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Kategorie: Naturwissenschaft

Biodiversity research in the US, is the so called American Way always a good basis?

A collegue from the field of entomology recently wrote me his impressions about the situation of scientific fundings in the western world, as he travels around and stays with each of his feet in another country. He said that everybody knows about the importance of the biodiversity on earth and that consequently everybody agrees that research on the biodiversity deserves to be funded. But he continued that this does not mean that the same people would agree that biodiversity research requires experts and that experts would even need to be paid. Thus many of his former students in the US or Germany need to survive with temporary jobs other than their expertises would require.

But also an international unbalance of financial resources, available for fundamental research in entomology or for example acarology (my discipline) can lead to experts being sorted out, although they would be urgently needed. The focus, based on the considered eligibility of research, changed withing the last 25 years. As before Germany was a hotspot for high-quality research in the fields of evolutionary biology, systematics and biodiversity research, that focus of interest is now located in the USA. They invest more money into these sciences than all European countries together.

This can additionally have consequences for the quality of such kinds of research. It is no secret that the general educational level in the US is at least in some areas comparably low, many people don’t speak foreign languages, they often don’t travel abroad, and they live in midst of a mentality, which says „America first“. Biodiversity research would in the old German world of science regularly be connected with many „but consider that…“ conditions. The American way, in some cases, might want to have it easier. They might say: what’s the problem? What do they want to have? Yes, right, they want the numbers of all discovered species. They ask for numbers, thus we do our best to give them numbers, as fast as possible.

Some privileged US-researchers might even misuse their financial power to decide, who in other countries is and who is not. But I say in a rhetoric „you“: Use your fundings to involve as many suffering experts from abroad as possible, instead of center too much work and responsibility on yourself, you won’t have enough time due to too many species, which still need to be discovered and described.  Don’t work too fast and don’t risk to become too superficial. Each species deserves time. Share the work with others and make science benefit from the different kinds of backgrounds in different areas of the world.

 

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A mite of the Histiostomatidae, found in Amsterdam in its original substrate as example for the topic „Acarology“

 

All copyrights (also of SEM photo): Dr. rer. nat. Stefan F. Wirth, Berlin July 2020

Mite Histiostoma piceae

The mite Histiostoma piceae Scheucher, 1957 is a member of the mite family Histiostomatidae (Astigmata, Acariformes). Scheucher discovered the mite based on all instars from spruce, infected by the bark beetle Ips typographus. She collected her samples in Regensburg, Höbing (bei Roth) and Harz. Scheucher reared her specimens on potatoes and bran, but describes that her cultures did grow well only to some degree.

According to her findings,  phoretic carrier (hosts) is the bark beetle species Ips typographus, she also found deutonymphs rarely on some staphylinids. She discovered that free living non-deutonymphal stages develop on fresh detritus, while deutonymphs appear only on old detritus („after it was for a longer time removed from the trees“, „wenn der Mulm einige Zeit aus den Bäumen entfernt ist“). I could like Scheucher culture the mites on potato, but a bit better in their original gallery substrate. Under laboratory conditions, they indeed did not rear very well in both kinds of cultures.

I collected H. piceae between 2000 and 2004 once from a wooden log infested by I. typographus in Berlin, then got access to microscopic slides from Europe in the collection of John C. Moser (Louisiana, USA) in 2007 and 2009, then I collected samples from Ips typographus and I. cembrae in Central Croatia (publication Wirth, Weis and Pernek, 2016) and found out that H. piceae is not restricted to I. typographus, but also to its sibling species I. cembrae. I finally collected the mite from I. typographus galleries between 2015 and 2016 in Western-Siberia near the city Tyumen.

I repeatedly observed deutonymphs of H. piceae under natural conditions (bark samples directly after the excursions) to develop in very high numbers, then attaching to all available arthropods nearby, smaller bark beetle species and numerous bigger mites of different groups, such as for example oribatids.

Published recordings of H. piceae from other bark beetles than I. typographus and I. cembrae are doubtful and need to be named Histiostoma cf. piceae. In some cases with I. typographus additionally present, I interpret the mites to have switched from their regular carrier (host) to an adjacent gallery of e.g. another smaller bark beetle species. In other cases, the existence of similar looking species new to science needs to be tested. In cases of determinations by non specialists from bark beetles other than the above mentioned two beetle species, it needs to be assumed that these people could not differ between similar mite species, such as Histiostoma trichophorum Oudemans, 1912, Histiostoma ulmi Scheucher, 1957 or Histiostoma crypturgi Scheucher, 1957.

 

I never before published the full set of SEM and light microscopic photos from these  times (except of my article about host specificity). In this explicite photo publication here on my homepage, I herewith publish SEM-photographs, objects sputtered with gold, which might be not unique to science, but very rare.

Any subsequent research on this mite in Europe is not happening (a few not too relevant findings are published by a former Russian colleague). Reason is that modern science does not understand, especially not in Germany, that fundamental research in applied fields is worth to be funded. It is for example known that deutonymphs of different mite species on bark beetles regularly carry fungus spores (different fungus species, just sticking on the mite’s cuticle), discovered by John C. Moser and confirmed by several of my own publications. This phenomenon is still not closer studied. Fungus transport into bark beetle galleries can influence the micro climate there.

 

 

Male and female of Histiostoma piceae, A venter of male, B dorsum of male, C mouthparts with Digitus fixus, D dorsum of female, E side-frontal view to female; Berlin 2002-2020, copyrights Stefan F. Wirth

 

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Deutonymph of Histiostoma piceae in ventral view, collected in Western Siberia, 2015 – 2016, copyrights Stefan F. Wirth

 

Systematics: Histiostoma piceae is according to my phd thesis from 2004 and according to my more recent research findings a member of a clade (monophylum) within Histiostomatidae with most species associated with bark beetles (Scolytinae) or other bark inhabiting coleopterans; these phylogenetic findings are based on morphological characters.

Mite Histiostoma maritimum

The mite Histiostoma maritimum Oudemans 1914 is a member of the mite family Histiostomatidae (Astigmata, Acariformes). Oudemans discovered the mite based on its deutonymph only from a Dutch island. The German acarologist R. Scheucher found the species in 1957 in mud at the riverside of Regnitz and for the first time could rear H. maritimum and was able to redescribe it by its adult stages, especially females look morphologically conspicuous due to a sclerotized cuticula shield around its copulation opening. She reared her specimens on potatoes, mud and bran, but describes that her cultures did not grow well.

Phoretic carrieres (hosts) are beetles of genus Heterocerus, some carabids and according her findings also rarely some staphylinids.

I discovered H. maritimum between 2000 and 2004 repeatedly in sapropel around ponds in an old gravel pit area in Berlin, forest Grunewald, named „im Jagen 86“. They were mainly attached to the beetles Heterocerus fenestratus and Heterocerus fusculus, but could regularly also be found on the carabids Elaphrus cupreus and Bembidion sp.. I could several times rear the mites, like Scheucher almost unsuccessfully on potatoes, but well on cadavers of their carriers. I thus reconstructed a so called necromenic life-strategy for H. maritium. This means that a phoretic stage ascends a carrier, but never leaves, instead it awaits the carrier’s natural dead to develop on its cadaver (published in my phd thesis, online, 2004).

I will not publish my full set of SEM photos from earlier times here. Some photos will be saved for one of my upcoming paper submissions in scientific and peer-reviewed journals. In this photo publication here on my homepage, I at least publish some interesting SEM-photographs, based on objects sputtered with gold and a subsequent critical-point-drying procedure.

Adults of Histiostoma maritimum: A left male, right female, B, C, copulation opening, D dorsal view to female with mouthparts and copulation opening

Systematics: H. maritimum shares morphological characters of deutonymph (setation, apodemes) and adults (mouthpart details, shape of Digitus fixus) with species like Histiostoma feroniarum, H. insulare, H. litorale, H. palustre, H. polypori, H. myrmicarum. This might indicate a separate clade, but according to the old findings in my phd thesis, also a paraphyletic grouping including these species is thinkable.

Copyrights Stefan F. Wirth, 10 June 2020

Christian hate preachers in Germany? The dubious case of a hardliner

He is 53 years old, a hunter and a strength athlete, but Olaf Latzel is unfortunately also an evangelical pastor of the St.-Martini church municipality in the German city Bremen. Livestreams of his church services during times of the corona-crisis since February 2020 had up to 30000 clicks. He and his work are well liked not only in his own municipality. But fortunately, there is also much and harsh criticism against his preaching.

His style of sermonizing is, according to what I saw on his Youtube-Channel, very passionate. His sermons have a very dominant and commanding pitch, and when he talks against homosexuals and other religions, his emotions force his significant nasolabial wrinkles downwards to a grim face, and his eyes peer to the ceiling, when he emphasizes that we had one lord only, and he often shouts an almost hysteric „hallelujah“, when he subsequently continues with statements like „ein Knecht, ein Sklave, hat nur einen Herrn (a servant, a slave, has only one lord)“ and later „kein Knecht kann zwei Herren dienen…(no servant can serve two gods)“. He accordingly is strictly against mixed church services, wants Buddha statues or amulets in households to be destroyed and is such focused on details of ancient text details of the bible that female pastors in his church are not allowed to wear a talar (robe of an evangelical priest) or to preach from the pulpit. Homosexuals are welcome in his municipality only according to the principle „against sins, but for sinners“. Muslims can be treated with mercy, again only following the same principle. But I say: It is a sin to create sinners based o the natural diversity of life!

