My Opinion: Keeping Trilobite Beetles (Platerodrilus spp.) In Captivity

[Hisserdude]

I've been seeing a lot of posts in breeder groups lately of people showing off their trilobite beetles, those posts usually get a ton of likes and comments from jealous hobbyists who want some themselves. Now a lot of people seem to think they are very difficult to keep in captivity, but the truth is that they are nearly IMPOSSIBLE to keep alive long term, and breeding them is almost certainly out of the picture for the average hobbyist.

If anyone here is thinking of getting their own trilobite beetles, or wants to learn more about why they are such horrible captives, please read the following post:

https://invertebratedude.blogspot.com/2019/03/my-opinion-trilobite-beetles.html

 

[schmiggle]

This is overall a very good point and sensible article. It's honestly a bit sickening that no one imports males.

I have two thoughts. First, are you sure that the beetles that die after three months in captivity weren't feeding? You mention survival of the subadult larvae (penultimate instar?) for three months and through one molt. Wong says they only lived six to eight weeks in captivity, and also that the presence of fat bodies indicates that his were feeding. I am wondering if people may have already succeeded in feeding these but that their adult lifespan is just short. The only way to know would be to dissect post-mortem. I will say that if no one has observed beetles laying small unfertilized eggs, as Wong mentions, that that is not a good sign.

Second, Wong says that log species wasn't predictive of where larvae would be found, but that larvae would only take relatively intact logs. This suggests to me that there is reason for optimism regarding the microfaunal diet of these beetles. Most fungi imperfecti (fungi that don't have large fruiting bodies; not a taxonomic term) have cosmopolitan ranges or are present across continents at the appropriate latitude. I would bet that it is possible to breed the food microbes (probably fungi, because fungi are commonly the most effective degraders of lignin) in captivity in the temperate zone, because they sound to me like generalist wood degrading fungi.

None of this is to say that the current importation and purchasing practices are ethical, but I think feeding may not be as difficult as all that. Breeding, on the other hand, seems to be quite challenging. One potential early problem would be that males are likely too short-lived to survive importation. I do think that if a species cannot be bred then it should not be imported.

 

[Salmonsaladsandwich]

Has anyone even tried multiple attempts to feed them damp rotting wood? The larvae died but it doesn't say anything about the temperature, humidity, ventilation etc. of the enclosure. There are so many other factors that can make things seem difficult to keep. I completely fail to see why it will "never be possible" and I wouldn't be at all surprised if they could survive on logs collected from moist forests or inoculated with forest debris and allowed to decay under moist conditions.

 

[schmiggle]

PS @Hisserdude does this mean you're back in the hobby?

The larvae died but it doesn't say anything about the temperature, humidity, ventilation etc. of the enclosure.

I wonder if these guys are being kept too warm. If they live in damp logs, they might be vulnerable to high temperatures. This is especially true given that they come from Southeast Asia--might they be found at elevation?

 

[SonsofArachne]

If anyone here is thinking of getting their own trilobite beetles, or wants to learn more about why they are such horrible captives, please read the following post:

This reminds me of what happened with giant pill millipedes - many were imported - all died. With the possible exception of Rhopalomeris carnifex which I read do fairly well in captivity. The fact that I saw some R carnifex for sale on FB a couple of days ago reminded me of this.

 

[schmiggle]

This reminds me of what happened with giant pill millipedes - many were imported - all died. With the possible exception of Rhopalomeris carnifex which I read do fairly well in captivity. The fact that I saw some R carnifex for sale on FB a couple of days ago reminded me of this.

This is good information--I wasn't aware any glomeridians do well in captivity. My mind also immediately sprung to these, because I suspect figuring out one will allow hobbyists to figure out the other. I think there's basically a niche that's just hard to work with.

 

[SonsofArachne]

This is good information--I wasn't aware any glomeridians do well in captivity. My mind also immediately sprung to these, because I suspect figuring out one will allow hobbyists to figure out the other. I think there's basically a niche that's just hard to work with.

http://arachnoboards.com/threads/pi...sibility-of-raising-them-in-captivity.292683/

 

[Hisserdude]

I have two thoughts. First, are you sure that the beetles that die after three months in captivity weren't feeding? You mention survival of the subadult larvae (penultimate instar?) for three months and through one molt. Wong says they only lived six to eight weeks in captivity, and also that the presence of fat bodies indicates that his were feeding. I am wondering if people may have already succeeded in feeding these but that their adult lifespan is just short. The only way to know would be to dissect post-mortem. I will say that if no one has observed beetles laying small unfertilized eggs, as Wong mentions, that that is not a good sign.

