The importance of associating reared adults with their immature stages


Material Information

The importance of associating reared adults with their immature stages
Physical Description:
2 p. : ; 27 cm.
Sabrosky, Curtis W ( Curtis Williams ), 1910-
United States -- Bureau of Entomology and Plant Quarantine
U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


Subjects / Keywords:
Parasitic insects -- Classification   ( lcsh )
Host-parasite relationships   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


General Note:
Caption title.
General Note:
General Note:
"April 1952."
Statement of Responsibility:
by Curtis W. Sabrosky.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030363709
oclc - 783640732
System ID:

Full Text
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April 1952 ET-300

United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine


By Curtis W. Sabrosky,
Division of Insect Detection and Identification

Recent studies of a species complex in Larvaevoridae (Tachinidae)
have highlighted the importance and usefulness of associating immature
stages, hosts, and reared adults whenever possible. It seems worthy
of a note to emphasize this for anyone who may have opportunities to
rear hosts and their parasites. Only through the long and patient accu-
mulation of such materials and information can the taxonomist build
toward a truly natural classification of the adults, as well as toward
more reliable identifications. The following remarks apply especially
to parasitic flies, but undoubtedly they are pertinent for other orders
as well.
Certain small, more or less shining black larvaevorids, usually
parasitic on phalaenid larvae, are classified by some authors in the
single genus Wagneria, by others in several genera under such names
Wagneria, Polideosoma, Phoricheta, and Metachaeta, because of
varying opinions of the taxonomic worth of certain adult characters.
Puparia of five species are available, and examination of them reveals
two such startlingly different types of structure, especially in the
spiracular plates, that it is scarcely conceivable that all belong to one
natural genus. Division of the five species into two groups on the basis
of these two types of puparia cuts across the currently accepted generic
limits of those authors who recognize more than one genus in the com-
plex, and indicates that a different combination of characters may be of
generic significance. Were our knowledge complete, or even somewhat
more extensive, the work could be advanced considerably.
Parasite material submitted for identification often consists of adults
only; and of course, for purposes of identification under current classi-
fications, that is usually sufficient. But it would take only a little more
effort to obtain the immature stages and thus contribute to the growing
accumulation of information for future work.
Larvaevorid larvae are usually not noticed, but the puparia can
generally be located, commonly inside the larval or pupal skin of the
host. It is desirable to save the immature stages of both parasite and

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host, so that the identities of both can be rechecked at any time if the
identifications are questioned. The association of host material is
perhaps not so vital when one is rearing common and well-known
species. Even here, however, the general principle could well be
observed, for the future may bring new problems from the standpoint
of either host or parasite, or both, that would benefit immeasurably by
having authentic material available for review. Obviously, for less
common species all material is important.
A puparium is often glued to a paper point on the same pin as the
adult, or sometimes pinned directly below the adult, but it is much
better to place it in a gelatin capsule in which it will be protected against
breakage and loss of parts during handling and shipping. Each capsule
can either be pinned below the corresponding adult or, if space does not
permit, be pinned separately with appropriate labels to associate the
two. The remains of the host can be placed in another capsule and pinned
with the parasite or its puparium. Even shriveled and apparently worth-
less larval exuviae may be worth saving, for they can be especially
treated for study. Labels should bear not only the customary locality,
date, and collector, but also the identity of the host, if already known.
Obviously, a puparium (or host remains, or any other stage of any
insect) should be mounted with an adult only if it is positively associated
with that particular specimen. If any factors, such as mass methods of
rearing, do not permit a positive association, the various parts should
be mounted or preserved separately with appropriate labels to indicate
the general or probable association. In pure cultures, or even in mixed
cultures with obvious differences in size or frequency of the species,
mass association will be as useful to the taxonomist for practical purposes
as if adults, puparia, or other stages were individually associated.
One point is often missed by those who do mount puparia with adults--
that one or both halves of the cap at the anterior end may break off and
be lost. If they are broken off, they should be located, if possible, and
placed in the capsule along with the main body of the puparium. One-half
of the cap bears the anterior spiracles, and adhering to the inside of the
other half are the mouth parts of the mature third-instar larva. Both
features are essential in identifying the immature stages and may be of
importance in classification.