Programmed stages/life expectancy of mantids

[GreenBean]

For those of you who have oft witnessed mantids in the wild, captured them, raised them, observed closely, taken notes, OR for the straight-up entomologists out there, here's my question:

I am really interested in understanding programmed development in mantids. It's not that I'm doing a scientific study in the pure sense, but that I'm DAMN FRUSTRATED at trying to pin down (with SOME amount of predictability and expectation) this molting business and general stage development in hopes of better understanding their demise--is it disease process, injury (easy to tell), OR pre-programmed life expectancy? Here's the detailed situation if you are interested (or skip to "Crux" below):

I have, for the last several years, captured mantids in the wild between Santa Fe, NM, and The Columbia Gorge, OR/WA. I have learned much from these fascinating creatures. Only this season did I actually come upon some that were not full-blown adults (don't know if my eye is keener now, OR if there was some weird thing this season that caused staggered hatchings throughout the summer season). In any event, I am down to my last wild child of the season whom I was stunned to find so young, so late. I've had her for about 3 months now, seen her successfully through 2 molts. She has her wing buds and they are swelling, she is slowing down...could be obvious signs of an imminent molt. HOWEVER, on closer inspection, she appears to be very defensive, much like a neurologically degenerating late adult, in that she is often falling from her molting perch and remaining on the bottom of the cage until I gingerly assist her to top again, and she has started giving me that scary "stayawayfrommeoriwillkillyou" posture (rears up, arches, reveals "eyes", ready to snap my head off with those formidable forelegs--all 1.25 inches of her). You might say she is just ready to molt and I should leave her to be, but it's not playing out quite that conveniently. She obviously can't molt while on the bottom of the cage, and she's not making much attempt to get to top of cage and hang again. Cage is plenty humid, temp just right, easy-to-climb sides and wonderful hanging perches--all safeguards in place.

Additionally, I just had another sub-adult who appeared perfectly healthy and spry for months, also up and die just as wing buds appeared to be taking her into final molt. Molt never even started. She just really slowed down about 3 days before I found her on her back, lifeless. She even was still eating from tweezers in those final days, and no signs of aggressive behavior. Then, there was one other subadult, I believe was a male (very slender, think I counted more ab segments, plus clearly longer antennae), that passed in a very similar way just before final molt (that was a few weeks ago.) And, then there was another female I actually found in the wild AS she was just finishing up her final molt, very late in season, about a week or so after I thought mantids were done for the year due to outdoor temps (I posted about her recently). She was beautiful, healthy, but died way too early as an adult with no obvious signs of disease or injury.

If you skipped all that, here's the crux of the matter:

1. Someone once posted that perhaps there was a programmed life expectancy to mantids and that maybe some bugs were, for whatever reasons (which leads me to another part of my inquiry), spending an unusually long time in early stages (instars), but in the end, still lived close to full life expectancy. But since one cannot know when bug first sprang from ooth (having not witnessed that), one cannot know for sure the age of subject.

2. I also wonder what other confounding factors there might be: could colder outdoor weather prolong or distort the developmental process in some late bloomers (late enough in season that they would be more likely exposed to cooler fall temps, but not cold enough or long enough to snuff out their fragile lives)? And, what is a possible explanation for hatching much later than others...and I am talking about same species found in the same 1 block area, so species and location need not enter into this discussion.

3. One more burning obvious question: does captivity, even under the most ideal (simulated natural) and controlled circumstances, adversely affect mantids development?

4. I have not yet raised my own bugs from birth through adulthood (I have traditionally released them in spring so I may return my attentions to my own, human children once again). I suspect those of you who have, and have burning interest in understanding these wonderful creatures, can shed some light here for me.