Apart from discriminating statements against Islam, Buddhism or homosexuals, the slave and servant idea is one of his main topics. According to his preaching, the believers represent nothing else than slaves or servants of god, who even paid for this slave service due to the blood of Jesus Christ. Olaf Latzel is a hardliner, and he does not try to hide this. But the distinct reduction of believers to slaves, to a herd of sheep in the full sense of this term, is also a very clever gambit against individualism, independent free thoughts and criticism. Stupid sheep are easy to control, they ask no critical questions, they even don’t express doubts about statements, written in a thousands of years old ancient book. But there is no god, who demands for thoughtless sheep, there are only very secular authorities in the disguise of religious leaders, who need sheep to fulfill their very secular motivations, namely to live a privileged life on the costs of their slavish subjects. If god preferred sheep instead of humans, he would have appeared as sheep among sheep.

Jesus Christ was the historical human being Jesus from Nazareth. He was an individualist with free thoughts and represented a critic of old and traditional religious attitudes. He considered the stupid human sheep in the Temple in Jerusalem his opponents, and his major aim was to teach and practice charity. His followers were women, who he met as equals, and unmarried men with unknown erotic preferences  (Who knows, may be some considered themselves even as non-binaries!). The disciples of Jesus from Nazareth had a subversive and creative power to modernize the communities, they did not look back to their ancient past, but instead invested their energy in a more human future (at least originally). They today would not find any of their ideals in municipalities with Christian hate preachers.

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Jesus meets two strangers in an evening twilight scenery, a man and a woman, on an equal level. Both strangers are proud of being free thinkers, the man might even be gay, we don’t know. Oil on canvas, Berlin May 2020, copyrights Stefan F. Wirth.

 

 

Berlin, May 2020, copyrights Stefan F. Wirth

Systematics and biology of termites and about their phoretic associations

They live in eusocial communities, but are not closer related to ants or bees. Termites belong to the cockroaches.

 

Queen, king and castes

 

Usually one queen and one king are reproductive and act as heads of the nest. The different work fields of a nest are executed by infertile specimens, which can show very different and specialized body shapes. The diversity of different castes is in phylogenetically „primitive“ taxa lower than in „higher developed“ termite groups.

 

As example specimens of a deadwood species from Italy

 

This species was found in deadwood of a small forest in Portici (Gulf of Naples, Italy) and might represent the taxon Kalotermitidae. This taxon branches off rather basically  in the systematic tree of termites. Nest work can be taken over by nymphs of later alates.

 

deadwood-termites from Italy, Youtube: copyrights Stefan F. Wirth, April 2020

 

 

How is wood-eating possible?

 

Wood eating termites bear bacteria and protozoans  in their digestive tracts, which perform the digestion of cellulose.

 

Evolution, sister taxon and endosymbionts

 

Termites (Isoptera) evolved within the cockroaches (Blattodea). According to modern systematics (e.g.  Beccaloni & Eccleton, 2011) the cockroach taxon Cryptocercidae is the sister-clade of the termites. But there are controversial theories existing.

According to such reconstructions, the last common ancestor of cockroach taxon Cryptocercidae and termites possessed bacterial and protozoan endosymbionts. Molecular data proved that endosymbionts in both groups are closely related to each other. The last common ancestor of both groups showed in case of their indeed sister-group-relation a tendency towards social communities. Cryptocercidae live temporarily in bigger groups together with their offspring.

 

Subsocial lifestyle in Cryptocercidae

 

Cockroaches of the Cryptocercidae as putative sister taxon of termites live inside galleries in deadwood and feed on wood fibres. At least one parent and its nymphs live subsocially inside their galleries. Cryptocercidae adults and nymphs groom each other, and parents feed juveniles with wood fragments afer these had passed their anus openings.

 

According to recent systematic/ phylogenetic reconstructions the Kalotermitidae belong to the basically branching termite groups. Such basic groups of termites still show a low diversity of castes only.

 

Associates, commensalism and phoresy

 

Like ants or bees, termites share their nests regularly with associates of other groups of animals,

often mites and nematodes. Some of these organisms use termites as carriers for a transport over bigger distances. details of such associations between insects and mites are not well studied yet. But carrier-passenger-situations with transfer („taxi“-) purposes are called phoresy. Phoresy ist mostly considered as a neutral association between different organisms and is thus interpreted as commensalism. Commensalism is differed from strategies like parasiticm or symbiosis and requires that two organisms in association do not harm or noticeably benefit each other. The term commensalism often includes associations, in which the true context for both organism partners is simply not understood yet.

 

Not yet mites of the Gamasina (Parasitiformes) were reared in greater numbers out of my Italian termite substrate. They might represent phoretic cohabitants of those termites. Other mite species of different mite groups (Parasitiformes and Acariformes) were only found in smaller numbers and died out too quickly for collections and determinations under my culture conditions, unfortunately already before the beginning of my shootings. seemingly microclimatic conditions had become too unfavorable.

 

Copyrights Stefan F. Wirth, Berlin 2019 – 2020, all rights reserved

Wild bee Andrena flavipes and nesting behaviors

The bee Andrena flavipes is also known as the common sand bee, as this species represents the most common of several regularly present sand bee species in Central Europe.

 

Aggregations at suitable nesting sites

 

Bee females create solitary nests, which is unlike to social hymenopterans such as the honey bee Apis mellifera. However huge and from a distance well visible aggregations of nesting A. flavipes specimens can appear. It is said that these aggregations are due to mated females being attracted to similar suitable nesting sites. In fact also a tolerance for conspecifics very close by is required to allow conditions, in which the whole ground seems to consist of bees, flying around and preparing their nests or importing pollen or nectar to feed their larvae. By the way: One nest contains contains about 2-3 brood cells only.

 

Specific conditions, in which specimens of my footage were found

 

The bees of my video were filmed between 4-6 April 2020 in the urban park around lake Plötzensee in Berlin. The site for my recordings was an area with forest edge character, interrupted by dry meadows, all at least in the afternoon exposed by the sun (temperatures between 15-20 °C).

 

 

Females of Andrena flavipes cleaning their nests, youtube: copyrights Stefan F. Wirth, April 2020

 

 

Orientation and nest cleaning behaviors of A. flavipes females, hindlegs as multifunctional organs

 

Contents of my behavioral documentation is the cleaning of nest hole entrance areas and behavior patterns, which seemingly support the orientation and finding their own nests again in midst of a sandy forest ground covered by fallen leaves.

To be enabled to recognize the entrance of the own nest again, bees perform regularly smaller walking tours around their nests to memorize soil structure and other details, being suitable to characterize this specific nesting site.

The bee’s hindlegs represent important multi-functional organs. They walk on them, collect pollen, which adhere to specific structures on legs III, and they are used to clean the areas in front of the nest openings from dirt, such as smaller stones or wooden particles. As nest entrance areas stay opened during the day, a proper cleaning of the soil around is regularly necessary. The bee performs that work mostly while backward-walking using its hindlegs like shovels to sweep dirt some centimeters away. This behavior is well visible in my footage.

 

General and short  information about mite associations

 

Andrena flavipes and other soil breeding wild bees are generally also of acarological interest. As presumably all hymenopterans, they have for example associations with phoretic mites, for example mites of the Scutacaridae (such as Imparipes apicola). I so far did not study mites on these bees, but phoresy means that mite instars use the insect as carrier to reach their final sites, in which they develop and reproduce. In case of Imparipes, adults feed on fungi and waste inside the bees brood cells.

 

 

Copyrights Stefan F. Wirth, Berlin april 2020, as always: all rights reserved

Host specificy, host change and intermediate hosts in different organisms – with special reference to viruses and Sars-CoV-2

We recently read a lot about the pandemic consequences of infections with the new corona virus Sars-CoV-2, most are medical issues, hygienic advises and information about political reactions in different countries worldwide. But there is not much known about the biological host reservoir, putative intermediate hosts and how the human infections might be explained. It is a normal lack of information, because the scientific research about topics, being generally new to science, is time costing, especially, when life strategies and the population dynamics of organisms a concerned. Organisms? Viruses are per definitionem not considered organisms, because they lack important aspects, which characterize real life: they cannot reproduce on their own power, they do not have an own metabolism, no ingestion, no excretion. But they are organic and show traces of life by possessing a genome, which might indicate that they evolved from living cells. Viruses represent a diverse group of protein bodies containing nucleic acid, either DNA or RNA.

