Help: L2 Dynastes tityus Larvae Dying For Unknown Reasons

B

Bill Myers

Tenebrio
First of all, a little background:

I learned a long time ago to isolate my larvae in individual containers so that if there was a disease, it wouldn't result in mass fatalities.

So, this has me befuddled:

A few weeks ago, I noticed that my D. tityus L2's weren't looking very healthy and some of them had died.

Suspecting that the substrate I used might be the problem, I went out to the woods and collected some decayed hardwood and processed it (via the submerging method and drying it out on a trampoline).

(Pro Tip: A trampoline is an excellent sieve for getting the water out of your substrate. Depending on temperature and wind, it usually takes only a day or two to dry everything out to the perfect moisture level)

Anyway, be that as it may, I removed the old substrate from the L2 containers and put the new substrate in.

I checked on 3 or 4 of them at random a couple of days later and they all looked like they were recovering just fine. So, I thought all was well and decided to leave them alone for a couple of weeks before disturbing them again.

Well, yesterday, I went to mist their containers with some distilled water, and I encountered dead L2 after dead L2!!! They were almost completely dissolved and must have died about a week or so ago.

All tallied, I've lost over 30 L2's and only have 12 left!!!

I haven't a clue as to what is going on!

I know my wife used some flea drops on the dog and cats about a month ago, but I don't think that's the culprit because my D. tityus L3's and D. grantii L2's and L3's are doing just fine.

Nothing makes any sense.

Anyone have any suggestions?

 
My first guess would be something in the substrate. When you processed the sub is there any way something could have fallen in there that could be toxic to the larvae? What if you take half of the ones that are alive and switch them to a different substrate that is collected from a different source?

 
If you don't process your substrate, it's possible to introduce pathogens, predators, and parasites. Did you bleach your old containers before re-using them? You can encounter contamination by using contaminated containers or by spreading it from one container to another by contaminated tools, your hands, and by using contaminated containers.

I can't say whether or not your problem is the result of environmental contamination in the form of pesticides, but it's common to find that one stage or instar of an invertebrate is susceptible to some pesticide while the other instars are unharmed. Different species are also easily different in susceptibility.

It's also likely that whatever they had was still in its gestation period in the larvae that died in the new susbstrate.

 
I know this probably gets asked more than it needs to, but did you remove all the old substrate and replace it with 100% new or did you leave at least 30% old? They may have had a bad time adjusting to the new substrate. Other than that, the location you collected could've very well been sprayed with herbicides or pesticides. Reading you post over again, it seems the larvae were already having some problems, they might have been diseased from an unknown source and the move compromised their immune system further.

 
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