To sum: I would LOVE to know of any relevant observations and conclusions you have drawn or researched on this subject. I have wonderful scientific mantid books, I am a Google Monster (thankyouverymuch), and I cannot find a satisfying answer to these things. Closest I am going to get is by hearing from others' experiences.

thanks in advance,

Yours truly,

Green Bean*

*(name chosen because of striking resemblance the skinny, green, male Chinese/Euro mantids have to said legume)

 

[angelofdeathzz]

sorry dude but you may need a professional on this topic, maybe Philin Yuma can help? he lives for this sort of thing. lol

 

[PeterF]

On #2. Sure, entirely possible "could colder outdoor weather prolong or distort the developmental process in some late bloomers".

As for difference w/ in a block. The temp difference for an egg mass is potentially variable w/ in a block due to actual location. Shade, other cooling factors.

There is also the issue of a difference in times they were laid. I am uncertain that has much of an effect after wintering, but I would expect it to.

Temp, and food intake. Those are the two primary influences on arthropod development.

And can be variable enough with in 1000 feet.

But, what was your fall like last year? Could oothes have been laid unusually late? (all this takes is relatively mild weather, this year we still had europeans out after the first two light frosts).

 

[Rick]

I believe that it is due to nutrition/food availability and environmental conditions. . Since all mantids of the same species are in direct competition with one another, some are going to be more successful at catching food. These individuals are going to grow faster compared to others who are not so fortunate.

Other factors that restrict nutrients are going to have same effect. I often find nymphs in the wild that are not adult yet despite it being late in the season. These mantids are often carrying parasitic fly larva. Obviously these parasites are taking some nutrients away from the mantis causing slow growth.

All ooths do not hatch at the same time in the wild. This may be because the ooths were laid at different times. Or perhaps one ooth is in the shadow of a large tree or building, thus not receiving as much sun/heat. Or why ooths do not all hatch at the same time could be much more complicated than that.

I don't think captivity affects development unless the captive mantis is not receiving enough nutrition to support proper growth.

I think that once you have been in this hobby for awhile you will answer all of these questions quite readily.

 

[PeterF]

Oothes hatching at different times and therefor nymphs being different sizes at the same time would help the survival of the species by keeping them from competing for the same food (because it will be different sizes).

Similar to how the completely different feeding habits of caterpillars and moths (of the same species) eases them living in the same spaces by not competing for food

 

[Rick]

Oothes hatching at different times and therefor nymphs being different sizes at the same time would help the survival of the species by keeping them from competing for the same food (because it will be different sizes).

Similar to how the completely different feeding habits of caterpillars and moths (of the same species) eases them living in the same spaces by not competing for food

That is a good point. But then again in many areas the growing season is only so long. Those late bloomers may not reach sexual maturity to pass along their genes. You could think of it as a form of natural selection.

 

[PeterF]

That is a good point. But then again in many areas the growing season is only so long. Those late bloomers may not reach sexual maturity to pass along their genes. You could think of it as a form of natural selection.

Yes, but in most areas the season is long enough to support staggered hatching, even though it won't support multigenerations per year.

Also, the later hatching mantids will have a shorter time between birth and adult hood (more food, warmer temps) in general.

 

[Ntsees]

Rick pretty much summed it up. Regarding pre-programmed life expectancy, if I'm getting it right, it's not really pre-programmed at all. The amount of available food, and other factors like temperature, plays a part. A mantid that hatched early and rarely fed will fall behind another mantid that hatched later and fed often. Also, as mentioned in other posts, mantids that hatch at the same time from the same ooth will all not grow at the same rate. Some may be 2-3 molts behind when others have already become adults.

 

[PhilinYuma]

Yeah, I think that Rick and Peter have just about nailed this one, but that won't stop me from adding a few thoughts.

Properly managed captive mantids live under conditions closer to optimal than in the wild. Adequate or overfeeding though (this is the US after all) shortens the time from hatching to maturity but also shortens the mantid's life.