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New corona virus Sars-CoV-2, Wikipedia: CDC/ Alissa Eckert, MS; Dan Higgins, MAM / Public domain

Viruses in general, host specificity, host increase, host change

For reproduction viruses depend on living host cells, which they reprogram by inserting their virus genome into the cell’s genome in order to stimulate the forming of a number of virus copies, all that happening on cost of the host cell’s life. Thus viruses need to be named parasites as they harm their hosts to their own advantage. Different groups of viruses attack different kinds of cells using in detail different methods to enslave their host cells. There are plant viruses, viruses associated with bacteria (named bacteriophages) and animalistic viruses. They all show characters, which are typical for parasite – host – relationships. Parasitic partners of any kind of host – parasite – relationship can be exclusively associated with one host species only (host specificity) or a limited group of systematically closely related hosts, while others can have a wider range of different host species. The latter generally might have evolved out of the former, although also the opposite direction is thinkable. When former host-specific parasites make themselves one or even several further hosts accessible, then this phenomenon is named host-increase (Wirtserweiterung). In case an new host was infested as permanent host, while the former host is given up, then a so called host change (Wirtswechsel) happened. The same term is also used in a different context, namely when a parasite requires in its development a change between different hosts.

Host specificity: A parasite (or an organism with similar life-strategy) is associated with one host only, which requires a specialization and a competition between host evolution and parasite evolution (coevolution). This strategy needs to be separated from generalism, which means that a parasite has a very wide range of not related regular main hosts. Host specificity is more common than generalism. But this also depends on definitions. I herewith define the association with one main host species only as host specificity. But I furthermore consider host specificity also given, when parasite-host relations are specific on a higher taxonomic level, for example, when certain closely related genera of parasites are specialized for certain closely related genera of hosts. This part of my definition has variable borders. In the chapter after next, I describe the parasitic case of the trematode Leucochloridium paradoxum, whose main hosts are represented by different systematically not closer related bird species. A host specificy on the level of birds in general (Aves), then present in only some species with similar food preferences might already need to be named a limited generalism.

Obligatory host change in ticks and lifstyle-change in water mites

Some parasites need several hosts to be enabled to finish their life-cycles. This is another context, in which the German term „Wirtswechsel“ (host change) is used. In that kind of parasite – host – association, the host change is often obligatory, meaning that the parasite cannot survive in the absence of one of the required hosts. The castor bean tick Ixodes ricinus represents a parasite, which needs a host change to successfully go through its full development until adulthood, but there is a wider range of suitable hosts, as intermediate host and as final host. Thus the tick is a generalist with obligatory host change. Water mites (Hydrachnidia) are parasitic as first nymphs (juvenile instar, usually named „larva“) and predators as older nymphs and adults. A host specificity of „larvae“ can appear, but a wider range of host species is common. These mites perform a life style change during their development.

Intermediate host, for example in the parasitic flatworm Leucochloridium paradoxum

An example for a parasite, obligatory requiring a specific intermediate host, is the flatworm Leucochloridium paradoxum („green-banded broodsac“, Trematoda, Platyhelmintes), whose larvae (miracidium) need to infest snails of the genus Succinea. This trematode parasite is host specific for a genus of snails, while there is no specificity for their main hosts. They parasite birds, but infest different bird species, which are not closer related to each other, such as finches, the crow family Corvidae or woodpeckers. Although there is a main host specificity on the very high taxonomic level of Aves, the use of the term (limited) generalism might in this case even be appropriate. Inside the smail’s midgut gland, miracidia (larvae) modify into another larva-form, named cercaria, which invade the liver, where they form so called sporocysts, sac-shaped muscular tubes, which grow through the entire snail host until they reach the snail’s tentacles, which they fill up with their tube-shaped bodies entirely. Lastly the snail is unable to retract her swollen organs. The snail tentacles are now well visible as conspicuous greenish stripes, pulsating permanently. The sporocysts as larval stage of this trematode parasite do even more than only increasing the visibility of the snail for bird predators, which represent the worm’s final host. They additionally manipulate the nervous system of the snail so far that the snail performs an unusual behavior and moves towards very well exposed elevated areas, such as leaves of adjacent plants. Thus the probability to be eaten by birds is remarkably increased.

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Parasite Leucochloridium paradoxum, sporocysts inside the tentacles of a snail of genus Succinea, Wikipedia: Thomas Hahmann / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Host specificity on humans with side-hosts and coevolution with the ancestor line of Homo sapiens: skin mite Sarcoptes scabiei

An interesting example of a host specificity with numerous side-hosts and even an additional host-increase is the skin parasitic mite Sarcoptes scabiei (also named the „seven-year itch“). It was originally exclusively specific for Homo sapiens and accompanied mankind over its entire evolution (e. g. J. R. H. Andrew’s Acarologia, 1983). Systematical relatives of that mite species can only be found within the Great Apes. Originating from the recent Homo sapiens, S. scabiei conquered the human’s domestic animals, such as dogs or bovine animals within long-term periods, in which humans and their domestic animals had shared the same buildings or even rooms. Domestic animals may transfer the mite-parasite subsequently to wild animals. In case main host (humans) and side hosts (domestic animals, wild animals) can supply everything, which the parasite needs for its development without the necessity to leave its host specimen, one might speak about real hosts. In case side hosts cannot supply the necessary basic equipment, they represent either intermediate hosts or dead-end hosts. It can for example be discussed, whether dogs might in fact be dead-end hosts, as the skin disease can harm them under certain conditions to dead.

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Mite Sarcoptes scabiei (Astigmata, Acariformes), Wikipedia: Kalumet / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)

Host increase due to the globalisation and human economic interests: example honey bee parasite Varroa destructor (mite)

Another example of a former host specificity on a species‘ level with host increase is the mite Varroa destructor (Parasitiformes, Mesostigmata). It was originally specific for the Eastern honey bee Apis cerana. The mite could only switch over to the Western honey bee Apis mellifera due to a human influence: Men transferred A. mellifera for economic reasons to the natural habitats of A. cerana in Eastern Asia, were it got infected by the mite V. destructor. A subsequent transfer of the Western honeybee back home established the mite parasite in Western countries. As A. mellifera colonies are much more harmed by V. destructor than its original host, our honey bee must be considered as an intermediate case between a new host and a dead-end host. Human international traffic enabled this host-increase primarily, although there are areas between Afghanistan and Iraq, where both bee species coexist due to natural distribution. But there is an almost insurmountable (allopatric) desert border between the population of both species of about 360 to 600 kilometers, although there are evidences for bees rarely surmounting this border. Thus a natural mite transfer between closely related bee species might have happened additionally. Species of animals, plants, fungi or bacteria and even viruses, which successfully established new (additional) living spaces are named neobiota or alien species.

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Mite Varroa destructor, Wikipedia: The original uploader was Tullius at German Wikipedia. / Public domain

Can viruses as non-living genome possessing lumps be subject of evolution and complex host – parasite relationships?

Can this high complexity of modes of parasite – host – relationships in living organisms also be found in virus – host – relationships, although viruses do not represent living organisms at all according to biological definitions? The answer is yes, because viruses do not only share a genome with living cells, but based on this genome even are subject to the mechanisms of evolution. And evolution was the most important factor in all the mentioned complex parasite – host – interactions.

Parasitism versus mutualism or harming the host or not harming the host

Two different life-strategies with similar mechanisms as organism – to – organism associations

Are there other organism – to – organism relationships, being subject to a similar complexity than found in parasites with their hosts? Yes, a superordinate term for other close associations between different organism species is mutualism. While parasites need to harm their hosts by using them as final living-sources, mutualists are considered to practice a more neutral host contact, which per theoretic definition means that nobody harms anybody. But the assumption of a neutrality is in fact an artificial construct, as in detail it can come out that some of these organism associations represent unrecognized parasite-relationships, while in other cases a benefit for both partners (symbiosis) or for one partner only might be discovered in future studies. At least so called mutualists share as a feature that harmfulness or benefit are not easily noticeable.

Phoresy: taking a ride on a taxi-host as example of mutualistic relationships

An example for a more neutral organism, at least not harming association is called phoresy. It is often performed by nematodes and mites. These tiny organisms take a ride on bigger animals in order to become carried from one habitat to another. This „taxi-association“ is considered being of advantage for the phoretic part and harmless for the carrier (in English also often named host). But there are seeming phoretic interactions known, which based on developing technical scientific standards could be identified as unusual cases of parasitism. An example is a phoretic instar of an astigmatid mite (Astigmata, Acariformes), which as all phoretic instars within this big mite clade has no functional mouth, but sucking structures to fix itself to its host. This specific mite species had evolved a mechanism for opening the host cuticle in order to incorporate blood of its host using these sucking organs. This is unlike the common use of homologous suckers in related mite taxa, where they (as far as known so far) only support the adherence.

Another interesting example of a phoretic mite is Histiostoma blomquisti (Histiostomatidae, Astigmata), which is specifically associated with the red imported fire ant (sometimes referred as RIFA) Solenopsis invicta, which worldwide appears as troublesome neozoon, again a result of human global traffic. I am the scientific describer of that mite, and my research about it’s biology and abundance in ant nests refers to populations in Louisiana (USA). An interesting aspect is that the ant is originally native to Southern America. We lack studies, whether the mite appears in the native habitats of the ant also as its specific cohabitant or whether it originally deals with a wider range of phoretic hosts. We do not even know, whether the mite is at all native to the same area, in which S. invicta had its natural distribution. On one hand, we hypothesise that, but there is also a theoretical option that the mite performed a subsequent host change in areas, for example in the Southern USA, where the ant was accidentally established via sandy ballast substrate of ships as neozoon. It is further more not known, whether the mite – ant – relationship is indeed neutral, at least with no noticeable harming features. I discovered (S. Wirth & J. C. Moser, Acarologia 2010) that mite deutonymphs (= phoretic instar) can attach to active nest queens in such extraordinary high numbers (hundreds of mite specimens) that mobility restrictions for the concerned queens were sometimes visible. On the other hand, my video documentations showed that even completely overcrowded queens could still freely move and, much more important: stayed reproductive. The purpose of the mites inside the fire ant nests is unknown. But generally, mites of the Histiostomatidae can appear as beneficial animals in ant nests. At least according to my findings about the mite Histiostoma bakeri, which is a phoretic associate of the leafcutter ant Atta texana in Southern USA. I discovered these mites improving the hygienic conditions inside specific nest chambers (detritus chambers) due to their fungi and bacteria feeding activities (Wirth & Moser, European Association of Acarologists proceedings, 2008).