I don't remember mentioning survival of subadult larvae, but some larvae can survive some months in captivity and even molt once. So far as I know though, no one who didn't have a supply of rotten wood from their native habitat has been successful in keeping any life stages alive longer than a few months. Adults do have a short lifespan, yes, but that doesn't explain why smaller, immature larvae die off as well.
And nope, I've never heard of ANYONE besides Wong getting any eggs from their Platerodrilus...

Second, Wong says that log species wasn't predictive of where larvae would be found, but that larvae would only take relatively intact logs. This suggests to me that there is reason for optimism regarding the microfaunal diet of these beetles. Most fungi imperfecti (fungi that don't have large fruiting bodies; not a taxonomic term) have cosmopolitan ranges or are present across continents at the appropriate latitude. I would bet that it is possible to breed the food microbes (probably fungi, because fungi are commonly the most effective degraders of lignin) in captivity in the temperate zone, because they sound to me like generalist wood degrading fungi.

Well the thing is, it's likely that not only are they eating fungi, but protozoans, rotifers, and other tiny micro fauna as well. So fungi alone may not be enough to sustain them. Additionally, so far as I know, most European breeders have offered theirs rotten logs from Europe, and they still died out fairly quickly, indicating to me that they are picky and need microorganisms native to their natural habitat to feed on.

Has anyone even tried multiple attempts to feed them damp rotting wood? The larvae died but it doesn't say anything about the temperature, humidity, ventilation etc. of the enclosure. There are so many other factors that can make things seem difficult to keep. I completely fail to see why it will "never be possible" and I wouldn't be at all surprised if they could survive on logs collected from moist forests or inoculated with forest debris and allowed to decay under moist conditions.

Yup, European breeders have used rotten wood in most of the Platerodrilus setups I've seen, they still all died off. Pretty sure they need specific microorganisms from their native habitats to feed on, not just microorganisms from any continent. As it is, not enough research has been done on what specific microorganisms they feed on, so I think that bringing them into captivity at this point is a waste of resources and cruel to the Platerodrilus themselves.

Temperature could be an issue, but improper temps would likely kill them even quicker, most breeders keep them very humid, which I assume is the correct thing to do, as they are typically found in rainforests. IDK about ventilation. Point is though, what they eat has been the biggest mystery thus far, and seeing as most cultures kinda slowly dwindle down, I'm thinking an improper diet is the reason most people fail with them.

PS @Hisserdude does this mean you're back in the hobby?

Nah, I'm just here on the outskirts for now...

I wonder if these guys are being kept too warm. If they live in damp logs, they might be vulnerable to high temperatures. This is especially true given that they come from Southeast Asia--might they be found at elevation?

Eh, could be temperature, but I feel like that'd kill them off way faster, and from what I've been able to find out, most people's beetles don't die off immediately. And I think most of the species live in fairly warm climates, though there are some mountainous species.

 

[Hisserdude]

This reminds me of what happened with giant pill millipedes - many were imported - all died. With the possible exception of Rhopalomeris carnifex which I read do fairly well in captivity. The fact that I saw some R carnifex for sale on FB a couple of days ago reminded me of this.

Yeah, the really large pill millipedes are often collected in horrible condition, and are very sensitive to shipping, thus most are half dead on arrival.
However, several of the medium sized Asian pillipedes, as well as the European Glomeris and US native species do fairly well in captivity and have been bred successfully.

 

[schmiggle]

I don't remember mentioning survival of subadult larvae, but some larvae can survive some months in captivity and even molt once

I probably misunderstood this bit. When you said large larvae I assumed you meant subadult, and also all of similar life stages.

Well the thing is, it's likely that not only are they eating fungi, but protozoans, rotifers, and other tiny micro fauna as well. So fungi alone may not be enough to sustain them. Additionally, so far as I know, most European breeders have offered theirs rotten logs from Europe, and they still died out fairly quickly, indicating to me that they are picky and need microorganisms native to their natural habitat to feed on.

Again, not necessarily. It's hard to know why they weren't eating, or even that they weren't eating. For example, I remember seeing that part of what killed those green Madagascan pill millipedes was that their gut flora were killed off by high temperatures during shipping--sometimes there are die offs in the wild from high temperatures due to the same process. Gut flora are a lot more likely to be species specific than log fungi, especially with a specialized and not particularly digestible diet and especially given that log species is irrelevant.

