Lost two Adult T. Sinensis - Anyone recognize these symptoms?

I lost two adult T. Sinensis females in the last few weeks to identical symptoms.

The problem seems to start with the mantid becoming less alert and losing control of its abdomen. When it hangs, the abdomen seems to hang down freely--not in line with the mantid's body. Eventually the mantid becomes weaker, and its rear legs no longer touch whatever it is hanging from.

In the next few days, the mantid becomes progressively weaker and then dies.

Without fail, the abdomen:

1. Appears bloated

2. Seems cold to the touch

3. Does not react when the cerci are touched.

4. Does not eliminate feces at all, or if it does, they either dribble out or come out in "strings."

The overall indicator that something is seriously wrong is that the mantid stops voluntarily eliminating--it's almost as if the mantid is constipated or the abdomen has "died." I can still see the abdomen pulsing, but nothing else happens.

I'm alarmed that this is happening to my mantids. Has anyone noticed any corrolating (or causative) links to these symptoms?

Your mantids sound like they have died of old age. Guessing you found these outside? That's normally what seems to happen. When they get to that stage I put them in the freezer for about 30 mins to get it over with .

Rick said:

Your mantids sound like they have died of old age. Guessing you found these outside? That's normally what seems to happen. When they get to that stage I put them in the freezer for about 30 mins to get it over with .

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Nope, these were ones I hatched in August. They've been adults for only a few weeks.

Headspace said:

Nope, these were ones I hatched in August. They've been adults for only a few weeks.

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Did they eat the same food? Have other mantids eaten the same food and remained fine?

Headspace said:

Nope, these were ones I hatched in August. They've been adults for only a few weeks.

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Well that can't be it then though the symptoms are the same. What have you fed them?

My mantids are currently all fed on house crickets (the standard kind you find at pet stores). I will stress that when I get new ones, I let them eat the food I provide for several days before they're fed to the mantids. I clean their enclosure twice a week.

All of the mantids eat the same food; from the same batch. The others I have are fine (as far as I can tell).

The food I use for crickets is rolled oats mixed with cat food and ground up. Occasionally I'll feed them some lettuce.

Not sure about the rest of the symptoms, but I did have one adult female that died after getting progressively weak like that. After her molt to adulthood, she did not eat except some honey and pollen that I offered after I noticed she was not hunting/eating on her own. Took about a week for her to die. I think that was about two weeks after the final molt.

The only problem that she had as a nymph was the folded abdomen problem that many T. sinensis seem to have. I doubt that was what killed her.

Headspace:

I guess that we'll never know what killed your sinensis, and any suggestion is only a guess, but there is one possible explanation that may be of interest. You mention that the mantids' feces came out in "strings", which often means that part of the gut is prolapsed, but it is possible that they were infested by hairworms (Nematomorpha). These worms are known to parasitize a small percentage of crickets in North America. Their life cycle is interesting in that they cause the infected cricket to "commit suicide" by falling into water (Google should tell the bizarre story), but will enter the gut of any predators, including mantids, that eat them. It is possible that the abdominal "pulsing", and "fullness" was due to the worm as it occupied more and more of the victim's abdomen, precluding eating and precipitating gut prolapse. It would seem that this is unlikely if the crickets were bred and raised under controlled conditions, but that may not have been the case. Your exemplary practice of gut loading the crickets before feeding them to your mantids would not have any effect in this case.

As always, I would be interested to hear a correction of this idea by any expert in the field, but it seems to be at least a possibility, and actual parasitization of mantises in this way has been recorded. The strongest objection to it is that you don't record a long, threadlike worm emerging from the victim peri or post mortum.

If it wasn't a parasite, is it possible that it could've been a nerve issue? Perhaps a nerve center controlling the abdomen of the mantis was damaged somehow by a virus, bacteria, or something else. I don't know much about mantis anatomy, just thought I'd provide a guess. It sucks you can't really do anything when they get sick.

PhilinYuma said:

Headspace:I guess that we'll never know what killed your sinensis, and any suggestion is only a guess, but there is one possible explanation that may be of interest. You mention that the mantids' feces came out in "strings", which often means that part of the gut is prolapsed, but it is possible that they were infested by hairworms (Nematomorpha). These worms are known to parasitize a small percentage of crickets in North America. Their life cycle is interesting in that they cause the infected cricket to "commit suicide" by falling into water (Google should tell the bizarre story), but will enter the gut of any predators, including mantids, that eat them. It is possible that the abdominal "pulsing", and "fullness" was due to the worm as it occupied more and more of the victim's abdomen, precluding eating and precipitating gut prolapse. It would seem that this is unlikely if the crickets were bred and raised under controlled conditions, but that may not have been the case. Your exemplary practice of gut loading the crickets before feeding them to your mantids would not have any effect in this case.

As always, I would be interested to hear a correction of this idea by any expert in the field, but it seems to be at least a possibility, and actual parasitization of mantises in this way has been recorded. The strongest objection to it is that you don't record a long, threadlike worm emerging from the victim peri or post mortum.

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Very unlikely. You're going to have the cricket haters jump all over this thread I am sure. Get your crickets from a good online breeder. I feed 95% crickets and have only had a problem once or twice in several years. It happens, plain and simple. Buy a batch from a good breeder, keep them on a substrate of dry oatmeal and feed them leafy greens (not iceberg lettuce) and occasional dry dog food. I doubt you will have this problem much.