I will in different chapters of this article repeatedly refer to examples with phoretic mites of the family Histiostomatidae (Astigmata, Acariformes). As mutualism and parasitism follow similar organism-host association patterns, I will in those chapters not each time mention again that examples with these mites do not concern parasitism, but mutualism. It is by the way no accident that both life-strategies share common features, as there are examples known, which indicate that one strategy can evolve out of the other.

Mite Histiostoma blomquisti Wirth & Moser, 2010 (Histiostomatidae, Astigmata, Acariformes) on queens of ant Solenopsis invicta, Pineville/ Louisiana, copyrights Stefan F. Wirth

Mutualism often used as neutral term for organism associations with unknown effect of both partners to each other.

The copepod (Crustacea) Ommatokoita elongata on Greenland and sleeper sharks

So called mutualistic associations can sometimes represent interactions of unknown benefits or damage regarding both of the associated partners. Another interesting example of such an association with a not yet understood status is the copepod Ommatokoita elongata (Crustacea), which was discovered as specific cohabitant on the Greenland shark (Somniosus microcephalus) and the pacific sleeper shark (Somniosus pacificus). Larvae of the crustacean in their copepodit stadium and adult females attach to the ocular globes of the shark, where they can cause visible tissue damages. They are thus considered being parasites, although alternating hypotheses assume a more neutral mutualistic copepod – shark – association, based on the sometimes high abundance of the crustacean on one shark specimen (B. Berland, Nature, 1961). There are even assumptions about a benefit contributed by the copepode to the sharks: reasearchers say that it might improve the shark’s hunting success by attracting suitable prey with bioluminescence signals.

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Shark Somniosus pacificus, Wikipedia: National Oceanic and Atmospheric Administration / Public domain

Greenland shark with copepod Ommatokoita elongata, hardly visible, when the shark turns to show his right eye, Youtube: copyrights The Canadian Press, video by Ben Singer, footage Brynn Devine, Marine institute of Memorial University of Newfoundland

Human parasites with mutualistic features: the mites Demodex folliculorum and D. brevis

Can viruses be compared with some mites, nematodes or copepodes by performing mutualistic virus – host – relationships? A priori it must be stated that they are unable for a neutral relationship with another organism, as they need the destruction of living cells for their own persistence. But indeed there are viruses known, causing no known diseases and thus being named passenger viruses. But first, an example of an organismic example of parasitism without harmfulness will be presented: the mites Demodex folliculorum and Demodex brevis (Trombidiformes, Prostigmata), which appear as so named „face mites“ inside hair follicles of humans, preferring eyebrows and eyelashes, but also other hairy body parts. The abundance in humans is high and grows with a human age. According to Schaller, M. (2004), new born children are free of Demodex, while over 70 years old people are at almost 100 percent infested with the mites. The mite in fact is a parasite and feeds on sebum from the sebaceous glands. Incorporating needed human gland secretions must be named parasitism. Nevertheless mites under normal conditions cause no visible damages nor do they seem to harm their host noticeably.

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Mite Demodex folliculorum, Wikipedia: Information |Description=Demodex folliculorum |Source|Date=2009-09-08 08:34 (UTC) |Author=: http://www.legart.ru/demodex

So called passenger viruses as mutualists with a more or less neutral affect to their human hosts

Such a parasitic relationship might be comparable with so called passenger viruses, which do not harm noticeably, although they destroy living tissue as all viruses do. They can accompany more harmful viruses and even might harm the pathological success of the diseases, caused by these harmful viruses, and for example might slow the disease’s progression. An example is the GB virus C (GBV-C), which was before known as Hepatitis G virus. The virus is common in humans and shows no pathogenic damaging effect. According to an US-study, about 13 percent of probands, whose blood was examined, possessed antibodies against the virus. GBV-C is considered to slow the effects of an HIV disease by negatively effecting the replication of the HI-virus.

Host increase towards systematically not closer related new hosts

Example for a transfer within related host taxa in mites is the bark-beetle-clade within Histiostomatidae (Astigmata), an example for non related side hosts is the mite Histiostoma maritimum (Histiostomatidae, Astigmata)

Do side-hosts or intermediate hosts as results of host increases commonly need to be systematically close relatives of the main host? The answer is no, although parasites are usually better pre-adapted in infesting a host, which shares a maximum of common characters with the main host. Within the mite family Histiostomatidae, there exists a clade of mites being associated with a clade of beetles. I named it bark beetle-clade (e.g. Wirth, phd thesis, 2004). Mites and bark beetles performed a parallel evolution, which required host increases and host changes towards related hosts and subsequent evolutionary adaptations to harmonize with these new hosts, either to become specific for a new host or to deal with a range of host species.

But the transfer of a parasite to new hosts can also happen towards not closely related host species, representing a scenery being based on a common ecological context between main hosts and side hosts. The phoretic mite Histiostoma maritimum for example is host specific for at least two closely related beetle-species of genus Heterocerus (Heteroceridae). But the mite regularly also appears on predatory beetles of genera Elaphrus and Bembidion (Elaphrus cupreus and Bembidion dentellum, Carabidae) (S. Wirth, phd thesis 2004 and subsequent studies). These beetles partly share the same habitats with Heterocerus: sapropel around ponds, being exposed to sunlight and warmth. In my research about the mite H. maritimum, I hypothesised that the phoretic mite instar might switch over to Elaphrus and Bembidion, for example when these predators feed on adult Heterocerus beetles, larvae or cadavers. Although I could regularly find mites in lower abundances over years on the side hosts (collected in the Heterocerus sampling sites), it is unknown, whether the „switch-over“-scenario was a starting event in an evolutionary past to establish the mite to new additional hosts, where they would today survive more or less independently from the original Heterocerus source, or whether the mites regularly need to switch over in the above mentioned situations, and in consequence side hosts with no Heterocerus-contact would thus lack the mite. A possible support for the latter hypothesis are my laboratory findings about the preferred developmental habitat of the mite, which was cadavers of died Heterocerus beetles. In my experiments the mite remained on its Heterocerus– carrier until this died. Mites subsequently developed on the beetle’s cadavers, feeding there on bacteria and fungi (the phenomenon is named necromeny). Mites under laboratory conditions developed also seemingly successfully on E. cupreus– and B. dentellum-cadavers. But I could so far never continue these studies and don’t know, whether or how well mite colonies with having only cadavers of these two side-hosts available would reproduce compared to mites being reared in Heterocerus settings. In case of a strict substrate specialization for Heterocerus cadavers, the side hosts would be dead-end hosts, and permanent reinfections from the original host source would be required to explain the regular mite abundance in Elaphrus and Bembidion.

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Histiostoma maritimum, a adult female with conspicuous copulation opening, b both adult genders in dorsal view, c, d copulation opening in dorsal and sideview, SEM, Berlin 2020/ ca. 2002, copyrights Stefan F. Wirth

Assumed transfer of virus SARS-CoV-2 from bat main hosts via a pangolin as intermediate host towards humans:

There is an ecological context between bats and pangolins

The new corona virus SARS-CoV-2 is assumed to be host specific to a group of animals and from there infesting another animal as intermediatehost, from which presumably humans were opened up as new host source. There are researchers interpreting us humans as an dead-end hosts, as unlike in bats human people can be harmed remarkably with the lung disease COVID-19 (corona virus disease 2019), triggered by SARS-CoV-2. As at least from a general statistical point of view a high majority of infested people shows no or only slight symptoms, thus it can up-to-date not be excluded that Homo sapiens is in order to become a fully potential side host, because all a parasite needs in order to „survive“ before all other requirements is the (statistically) surviving of its host.

There is evidence that bats (Chiroptera) represent the main host, thus representing the „natural virus reservoir“, while pangolins (Pholidota) presumably act as intermediate hosts. This main-host-to-intermediate host context is for example reported as putative scenario by Ye Z.-W et al. (Int Biol Sci, 2020), who stated that based on molecular features the bat Rhinolophus affinis (Rhinolophidae, Chiroptera) is hosting a virus most similar to SARS-CoV-2 differing from all other known corona viruses (Similarity 96.2 %, nucleotide homology). The pangolin species Manis javanica was identified to carry formerly unknown CoV genomes, being according to the same authors with 85-92 % similar to SARS-CoV-2 (nucleotide sequence homology).