Eh, could be temperature, but I feel like that'd kill them off way faster, and from what I've been able to find out

Yeah, you're probably right. And humidity wasn't enough to save the eggs, either. I doubt they want it dry...

The thing is that, when they've done studies on microbes around the world, none of the major groups are geographically limited--you can find closely related species on a given substrate for the most part, because of the incredible dispersal abilities of small organisms. Coupled with the fact that these beetles will eat any log at an appropriate stage of decay, it seems to me that if they were specialized on any specific microbe or microbial assemblage they would die out fairly quickly in the wild. I'm feeling bullish on the gut fauna being the secret at the moment, but I'm sure that's because of my bias towards assuming that symbiotic microbes rum everything always.

Nah, I'm just here on the outskirts for now..

 

[Hisserdude]

Again, not necessarily. It's hard to know why they weren't eating, or even that they weren't eating. For example, I remember seeing that part of what killed those green Madagascan pill millipedes was that their gut flora were killed off by high temperatures during shipping--sometimes there are die offs in the wild from high temperatures due to the same process. Gut flora are a lot more likely to be species specific than log fungi, especially with a specialized and not particularly digestible diet and especially given that log species is irrelevant.

Another person mentioned something similar, that certain microorganisms within their stomachs which they obtain from the rotten wood may aid in digestion. However if that's the case, then yeah, as soon as they're shipped, they'll lose said fauna, and likely wouldn't be able to obtain it again without access to rotten wood from their native habitat.
Just judging by how they do in captivity, I'm assuming the main problem is malnutrition, they may be eating some stuff people offer them, but I just don't think it's enough. I could be wrong of course, I've never kept them, this post is just my opinion based on all the information from scientists and hobbyists I could find.

Yeah, you're probably right. And humidity wasn't enough to save the eggs, either. I doubt they want it dry...

The thing is that, when they've done studies on microbes around the world, none of the major groups are geographically limited--you can find closely related species on a given substrate for the most part, because of the incredible dispersal abilities of small organisms. Coupled with the fact that these beetles will eat any log at an appropriate stage of decay, it seems to me that if they were specialized on any specific microbe or microbial assemblage they would die out fairly quickly in the wild. I'm feeling bullish on the gut fauna being the secret at the moment, but I'm sure that's because of my bias towards assuming that symbiotic microbes rum everything always.

Yeah, probably would die off immediately if not kept very humid, the eggs especially!

Maybe you're right on that, but if so I fail to see why they'd die when given rotten logs from Europe for example, if the microorganisms in them were enough for the Platerodrilus to survive, they should have done much better, especially since humidity, temperatures and ventilation seem to have been pretty OK in most of those enclosures.
Of course, if they need Asia native microfauna in their gut to digest their microorganism food, which they lose after being shipped, then we still have the same problem of them needing rotten wood from their native habitat to replenish said fauna, which is an unsustainable method I went into in my post, and who's to say the microfauna on the logs wouldn't die during transit?

 

[schmiggle]

Of course, if they need Asia native microfauna in their gut to digest their microorganism food, which they lose after being shipped, then we still have the same problem of them needing rotten wood from their native habitat to replenish said fauna, which is an unsustainable method I went into in my post, and who's to say the microfauna on the logs wouldn't die during transit?

The major difference you have is that, if the gut microorganisms are specialized, then they almost certainly don't just pick them up from their environment, they probably provide them to offspring. The relevant gut microfauna in that case may not even be able to be found in the wild.

If microfauna are the problem, what I think you would need to do is import the beetles in a less stressful way that preserves the gut microfauna. There's no way the people collecting these are particularly kind to them during the process--they probably arrive with a parasite load in addition to everything else, which only exacerbates the problem. If you imported a generation with microfauna intact, then you wouldn't have to worry about them ever again, since they would be a part of the colonies already present.

If they are picked up from the environment, it's a more significant problem, but I would be surprised if those couldn't be cultured. Figuring all that out, though, would be quite an ordeal.

The gut microfauna of trilobite beetles would actually make a pretty good PhD thesis lol.

 

[Hisserdude]

The major difference you have is that, if the gut microorganisms are specialized, then they almost certainly don't just pick them up from their environment, they probably provide them to offspring. The relevant gut microfauna in that case may not even be able to be found in the wild.

