biologe

Blog and online journal with editorial content about science, art and nature.

Tag: Stefan F. Wirth

Macro Life in urban Parks of Berlin

Berlin is a green city. Each district has several urban parks of different sizes. Besides Tiergarten and Tempelhofer Feld in the center and South of Berlin, the northern district Wedding has an unusually large park area, the „Rehberge“ (originally connected with Schillerpark and Goethepark), which is based on several sand dunes as relicts of the last glacial period. Before the responsible governmental institutions began in the 1920th to create a large city park with sports and nature sites, the sand hills were connected by extended swamps. Today the park, to which also the location Plötzensee is belonging, consists of a mosaic of different habitat types. A cut meadow area is made for people to rest or to practice sports of all kind. Adjacent lay forest areas with partly conifers mostly, wild growing (dry) meadows, sandy areas and wetlands (around ponds and lake Plötzensee).

my film about arthropod biodiversity in the first half of 2020, all copyrights Stefan F. Wirth

There is quite a remarkable biodiversity inhabiting this urban nature refuge. Besides aquatic organisms and birds, arthropods, gastropods, lichens, mosses and different taxa of flowering plants inhabit the „Rehberge“. I did not try for this video project to seek for very rare species. Instead I just intended to record some (more or less) common macro life examples. Main purpose was a camera move through the park focused on the unusual perspective to the tiny life forms. Species names are visible underneath in the corresponding video parts.

Copyrights Stefan F. Wirth, Berlin, Rehberge/ Plötzensee, May 2020

Germany on the way from a part-lockdown to a full-lockdown?

Leaders of the German national subsidiaries and the federal government, above all the chancellor Merkel, ask for stricter contact limitations. Although the current conditions in form of a part-lockdown as reaction to increasing numbers of covid-19-infections throughout Germany restrict numbers of people, who are allowed to meet up inside or outside as well as the numbers of households, to which they belong, already remarkably. All public places for socializing and cultural activities are closed, also sport clubs, public swimming trainings or outdoor sport activities in greater groups are impossible. That means, bars, cafés, restaurants are closed. Theaters and opera houses as well. Especially „smaller“ stage artists suffer existentially.

Only the german football (soccer) is still omni-present in the news reports. I don’t know why. Seemingly their games can happen under limited circumstances. I am not interested in football at all. It is also not football, which is since the beginning of the human evolution a major fundament of our societies, it’s art. Art is not only creativity, it also stands for legal criticism against all aspects of social and political interactions. Thus something important is missing. And private life? It is already in the recent part-lockdown harmed in a way, that acts against the human biology as social primates. Not only old people in retirement homes live almost under conditions of a dentation centre, also single-persons of all ages, living in smaller apartments, need to tolerate loneliness. The Homo sapiens is a social species, too much isolation can cause longtime-damages, emotionally, psychologically, in case of older people even physically. Not to forget those citizens without any kind of home. The many homeless people, especially in Berlin, are very sensible victims of recent restrictions. Are all these risks, the Germans actually are exposed to, worth to happen? I think yes, they are, if it is for a limited time and under circumstances, which do not cause more damages than the virus infections themselves. It is fact that the new corona virus can be harmful to people of all ages, especially when there are significant medical histories existing. But as all these sanctions represent limitations of our basic laws, it is important that all these limitations are reversed when the pandemic is over.

Critical questions are allowed. They are also important and necessary. And you even do not need to be a believer of modern religious movements like Qanon. I for example ask for the relevance of indirect contacts between individuals for the still too high infection numbers. When I see super markets, forcing their clients to use shopping baskets or trolleys without employees existing, who desinfect each of them before and after use, then I hear the virus clapping amused its non existing hands: „We couldn’t get you so far? Here we are, left behind from hundreds of people per day, who touched this basket or this trolley before!“ Are such contra- productive rules necessary, even when the argument is that baskets and cars force a proper distance between customers? Also in U-Bahn cars (subway etc.), trams or busses, an indirect virus transfer between passengers needs to be much better prevented . Shouldn’t it be possible to employ people, who permanently walk through the cars and desinfect seats and handrails whenever possible?

