Eye Rub

[ohaple]

So I have noticed black spots on my mantises eyes (not the pseudopupils). He is an adult h. majuscula. The next day I caught him hanging onto the wall of the enclosure rubbing his face in the dirt. I have never seen any behavior like that. He is fed regularly, and has been otherwise healthy. Any thoughts about what he is doing or how to get him to stop? I don't want his vision to become impaired because I know many animals become fearful when they lose their vision.

 

[bugboymark]

I noticed this happened too, with my last batch of adult H. venosas!  Some started developing the spot as pre-subs and sub-adults, but all had it by the time they were mature (or soon thereafter).  All of them could still see enough to eat, but I have to imagine it obscured their vision.  I honestly just assumed this was from bumping their head/eyes against the side of the enclosure, creating some sort of scarring tissue. 

The odd thing, was this ONLY happened to a second generation from mantises from the same ooth.  Coincidence?  Maybe.  It just seemed weird that the previous generation was fine.  All were raised in similar enclosures and environments.  Still seems so odd that every adult in the subsequent generation experienced the eye-spot thing.  Fortunately, as I mentioned before, they all seemed reach maturity in good shape and lived normal lives.  

Sorry to hijack this thread ohaple, but I've spent a fair amount of time thinking about how stuff like this could be an inbreeding thing!  For example, I recently had 5 adult female H. venosas.  Second generation (inbred) again.  When I mated them with males (also second gen from the same ooth), I only got 3 ooths out of 5 females!  They all lived for a couple months and died egg-bound, either producing only one ooth or none at all.  I tried all kinds of stuff.  Multiple mating/different males.  More food. Less food. Different food. Change in temps. Change in humidity.  No dice.  All failed.  Starting to wonder if there's more to this inbreeding thing than I originally thought.  I'm pretty sure some species are more predisposed to deleterious effects from inbreeding than others...but you'd have to imagine our hobby/trading community will start seeing more and more of this unless new blood is being imported from "off-shore"/native locations.  I hope not, but I wouldn't be surprised. 

There's my ramble for the day!

 

[ohaple]

My question was answered yesterday when he passed away. I have heard that mantids get these black spots and have strange behavior shortly before dying. He was (I believe) an appropriate age to go based on feeding schedule and temperature. I always leaned towards keeping him warm and fed rather than trying to extend his life some. I do not find any other evidence of disease or parasites, so I believe it was just age.

 

[MantisGirl13]

Sorry you lost him!

- MantisGirl13

 

[Mantis Lady]

Sorry for your loss

 

[hysteresis]

Well, he was warm and well fed!

A life well-lived in comfort.

 

[The Mantis Menagerie]

I noticed this happened too, with my last batch of adult H. venosas!  Some started developing the spot as pre-subs and sub-adults, but all had it by the time they were mature (or soon thereafter).  All of them could still see enough to eat, but I have to imagine it obscured their vision.  I honestly just assumed this was from bumping their head/eyes against the side of the enclosure, creating some sort of scarring tissue. 

The odd thing, was this ONLY happened to a second generation from mantises from the same ooth.  Coincidence?  Maybe.  It just seemed weird that the previous generation was fine.  All were raised in similar enclosures and environments.  Still seems so odd that every adult in the subsequent generation experienced the eye-spot thing.  Fortunately, as I mentioned before, they all seemed reach maturity in good shape and lived normal lives.  

Sorry to hijack this thread ohaple, but I've spent a fair amount of time thinking about how stuff like this could be an inbreeding thing!  For example, I recently had 5 adult female H. venosas.  Second generation (inbred) again.  When I mated them with males (also second gen from the same ooth), I only got 3 ooths out of 5 females!  They all lived for a couple months and died egg-bound, either producing only one ooth or none at all.  I tried all kinds of stuff.  Multiple mating/different males.  More food. Less food. Different food. Change in temps. Change in humidity.  No dice.  All failed.  Starting to wonder if there's more to this inbreeding thing than I originally thought.  I'm pretty sure some species are more predisposed to deleterious effects from inbreeding than others...but you'd have to imagine our hobby/trading community will start seeing more and more of this unless new blood is being imported from "off-shore"/native locations.  I hope not, but I wouldn't be surprised. 

There's my ramble for the day!

I do not think the eye issue is from inbreeding because I had a Chinese mantis this summer that had this issue. The mantis was wild-caught from an area with a large population of Chinese mantids and could not have been inbred. 

 

[ohaple]

I noticed this happened too, with my last batch of adult H. venosas!  Some started developing the spot as pre-subs and sub-adults, but all had it by the time they were mature (or soon thereafter).  All of them could still see enough to eat, but I have to imagine it obscured their vision.  I honestly just assumed this was from bumping their head/eyes against the side of the enclosure, creating some sort of scarring tissue. 

The odd thing, was this ONLY happened to a second generation from mantises from the same ooth.  Coincidence?  Maybe.  It just seemed weird that the previous generation was fine.  All were raised in similar enclosures and environments.  Still seems so odd that every adult in the subsequent generation experienced the eye-spot thing.  Fortunately, as I mentioned before, they all seemed reach maturity in good shape and lived normal lives.  

Sorry to hijack this thread ohaple, but I've spent a fair amount of time thinking about how stuff like this could be an inbreeding thing!  For example, I recently had 5 adult female H. venosas.  Second generation (inbred) again.  When I mated them with males (also second gen from the same ooth), I only got 3 ooths out of 5 females!  They all lived for a couple months and died egg-bound, either producing only one ooth or none at all.  I tried all kinds of stuff.  Multiple mating/different males.  More food. Less food. Different food. Change in temps. Change in humidity.  No dice.  All failed.  Starting to wonder if there's more to this inbreeding thing than I originally thought.  I'm pretty sure some species are more predisposed to deleterious effects from inbreeding than others...but you'd have to imagine our hobby/trading community will start seeing more and more of this unless new blood is being imported from "off-shore"/native locations.  I hope not, but I wouldn't be surprised. 

There's my ramble for the day!

To piggy-back on this, I also do not believe it to be inbreeding. From my limited knowledge, the more simple the animal, the less inbreeding matters. While even one or two generations in humans can have serious negative effects, colonies of insects are very often inter-bred. When you look at shrimp or isopods, it is common to breed many generations with each other to isolate certain traits. There is a somewhat noticeable decrease in their resilience, but otherwise the individuals seem to act normally and live normal lifespans. Good breeders will trade specimens with other breeders working on the same trait so that they can decrease the effects of inbreeding while still keeping the desired trait.

Also, even within inbred populations, more animals will exhibit reproductive preferences toward the most genetically dissimilar mates. So even if they come from the same gene-pool, they will try to select the mate that will result in the least "inbreeding."

Mantises are on the more complex side of inverts, so I expect the inbreeding to have more effect than in isopods or shrimp, but I wouldn't expect this sort of thing to show up for several generations. Would be interesting to see some formal studies confirming or denying my belief, but I didn't see anything in my short google search. Also somewhat problematic for mantises is that we do not allow them to exhibit their own sexual preferences for dissimilar mates. We typically put one female and male together and their choice is to mate or not. Since they cannot select a dissimilar mate, your choice of pairing could impact the effects of inbreeding.