If microfauna are the problem, what I think you would need to do is import the beetles in a less stressful way that preserves the gut microfauna. There's no way the people collecting these are particularly kind to them during the process--they probably arrive with a parasite load in addition to everything else, which only exacerbates the problem. If you imported a generation with microfauna intact, then you wouldn't have to worry about them ever again, since they would be a part of the colonies already present.

If they are picked up from the environment, it's a more significant problem, but I would be surprised if those couldn't be cultured. Figuring all that out, though, would be quite an ordeal.

The gut microfauna of trilobite beetles would actually make a pretty good PhD thesis lol.

However, I believe Wong was near where these beetles lived, and collected them himself, had access to rotten wood, etc., and they still didn't do well, couldn't get his mated female to produce fertile eggs, and the three larvae he hatched from a wild clutch of eggs still died within three weeks... Which just adds to the confusion really.

Right now, my post is just going off of what's been established in the scientific community, maybe they do have important gut symbiotic microbes and such, but there are no papers supporting that theory ATM... I really think more research needs to be done on these beetles' diet and such before hobbyists even attempt to culture them, because as of right now, no one has had long term success keeping them alive, and certainly not in breeding them. Buying WC individuals right now is basically just a waste of time, resources and the lives of the beetles... I don't think the average hobbyist is going to be able to culture these until more work is done by scientists.

 

[schmiggle]

Buying WC individuals right now is basically just a waste of time, resources and the lives of the beetles... I don't think the average hobbyist is going to be able to culture these until more work is done by scientists.

Sure, that makes sense. Depends who your intended audience is.

Re: Wong, it's impossible to know why he had problems. His sample size was tiny. The male or the female might have been sterile, and if he only hatched three eggs that batch might have had genetic problems too. There is essentially a sample of size of 2 in his case--2 egg clusters--so his failure probably stems more from bad luck than anything else. His female had enough nutrients to produce a clutch of eggs, and he did mention that they had fat clusters, so he definitely got them to feed. The problem was somewhere else along the line.

 

[Salmonsaladsandwich]

What if the problem isn't the way they're being kept or fed (or the destruction of gut flora, temperature etc.) but simply that they aren't being fed enough? If they only feed on juices pressed from the surface of rotting wood, there can only be so much nutrition present on the surface relatively small amount of wood that can fit in an enclosure, which may not break down quickly enough to provide adequate nutrition for the beetles even if it decaying correctly. Maybe they would do better if supplied with much larger quantities of wood.

Also, Wong's paper mentions a reference to larvae being observed on fungi and apparently feeding on fungal growths on the wood. Just because they sip log juice doesn't mean they couldn't also require more sunstantial foods. Other members of Lycidae have been observed preying on soft bodied invertebrates as larvae, similar species have been reported feeding on rotting wood fluids just like trilobite beetles. It's possible that no one knows what else they feed on.

 

[schmiggle]

Also, Wong's paper mentions a reference to larvae being observed on fungi and apparently feeding on fungal growths on the wood. Just because they sip log juice doesn't mean they couldn't also require more sunstantial foods. Other members of Lycidae have been observed preying on soft bodied invertebrates as larvae, similar species have been reported feeding on rotting wood fluids just like trilobite beetles. It's possible that no one knows what else they feed on.

Lending more support to my supposition that this should be someone's graduate thesis.

I will say, though, that Wong was reporting on gut contents, and also it seems like his larvae were eating enough, again given the fat stores. I think the volume is nevertheless a good thought. I wonder if it might be possible to grow whatever they're eating in a more concentrated mixture, because no one's going to fit an entire log in an enclosure. I do think more observation in the wild and in captivity near the wild (where logs and whatnot are available and conditions are easier to make appropriate) will be necessary before anything is understood with any depth.

 

[Cresto]

If they actually do feed on fungal patches, it would be pretty easy to propogate the fungus. If someone could isolate the microfauna, they could possibly propogate it just like springtails.

 

[Cresto]

From research I have done it has been said a lot that "They feed on fresh decomposing wood, fungi and algae slime"

 

[Hisserdude]

From research I have done it has been said a lot that "They feed on fresh decomposing wood, fungi and algae slime"

That's just speculation, no studies have confirmed that they feed on decomposing wood or algae slime, so far there's only been one scientific publication lending any reliable information on their diet, which was the one by Wong.

 

[Cresto]

That's just speculation, no studies have confirmed that they feed on decomposing wood or algae slime, so far there's only been one scientific publication lending any reliable information on their diet, which was the one by Wong.

There are so many thing in nature that we don't know or havn't observed. It is really frustrating when you are expecting to find information, but no one has done any field observations.