Resources



The Ashmead Project

The Platygastrid Sketchbook

M.W,MacGown

matt@entomology.msstate.edu

Introduction

Robert Fouts (1924) revision is the starting point for any study of North American Platygastrinae, and I often reiterate that his descriptive material is excellent. But without numerous diagrams and pictures, it is impossible to even remotely conceptualize this group of wasps. My work (MacGown, 1979) on the species from the coniferous biome in North America contained some simple drawings, and I hope to have since improved upon those. I had very little idea then of the importance of detailed illustration, coupled with studies of biology of both the host and the parasite, to the taxonomy of Platygastrinae. I now understand this to be a study that warrants a lifetime of work, but also one that will never recieve a penny of research money from any granting agency, with only minor exceptions. I study the group simply for fun - to learn new techniques in microscopy, slide preparations, illustration, and whatever else may be of interest, and if it takes another 50 years to develop an understanding of Platygastridae in North America, so much the better.

The sole purpose of the drawings is to amplify the descriptions given by Fouts and others, including myself, and make them available to at least a few other students of the group. I have no intention of creating a monographic or revisionary study of Platygastrinae, now, or ever in the future. The job is presently too complex for a single individual. When I began studying platygastrines in 1969, there was no objective reference for most of the species, save those from wheat midge. And in fact, the situation has hardly changed, although there are a few diagrams and some pictures now in the literature.

The North American types, unlike those of European species, are readily accessible and mostly housed in a single place, the National Museum of Natural History, in Washington, D.C. I have chosen to focus on those from North America, although some may have holarctic distribution. The holarctic species tend to be found in the Pacific Northwest through to Alaska, and strung out through the northern coniferous biome. From there, they appear to run down the coastal regions of far eastern Russia, into the northern portions of Japan. Therefore, it is advisable to gather up as much of the world literature as possible if you wish to study this group for the whole of North America.

W.H.Ashmead, at the turn of the 20th century, was the platygastrid pioneer in this country, and was responsible for setting up most of the types for the species that we now study. Fouts' revision is basically a redescription of Ashmead's species, along with the new ones that he created himself. Ashmead very often erected a species on the basis of one, two, or a very few specimens, and sometimes these are not very amenable to detailed study such as can be done with cleared material on a slide, or on SEM. They are point mounted, usually glued to the point with a dark amber colored varnish. Platygastrids are actually best studied from either cleared microscope slides or SEM stub-mounted specimens, therefore there is a limited amount of information available form the Ashmead types. One of my main objectives has been to accumulate more specimens of the Ashmead species, so that they may be studied from slides or in SEM. It is a very time consuming project, at best slow, but produces a much clearer view of the material that that from point mounts under a dissecting microscope.

Therefore, I have opted to call this "The Ashmead Project", inclusive of all the U.S. species named by him and since him. It is rather ambitious in scope, but is given new impetus by the collecting of S.M. Fullerton and P. Russell at the University of Central Florida, since many of Ashmead types originated in Jacksonville, FL., where he resided for several years.

I use the conservative classification of the Catalog of Hymenoptera in America North of Mexico (K.V. Krombein, P.D. Hurd and D.R. Smith, 1979. Smithsonian Institution Press, Washington, D.C., 3 Vol.) realizing that there are newer concepts available. But the higher classification of platygastrids has been in a state of rapid flux for the last couple of decades, and seems at best unstable. The present study is aimed strictly at species level decriptive taxonomy, and makes no attempts to extrapolate into higher categories.

Types were drawn from pinned specimens, using a camera lucida, not always an easy chore, because many are in poor condition. I made some adjustments in numerous cases, to show details more clearly, therefore the drawings may not be rendered precisely as the specimen appears on the pin. Lately, I have been drawing mainly from slide mounted, KOH and lactophenol cleared specimens mounted in carboxymethyl cellulose (CMC) , to which I add a contrast stain such as safranin, or, alternatively, mounted in balsam. CMC with stain has produced very good results but is very time consuming, sometimes requiring a few days to prepare a decent slide. Since I am not in a hurry, it seems worth the extra effort when there are enough specimens to warrant this treatment. Ordinarilly, I remove the antennae and wings, and often the legs, for separate slides. The specimens can be drawn at 400X-1000X with a compound microscope, largely circumventing the need for SEM for those of us who don't have one on our desk.

