Conservation of parasites.

[Pycnogonid]

That hate towards parasites is astounding. Even on this forum I see it. People will even claim ecosystems will be better without them. Such lunacy.

Parasites regulate populations of organisms. In fact, they do a better job than predators a lot of the time. Plus, they keep populations healthy bu ensuring only those with robust immune systems get to pass on their genes.

Yet in zoos, animals are always cleaned of parasites.

I think we should let zoo animals keep some of their parasites to ensure a healthy population should the species recover. What do you think?

 

[Batto]

Your approach is a little one-sided. You're correct that parasites are (for obvious reasons) not very popular among humans - except for the very limited numbers of parasitologists and parasite geeks. This has a direct impact on the conservation of parasites, as the fate of Colpocephalum californici exemplifies.
However, you should be aware that zoos are systems created and managed by humans. As such, parasites can be a very negative factor impacting the health of the animals (and in the case of zoonotic transmission, also humans). Therefore, their presence and distribution in zoos isn't desirable. And if you ever had an animal in your care suffering or even dying due to parasites, you would understand that.

 

[Pycnogonid]

Your approach is a little one-sided. You're correct that parasites are (for obvious reasons) not very popular among humans - except for the very limited numbers of parasitologists and parasite geeks. This has a direct impact on the conservation of parasites, as the fate of Colpocephalum californici exemplifies.
However, you should be aware that zoos are systems created and managed by humans. As such, parasites can be a very negative factor impacting the health of the animals (and in the case of zoonotic transmission, also humans). Therefore, their presence and distribution in zoos isn't desirable. And if you ever had an animal in your care suffering or even dying due to parasites, you would understand that.

First of all, a lot of parasites tend to be host specific, meaning they can't transmit to humans under normal circumstances. And, animals with stronger immune systems actually do harbor parasites with few ill effects, so having internally stronger individuals keep parasites would be beneficial for the population as a whole. How else should we go about conserving parasites of endangered animals?

 

[d1am0ndback]

I think you would understand why people generally don't like parasites and why zoos keep their animals parasite free if you let tape worms make a host of your body.

 

[Ned]

If a population of zoo animals was destined for reintroduction to the wild, I could see the point in exposing then to the parasites they would come in to contact with. A species that had been kept free from parasites for many generations might lose their immune response to the parasites but in reality that would be relevant to very few species.

 

[Batto]

First of all, a lot of parasites tend to be host specific, meaning they can't transmit to humans under normal circumstances

And that's part of the issue: zoos create circumstances that aren't "normal", among others by bringing together species from complete different habitats into new habitats. This causes increased stress (which is detrimential to the general health of the animal), furthers interspecific parasite transmission and the confrontation of animals that they are not adopted to. And how to correctly define the "right" amount of which parasite for each zoo species? I acknowledge your intention, but you appear to be unaware of the practical implications of your idea.

 

[Coelacanth18]

It's already difficult to maintain and/or grow captive populations *with* standard veterinary care, which includes treating for parasites. Allowing a mortality of "weaker" animals would be detrimental to many current zoo populations. Not to mention the fact that zoos have an obligation to provide a comfortable and secure life for their animals; letting them die of parasitic infections is therefore highly unethical.

As to the argument that they might be losing their adaptiveness to parasites: that should not be a concern unless the species is actually in the wild trying to survive. When reintroducing a species, you want to release a very large number, expecting there to be high mortality in the first generations. In other words, Nature will weed out those individuals, not us. And if the species is not in a current process for being reintroduced into the wild, then it shouldn't even be relevant.

 

[Pycnogonid]

You all make good points. My point only applied to populations planning on being released into the wild. Obviously, we should take care of them. I'm just saying that at least some individuals should harbor some parasites.

 

[Batto]

First of all, a lot of parasites tend to be host specific,

Some, but not all. And especially in regard to "exotic" parasites with so far little impact on domestic livestock or humans, their potential to cross species barriers is little known. Baylisascaris procyonis is a good example for such a parasite. At first of little research interest, it caught the eye of the CDC and other Public Health agencies when the first human cases were diagnosed. In zoos, it started with infected parrots. Little is still known about the other Baylsascaris species.
Beyond the raccoon roundworm: The natural history of non-raccoon Baylisascaris species in the New World

So it's not about making "good points", but being realistic. Just because you "like" some parasites doesn't mean that their spread should be furthered as an "evolutionary fitness factor". If one were to follow such a concept more consequently, specimens set for release shouldn't receive any medical support at all, to sort out "the weak"...