As a natural scientist and active researcher as well as reviewer for scientific journals I know that statistics generally bear many reasons for critical questions. It can easily happen that submitted natural-scientific papers in peer-review journals are rejected by the reviewers based on doubtful or insufficient or even wrong statistical methods. We read or hear in the news permanently about growing incidence numbers. Many people might think that these are given facts, about which questions or critical remarks are not appropriate or necessary. Based on the limited informations via the popular media, the following questions are very sure and from a scientific point of view of interest: How many people of a specific region, for example a district of Berlin, were tested and how many were not? In case of higher numbers of non-tested citizens, statistical means need to be used in order to extrapolate to the whole population of the corresponding region. It is important that a statistical variance within the tested people is guaranteed. There would for example be a lack of a sufficient variance, if it came out that specific genders or specific occupational groups had more reasons or even forces to participate test procedures than others. Statistical tests always have a defined probability of errors. But more and illegitime errors can for examples be added, when research institutions need to provide a defined high number of data in a defined period of time, especially when the procedure is well paid and „success“ thus economically important. According to my knowledge and experiences, scientific studies can only be finished, when they are finished. Evaluations in defined time periods with defined numbers of sample sizes are prone to error. I know from commercial institutions for market and opinion research that the time pressure is often or sometimes used for the disadvantage of a sufficient variation of test persons. Some facilitate their work by contacting such people for phone interviews, who’s telephone numbers were part of a commercial phone number trading. That means they buy existing phone numbers instead of generating them via a random number generator. Additionally/ or they facilitate statistical methods, which were developed to guarantee a variation of test persons. An example is the „Geburtstagsschlüssel (birthday key)“, which requires from the interviewer to strictly only talk to that person of a household, who was the last to have birthday or alternatively will be the next to celebrate it. If that person, so the rules, is not available, the interview cannot happen. Based on economic interests of the institutions and the time pressure, facilitated versions of the „birthday-key“ are sometimes used. Such as: asking for the birthday person in the household, and if the person is not available interviewing everybody available instead, or even leaving the birthday key completely out. Results of such „manipulated“ evaluations can be representative nevertheless. But they also might not be representative at all. There exist examples for extrapolations of upcoming electoral successes, being far removed from the real situations. What does all this have to do with evaluations about covid-19-infection numbers? I hope that independent sources regularly control the responsible research institutions regarding the proper use of statistical methods even under time pressure conditions.

In case it is made sure that indeed bars, restaurants, theaters and opera houses and not indirect contaminations elsewhere or statistical errors or manipulations cause the permanently high numbers of new infections everywhere in Germany, a total lockdown will be unavoidable. The German government and the federal state representatives will come together for further deliberations still before Christmas. This was announced in the news today. It is important that the decision for stricter measures need to take those groups of the German population under consideration, which might physically, psychologically or financially too much harmed by a full-lockdown over a longer period of time. It furthermore needs to be excluded that participating politicians have other motivations than protecting us from a pandemic virus, such as lust for power, interest in totalitarian experiments or a total lack of empathy.

Berlin, 08.12.2020, copyrights Stefan F. Wirth

Linyphiid spider visits much bigger snail and bites into mucus

During a photo shooting with a specimen of the snail Arianta arbustorum in an evening outdoors in urban park Rehberge in Berlin with artificial light from an extra lamp and camera LED light, a tiny spider of Linyphiidae (seemingly Bolyphantes sp., may be still a juvenile) appeared unexpectedly and walked seemingly targeted to the snail’s head, which was partly retracted into its shell, and stayed there for about 3 minutes, biting repeatedly into the snail’s mucus and remained subsequently each time for seconds in that position. In between it skillfully and repeatedly rearranged the positions of its legs, presumably to be not in danger to remain stuck.

While doing so, it sometimes lifted legs, when not needed, in the air, may be to reduce that way the probability to remain stuck. After about 3 minutes the spider left its position around the snail-head mucus and walked partly sidewards to the top of the shell, where it carefully cleaned its legs from remaining mucus. Due to the difficult light conditions and the unexpected spider visit, I was in this short time unable to move the camera closer to the spider (would have been technically possible, when more time and more light). Thus-close-ups with a high magnification in my video were only due to digital magnifications out of the original 4K footage. Only one biting action could be clearly documented as video file. The same short scene is in my video three times repeated to exemplify that behavior.

Spider visiting a snail, in order to incorporate mucus? Berlin May 2020, copyrights Stefan F. Wirth

The last repetition is additionally modified into slow motion. There was furthermore no video footage of legs adjusted in the air. Thus the corresponding short scene is one of numerous photos, which I captured before filming. It is unknown to me, what the purpose of the spider’s behavior was. I also did so far not find any scientific publication mentioning tiny spiders visiting much bigger snails on purpose. It looked to me as if the spider would incorporate mucus or moisture or other components excreted by the snail. I do not know, whether such a spider behavior happens regularly or at least occasionally, as I only have this one observation. I would exclude the possibility that the spider was disturbed by my photo activities in its web may be in the adjacent meadow, tried to flee and accidentally landed on the snail and just observed this unusual surrounding with its mouthparts. All looked too much like a targeted behavior with even specific behavioral adaptations. There is generally not much known about spider and snail interactions. The scientists Nyffeler and Symondson (Bern, Switzerland) published in 2001 about malacophagy in the sense of gastropod feeding by spiders (Ecological Entomology 26). But that paper deals about bigger and even big spiders feeding on snails of adequate size, which is unlike the size relations in my observed case.

It is not trivial for a spider to incorporate anything from snail mucus, as this very sticky slime acts besides other functions as defense mechanism for the gastropod. In that context the above mentioned authors cite Tretzel (1961) by mentioning that mucus production of gastropods seems to have no deterring effect on some spiders. The question then is the efficiency of spider enzymes against snail tissue, a topic, about which I did not do more literature research. According to the above mentioned authors, moisture can in malacophagous spiders be an important factor, as gastropod bodies consist to a high percentage of water. They refer to Lain (1982), who published about New Zealand mygalomorph spiders. In the case of my observation it would eventually be of interest, referring to the context above, that also gastropod mucus contains a high water percentage. More observations such as mine would be needed to find out, whether the behavior of the linyphiid spider on a much bigger slug is a specific behavior or not.

