Any beetle parasite/illness experts out there?

[Rylee Isitt]

I recently found a Tenebrionid darkling beetle behaving very strangely. It's almost as if it's having a stroke... its left palp is vibrating, it has several paralyzed legs, and it staggers and falls when it walks. It walks with its head touching the ground and its abdomen raised, and I've noticed it excessively grooming its ovipositor, with its elytra raised and the ovipositor extended quite some distance (perhaps half a cm).

Then, it seems to recover for much of a day only to repeat the process later. I'm starting to think it may be infected by a parasite. I originally planned to keep it overnight with some damp KimWipes and some decaying vegetation (food source), but when I noticed this behavior I've taken to keeping the enclosure maintained to see what happens. I am half expecting it to end up dead one day, having larvae emerged from it.

Any idea what might be going on here?
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[DQE]

I am NOT any sort of expert, but I've seen somewhat similar behavior in a bug that had been attacked by a spider. It seemed as if the victim received a less than lethal venom dose, and most such victims/prey (I have only seen a handful of examples) don't seem to fully recover.
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-Phil

"Diffraction never sleeps"

[Rylee Isitt]

Interesting...

I suppose that insect veterinarians are hard to come by, but maybe that's what happened...

At the moment the beetle is behaving normally and seems to have fed on some of the decaying wood and leaf litter I put in there.
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[Rylee Isitt]

I may have figured this out.

I started to notice that the occurrence of the symptoms was correlated with me misting the container to provide water. I've been using tap water, and our local water is chemically treated with a variety of things to kill pathogens.

I switched over to distilled water, and since then the beetle has been much more active and behaving normally, including feeding and drinking.

So perhaps it was a reaction to chlorine or flouride?
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[DQE]

Your note about using distilled water triggered something I was told, now partially stored in my distant memory banks.

I recall that a highly regarded chemist where I worked once mentioned that sometimes distilled water causes more problems than just using tap water. Specifically, he said that the lack of various ions and other "impurities" in distilled water would sometimes cause the immersed "object" to lose its own ions and minerals, trace elements, etc. If instead one used ordinary tap water, the "object" may actually be less stressed.

I asked when this was true and when it was not true, and I only got back an "it depends" answer. Yet his comment does make one wonder about using distilled water in certain circumstances. I *think* he mentioned that a car radiator would do worse if one used distilled water, but that a car battery would do better with distilled water.
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-Phil

"Diffraction never sleeps"

[Rylee Isitt]

Most things are soluble to a certain extent, even things like minerals. But as the concentration of a dissolved substance in water increases, its ability to hold more decreases.

So it does make sense that distilled water could leech minerals out of whatever it comes into contact with to a better extent than tap water, at least until the concentrations of minerals in the water reaches saturation.

In my case, I suspect that distilled water is somewhat more akin to rain water than is tap water. Rain water will have dissolved atmospheric gases in it, including nitrogen, oxygen and CO2, as well as some amount of carbonic acid. Rain water will likely also have small particles of nucleating agents. This last thing is something that distilled water won't likely have. However, since I'm adding it to a very "messy" enclosure (in the sense that it contains dirt, organic debris, etc) I don't think it will be harmful to the beetle.

We'll see. I'm fairly certain the tap water was not a good idea in this case, although I will probably never know exactly what in the tap water was to blame. Conventional wisdom says that letting tap water sit around for a while should cause the chlorine to evaporate out. I did this, but it didn't seem to help. So perhaps chlorine is not at fault here.
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[Harold Gough]

[Rylee Isitt]

My source is the supermarket, and all I have to go on is the product label, "Distilled Water".

We use DI water in the lab. But distilled water is easy to make by re-condensing steam. I have no reason to doubt the supermarket's claims
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