 

[Jurek7]

Zoo animals are actually rarely completely free of parasites, even after generations in zoos.

Actually, rare animals and plants may have no species-specific parasites. For the parasite, hosts are disappearing habitat. So species-specific parasites likely go extinct long before the endangered host species, or never evolve in the first place.

Maybe an exception would be isolated species one-of a kind, e.g. Fiji iguana or solenodon or dugong, which probably have parasites but there is no closely related host species which could share parasites in their range.

 

[Pycnogonid]

So it's not about making "good points", but being realistic. Just because you "like" some parasites doesn't mean that their spread should be furthered as an "evolutionary fitness factor". If one were to follow such a concept more consequently, specimens set for release shouldn't receive any medical support at all, to sort out "the weak"...

That's why I said some individuals should keep parasites, and not all. And sometimes, parasites have little to no effect on the host. An example is the rhinoceros botfly. Botflies don't actually do too much in general. They just sit there, eat some flesh, and pupate. Because rhinos are so big, they can have dozens of rhino bot fly larvae and not even notice. Of course, other parasites have much more drastic effects, but this is an example of how keeping the parasite doesn't put the host in danger too much.

 

[Batto]

Botflies don't actually do too much in general.

Sorry, but that is incorrect. Major botfly infestations can have a significant detrimental effect on the health of the animal, especially when the wounds get infected. Among others, I've observed this in local wildlife, such as European roe deer infected by Hypoderma diana.

 

[Pycnogonid]

Sorry, but that is incorrect. Major botfly infestations can have a significant detrimental effect on the health of the animal, especially when the wounds get infected. Among others, I've observed this in local wildlife, such as European roe deer infected by Hypoderma diana.

Well, because deer are fairly small. Rhinos are really big. Healthy rhinos have been observed with dozens of botflies with no major effects.

 

[Ned]

Beyond the slight overreaction to Pycnogonid's comments is a question many livestock keepers ask, whether to treat our not to treat? Some individuals are able to cope with parasites, their immune systems keep the parasites down, others are effected more. Treating unnecessary not only costs money it could also lead to a super parasite immune to current treatments. It may be better to selectively treat the most effected individuals and leave others who's immune systems are coping.

 

[Batto]

Well, because deer are fairly small

You're aware that this generalisation is incorrect, also in regard to large species such as the moose or the elk?

Healthy rhinos have been observed with dozens of botflies with no major effects.

Could you please quote a qualified source for this? Thanks in advance.

As previously mentioned aka the so-called "slight overreaction" @Ned, this also depends on the species (both host and parasite), the environment and the pathogenicity of the parasite. In some cases (like Oxyuris sp. in herbivorous reptiles), the line between parasitism, commensalism and even mutualism can be blurry.

 

[DesertRhino150]

The idea of bringing in parasites, even specialised ones, to infect animals in zoo populations is all but impossible, both financially and legally.

Let’s use rhinoceros botflies as an example. The first and most basic problem is importing them – these flies only live between three and five days in their adult form so by the time someone has caught them, boxed them up, driven them to the airport in Africa and flown them to Europe they would already be nearing the end of their lifespan without the added problems of passing through customs and driving them to their destination. I can guarantee any attempt would see the entire brace die before they even arrived.

Let’s assume some rhino botflies arrive hale and hearty, are released into the rhino house and get to work parasitizing the animals. If they can survive in a temperate climate (which is of course, no guarantee) then they can potentially move between different zoo collections. In essence, if one zoo decided to do it, every zoo within a given distance has the capacity to end up with parasitized rhinos. Not every zoo will want that (in fact, I would say the enormous majority wouldn’t); the importing zoo would then be left in legal limbo. If an animal in a neighbouring zoo gets a heavy infestation and sickens or dies, the importer would be culpable for that.

And finally, the thing that would really put paid to any attempts would be the lengthy and extremely expensive process of ascertaining their threat level. Rhinoceros botflies only parasitize rhinos, but not everyone is going to be convinced by that. Quite rightly, the parasites would have to go through a rigorous testing process to ensure they cannot infect any other local animal, wild or domestic, in order to appease all the local farmers, pet-owners, wildlife managers, hunters and indeed probably the destination zoological collection itself.