Berlin, May-November 2020, urban park Rehberge, copyrights Stefan F. Wirth

Fox and Witch – a fable – Part II

Exhausted and with a missing right ear and with both hind legs broken, the fox very slowly crawled up to the top of the sandy hill on the other side of the restless and hissing little stream. He felt no pain and thought that the release of all his left power would be still enough to continue his way. The moonlight swished through the tiny bilberry bushes along the edges of a rounded forest clearing. Dewdrops mirrored the light, and the ground sparkled and glinted, when suddenly hundreds of male fireflies started their flights in the air. And while these living tiny stars formed up a very motile starry sky directly around the fox’s head, his brain refused its attentiveness. He closed his eyes and tried to listen to the sound of his forest, with one ear only. Silence, only an incidental rough nasty grunt of the old owl from far away, no wind and no other birds, neither singing nor fluttering around. The fox laid immovably on the ground, where the white, grainy and supple sand, still warm from the daily summer heat, smoothly cuddled his body. Two streams of ruby-colored blood meandered downward the hill. A third one filled up his closed eyeballs from outside and made them both resemble very tiny little ponds. From there they flowed off to the chalky sand, which drop by drop changed its color from wine red to ebony.

 

 Mushroom Man

 

He would only rest a little while and then continue his way, as this way was all he had, thus it needed to be continued in spite of his wounds. The fox’s front paws were strong, he knew they would bring him forward, step by step. But all of a sudden, he heard a fast rustle and crackles and a hoarse „hihihi“. And zap, a first ax blow, and zap, a second ax blow severed both of his hind legs.

 

 

P7250919a Kopie

 

 

„Hihihi, poor fox, you should have stayed, where you were, should have found a new way through another forest. You don’t belong here any more, hihihi, now see, what happened to you. You are dirty and full of parasites, you destroy the peaceful silence of our woods. You should have expected the woods beating back. Hihihi, but however I feel compassion with you, that’s how I am, my little heart is always filled up with too much sympathy. Hihi, your legs were both broken numerous times. You would have died by inflammations and blood poisoning….“. The fox opened his eyes and saw everything distorted and in red. His lungs lacked enough blood and thus he could scarcely breath. His tongue couldn’t form one word, and his whole body trembled, while his heart was beating irregularly and became louder and louder. Still no pain. „Good to know“, the fox thought, „that one can lose the ability to feel the pain“. And his eyeballs moved to all sides, searching for the mushroom man, whom they finally detected on top of an adjacent tree stump.

He was about as tall as the fox’s head, wore blue striped knee breeches and a wide green shirt with a yellowish necktie. His still young and reddish face lacked a dense beard growth, thus only some single grown long whiskers around his narrow mouth formed a fuzzy parody of a moustache and a goatee. His weird and curly brown protruding hair was intertwined with tiny withered leaves, while the upper part of his head covered by a flat, bulging and dried fruit body of a tree fungus as hat, almost hiding his crooked nose and his green narrow slit eyes. He giggled constantly, even when there was no reason at all to giggle. He giggled, because he considered generally all life a funny rhapsody. The fireflies dancing above his head. „Hihi,…“, he said, „this morning, I slew a too snoopy rat. I carefully eviscerated it, ate its tasty little heart and its vitamin-packed kidneys and draw off its fur, which I sew together into two elegant booties. I twirled its intestines to yarn, should be dried meanwhile, hihihi, …oh, you urgently need my treatment, can you hear me?“ The fox could only sigh, and saw the tiny man, stretching out his narrow chest, and standing there in his new hairy booties with his legs apart, seemingly hoping to appear that way much bigger than he was. „Hihihi,.. I’ll quickly pick up the yarn to suture your wounds, as I don’t want to see you bleed to death..“. And he disappeared, hectically hopping from one tree stump to the other, by keeping his balance with his extended skinny arms and his delicate slender fingers of both hands, alternately moving up and down.

The fox’s body was laying in a lake of blood and slowly attracted swarms of carrion flies, which he never saw flying at night, flying without any noise, no humming and no mumbling, it never was so silent in the fox’s life before. The moon had left the forest clearing, it became darker, and even the fireflies vanished without any trace from the scenery, instead only these legions of blackish carrion flies, buzzing around his head, without producing any noises, like an army of zombie souls of former flies, which already had died decades ago. The fox suddenly felt a short draught, then both of his thighbones were quickly grabbed and sewed up with the surrounding drooping lobes of meet. „Hihi, my old friend is saved, he won’t lose more blood, he will lick his wounds and survive. And see, I connected two small wooden wheels to each of your stumps“. And the mushroom man jumped with a nimble motion on the fox’s neck, with his tiny rat boots frenetically knocking against his bloody shoulders. „Hop, hop, hihi,..“, he said, „get up, trust in my navigation, stretch your shoulders, lift up your body, hihihi“. And the fox, feeling at least as dead as the clouds of zombie flies around him, tried his best to send signals via the neurons from his brain directly to both of his collapsed heart sacs and ordered them to beat. And, a miracle, they first twitched alternatingly, and then contracted faster and faster, bump, bump, bump, and the fox began to pant for oxygen, until the muscles of his forelegs received enough energy to finally and successfully fulfill their service. „hihi, yeah, walk like a fox, hihihi, one step after the other. You are doing it right, my friend, so right…“. And the fox walked forward, still slowly, but with his head courageously raised, while his hind body followed on squeaky wheels.