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Megabat Cynopterus brachyotis as example for a species native to Southeast Asia, Wikipedia: Anton 17 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

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Bat Rhinolophus affinis as known reservoir of a virus most similar to Sars-CoV-2. Wiki commons: Naturalis Biodiversity Center

Pangolins and Chiroptera (bats and megabats, this taxon subsequently sometimes refereed as „bats“) are systematically not closer related to each other. Pangolins (Pholidota) are considered to represent the sister taxon of the clade Carnivora. Chiroptera were reconstructed as sister taxon to the clade Euungulata (containing animals such as horses, cattle or whales). But both, Chiroptera and Pholidota, can be connected by an ecological context. Pangolins (Pholidota) are species, which are either adapted to live preferably on the ground, or to spent most of their time on trees. Both types are specialised ant and termite feeders, which use cavities on the ground or inside trees as hideaways. They additionally give birth to their offspring inside these burrows and subsequently use to stay there with their young for a while. Such cavities can accidentally be the same time aggregation and resting places for bats, excluding megabats, which use to rest during daytime on exposed areas on trees. Manis javanica has a semi-arboricol life-style, spending time in trees and on the ground. This pangolin uses different resting cavities, either subterranean burrows or tree cavities.

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Chinese pangolin Manis pentadactyla, a ground living species, Wikipedia: nachbarnebenan / Public domain, Zoo Leipzig, Tou Feng

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Pangolin Manis javanica as known host of a virus similar to virus SARS -CoV-2. Wikipedia: creative commons Piekfrosch / CC BY-SA

Chiroptera and Pangolins are in South Eastern counties often subject to hunting, as both for example play a role in the traditional Chinese medicine. Thus a virus transfer to humans via main host or via the putative intermediate host is assumed to have happened on animal markets (in the province Wuhan in China).

Which indications point to animal hosts as original source of virus SARS -CoV-2 ?

The scientists Andersen et. al (2020) explain there was no virus-engineering instead of a natural evolution

But which proofs exist that animal hosts sources such as Chiroptera and pangolins are involved in the transfer of the virus SARS -CoV-2 to humans? The lack of general knowledge is still fundament for conspiracy theories, such as an artificial creation of the new corona virus in laboratories with biological warfare purposes.

K.G. Andersen et al. („The proximal origin of SARS-CoV-2“, Nature Medicine, 2020) concluded based on their molecular research that the genetic template for specific spike proteins forming structures, which the virus body possesses on its outside for holding on and penetrating into the host cells, showed evidence for a natural evolution and not for an engineering. They argue with the strong efficiency of the spikes at binding human cells, which makes an engineering implausible and evolution based on natural selection highly probable. The authors additionally examined the overall molecular structure of the backbone of SARS-CoV-2. Backbone can be explained as the „skeleton spine“ of a macromolecule as a continuous row of covalent bond atoms. This overall backbone structure of the new corona virus is according to the authors similar to viruses, which were isolated from Chiroptera and pangolins and dissimilar to other corona viruses, which are already known to science.

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Spikes (here in red) in Sars-CoV-2 hold on and penetrate into host cells, Wikipedia: CDC/ Alissa Eckert, MS; Dan Higgins, MAM / Public domain

Can a host increase happen more or less spontaneously with a subsequent enormous success (as for example in virus SARS-CoV-2)?

And: Can the complexity of adaptations to a main host decide for the option of a host increase?

An example for a tendency to spontaneous temporary host changes is mite Histiostoma piceae (Histiostomatidae, Astigmata)

Is it imaginable that a host change or a host increase happens spontaneously and subsequently having such a remarkable impact to the new host, as it is recently ongoing with the SARS-CoV-2 pandemic? Host specificity, host changes and parasitism or mutualism in general are result of evolution. The most common case of evolutionary changes in organisms or viruses is a slow process of stepwise modifications being based on mutations and natural selection.

But it needs also to be stated that as more complex the pattern of characters is (genome, morphology, behavior, function-morphology, reproduction biology etc.), which binds a parasite or mutualist to a specific host, as more evolutionary steps are necessary to perform a host change and as longer an exposure to mutation and selection would need to take place. However it is alternatively possible that a host specificity is only based on a few, but important features. Slighter ecological pressures focusing towards these features might then theoretically allow rather fast host changes.

As an example with a putatively reduced complexity of host adaptations I herewith introduce the phoretic mite Histiostoms piceae (Astigmata, Histiostomatidae), which I repeatedly studied and reared under laboratory conditions. The scientific describer of this species (Scheucher, 1957) discovered a strict host specificity to the bark beetle Ips typographus. According to my and her research, the mite has along the geographic distribution of that bark beetle a high abundance, beetles without the mite are rare. In 2016 I discovered H. piceae being additionally associated with Ips cembrae as a second regular host. I cembrae represents the sibling species of I. typographus (Wirth, Weis, Pernek, Sumarski List, 2016). Exceptions are smaller bark beetle species, which regularly burrow their galleries into those of I. typographus or I. cembrae. It is unknown, whether these small bark beetles as cohabitants of I. typographus carry the mite temporarily or regularly. But the former might be confirmed by the following interesting phenomenon in the mite H. piceae:

In case of very high numbers of mites inside bark beetle galleries and a relatively low numbers of corresponding Ips species, the phoretic instar of the mite attaches under natural field conditions all available arthropods inside or adjacent to the galleries of the main hosts, including bigger mite species, different beetle species or – as already mentioned – smaller bark beetle species (for example my studies in the area of the city Tyumen, Siberia, Russia, 2015-2016). This indiscriminateness for specific hosts under certain conditions might indicate that the substrate specificity of the mite H. piceae is more developed than the phoretic specificity for the host insect itself as a carrier . In such a case, I would generally expect that a host change or a host increase might faster happen in future evolutionary steps than in mite species, which are strictly choosy for their specific host carrier. In H. piceae the tolerance for a variety of carriers (unlike the specificity for substrate conditions) might in a future evolution even succeed as pre-adaptation, which under suitable circumstances might spontaneously allow a regular transfer to new hosts. A second important step towards a real host increase would require that the mite becomes able to stay permanently on its new host. In the H. piceae context the evolution of a tolerance for different substrate conditions might once become an important selective factor in may be opening up new permanent host-associations.

Temporary side hosts, as described in the above explained observations, would represent nothing then dead-end hosts, as they are unable to carry the phoretic mite to suitable habitats for its development. But under favorable circumstances, a former dead-end host might even become a new permanent host.

Histiostoma piceae, a adult female in side view, b in dorsal view, c mouthparts and digitis fixus, d adult male in dorsal view, e in ventral view, Berlin 2020/ ca. 2002, copyrights Stefan F. Wirth

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Phoretic instar of Histiostoma piceae, ventral view, lightmicroscope with dig contrast, Tyumen (Siberia, Russia), 2016, copyrights Stefan F. Wirth

Two possible ways of virus transfer from bats to humans according to Andersen et al. (Nature Medicine, 2020)

Did the virus evolution towards the recent state happened prior to a first human infection, namely inside animal main host populations, or did it happen afterwards inside human populations?

As there is not yet much known about the presumed host specificity of the virus SARS-CoV-2, Andersen et al. (Nature Medicine, 2020) reconstructed based on their up-to-date knowledge two possible ways of a virus transfer from bats to humans and finally to the recent pandemic situation in the world:

The virus might have evolved its recent human-pathogenic features within the main host populations of bats. Natural selection must have been the corresponding major driving force. The relevant adaptations are represented by the above mentioned two molecular characters of the spike proteins in SARS-CoV-2 (receptor-binding domain for host cell binding and cleavage sites for an opening up of the virus). Under such circumstances the authors expect that the infection of humans could have happened with an immediate effect, leading at once into the pandemic situation of today. An intermediate host would in this option be not obligatory. A direct transfer from bats to humans might be imaginable.

The second option is based on findings that corona viruses in pangolins possess similar receptor-binding domains (RBD) as in the human SARS-CoV-2 version. Thus the authors reconstruct a version according to which a non or less pathogenic form of the new corona virus was via pangolins transferred to humans and circulated there for an unknown period of time. Even further possible intermediate hosts, such as ferrets or civets, are considered to have been involved in that scenario. During its time inside human populations the virus would have developed its recent features due to evolution and finally was able to be spread explosively between human populations on a pandemic level.

A higher probability for one of the two scenarios can according to the up-to-date knowledge not be assumed

I am not sure, whether the authors take under consideration with their second option that pangolins might even represent a main host and whether bats would not necessarily be involved in the animal-human transfer of the virus. But according to Ye Z.-W. et al. (Int Biol Sci, 2020) the context between bats, pangolins and humans was stated: „We cannot exclude the possibility that pangolin is one of the intermediate animal hosts of SARS-CoV-2“. But whether the pangolin is intermediate host or main host would at this point not effect the general conclusion of each of the two scenarios. The virus was either pre-adapted regarding efficient spike protein characters and then infested human populations rapidly or was transferred to humans via an animal host and subsequently evolved its key-features for a pandemic „success“ within human populations. Although the authors have up-to-date no indications allowing a preference for one of the scenarios, they point out that the potential of new SARS-CoV-2 outbreaks after the extinction of the recent human pandemic would be much higher in case of the scenario one, as the pathogenic virus would under these conditions survive in the animal main host populations.

