Aphid Identification II

Since the last description of the techniques I have been using to identify aphids I have greatly improved my techniques. Therefore in the unlikely event that anyone is interested in doing similar on aphids or other species I thought I would describe my current methods

The first change I made was moving from Euparal, to Canada Balsam in a method close to the method described on the Aphid Trek website. The new technique consists of:

1. Poke the aphids with an insect pin, then put them in a ~10% sodium hydroxide solution for 12-24 hours. I am not real scientific here, and just dump some crystals into distilled water until it looks like about 10%.
2. Squish the aphids as shown in the USDA video. 
3. Put the aphids back in a new ~10% sodium hydroxide solution. Usually I heat them up to ~50C for two hours, but depending on my schedule I may leave them at room temperature for 12-24 hours.
4. Put them in 70% alcohol for two hours or longer. I have been using tiny beakers for this purpose, although the Aphid Trek website pointed me to contact lens cases. Those are way more convenient so I will be moving to those.
5. Repeat the same process with 95% ethanol.
6. Repeat the same process with clove oil. I just bought the cheapest clove oil I could find on Amazonand it appears to do the job.
7. Spread out some Canada Balsam on a slide and position the aphids. This is by far the most difficult step. Moving the aphids into position is really difficult. I use an insect pin to push them around but this isn't as easy as it sounds. I learned that using orange oil to make the Canada Balsam flow better made it easier to position them. Still though, I am always breaking off legs or antenna. Ideally I get an aphid on its back with intact legs, antenna, as well as a visible cauda, and head. I learned that putting 5-10 aphids on a slide greatly increases the chances I get one right.
8. Put the slide coverslip on, and let the slides sit for a few days at room temperature. It would be better if I could heat them, at room temperature it takes weeks to months to actually be dry. Still though, after a couple days they can be worked with easily enough.
9. Photograph using the same process as my last blog post.

The second main change I made was to add better scale bars. This is because aphid ID is so dependent on comparing lengths of various body parts. First I learned to make scale bars. I found that really wasn't enough though. What I needed was actual measurements the photo. So I use Photoshop to measure the relevant parts, and make custom length scale bars to put right next to the parts. This is really inefficient, someday I need to find a way to more easily label a bunch of lengths in a photo. Still though, it works.

Even with all this trouble I am only able to identify perhaps two thirds of the species I find. Sometimes the problem is poor slide mounts, but the rest seem to be divided between poorly described (undescribed?) species and species that I lack sufficient magnification to ID.

Being an Engineer, I am always game for fixing a problem with more complicated gadgets. So I just put in an order for a Labophot microscope, a phase contrast condenser, and a 10X phase contract objective. That should give me enough magnification to identify almost anything. If that fails, it would be easy enough to procure a 20X, 40X, or 100X objective.

Posted on August 27, 2017 06:14 PM by glmory