He left a lake of coagulating blood behind, at which all zombie flies lunged in their erroneous assumption to find dead meat underneath, where they could deposit their undead eggs. „Hihihi, well done, fox, now try to follow your path once again and then never come back. There is no space for foxes in this forest any more. I mean, all we inhabitants of these woods will always honor the good memory of you. But all kinds of external effects harmed our woods: the weather, the climate, the decrease of our species and the dispersal of foreign species from far away into our land, all these things have changed our habitat forever. It became dangerous for foxes, and we all became sensitive for their ticks, we all suffer from their diseases as never before, hihi“. With a slight jerk the fox threw his rider off. And with sticky blood around his tongue, he gurgled: „Do I have to be grateful to you now?“. And the mushroom man answered: „All I ever did was due to selflessness. Get well soon again. Your strong shoulders will always carry you. And I promise you that I will regularly send you a new set of handmade wheels to your foxhole, hihihi, there is only one thing I want to ask you for: You know that I am a passionate collector, hihi, leave me your hind legs, you don’t need them any more; hihi, I will prepare them to persist for hundreds of years; Future generations will study these of your remnants, and they will recognize that you once were a member of our community. Hihihi.“ And the fox, who now suddenly began to feel his pain all over his body, tried to respond, but a new surge of blood from his missing ear came into his mouth, and thus his answer was only a suffocated noise: „mpfff“. The mushroom man took the fox’s broken legs, which he had already covered with a blanket to repel the ghost flies, and nimbly disappeared without saying any other word.

 

Old Owl

 

The fox followed his path for a while with squeaking and rattling wheels. And always, when he felt exhausted and tried to rest, his entire body was filled up with a pain, which blazed like a flame inside his wounded body and forced him to continue. He never reached the big incrusted rock that stood far out in the forest landscape, the home of the old owl, which due to his enormous age was already for a long time unable to fly. His prey needed to move astray upward to his platform, where he sat inside a dome, formed by his own dried excrements. The owl couldn’t see any more, but his hearing was still exceptional. It helped him to localize his food and to hear all noises throughout the forest. What a useless ability in such a frightening silence, the fox thought.

Bravely and without complaints he slowly, but purposefully, with powerful steps of his forelegs, followed the sandy narrow path alongside the big snowberry hedge area; still no noise, and his still bloody eyes discolored his surrounding into red shades. Some of the undead carrion flies had followed him, but the many bats, whizzing lightning-fast through the air, discarded him accurately and silently from his somehow inanimate persecutors. His forward locomotion was a fight, and the fox thought that each forward direction is the most important aim in life, which always deserves all available investment. His badly wounded body begged for a rest, but he answered with more oxygen and panted with his widely opened mouth. He crossed the wet meadow, passed the birch grove and was on his way down to the rocky little valley, when he noticed that the wheels, which replaced both of his hind legs, tried to run faster than his paws could, it became an energy-sapping and tedious procedure. Finally down in the valley, there was a fork in his way. One path went further down to the stream, which at this point of the forest was already swollen into a little river, and continued along the riverbank, while the other led to the old owl’s rock. The fox didn’t know yet that he wouldn’t arrive at the lonely rock to talk to his former owl friend, but it was at least his intended destination, after a short rest at the waterside. His body entirely refused his service, and the fox needed water to quench his thirst and to carefully wash thoroughly his throbbing ear injury and finally to cool down his overheated head. The tight stony riverside welcomed him with a warm and humid air and the aromatic scents of marsh-marigold, water forget-me-not and ragged-robins. The moon had disappeared to the other side of the forest and thus, and the fox crouched down in the midst of a rather dark night scenery, interrupted by some single rays of light, which were wandering around.

When the fox was just in order to tilt his snout down to the water surface, at this point of the forest surprisingly calm and silent, a deep and croaking voice cut through the mysterious quietness of the forest: „Fox, I could hear the sound of your wheels, and I am very well informed about your misfortune, which is based on your own recklessness and stubbornness. Times have changed, fox, today, we prefer the silence. Your noise disturbed my trains of thought. I doubt that you’ll ever learn how to behave appropriately. Listen to my well intentioned advice. Get back to health soon, and when you then still think that this world was not fair to you, climb on the highest mountain, you can find, and then look down and see the minuteness of the world and the insignificance of all individual worries“. „I can’t climb up a mountain any more and I don’t think about fairness, only about survival and moving forward“, the fox thought, but couldn’t answer any more, as the weights of his wheel-apparatuses drew his hind body down into the water and his struggling paws couldn’t resist these forces at all, he fall.

 

River

 

The water was rather warm, and it smoothly washed around his sticky fur. The fox slowly drifted away, following the flow direction of the quiet river, and he did not oppose it. He felt weightless, and some occasional colder drifts from lower depths calmed his deep wounds. His eyes were clear again, and he saw extended reed beds passing by and even two sleeping swans, but both with an astonishing blackish plumage. The wood of his wheels increasingly swelled up due to the wetness, and after a while, both constructions broke coincidentally and came loose from the seams of his leg stumps. A relief, and soon, the fox noticed that he could even control his mutilated former hind legs, and he carefully began to paddle with his stumps, and seemingly thanks to the smooth and calming water, this caused him no pain at all any more. „An interesting phenomenon“, he thought, „first the shock prevented me from noticing the pain, which wounds would normally cause, then they appeared with delay and then unbearably heavy, while the later situation created an insensitivity again, an immunity based on a permanent stimulation, or was it a miracle? The river soon got wider, while the water flow was still surprisingly smooth. The reed beds were meanwhile replaced by carrs on both sides, mostly consisting of black alders. Again black swans. And even the mallards, sleeping on a tiny bald headland slope, seemed to have lost all colors. There was no audible, but visible active life: The moor frogs entirely replaced the water surface along the river banks. They submerged and emerged, a bustle consisting of heads, paddling legs and splashing water, all fully soundless.