I would as addition to scenario two suggest to test a modified hypothetic scenario, in which the non pathogenic ancestral version of the virus did not only circulate between human populations until it reached its pandemic key-features, but even circulated between humans and animal hosts forth and back for a longer time. This would according to my understanding of evolution improve the probability of a stepwise evolution of important key-features.

Special and unusual features of main hosts can improve the diversity within their parasites, important conditions for subsequent host changes: a very efficient immune system in bats pushes the evolution of their viruses

Chiroptera (bats and megabats) are not only known as putative main hosts for SARS-CoV-2, but also for Mers, Sars, Marburg and ebola viruses. Scientists did a research about the question, whether there are specific features existing, which explain, why Chiroptera are favorable hosts for viruses with a seemingly potential for epidemic and pandemic effects in human populations.

C. E. Brook et al. (eLife, 2020) discovered an unusual efficient immune system in Chiroptera, which they think protects these hosts from harmful diseases by their virus parasites. This bat immune system is considered being the evolutionary driving force for the variety of viruses and their relatively fast modifications, as they would need to compete with immune system responses by regularly evolving new adaptive features.

The authors discovered that the antiviral messenger substance interferone-alpha is released in most mammals as a response to the detection of viral genetic material inside body cells. Whereas they found Chiroptera releasing this messenger substance permanently. This would according to the scientists enhance the virus defense in bats and might explain that the above named viruses do not trigger noticeable diseases in their main host recervoir.

I would resume that such conditions might support the scenario one of Andersen et al. (Nature Medicine, 2020), according to which viral key features to infest humans had evolved prior inside the animal host populations. Regular new virus modifications as result of the competition between these viruses and their bat-host immune responses might support the randomness of the development of features, which as pre-adaptations could support a relatively fast host change. Even when I generally prefer scenarios of stepwise adaptations of organisms to new conditions, a higher probability of the availability of suitable pre-adaptations might at least accelerate evolutionary proceedings.

Longtime parasite – host – relationships, a dead-end for the parasite?

Are relationships between organisms over longer time periods of advantage or disadvantage for parasitic or mutualistic passengers? A longtime host specificity of a parasite (or mutualist) requires a strict specialisation, which means complex morphological, ecological and behavioral adaptations.

According to the acarologists P. B. Klimov & B. Oconnor (Systematic Biology, 2013) long-term specialisations could impede the flexibility of such organisms to react to environmental changes via evolutionary adjustments. Thus parasites with long-term relationships to the same hosts might be endangered to reach a dead-end. They would die out. A possible way out from such a disastrous end can be a re-evolution of the parasite back to its ancestral free living conditions, a situation prior to the evolution of its parasitic host specificity. But Dollo’s law states that a complex trait cannot re-evolve again. Thus long-term parasitism could according to the law not other than leading into a dead end. Nevertheless the authors could present an impressive example as proof to the contrary: based on their complex research about house dust mites, the acarologists reconstructed that these mites were originally parasites of warm blooded animals and subsequently evolved into free living associates of mammals, as which they are of medical relevance due to the remarkable allergic reactions in humans.

I think that the access of this paper does contain enough general biological aspects to ask, whether the dead-end scenario of long-term parasite relationships might also concern viruses, which don’t have an option for a free living existence, as they don’t live at all and are unable to perform independent strategies. At least might this long-term scenario support the findings of C. E. Brook et al. (eLife, 2020) that only unusual and regularly changing features of a long-term host might trigger regular corresponding responses by the parasite, another option to prevent a parasite from a dead-end due to a long-term host relation. This might explain, why certain viruses often parasite bats and successfully persist there, while other suitable hosts lack the very efficient immune system of bats and thus cannot host a specialized virus permanently. Regarding SARS-CoV-2 such theories might indicate that the virus would finally move towards dead-ends in humans and other host species, but might permanently survive in chiropterans. It’s a statement only being worth of consideration, in case of scenario one of Andersen et al. (Nature Medicine, 2020). And only in case, it would come out that the virus adapts well to humans, which would require a much reduced harmfulness, as parasites cannot survive by killing their hosts. In case of a dead-end host due to high mortality rates instead of a normal host increase, aspects of a long-term relationship with such a host don’t need to be discussed, as a shorter temporary outbreak and no beginning of a long-term relationship at all would result out of it. One needs additionally to consider that viruses as non living organic bodies with genome and with an unusual ability for fast modifications might often not fit into biological models based on living organisms.

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House dust mite Dermatophagoides pteronyssinus. Wikipedia creative commons: Gilles San Martin from Namur, Belgium / CC BY-SA

Summary

Host specificity must be differed from generalism. Known host-parasite specializations include a complexity of strategies. And even different kinds of hosts must be named, such as main host, side-host, intermediate host or dead-end host. Evolutionary steps such as host increase, host change or temporary hosts can appear. Parasitism and mutualism differ from each other as life-strategies, but share common features as association between different organisms: host specificity follows similar rules, an indication that both life-modes can evolve out of each other. The human globalization sometimes supports the spreading of parasites or their hosts over the world, host changes or host increases can thus be performed including organisms, which would under normal conditions get no contact to each other.

Viruses do not represent living organisms, but protein lumps with a genome and depend on living host cells for their reproduction and „survival“. like in living organisms, also viruses underlay the mechanisms of natural selection and evolution. Viral parasite – host – relationships show general similarities with features in living organisms, including options for a host change or host increase, the use of intermediate hosts or a kind of mutualism (passenger viruses).
There is evidence that the main host reservoir of SARS-CoV-2 are Chiroptera, while pangolins (and other mammals) might represent intermediate hosts. Humans are either dead-end hosts (preferred by most authors) or result of a successful host increase. Researchers could not yet decide, whether features to infest humans in a pandemic context evolved prior to the transfer to humans inside animal main host populations or whether a harmless version changed to humans and in their populations evolved its pandemic potential. A major drive motor for a long-term successful relationship with bats is the unusual immune system in chiropterans.

Copyrights Dr. Stefan F. Wirth (phd), all rights reserved, excluding photos labeled as creative common content from Wikipedia sources. Berlin, 2 April 2020

References:

J. R. H. Andrew’s (1983): the origin and evolution of host associations of Sarcoptes scabiei and the subfamily Sarcoptinae Murray. Acarologia XXIV, fasc. 1.

B. Berland (1961): Copepod Ommatokoita elongata (Grant) in the eyes of the Greenland Shark – a possible cause of mutual dependence. In: Nature, 191, S. 829–830.
Cara E. Brook, M. Boots, K. Chandran, A. P. Dobson, C. Drosten, A. L. Graham, B. T. Grenfell, M. A. Müller, M. Ng, L-F. Wang, A. v. Leeuwen (2020): Accelerated viral dynamics in bat cell lines, with implications for zoonotic ermergence, eLife; 9:e48401.g W

Pavel B. Klimov, Barry OConnor, Is Permanent Parasitism Reversible? (2013): —Critical Evidence from Early Evolution of House Dust Mites, Systematic Biology, Volume 62, Issue 3, Pages 411–423.

Kristian G. Andersen, Andrew Rambaut, W. Ian Lipkin, Edward C. Holmes, Robert F. Garry (2020): The proximal origin of SARS-CoV-2. Nature Medicine.
Martin Schaller: Demodex-Follikulitis. In: Gerd Plewig, Peter Kaudewitz, Christian A. Sander (Hrsg.): Fortschritte der praktischen Dermatologie und Venerologie 2004. Vorträge und Dia-Klinik der 19. Fortbildungswoche 2004. Fortbildungswoche für Praktische Dermatologie und Venerologie e.V. c/o Klinik und Poliklinik für Dermatologie und Allergologie LMU München in Verbindung mit dem Berufsverband der Deutschen Dermatologen e.V. (= Fortschritte der praktischen Dermatologie und Venerologie. 19). Springer Berlin, Berlin 2005, ISBN 3-540-21055-5, S. 273–276.

Wirth S. (2004): Phylogeny, biology and character transformations of the Histiostomatidae (Acari, Astigmata). phd thesis. Internet Publikation FU Berlin, http://www.diss.fu-berlin.de/2004/312.

Wirth, S. & Moser, J.C. (2008): Interactions of histiostomatid mites (Astigmata) and leafcutting ants. In: M. Bertrand, S. Kreiter, K.D. McCoy, A. Migeon, M. Navajas, M.-S. Tixier, L. Vial (Eds.), Integrative Acarology. Proceedings of the 6th Congress of the European Association of Acarologists: 378-384; EURAAC 2008, Montpellier, France.

Wirth S. & Moser J. C. (2010): Histiostoma blomquisti N. SP. (Acari: Histiostomatidae) A phoretic mite of the Red Imported Fire Ant, Solenopsis invicta Buren (Hymenoptera: Formicidae). Acarologia 50(3): 357-371.

Ye ZW, Yuan S, Yuen KS, Fung SY, Chan CP, Jin DY (2020): Zoonotic origins of human coronaviruses. Int J Biol Sci ; 16(10):1686-1697. doi:10.7150/ijbs.45472.

