Are SEM images worth the cost?

And now, a dispatch from my current research. Consider these two images of the same species of Heterospilus wasp:

The color image was produced with standard light microscopy, the crisp monochromatic one using a Scanning Electron Microscope (SEM). We are currently deciding the extent to which we should pay to include the more expensive SEM images in a taxonomic monograph describing hundreds of new species.

The details of surface sculpture turn out to be rather important in separating Heterospilus species- and SEM reveals these characteristics in stunning detail. Points for SEM.

But users of the monograph will generally use only light microscopes, so it’s not like they’ll be able to make comparisons of their specimens to our SEMs. Points for light microscopy.

The cost of including SEMs is both time- it’ll take an extra month or two to take and process SEM images of each species- and money, in the form of salary and the $50/hour rate of using the machine. This, ironically, may lead to a print publication with fewer illustrations as we could eat into publication costs to pay for the SEMs.

The benefit to including more SEMs is a final online product that is better illustrated with respect to key characters.

I mention this not to coax opinions from the blogosphere, but just as an example of the sorts of decisions that are made in budgeting a NSF-funded biodiversity project. Plus, it’s on my mind this week.

10 thoughts on “Are SEM images worth the cost?”

  1. Your SEM only costs $50 an hour? Jealous… The one I use is $75-$125 an hour! And even though I went through the training to use the microscope without the assistance of a tech (the training cost $750), they still insist that the tech sits with me, which means I have to pay full price for scope time. So obnoxious.

  2. Henry Hespenheide

    The sculpture is clearly better on the SEM, but of course there’s no color. I guess it depends on what you want to show.

  3. I’m not sure if you are basing your cost analysis on the cost of printing or the cost of obtaining the images. There doesn’t seem to be much difference in the cost of printing line drawings and grey scale pictures anymore, but there still seems to be a premium on colour plates.

    If you need the SEMs for character analysis, then you are stuck with that cost.

    In my experience, SEMs are profitable during the analysis phase for understanding structures and finding new characters. However, as you note, if someone is going to use a taxonomic work for identification with a light microscope, then SEMs are of dubious value. I can think of a key to sawflies that uses SEMs that leaves me grouchy and nameless most of the time. I would concentrate on line drawings and light micrographs for the monograph and use SEMs to illustrate only characters that are not visible on the other illustrations or to explain the underlying nature of the characters. That would at least free up more of the budget for the more user-friendly images.

    SEMs are also provide very strong support for talks (especially if the data is weak) and are an outstanding tool for teaching. If you factor in the extra use you can get from your SEMs, beyond the monograph, then they aren’t so expensive.

  4. You could be old-fashioned and draw your beasts using what used to be called a drawing tube. Tedious but probably cheaper and you can show the diagnostic features; focussing up and down enables you to draw things in focus. Just a suggestion but many moons ago I got quite good at it in just a few weeks of practice.

    Colour is very useful if the colour balance is correct. Both SEM and automontage with diffuse light kills all the life of the original!

  5. Well, you have coaxed an opinion in the blogosphere.

    I recommend seeking out a collaboration with a colleague at a local small college or university who has unrestricted and free access to an SEM at their institution. Many schools have SEMs sitting around unused and in working condition, and faculty and trained students can use them for free. Students from the school can be trained to do the imaging. This would seriously bring the cost of the SEM imaging to almost nil, aside for a little support of the collaborator, and also increase your broader effects up the wazoo.

  6. Quoting Dave above, “In my experience, SEMs are profitable during the analysis phase for understanding structures and finding new characters. However, as you note, if someone is going to use a taxonomic work for identification with a light microscope, then SEMs are of dubious value.”
    I suppose him to mean, and myself had this experience when revising tiny little Nylanderia, that a few SEMs can train the eyes to see things that one didn’t notice before, but then become unnecessary (or at least, less necessary).

    If the choice is between the two images above, the SEM is far preferable, but if the stacked image light photo can be improved with sufficient combined images to render it really crisp, good color balance, and a bit less dulling diffusion, use light photos.

  7. If you don’t mind a comment from a non-biologist, I love SEM pictures for their sculptural qualities. For a long time, I’ve wanted somebody to mount a big museum show of SEMs of the heads of various arthropods juxtaposed with classic busts of the Roman emperors. Of course I also still watch reruns of Perry Mason because the crisp black and white photography made the faces of all those character actors you recognize but cannot name so wonderfully clear.

  8. I’m not a biologist, but I would keep the SEM photos in a monograph because even when using a regular microscope, the SEM photo can show you what to look for. For instance, in the two photos, you can make out most of the features in the regular shot that are highlighted in the SEM shot, but you might miss them if you didn’t know they were there.

  9. I saw the comment from Anon re. seeking a collaborator with access to a SEM, that description fits me pretty well. I teach a SEM class and am always looking for projects for my students. I have free use of a SEM and have won several awards for my work. Collaborations are always interesting, e-mail me if you are interested in discussing this further.

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