The fox quickly learned performing meandering movements with his body, first barely noticeably, then always more confidently, and he paddled increasingly skillful with his leg stumps, moved them alternating up and down, until he found a stable rhythm, and lo and behold: he gathered speed, did not only float passively any more, but controlled his way with advancement and even a certain elegance. He then discovered the sideward rowing by turning his hind body slightly to one side that his hind-leg-rudders needed to change their angles and allowed him to swim a small circle, and even to stand against the soft water flow direction. He supported his maneuvers with courageous strokes of his paws, while the river made a sharp right turn. Shortly after, the fox lifted his head a bit above the water surface and blinked with his eyes, as if he was looking for a very tiny specific detail. And indeed, a greyish obstacle appeared in the near distance, coated with fumes, while the moon behind him generated billowing reflections on the body of water and irradiated the obfuscated tiny island.

The fox knew the little island very well and noted to his satisfaction that he was still on his way, another mode of locomotion, but yet the right direction. His maneuverability grew, and his sensation of pain decreased. And he turned around his own axis like a seal, but it was no expression of exuberance or recklessness, it was an expression of the awareness of new opportunities. Improvement instead of death, new advantages based on the woundings of his hurtful discrimination; and the fox puckered his mouth to a broad grin, he smiled at his own amazement, which seemed to be an amazement about the time in itself. About the last two single hours, standing fully against his entire life, which at least already had seen around 40.000 hours passing by; complete changes almost within a wink of an eye.

The closer he got to the island, the more it seemed released from its misty cover and presented a miniature landscape of tiny rocks, older conifers of a too small height, and it was covered with gloriously shining yellow blossoms of loosestrife flowers, softly illuminated by the last beams of an already very low standing moon. The small and sickle-shaped piece of land was a firm component of his daily route through the woods, which he usually passed via the narrow rabbit way on the opposite very close river bank. Thus its presence, meanwhile just ahead in front of his snout, was a proof for still being on the normal way, albeit under abnormal conditions; and with a certain satisfaction, he nodded imperceptibly with his head, which meanwhile had been sunken back down beneath the water surface.

His destination was the small gap of water between island and the rabbit trail ashore, where he planned a short rest, not from exhaustion any more, but to savor the mild fruity scent of the insular flowers, the deep flavor of the adjacent deep forest and the warm, somehow very complex, but also heavy smell of the water. When he arrived at his desired position, he could feel a network of roots closely beneath the water surface and could hold on the strongest of them with both of his remaining paws. The mere sight of the blooming loosestrife flowers awoke a warm and almost forgotten feeling of delight inside his head. The fox knew that blossoms of this beautiful plant, being colored like an golden hour evening sunlight, could differ from each other, depending on blooming in the shadow or being exposed to the daylight. Light bloomers owned a reddish-yellowish color shade and elongated pistills, while shadow bloomers were shining in a bright yellow shade with shorter pistills. Some flowers carried already seeds, and he saw a short and slight gust of wind blowing some of these rounded tiny capsules into the air, from where they slowly sailed down to the water. There, directly in front of the fox’s snout, they performed a quickly merry-go-round and then disappeared with the soft water flow.

 

Death

 

All of a sudden, something inexplicable changed about the normal working procedures of his internal organs, his heart flickered in a surreal fast motion, while his lungs remained fixed in their inhalation mode, and daylight and moonlight alternated within seconds, blossoms withered in the rhythm of several winks of his eyes. The fox’s fur colored from orange-red to a muddy deep-brown and shrank piecewise from his body. Seasons had imperceptibly changed and suddenly autumn laid in the air, the forest was ablaze with motley colors, while the tendrils of the underwater featherfoil plants all at once enclosed the meanwhile fully naked body of the fox and relentlessly dragged him slowly deeper and deeper. And before the fox completely disappeared in the depth, a bitter cold winter moon emitted misty light beams through the bald skeletons of trees.

 

 

P7250945a Kopie

 

 

The fox’s body came to lay between a rocky protrusion with a hook-shaped tree root around his neck, still embraced by dozens of featherfoil tendrils. He couldn’t feel nor could he hear any more, but he saw. The water was clear, and the ground deeply beneath his body, which now more and more began to decompose. A „You are dead“ whispered through his head, while his brain was surely still alive. And it fought against its decay with an unearthly power, which the fox never released before. And indeed, his heart at once began to beat again, his lungs suddenly demanded for air, and blood began to circulate throughout his almost fully rotten corpse. He tried to move, but he couldn’t, and then forced by a rapidly increasing respiratory distress, he grasped an adjacent hollow tube of a reed plant only with his snout, and carefully bit a piece out of its wooden wall, and then began to breathe, to slowly inhale his new life.