Good dissecting microscopes for drawing pin - mounted platygastrines with a camera lucida are not all that easy to find. Older scopes, especially those with flourite 6X to 7X objectives, may be much better for this than most of the newer ones. Coupled with recently engineered high power oculars, they can produce quite startling images. Most newer scopes with wide field collecting lenses need a 2X auxilliary objective, which produces excessive curvature of field, resulting in considerable distortion of the final image. Even with older microscopes, the image must be taken from the center of the field of view, and needs to be drawn quite large. Thus I use montages of overlapping drawings, sometimes resulting in drawings as much as 3 or 4 feet wide and tall, which are then reduced on a photocopy machine. It is essentially the same situation that cartographers face when drawing from aerial photos, ie., only the central third of the photo is closely accurate. It's a difficult situation to avoid, since I am very reluctant to place a type specimen from Ashmead's work - quite likely to be the only specimen - under an electron microscope. It seems better to learn the skills required to do it the old fashioned way - and that takes some time.

Fouts described his microscope as a "Bausch and Lomb binocular microscope (no. 5 ocular and 24 mm. objective)", used with a disk micrometer graduated in tenths of a millimeter. For several years I sought to duplicate this scope, to see things as Fouts saw them, and then to improve upon the equipment. Two or three of the old B&L scopes have come my way, but only recently have I found the "no.5 oculars", enabling me to replicate his arrangement. It is quite remarkable that he was able to make such accurate descriptions based on this set of tools, none-the- less, they are -if barely- sufficient. I now use two of the old B&L scopes, but with new optics and illuminators (three, mounted on the scope barrel). A hundred watt indoor flood light in a parabolic shade is excellent for viewing microsculpture. Several new ocular combinations, ranging from 6X to 20 or 25 X, are ideally suited to these old scopes.If not available, they can be constructed from other eyepieces.

Good old microscopes abound at colleges and universities, gathering dust on back shelves and in old cabinets, but - they usually require an inordinate amount of restoration- so one is lucky if he finds a scope which will be useful without requiring hours of labor. Yet, it is a great saving, since new scopes, often inferior to these, are extremely expensive.

The higher magnification microscopes aren't suitable for sorting and pinning material, making microscope slides, or for other more routine work. The field of view is far too restrictive. There is a wide variety of microscopes that are good for these purposes. Good, general purpose dissecting scopes are not difficult to find at a university lab.

Because I like Fouts' descriptions, and have studied them more or less atomistically in relation to the specimens upon which they were based, I have opted to scan the descriptions into this paper, adding my drawings for amplification. I use an OCR program for this, with flatbed scanner, then put both the text and pictures into a Microsoft Wordâ document. The pages can also be put into a web page if that's desirable. They are stored on 100 MEG Zipdisks from IOMEGAâ .

Inexpensive Videomicroscopy for Parasitic Wasps

The methods described here are fairly simple and inexpensive, and will suffice for a broad variety of purposes requiring computer microscopy. They are excellent for low and medium magnification studies of cleared specimens mounted in CMC, with a contrast stain, and can also be used with balsam mounts. CMC is my prefered medium for this work. High resolution and very high magnification light microscopy will require more sophisticated and expensive equipment, such as the high quality digital cameras and a good phase contrast or DIF microscope.

A student microscope modified with a 0.9 to 1.25 Abbe condenser and iris diaphram is essential. Video microscopy insists on a goood condenser. But these are built in on many good student scopes. I inserted a 1.25x auxilliary lense into the bottom of this scope, mounting it in a styrofoam ring. It produces a pseudo - infinty optics effect, that is, enables me the use of infinity objectives from older microscopes such as later model AOs at a 250 mm tube length. The auxilliay object came out of an old Leitz, and is mounted only a few millimeters above the objective shoulder in the main tube. It is not necessary to have these, however, and a plain tube will still work well.