Zhang W., Chaloner K, Tillmann HL, Williams CF, Stapleton JT (2006): „Effect of Early and Late GB Virus C Viraemia on Survival of HIV-infected Individuals: A Meta-analysis“. HIV Med. 7 (3): 173–180.

https://www.sciencedaily.com/releases/2020/03/200317175442.htm

They are well paid: Medical doctors do their jobs and are not automatically heroes;and toilet paper does not belong to the essentials

A feeling of spring is in the air, the two-leaf squill forms bright blue carpets at the roadsides and on the meadows of urban parks, there are clouds, but it’s 14 degrees, even in the late evening. Normal traffic on the walkways of Berlin, and the adjacent supermarket is well equipped, only the toilet paper is sold out, which became a quite common curiosity in times of the corona-pandemic.

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Two-leaf squill Scilla bifolia on a meadow in Berlin urban park Plötzensee, 20 March 2020, copyrights Stefan F. Wirth

Racism

People are friendly, some couples and numerous single customers. Most of them discretely stay in an appropriate distance to each other, unfortunately only one cash desk was opened, making the forming of a waiting line inescapable. But the atmosphere was quiet, no scramble, enough space between the customers to keep their potential viruses with themselves. In front of me (at the end of this line) an old, slightly weighted woman, of a rather small height was waiting to pay for her purchases. As a Muslim, she wore a blackish grey headscarf, inconspicuously, modesty, visibly less mobile by foot, her hands like paws, undeniably a woman, who for her entire life was used to persistent and hard physical work, may be as her own housekeeper and educator of children. Her facial expression a bit grimly, she had a little bit to struggle to push her shopping cart forwards.

Suddenly a shrill scream, a nervous, but well articulated voice: “ For your own safety, stay in a distance!“. All people were startled by that noise, except of the older lady in front of me, who apparently was tired and since minutes sunk in thoughts. „Yes, I say it only, because I am concerned about your safety!“, the slim and tall woman in her mid-fifties, youthful short haircut, colored in violet and light blonde, flailed with her hands through the air, until she all of a sudden pointed her forefinger at the old lady, who finally, but still slowly, became aware that she was the stumbling block. Her lips quivered slightly, and it looked, as if she would need some power to mobilize her voice to express ber very reasonable defense.

The woman meanwhile had reached the cashier, and repeated an emotional: „I said it just for her own safety…“, while the cashier answered with a conversant voice, not avoiding a slightly disgusted sideways glance towards the old lady: „We will place a tag there to respect the distance rules tomorrow.“ She did not say: I didn’t see the old lady breaking any rules. She also did not mention: I will conduct everything that the other two cash desks will be opened immediately too in order to avoid such waiting lines. The cashier didn’t even think about performing any of such reasonable actions, she did not, because she was persuaded that accusations against old Muslim women are generally appropriate and true. The cashier was sure to know her candidates, while the permanently complaining woman with her upright standing violet tufts of hair was a hysteric racist, concerned only about her own safety and not for the one of others, considering people from a divergent cultural background generally not practising any nessesary hygienic routines and thus representing nothing else than a pure infectious potential on two legs.

Then the old lady found her voice, unexpected for everybody, and what a voice this was! Her „I did not….“ roared like a thunderclap through the store, and nobody figured out, how she would continue to express her innocence, because I interrupted her with an angry: „You didn’t do anything wrong.“, and again: „You really did not do anything wrong“.

I paid and found an empty storage area to bag my purchases into my knapsack. The old lady meanwhile had left the market, while the tall woman observed me, until she finally plucked up her courage to talk to me, saying something unexpected and never heard before: „It was just for her own safety!“.

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Lonely in a weird forest, isolation and waiting, oil on canvas, Berlin 20 March 2020, copyrights Stefan F. Wirth

Chancellor Angela Merkel and our health care system

Yesterday, chancellor Angela Merkel talked to the nation via a television broadcast. She said things like: „Its serious, take it seriously…“ or „we all lack the encounters that are normally taken for granted (Uns allen fehlen die Begegngngn (sic!), die sonst selbstverständlich sind)“. And she expained: „I believe deeply that we are up to the task, when really all citizens understand it as their task (Ich glaube fest daran, dass wir diese Aufgabe bestehen, wenn wirklich alle Bürgerinnen und Bürger sie als ihre Aufgabe begreifen)“. It was meant as comfort, but also as a constant reminder, as there seem still too many people acting too thoughtless. She continued: „Since the German unity, no, since the Second World War there had been no challenge for our country any more that depended so much on our common solidary acting… (Seit der Deutschen Einheit, nein, seit dem Zweiten Weltkrieg, gab es keine Herausforderung an unser Land mehr, bei der es so sehr auf unser gemeinsames solidarisches Handeln ankommt… )“. She exaggerates, and my dead grandma, who was a Trümmerfrau (rubble woman, who physically helped to rebuilt her destroyed city), would not agree. But the purpose of chancellor Merkel’s speech is clear: Please respect the rules in order to avoid a total lockdown like in other European countries! Journalists discussed the speech later controversially, some criticized that she avoided the use of the term „Ausgangssperre (exit lock)“, others lauded her reliable belief in sanity, presumably based on her natural-scientific education. And I agree that her speech very obviously considered an imminent exit lock as an Ultima Ratio only.

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Growing hope, oil on canvas, Berlin 2009, copyrights Stefan F. Wirth

But I became skeptical, when Merkel stated: „Germany has an excellent health care system, may be one of the best in the world. That can give us confidence … (Deutschland hat ein exzellentes Gesundheitssystem, vielleicht eines der besten der Welt. Das kann uns Zuversicht geben…)“. She then continued by explaining that even our hospitals would be overstrained with too many acute patients the same time. And that she is grateful to all medical staff dealing with this crisis situation. Many journalists even go as far as praising our physicians as if all of them only worked unsalaried.

When our chancellor visits her physician, she will experience the highest standards in both, technical equipment with corresponding competence of the staff and the health care service itself. But this does not apply to everyone. Because not everyone automatically has access to these highest standards. Our health care system is an inequitable system. Patients with a private insurance get a better support than statutory health insurance patients. Means: patients are asked to present their insurance cards at the registration desks. Private patients are forwarded to the highest medical competence in the hospital or a doctor’s practice, the others need to wait longer and are forwarded to the assistant physicians. Homeless people have generally very limited or even up to no rights. And as we here in Germany have a compulsory health insurance system, many freelancers with a low income need to be insured with a high deductible. That means for healthy people under fifty years a monthly payment of about 200 to 350 Euro to their private insurances for a deductible of about 1500 Euro. It is more or less the cheapest option, one can find over here. Poor and diligent freelancers pay about 300 Euro per month from their low salaries and nevertheless need to pay almost every visit to their medical doctor by themselves. Thus, some of them are forced to rarer visit their physicians than other people.

I expect (and did not closer research about the current health management rules) that in times of a pandemic, all these differences are eliminated and that everybody is treated equally. Because: „…since the Second World War there had been no challenge for our country any more that depended so much on our common solidary acting.“ By the way I do not see any reason for any adulation of the performance of German physicians at this point in the midst of a pandemic situation. They are not automatically heroes, but instead simply well paid to do their jobs as good as possible. And whether they managed a good or bad performance, whether they respected an equality of corona patients and whether there were indeed some heroes, who performed even much more than they were originally paid for, will only come out, when the acute situation is over. I unfortunately met since I live in Berlin too many physicians, who seemed to think that main purpose of their career is to become able regularly buying new and expensive prestigious cars. Are such people now able to perform their jobs focussed to an aim to heal and without other ulterior motives? Generally, our health care system is a highly capitalistic system. But what we need now is a „solidary acting“, and not an opposing situation to the disadvantage of the poorer people. I hope for equality at least in times of such a disaster, actually represented by the global corona pandemic.

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A pandemic covering the world, digital photo artwork, Berlin 2020, copyrights Stefan F. Wirth

Toilet paper

Although supermarkets are unlike other facilities announced to stay opened and although there are generally no bottlenecks for goods, one specific good is more and more difficult available: toilet paper. Panic buying people obviously think that the most important thing for a survival is toilet paper. What a ridiculous misconception!

I understand that people in the emergency of no toilet paper at all would not want to go into the forests and use the fallen leaves – as our prehistoric ancestors presumably did -, because they know, based on our successful modern educational system, that they might become infested by the fox tapeworm (Echinococcus multilocularis) that way, or even worse: that their human excrements, left somewhere on the forest ground, might infest the innocent foxes with our unpleasant pathogens or intestine parasites. In times of vegan and gluten-free lifestyles unthinkable! I was once told that they often used newsprint paper to replace toilet paper in times of the Second World War. But there would be problems with a hygienic disposal under nowadays conditions. So what to do in the emergency case of a toilet paper impoverishment? Let’s say generally in case of survival conditions, for example as extreme hiker somewhere outdoors in the Canadian wilderness. First we would need a self-burrowed deeper hole in the ground, additionally soap and water.

One specific character of the great apes, to which we humans systematically belong, is represented by very complex hand motor skills. They enable us to perform all kinds of things with these hands, as our finger tips are excellently innervated and the corresponding somatosensory cortex in our brain is incredibly well developed, thus well developed that we often do not need any additional tools at all in our daily routine, because our bare hands represent very flexible tools themselves.