There seems to be no doubt that ooths laid earlier tend to hatch earlier (this has been demonstrated in Chinese mantids), and there is probably no "better" time for the ooth to be laid; all that is important is that at least one adult male and female survive from among the offspring of one female parent. The earliest laid non-diapausal ooths stand the risk of hatching in the warm days of Indian summer and then being frozen by the first heavy frost, but if they overwinter, they may hatch in time to feed on young/small prey with less competition than their later hatching peers. Later ooths are less likely to hatch before winter, but by hatching later in spring, they are more subject to predation by small critters like spiders that their elder siblings will be old enough to prey on (this phenomenon, the reversal of prey/predator relationship between spiders and mantis nymphs has been documented). Peter mentions the advantage of nymphs of different sizes in the same micro habitat eating different sized foods, but the younger nymphs are likely to be on the menu of their elder brethren. Another advantage of staggered hatching, as we have discussed recently, is the fact that adult males mature earlier than their female siblings and fly off to mate with mature females that hatched earlier (tough luck for the first males of the season though

).

I think, though, that your main question was, is a mantid's life span pre-programmed, and the answer is simply (and complicatedly ) yes and for good reason. The purpose of a living organism is to reproduce. Once an animal is no longer able to perform this function or, where the offspring are altricial (born helpless), needed to care for the youngest offspring once they are independent, it generally has no more biological function, though, as in the case of some societies, such as those of humans elephants and bighorns, it may have limited social value.

Once useless, an animal puts an unnecessary stress on the biomass, continuing to eat food that productive members need for survival. Mantids in the US are univoltine, i.e. they only have one brood a year. They are "programmed" to wear down after they have fulfilled their reproductive function and in captivity we see them slowing down, losing their appetite and losing bits of their appendages. In the wild, they would also become increasingly susceptible to predators.

But this programming is not very precise. A few US species on the southern border will overwinter, even though there has been no evidence of them breeding in the following year, and some tropical mantids are bivultine. The New Zealand mantis, for example, Orthodera novaezealandiae has been observed overwintering and mating with the new generation on the South Island. Generally speaking, though, a US mantis, raised in the wild or under ideal conditions in captivity will die of old age in the fall or be killed by the first deep frost.

There!

 

[Rick]

Rick pretty much summed it up. Regarding pre-programmed life expectancy, if I'm getting it right, it's not really pre-programmed at all. The amount of available food, and other factors like temperature, plays a part. A mantid that hatched early and rarely fed will fall behind another mantid that hatched later and fed often. Also, as mentioned in other posts, mantids that hatch at the same time from the same ooth will all not grow at the same rate. Some may be 2-3 molts behind when others have already become adults.

I forgot about that. Mantids from the same ooth do often grow at different rates even when all things seem equal. However, I have only seen this in captivity since there would be no way in the wild I could know if two mantids are from the same ooth. Assuming it's just not a captivity issue and all things are equal, perhaps it is a genetics issue.

 

[Ntsees]

Hahaha, if you put it in Phil's way, he is right. A mantid won't live longer than it's capable (like most/all U.S. native/naturalized mantids won't live to breed with the following generation). I was thinking along the lines of "this specific mantid will get to this specific size in this amount of time frame" or "this mantid will reach adulthood in exactly 3 months".

 

[PhilinYuma]

I forgot about that. Mantids from the same ooth do often grow at different rates even when all things seem equal. However, I have only seen this in captivity since there would be no way in the wild I could know if two mantids are from the same ooth. Assuming it's just not a captivity issue and all things are equal, perhaps it is a genetics issue.

I don't think so. The growth rate is readily controlled in captivity by feeding one mantis heavily and starving another. There is a general rule that if a given trait can be due to a physical cause, like Kamakiri's S. limbata females with "crinkly" wings, then a redundant genetic explanation should not be sought. Were it genetic, I would expect that the most successful growth rate, whether fast or slow, would be selected for. If there is an advantage to having peers that develop at different rates, then so far as I know, no one has found it. l.E. Hurd, who has moved since he contributed to the Prete book has written on this topic. You can see the abstract and buy the article here: http://www.jstor.org/pss/4356

 

[MantidLord]

I agree with everything said above, except the captive vs wild development. Despite food intake and humidity, stress can be a huge factor for a captive mantis, and can restrict development of a mantis, or possibly cause an increase (more so than in the wild) of random deaths. Just wanted to add that in there, because I believe (unless I didn't read all the way) that stress was left out. Not to say that wild mantids don't get stressed out obviously, but they have adapted to their environment, rather than adapting to being confined in s small space for all their lives.

