascicles, at least a partial larval key.  As for
Costa Rican material, Peter Devries in the two volumes of the
butterflies of Costa Rica has numerous at least generically
informative figures of larvae and pupae.  I am personally collecting
immature information for books on Georgia moths (if I stay here!).

>         A related question - I know people used to take larvae and
> "inflate" them, so they could be mounted in a nice way and pinned into a
> collection dry with the adults. Has anyone ever tried inflating *exuviae*,
> or is this a hopeless cause?

I'm assuming you are talking about larval exuviae, as pupal exuviae
usually do not need such a treatment.  The answer is:  I don't know,
but . . .  I have never seen anything published on this, but I do
personally know that it *is* technically possible.  There have been
times where I wanted to look at some larval features after all the
reared individuals had pupated.  Though I did not inflate them, it is
possible to (at least temporarily) reconstitute them in water.  I'm
sure a more scientific method either exists or could be devised,
whereby a restretched larval skin could then carefully be inflated.
ONe other point.  Though this could work for some species, other
species have much more fragile/brittle larval exuviae, so it would be
pointless to try for these species.

James

Doug Yanega    Depto. de Biologia Geral, Instituto de Ciencias Biologicas,
Univ. Fed. de Minas Gerais, Cx.P. 486, 30.161-970 Belo Horizonte, MG   BRAZIL
phone: 031-448-1223, fax: 031-44-5481  (from U.S., prefix 011-55)
                  http://www.icb.ufmg.br/~dyanega/
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82