 

The tiny Tit

 

The time was passing in a fast motion speed, and then all at once fell back to its normal rhythm: The early summer approached, when the fox stepwise awoke to all his former life functions, he began to hear the far away bird’s twittering as a muffled noise, the crawling of mice along the riverbank, and he became hungry for the first time, since he had died. But he saw no other option than crying for help. His hoarse and broken voice mutedly sounded out of the on-air part of the reed tube, „help, help, I want to live“, but no one responded. And the fox fall asleep and dreamed of a forest under water, through which he swam like an elegant dolphin and was friendly welcomed by all animals of these surreal woods. He saw a community of harmony and a never before seen goodwill, when he suddenly woke up. He had slept over months, and now it was midsummer already, when the fox again cried for help. But this time, he unexpectedly received an answer from the other end of the tube. „Who are you?“, the tender voice of a bird asked. And the fox answered: „I was the decaying fox, but I want to survive, oh please give me food, I am hungry.“ The small penduline tit chirped amused in a language, which the fox did not understand. Then he said: „I am just a small bird, but I feel sorry for you and thus will try to provide you with everything I can, I need to impose one condition only, tell me about your life and tell me everything about the forest, I am still so young, make me understand the life that is expecting me here.“ The fox happily agreed and told the tit all he knew about the forest from times, in which most trees of today were still sprouts. In fact stories that he had heard himself by the old owl, stories about health and development. The tit was a passionate listener and captured a small grasshopper, which he carefully dropped into the tube opening, from where it directly landed in the fox’s throat.

 

 

P7250932a Kopie

 

 

Years passed by, and fox and tit were connected by a growing deep friendship, although they never saw each other. The fox’s body kept fixed by his fetters, but his naked skin was soon covered by a new fur in grey with white stains. And his hind limbs grew to fins, and if he hadn’t been tied up, he would have swum away like a seal. In the warm season, tit and fox met each other daily, with the bird always bringing a small insect or even an earthworm to their meetings; and the fox told him about his former friendship with the witch and about times, in which he used to offer the tiny mushroom man a ride on his back, and about the old owl, whom he provided with all kinds of things, which the old lazy-to-move bird couldn’t reach from around his rocky nest. And the tiny tit was so fascinated from hearing about older times and soon also from the fox’s warm and friendly voice that he fell in love with him and never looked for a bird mate, and in the winter time he only followed his migrating conspecifics as short as possible towards the warmer South. He was always the first penduline tit arriving back from the Mediterranean in early spring and then couldn’t wait to meet his friend at the still stable old reed-tube. The fox, who used to oversleep the winter time, then got his first food for the year, and the presence of his new friend warmed his almost decomposed heart, and he began to love him back. He loved him for his impartiality, his curiosity, his optimism and his lovely character, which made him begin a friendship with a dead fox, which he could not even see.

In the fourth year, it was early spring, the fox awoke from his hibernation and turned his head to the left, then to the right and even tried to bend it as far as possible to his underside, and what he saw did not resemble the weak body of a seal from the former year any more. All his muscles were enormously grown during the season of his inactivity, and he seemed almost be ready to break his bonds. Punctually he heard the voice of the tit, excited and full of a loving friendliness. He brought him the first worm that he could catch from a still frozen forest ground and twittered:“My dear and beloved fox, I missed you more than anything, and I couldn’t wait to meet you. Listen, so much happened, while you were sleeping and me being abroad. I heard it from the blackbird. The witch, who used to rear trumpet lichens around her teeth, which she considered the latest fashion for witches, became seriously sick, after a giant bird tick had bitten into her right butt cheek, when she was sitting on her wooden witches toilet. She became so weak that the lichens grew out of her mouth and covered her entire body until she almost could not move any more. She lost all control over her whirlwinds, which disappeared forever somewhere in the air. Flightless and unable to walk or to talk, she was lastly seen to crawl on her knees around a smelly pond, where she tried to chew on rotten algae, while her voice resembled the sounds of fire-bellied toads and moor frogs so much that even the old and blind grass frog mistook her with his aunt. It is a terrible tragedy, and the whole woods talked about it. But listen, fox, unfortunately also other things happened: Once, when the winter was especially cold, a lonesome wolf got lost into our forest, and the first, he met, was the mushroom man in his nasty winter clothes. He first took a ride on the wolf without asking for permission and lately even tried to cut off the wolf’s ear for his collection. But the tall loner couldn’t take a joke at all and devoured the tiny man with skin and hair and everything around.“ The bird’s voice became quieter with a very sad sound. „dear tiny friend“, the fox answered, „these people were part of my life, and thus I do not feel any malicious joy.“ And the tit responded: „It was sad to hear all that, my whole body was trembling, when the blackbird continued his stories. Finally the wolf couldn’t digest the gnarled little man and excreted him undigested and still alive. But he had shrank to the size of a mouse, his skin became green like a frog, and since that, he almost always hides inside his tree cave, as all rats of the forest had discovered him as a suitable prey. And that’s still not all I need to tell you. The friendly swallow from my neighborhood yesterday morning discovered the old owl fully enclosed by walls of its own guano, being obviously still very much alive inside, but nobody knows, how and where he would find his future food, but so far he fortunately didn’t stop to comment all incidents in the forest, just being less well audible. Fox, that’s not the forest, you were telling me about. How can I survive in such a rough and immoral world. Miseries everywhere…“.