The adaptor for the videocamera is any simple ring that will take an eyepiece and provide a deck for the camera lense - the function of course, is to keep the lense from hitting the ocular of the scope. I also have home made styrofoam adaptors. Specific adaptors are not needed for this system because the camera is mounted onto a copy stand, and simply rotates over the eyepice and back away when not in use. Since most of the microscopes are parfocal or close to it, there has been no problem of having to raise or lower the camera. Even when that situation arises, it is hardly uncomfortable.

A 6X or 6.3X eyepiece maximizes the image, any larger magnification is too much for most monitors and TV sets. Smaller is better, and 2.5 to 6 would be a happy combination. Old eyepieces that are in good condition are as good as new ones. Older video cameras with no digital zoom mechanisms seem to produce better pictures than new digital videocameras, but either works well. I suspect the new digitals introduce electronic noise into the system. I have a very old Panasonic VHS HQ, and a new RCA 72x digital. The latter is best for macro shots using a magnifying glass, the former, for straightforward microscopy.

Below I show the basic system, and a few pictures taken with it. The frames are grabbed with a "Snappy", piped through a switch box into the computer. The switch box serves scanner, printer and camera. It's convenient. Most of the pictures are best presented after running them through Adobe Photoshop, but the full program is unecessary, and PS Limited Edition has all the features needed to clean up and stylize, if desired, videomicrographs. In fact, there is a rather pleasant array of options suited for this in PSLE.

Several people, both in private and through listserver e-mail questions, have expressed curiosity about getting inexpensive video microscope pictures onto their computers, thence to the internet. This is my simplest response, and the system that I use most frequently, bearing in mind that we have available considerably more sophisticated equipment as well. But this serves for many of the more mundane computer microscopy needs, and in fact, can be used to prepare some rather nice pictures, with just a little extra effort in PSLE.



I have also included the following genera. Click the name to go to descriptive and pictorial information. Since this is progressive, there will be a lot of empty slots to be filled at the outset, but I have many pictures from all the genera, and they will eventually find their way into the page.

Included genera:

Inostemma

belonocnemae

californica

lintneri

Isostasius

Tetrabaeus

Acerotella

Allotropa

americana

Iphitrachelus

Fidiobia

Amitus

Metanopedias

Trichacis

Isocybus

Platygaster

abicollis MacGown and Osgood

alnicola (Ashmead)

americana (Ashmead)

antennariae (Ashmead)

anura Fouts

artemisiae (Ashmead)

ashmeadiana Huggert

astericola (Ashmead)

asynaptae (Ashmead)

atrae Fouts

atriplicis (Ashmead)

baccharicola (Ashmead)

beneficiens MacGown

burkei (Rohwer)

californica (Ashmead)

coloradensis (Ashmead)

columbiana Fouts

compressiventris (Ashmead)

confusa Fouts

cynipicola (Ashmead)

distincta Fouts

errans Fouts

eurotiae (Ashmead)

euurae (Ashmead)

exiguiae Fouts

filicornis (Ashmead)

flavitarsis (Fouts)

floridensis Ashmead

fumipennis Fouts

fuscipennis Fouts

gahani Fouts

herrickii Packard

hiemalis Forbes

huachucae (Ashmead)

kalmiae Fouts

kimballi MacGown

laevicollis (Ashmead)

lampronota Fouts

laticeps (Ashmead)

libocedri MacGown

leguminicolae Fouts

linearis Fouts

lucida Fouts

lupinicola (Ashmead)

mainensis MacGown and Osgood

marylandica Fouts

melanocera (Ashmead)

melliscapus (Ashmead)

nigricoxa Fouts

nigrifemur (Ashmead)

obscuripennis Ashmead

picipes (Ashmead)

pinyonicola MacGown

prolata MacGown

pseudotsugae MacGown

relativa Fouts

rowheri Fouts

salicicola (Ashmead)

semiglabra (Girault)

similis MacGown

solidaginis (Ashmead)

variabilis Fouts

virginiensis (Ashmead)

zosine Walker

Anopedias

Euxestonotus

Eritrissomerus

Piestopleura

Synopeas

Sactogaster

Gastrotrypes

Leptacis

Amblyaspis