If you think that is being overcautious, look at what happened when scientists in Britain tried to introduce the jumping plant louse Aphalara itadori to try and tackle invasive Japanese knotweed. They had to spend close to a decade testing every conceivable plant (and a lot of unconceivable ones as well) to ensure they would not get eaten as well. Without testing whether the lice could feed on aubergines and broad beans, about as different from knotweed as a plant can get, they would never have been allowed to introduce them. Testing would require a fresh batch of botflies to be imported to test each group of animals – the legal hoops required to bring these flies in would require at least hundreds, more likely thousands, to make the journey and be killed once each set of tests is over. And even if the tests prove the botflies cause no harm to other animals, yet more will need to be imported to actually establish the population, with no guarantee that they will survive beyond one breeding season (depending on their climate tolerance). If rhinoceros botflies are indeed threatened in the wild, such a pointless exercise would cause extreme harm to their populations for very little overall benefit.

That’s not even getting into the legal and moral aspects of deliberately infecting animals under a zoo’s care with parasites which, as mentioned, may not even get a significant help to their population while at the same time potentially reducing the fitness of the host animals. Would an animal from a ‘parasite zoo’ become less attractive for a breeding programme – if a zoo does not want an animal potentially carrying parasites from entering its grounds they will either refuse the animal (possibly denying beneficial pairings) or (more likely) bring it in and then eradicate its parasites, thus rendering the entire process of importing them pointless.

 

[Pycnogonid]

Well, your assuming we would need to keep importing tons of bot flies separately, when this is not the case. They would come with the rhinos, and would reproduce on their own in rhino enclosures. We can take one or a few specimens to test them on other animals to see weather or not they are truly specific to rhinos.

And, at least from what I know, bot flies do not effect the reproductive fitness of rhinos, and I don't see how they would. Admittedly, a lot is unknown about the fly. This is because, even in biology, parasites where largely ignored or demonized until recently. Only now do we start to understand them for what they really are. Of course, if they die in temperate climates, then the whole thing is pointless anyway.

The Oestrid Flies
If this is anything to go by, not only are they host specific, but also are in numbers little over a million, which is very small for an insect, especially a fly.

Now, if parasite infections became extremely large and out of hand, then we would have to kill them for the sake of the animal. But if there are few harmless/mostly harmless freeloaders at controllable levels with no ill effects, why not let them stay? Remember, as said earlier, the line between mutualism, comensalism, and parasitism is very blurry and subject to many factors, so we should obviously judge in a case by case basis. Stuff like malaria is obviously a no-no, but things like whale lice seem to have no major effects meaning they can be protected without harming the whales themselves. Remember that, in some cases, parasites can improve reproductive fitness.
Heritable true fitness and bright birds: a role for parasites? | Science

Could you please quote a qualified source for this? Thanks in advance.

Parasites lost | The San Diego Union-Tribune
This seems pretty accurate, but I'm not completely sure. Take with a grain of salt.

Some individuals are able to cope with parasites, their immune systems keep the parasites down, others are effected more. Treating unnecessary not only costs money it could also lead to a super parasite immune to current treatments. It may be better to selectively treat the most effected individuals and leave others who's immune systems are coping.

This is what I suggested, though I may not have made it clear.

 

[Batto]

We can take one or a few specimens to test them on other animals to see whether or not they are truly specific to rhinos.

DesertRhino150 already explained why this isn't so easy as you depict it. You would have a very hard time getting the approval to conduct such experiments, let alone get the funding.

Remember, as said [by Batto] earlier, the line between mutualism, comensalism, and parasitism is very blurry and subject to many factors

Take with a grain of salt.

Thanks; I do.

 

[Pycnogonid]

DesertRhino150 already explained why this isn't so easy as you depict it. You would have a very hard time getting the approval to conduct such experiments, let alone get the funding.

I can get approval issues, but funding? Just take a freshly mated rhino botfly from the exhibit (which would be admittedly difficult) and put it on another mammal. Difficult and tedious, yes, but not expensive.

 

[DesertRhino150]

I can get approval issues, but funding? Just take a freshly mated rhino botfly from the exhibit (which would be admittedly difficult) and put it on another mammal. Difficult and tedious, yes, but not expensive.

It would expensive because a scientifically rigorous test cannot be done with a single individual blowfly. To go back to my example of the jumping plant louse, the scientists involved had to test 87 species or varieties of plants (even though it was basically scientific common knowledge that the lice only fed on two species, plus hybrid between those two) and had to use over 146,000 individual insects to accurately test their impacts. For such tests, you couldn't simply rely on a few insects stowed away inside rhinos (which would need importing from Africa - not a common event nowadays and possibly not necessary now for the captive rhino populations); you would have to import the insects in large numbers.