 

Metamorphosis and Rebirth

 

The little tit felt as a stranger in his world and fearful saw the time passing, clinging to the only thing he had, the friendship with an invisible fox, which seemingly and hopefully was on his way to get back to a normal life ashore. The summer time had just begun, and one day, a somehow stronger water flow released the fox all of a sudden from his bonds, he first drifted away, far away and almost reached the wetlands with the witch’s house, until he got used in the water locomotion of a seal, from which his outer appearance almost didn’t differ at all any more; but then, hours later and due to vigorous movements of his hind leg fins, he arrived back at its tiny island, where he happily several times circled around, when he all of a sudden felt a pulling and drawing along his entire skin, and within one deep breath of air, his seal fur burst open from all sides, and the fox, who had already become a seal-like creature, molted back to a fox in the way a lizard or a snail would repel their old skin. His new fur appeared deep red and  clear, such an intense and shiny red, shinier and clearer than ever before he died as a fox. And the fox with hind leg stumps instead of fins crawled on shore, in order to finally see his new friend, after all these years, they had spent together, the fox in under-water bonds, the honest little tit ashore, on the other side of the tube: the only good soul he could find inside an increasingly evil surrounding, his new hope, which made him belief in the outstanding superiority of moral integrity. A new light in a malicious world. And the tit had desired nothing more than seeing his fox, his link to a better past and his hope for a bright future. But when the fox reached the outer part of the reed- tube, it was empty, nobody was waiting there. And the fox waited and waited and waited, but the tiny tit never came back, nor did they ever see again.

 

Epilogue

 

The wood fay visited the forest only once a hundred years. When she arrived this time, she flew along the river and sat down on an old tree stump, close to a tiny island, on which yellow blossoms in different shapes reflected a warm evening sun. While she enjoyed her rest, she discovered a lonely reed-tube, obviously dead since many years, on which a lonely little tit sat down with powerlessly hanging wings and waited. All other tits were busy with each other, only this one specimen stayed apart from everybody and seemed with sad eyes staring into the depth of the hollow tube. „What a beautiful little guy, so full of yearning and hope“, the fay thought, when suddenly an owl approached in flight and grabbed the tiny waiting tit, killed him with his giant beak and carried his lifeless bloody body away through the air. The fay couldn’t know that the owl was a son of the well known old owl, which meanwhile lived invisibly inside his guano cavity. But shocked by the unusual rudeness in a forest that she knew as a peaceful place from her last visit hundred years ago, she decided to stay for a while and to observe the changes that were going on. A week later, she discovered a very wondrous scenery. The most beautiful fox, she ever saw, with two ears of different sizes and with such vigorous hind legs, never ever seen on a fox, stood in front of the same reed-tube, and he waited there with tears in his eyes.

 

I will tell, and you will wonder, about the monstrous result of an ancient crime. But now the unaccustomed effort tires me, and, look, a poplar tree entices us with its welcome shade, and the turf yields a bed. I should like to rest here on the ground (Ovid’s metamorphoses: Orpheus sings Venus and Adonis).

 

“Bring me the two most precious things in the city,” said god to one of his angels; and the angel brought him the leaden heart and the dead bird. “You have rightly chosen,” said god, “for in my garden of paradise this little bird shall sing for evermore, and in my city of gold the happy prince shall praise me.” (Oscar Wilde, the happy prince)

 

 

Copyrights of text and all paintings: Stefan F. Wirth, Berlin July 2020

Paintings: in tempera colors on canvas

 

 

 

Fox and Witch – a fable – Part I

A fable about competition, hate and bullying

Once a fox and a witch had a competition about who of them would be the fastest runner over a distance of thousand meters through the wild forest. The fox won the competition with a big head start, but the witch was fully unwilling to accept this result, complaining she was in a disadvantage, because he was a fox and she a witch, who could fly like a bird, but had only two legs to run. The fox agreed without any opposition. But the witch could never forget her great failure nor could she ever forgive the fox his success.

Only two weeks later, the fox woke up in his earth-hole in a late afternoon. With narrowed eyes he lifted his snout in the air and smelled a hot summer day, knowing that it very soon would find its end, when a black cover of veil would swallow the red-glowing sun. The fragrance of wild roses and even lavender from the garden beyond the rotten big wall twirled with a slight gust around his head. Then the hissing beat of two heron wings, very close to his hole, which slowly disappeared flap by flap in the depth of the big forest with the huge swamplands at its opposite end.

The fox left his day’s lodging, and when he reached the top of the adjacent green hill, the cumbersome whirring of slowly tiring carder bees accentuated the magnificent final act of the passing day like a fainted opera orchestra . The sky pulsed in a deep bloody red, while streaks in purple and orange, billowing around the glowing horizon, were mercilessly drowning the setting sun. The entrance to the forest was close, and the fox already saw the two oaks, which since more than five hundred years guarded the bumpy path into the woods , and heard their continuous quiet creaking in that mild summer breeze.