Rick,

who do you suggest for a online cricket supplier?

Rick said:

Very unlikely. You're going to have the cricket haters jump all over this thread I am sure.

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Rick:

I agree about the unlikelihood. It is unlikely that if you caught 1,000 crickets far from water (i.e. a riparian habitat) that any would be parasitized, and I mentioned two other circumstances that further limit the possibility, but it is possible and consistent with the little evidence we have. I have always found the ability of parasites to induce bizarre behaviors in their victims, --crickets and grasshoppers in this case and some ants in Central Africa, for example -- which lead them to "commit suicide" to aid their killers and hoped that someone mght want to look it up.

Cricket haters, like Mexican immigrant haters and Chicago Bears haters (yes, I know that you're out there!) will persist in their unsupported beliefs regardless of anything that you or I might say to the contrary. I always remind myself that statements on this forum or elsewhere, made without adequate supporting evidence, are none the more valid for being spoken with confidence.

PhilinYuma said:

I have always found the ability of parasites to induce bizarre behaviors in their victims, --crickets and grasshoppers in this case and some ants in Central Africa, for example -- which lead them to "commit suicide" to aid their killers and hoped that someone mght want to look it up.

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I looked it up, Phil....

I'd considered the hairworm possibility, Phil. It would be pretty cool (in a really macabre sort of way), actually, because I've never seen them before and it would be neat to. But what would be even cooler is not losing any more mantids.

Let me elaborate on what I mean by "stringy..." the stuff kind of oozed out, as if it weren't being pushed out but just coming out on its own.

My running hypothesis is just that the mantids became dehydrated. This is the second time I've raised a big batch like this and the first time I've gotten them all the way to adulthood. So, it's been a learning experience. That particular mantid was right next to a radiator in the house and in an enclosure that had many vents which opened it into the air. It's possible that the misting schedule wasn insufficient. But who knows.

The latest victim is in the freezer right now. I'm going to do a dissection to see if I can learn more, once I have the time to sit down and do it. If the gut is prolapsed internally, I should be able to find out for sure.

Katnapper said:

I looked it up, Phil....

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Weird, huh? And if you enjoyed that, you'll love "zombie ants!" http://www.damninteresting.com/?p=54

Headspace said:

I'm going to do a dissection to see if I can learn more, once I have the time to sit down and do it. If the gut is prolapsed internally, I should be able to find out for sure.

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Headspace, you're a better man (woman in my case) than me! I wholeheartedly believe in, and truly like investigating and researching problems, causes, etc. But I won't go that far... eek, yuk, and urp... it's just not in me, lol.

Off to read about Phil's zombie ants.... Reading... now that's a research technique I'm comfortable with!

We did dissection of lubber grasshoppers when I took entomology in college (going on ten years now, but I'm sure insects haven't changed since then). I'm no expert but it's not particularly difficult. They have an integument that you cut away--carefully--and the organs are just there. Very simple.

Think of a lobster. Only smaller.

Ancillary to that, and now that I'm thinking of that course, we were told (in the course) that Mantids were of the order Orthoptera but everything I read in Wikipedia and elsewhere says that they're of order Mantodea. Was there a reclassification in the last 10 years or were they just dumbing it down for us?

Headspace said:

Ancillary to that, and now that I'm thinking of that course, we were told (in the course) that Mantids were of the order Orthoptera but everything I read in Wikipedia and elsewhere says that they're of order Mantodea. Was there a reclassification in the last 10 years or were they just dumbing it down for us?

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Like you say, Headspace, the critters haven't changed, but the classification has! The mantids and roaches were first split from the Orthoptera and became a new order, Dictyoptera, which has since been split into two new orders, Blattodea and Mantodea, but as Jane Fonda famously once said, "Come back next week!"

I look forward to hearing the result of your dissection.

Phil,

That explains it. I'm happy that I'm not remembering incorrectly.

I supposed you are all entitled to the results of my "autopsy." As much as it pained me to do it, I think it may shed some light on what was going on.

There were no wormlike parasites or anything of that nature. The foregut (or what I thought was the foregut), was absolutely full, and as soon as I pulled the abdomen open the foregut ruptured. The midgut and hindgut were mostly empty. Rupturing the foregut dumped all the liquid, which smelled bad but was otherwise uninteresting. It's amazing how much the mantids "chew" their food. There was almost nothing solid in there at all.

I was able to insert the blunt end of a pin through the rear into the hindgut, but there didn't seem to be anything blocking it that I could tell. It is strange that there wasn't much inside the hindgut but I am not knowledgeable enough about insect phyisology to draw any conclusions from this. Perhaps there was some blockage or something that limited the digesting food from passing through. Whatever the case, it's almost as if the digestive system had shut down and the contents of the mantid's crop were "under pressure."

Finally, and probably saddest of all, there were close to a hundred infertile eggs. Now I know why the female's abdomen is so much larger than the male's! The eggs are much bigger than I thought they would be.

This generated more questions than it answered, for me. What does everyone think? It's entirely possible that the gut had ruptured internally before I even opened it up, but there's no way to be sure. It certainly wasn't the most graceful of dissections, but I was able to separate most of the internal organs.