 

[GreenBean]

"Also, as mentioned in other posts, mantids that hatch at the same time from the same ooth will all not grow at the same rate. Some may be 2-3 molts behind when others have already become adults."

Wow, really?? That's a pretty significant difference.

 

[PhilinYuma]

I agree with everything said above, except the captive vs wild development. Despite food intake and humidity, stress can be a huge factor for a captive mantis, and can restrict development of a mantis, or possibly cause an increase (more so than in the wild) of random deaths. Just wanted to add that in there, because I believe (unless I didn't read all the way) that stress was left out. Not to say that wild mantids don't get stressed out obviously, but they have adapted to their environment, rather than adapting to being confined in s small space for all their lives.

kova

Yeah, I agree. We have talked about the stress of handling mantids, recently, but not the more pervasive stress caused by keeping mantids in poorly ventilated pots. No one gave a particular reason for misting (beyond infuriating our pets! ) but one good result of misting is that it causes evaporation and air turnover. One mantis lab mentioned in the Prete book mists twice a day, which seems like a good idea if you are going to do it at all, since it will give about ten hours of evaporation/circulation depending on the RH gradient.

 

[MantidLord]

Green Bean: I've had a third instar chinese and a sub adult chinese from the same ooth housed in the same conditions. It happens.

Phil: Yes, misting does seem to have a correlation with development. I'm curious though if that's the only form of stress (besides handling) that we have on our beloved pets that limits development.

 

[GreenBean]

Green Bean: I've had a third instar chinese and a sub adult chinese from the same ooth housed in the same conditions. It happens.

Thanks for that firsthand information. Just what I was looking for.

Phil: Yes, misting does seem to have a correlation with development. I'm curious though if that's the only form of stress (besides handling) that we have on our beloved pets that limits development.

I'm wondering why misting causes stress at all IF it is done indirectly (that is, not sprayed directly onto the mantis, but over the cage and allowed to settle, for example). I mean, if you think about heavy raindrops falling on them in the wild, a light mist falling on them doesn't seem like it would be a stress-inducing practice...or am I missing something here??

 

[PhilinYuma]

O.K., it's getting late and maybe I'm confused, but I don't think that I ever said that misting in itself is a source of stress. Certainly I never meant to, aside from squirting the little bugger so hard that it runs away or strikes a defensive pose. My guess, and it's only a guess, is that one of the major causes of stress among captive mantids is poor air circulation in 32 oz pots. Also, of course, mantis hobbyists who have spent more than a year in th hobby, learning husbandry, are probably a minority, and many forms of stress experienced by our charges are due to errors, like leaving too many crix in an enclosure, using poorly designed or inadequate enclosures, and trying exotic and sometimes bizarre foods, among many other things. Remember, if you have an ooth hatch and you succeed in raising enough mantids so that you have more than one successfully mating pair, then you are doing better than nature.

 

[PhilinYuma]

O.K., it's getting late and maybe I'm confused, but I don't think that I ever said that misting in itself is a source of stress. Certainly I never meant to, aside from squirting the little bugger so hard that it runs away or strikes a defensive pose. My guess, and it's only a guess, is that one of the major causes of stress among captive mantids is poor air circulation in 32 oz pots. Also, of course, mantis hobbyists who have spent more than a year in th hobby, learning husbandry, are probably a minority, and many forms of stress experienced by our charges are due to errors, like leaving too many crix in an enclosure, using poorly designed or inadequate enclosures, and trying exotic and sometimes bizarre foods, among many other things. Remember, if you have an ooth hatch and you succeed in raising enough mantids so that you have more than one successfully mating pair, then you are doing better than nature.