See how she leans her cheek upon her hand. O, that I were a glove upon that hand that I might touch that cheek“ (William Shakespeare, Romeo and Juliet)

For aesthetic and hygienic reasons we should not go such far, wishing to be a glove in between, but we theoretically could easily lean our cheeks upon our bare hands, and even more we are enabled to actively use our hand motor skills. Important would be only that they are afterwards very properly cleaned, at least with soap. Especially the tiny spaces between finger tips and finger nails would then deserve our very careful hygienic attention.

There are emergency cases imaginable, where our blank hands wouldn’t support us as they easily can in case of a toilet paper impoverishment. Take care that you are equipped with enough to drink and to eat and forget the toilet paper.

Berlin, 20 March 2020, copyrights Stefan F. Wirth

Aerial photography

It’s a new approach to photography for a photohrapher, when using a drone. Before starting for the flight, the photographer should at least have an idea about the possible perspectives, from which his copter shall capture the photos. This requires the ability of a three dimensional imagination. Unlike in the regular photography, the drone pilot does not see the scenery with his own eyes. Only a stepwise experience allows him to guess, how a forest and meadow landscape might look in a bird perspective at a level of 50 or even 100 m.

But despite of all three dimensional imagination abilities and experiences, much photography or videography is based on spontaneous shooting reactions, based on the transmitted live picture.

Edited landscape Drone photography, Berlin 2020, copyrights Stefan F. Wirth

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If full automatic camera modi shall be avoided, manual presettings can already be made before starting the flight according to the general light conditions, finer adjustments can then follow in each specific case, when the drone is in the air.

An aerial photographer needs to resist to the danger of perceiving the environment in top-down view after some time with the drone camera only. The German laws define that a drone is only allowed to be flown in a distance of a direct visual contact. One reason is that one otherwise losses the feeling for a safe controllable space limit.

Before drones as flying cameras became commercially available for everybody, aerial photos or videos needed to be captured under more risky and also more costly conditions. Smaller planes, manned helicopters or cameras on balloons needed to take over the same function.

Being able to fly like a bird under remote control conditions is freedom for the spirit and at the same time freedom for an incredible creative flexibility.

Landscape

All aspects of our world deserve being considered as drone photography motifs (respecting laws of course) . Whether a settling, a city, a street construction, people, architecture or nature sceneries, the drone technology enables new options and aesthetic experiences. I made experiences in different photo object types (the respectation of laws has always a priority). But for my own projects I prefer landscape, weather, season and art photography.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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Flying in more or less remote areas with natural landscapes reduces the probability that a drone accident might harm people or architecture. But it is of course additionally important to bring no animals or plants in danger.

Landscape photos are the more interesting the more complex their composition is. But a forest with adjacent meadows is per se no guarantor for an impressive photographic piece of art.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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Only the contrasts of colors, shapes and different landscape elements can under optimal conditions create complexity and a fulfilling picture composition. More or less sharp edges between for example forest areas and adjacent meadows might built up an impressive and even seemingly abstract pattern, making the shot to a fascinating piece of art.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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Season

City structures, such as architecture, streets or walkways, seem not to underlay bigger seasonal changes (in times withoug snow or rain) . Is that true? It of course is not, the seasonal different light conditions always cause different photographic or videovraphic looks of the same location. The lack of intense green or colorful vegetation spots in between creates additionally sceneries with very different moods.

Of course the effect of different seasons is especially distinct in the nature photography. Even in case that black and white photos would be preferred, leafless trees of a winter forest usually look remarkably more interesting than an amorphic mass of grey leaves. In the colored drone photography, nobody would doubt that the diversity of autumn colors allows a much more impressive composition of structures, shapes and lights.

But also in summer or spring, when only slightly differing green nuances dominate the sceneries, eye catching drone photography can be performed.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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In case the greenish landscape sculpture itself does not allow a photographic highlight, then a dynamic sky can prevent the whole photo from getting lost in a boring piece of sadness.

One needs to keep in mind that a positioning of the drone camera with being for a longer time straightly directed into the sun might harm the camera sensor. Against the light photography can look stirring, but it’s often of advantage to avoid the sun body itself completely. Against the light photos usually lead to dark landscape elements in the foreground, almost consisting of silhouettes only. To receive more details on the photo it is recommended to record a higher amount of information. Raw files can be the best choice in this context, as they allow to develop details during editing, which were not visible before.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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Editing

To become able for an improving editing of a photo, a minimum resolution of details should be available. A resolution of 20 megapixles or more offers enough buffer for art filters or manual changes of light, color, contrast etc. The Mavic 2 Zoom for example unlike its sibling brother Mavic 2 pro with a high quality 20 megapixles camera, offers different panorama modes. One of them is created as composition of several 12 megapixle photos, which the camera automatically puts together to a 45 megapixle piece. In case drone cameras allow a raw mode and additionally a high resolution, both of these options should be chosen.

Drone photography mostly in Northern Berlin and adjacent regions in Brandenburg, copyrights Stefan F. Wirth

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Editing can have different functions combined with different intentions of the photographer. An almost perfect photo sometimes needs being only slightly digitally improved. Alternatively the entire photo might need to be stronger modified for aestethic and creative reasons to create the planned piece of art. The creativity of the photographer and editor at this has no limits, but it should be tried to avoid the ‚killing‘ of too much picture information.

Not every editing tool has a modern high quality level. Lightroom, Photoshop, pixlr and similar software of other developers must be recommended.

Drone pilot and service offering

I have more than three years of experience in the fields of drone photography and drone videography. I herewith offer my videographic dronepilot service for documentary projects, smaller movie projects, such as film – students- projects, image movie purposes or the videographic documentation of important private events, such as marriages.

I additionally offer my drone photography abilities for all kinds of fields and purposes. Preferably in and around Berlin. Please contact me via Instagram or Facebook ‚Stefan F. Wirth‘. I fly a Mavic 2 Zoom. Flying license (Kenntnisnachweis) and insurance for commercial Drone flights existant.

Ich biete mich als freiberuflicher Dienstleister der Drohnen- Videographie und Drohnen-Fotografie in allen Bereichen wie Dokumentarfilmproduktionen, kleineren Spielfilmproduktionen, zum Beispiel Studenten-Filmprjekten, Image-Filmen und Ähnlichem an. Kontaktaufnahme bitte via Facebook oder Instagram unter ‚Stefan F. Wirth‘. Ich fliege eine Mavic 2 Zoom. Kenntnisnachweis und Haftpflichtversicherung zur kommerziellen Nutzung vorhanden.

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Some photo examples in higher resolution. Copyrights Stefan F. Wirth

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Berlin January 2020, copyrights Stefan F. Wirth

Locomotion behavior of Schizomida (Arachnida)

They look without magnification more like very motile and fast running ants or very tiny grasshoppers than like arachnids. But they indeed represent relatives of the web spiders and scorpions: Schizomida, a clade of whip scorpions. They are the sister taxon of Thelyphonida, the rather well known „big whip scorpions“, which are often kept as pets in terraria around the world. Schizomida are only rarely filmed in a higher resolution quality, which is due to their small size and their almost invisibility due to their semi-transparent cuticle and their very fast way of walking or even jumping. They are additionally difficult to be filmed as they strictly avoid all lights and tend to dry out quickly, when they cannot hide themselves by time in a slightly moist substrate.

 

Closeups of behaviors of a Schizomid species from a greenhouse in Germany. Copyrights Stefan F. Wirth

 

Schizomida in Greenhouses

 

Schizomids represent mostly tropical or subtropical organisms. But some species are regularly dispersed into greenhouses around the world. The filmed species might be Stenochrus portoricensis, but was not systematically studied in detail so far. As all known species, which appear in greenhouses, also S. portoricensis reproduces (apart from their original habitats) parthenogenetically with females producing females without mating procedures (thelytoky). I never found males so far.

 

 S. portoricensis: native to subtropical Zones

 

The specimens, which I kept since months in a small terrarium, were collected in autumn 2016 at the famous fun and wellness bath „Tropical Islands“ South of Berlin. There they are a natural part of the world’s biggest indoor rainforest. The species S. portoricensis is originally native to Florida, Mexico, Cuba, Nicaragua, Porto Rico and other localities in similar tropical zones. These microscopical tiny organisms are predators and do not harm human beings at all. According to the available organisms in a suitable size in my terrarium, they might feed on the numerous collembolans and/or mites. Especially mites of the Gamasina appear in greater numbers in my substrate, which represents the original substrate from the greenhouse. I enriched this substrate regularly by smaller pieces of fruits or vegetables to stimulate the growth of microorganisms. I keep them at room temperature (about 20°C) and with not too much moisture. I do not know, whether they reproduced within these months, but the specimens of my recent video footage represent all sub-adults.

 

Film set and topic locomotion

 

Focus of my film is to present the different ways of locomotion, cleaning behaviors and burrowing activities of these fascinating animals. During the filming procedure, I used two cold-light-lamps for a suitable illumination and an ILCE-6300 (internal 4K mode), connected to a stereomicroscope and a lightmicroscope (with uplight).

 

Berlin December 2019/ March 2017, Copyrights Stefan F. Wirth