When the fox was in order to enter the forest, the witch suddenly appeared. „Where are you going to?“ she asked. He answered: “ to the forest, my world, my habitat, the place, where I live.“

The witch laughed and informed him with a nasty laughter that the council of the forest had excluded him from the forest community of the old beech grove behind the green hills. „Excluded? Council?“ the fox responded surprised. „There is no council, the forest is a natural system, all regulation happens by itself.“ The witch, standing in the air and flying with her mysterious black robe, consisting of thousands of tiny black whirlwinds, laughed again, trying to make it sound compassionately: „I founded that council, because new times require new and much more efficient ways of organisation. All forest animals agreed, some of them representing the executive board members. The wise owl is the president, the tiny mushroom man its deputy. Our decision was democratic, not against you personally, it’s all about the safety of our woods. If you wouldn’t be a loner, if you only had a vixen, she would groom you at positions, which you cannot reach by your own, believe me, you miss something. The new pest of ticks in the woods can only be explained with you as their major vector. We reconstructed that very carefully. Different species of ticks, one even imported from Africa, by migrating birds. These bastards are so big. Once one of them followed me in my cottage and attached itself to my left butt cheek. …“. „I never had ticks in my life, never leave the human trails, didn’t you know that the ticks lie in wait in the grasslands and are dispersed by all their different hosts?“

 

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Witch and fox, oilpainting on canvas, Berlin 11 June 2020, copyrights Stefan F. Wirth

 

„My dear friend, oh poor fox, loners never control their parasites, wait…“, and the witch swished down towards the fox’s head, intending to embrace him consolingly, but she flew so fast that her body accidentally overturned. She scraped with her enormous dentition over the fox’s forehead, her incisors densely covered with trumpet lichens, what she thought was the latest craze in fashion, and faster than the blink of an eye her left canine tooth, angular like a lump of rock, reached the Fox’s right ear and cut it off. The fox howled stridently. Instead of his hairy upright earlobe,only a black amorphic hole remained, filled up with viscous whirling blood. His whole body trembled, the control of his legs failed, and he fell to the ground. His voice didn’t want to obey him any more. His eyes stared into an impermeable black haze. „For all the heaven’s ghosts sake, what a mishap, what an incredible misfortune, a tragedy. If only we witches were able to conjure, I would heal you immediately, but we witches can only fly. Oh fox, the next time, when someone approaches you, don’t move unexpectedly, the consequences may harm you forever…“ . And with a short hiss only the witch disappeared without any other word.

Laboriously the fox rose his painful body up again. His brain pulsing excruciatingly with each heart beat. He cumbersomely trotted along the forest path, passing the two old oaks, representing since hundreds of years the entrance to a former oak forest, today consisting of beeches in most parts. The night was dark, only diffuse beams of light went astray in the dense crowns of trees, emitted by the almost full moon , still swallowed by the shades of the forest.

A narrow runlet of blood divided his forehead into two asymmetric parts, dropping rhythmically onto his nasal root, while he noted remarkable changes in the woods, unusual noises, the odor of autumn in the midst of summer, an air humidity like in rotten moors, an oppressive misty wall around him, which he never saw before.

The fox passed the clearing with its fern growth, their leaves drooping as if there was a longer drought, silence. Did all birds oversleep the night? He finally reached the red narrow stream, which he always used to cross by passing the huge fallen birch trunk. But the old deadwood was now decayed into many bulky fragments of wood, scattered around an area of several square meters.

There hadn’t been any unusual weather conditions, no drought, no thunderstorm and no temperature drop in the hours and days before, a steady summer time, only rarely some rain droplets. The birch trunk was still stable and elastic, when he saw it the last night. A miracle that it broke into pieces all of a sudden. Silence, only his fast heartbeat that echoed in his seemingly permanently weight gaining skull cavity. He inhaled a glutinous mass through his nostrils, warm with the smell of iron and perspiration.

The tiny stream purporting to be a rushing torrent, a disturbing costuming, as it had obviously happened with the entire forest, which was absolutely familiar to him until only one day ago, but now had become a strange world, with himself as a stranger in the midst of a trascendent otherworldliness.

The weird impetuous water movements whirled well audibly, at least with his uninjured left ear. A misty twilight hid much more than it revealed. But that ebullient barrier still needed to be crossed. The fox carefully tried to adjust his eyes to the darkness, but with only a very moderate success. In the midst of cumbersome dark shades of an unsettling night, he could recognize the arrangement of all single remains of the trunk.

At first, there were two almost similar shaped and sized pieces of dead wood, aligned offset to one another. Thus the foxes balancing act would begin with the left block of wood, whereby he would need to switch to the right, after having left three-quarters of the first piece behind him. The second birch log staggered in the water flow, but the fox was sure to master this task even despite of his meanwhile very restricted sense of balance. After passing both logs, he would even have the choice between a branch on the right with a medium diameter, not much wider than the fox’s snout, running parallel to a much bigger rounded trunk piece on the right. A clear obstacle course to cross a tiny stream, suddenly disguising itself as kooky torrential river.

Blood slowly dropped into his left eye, deafness of his right ear, and he felt anxious about his general ability to hear even with his left side. No croaking of frogs or toads, no chirping of crickets or cicadas. The water noises in front of him sounded far away. It was still dark, and the fox saw the wobbly single components of his bridge mostly as silhouettes.

But he decided not to lose any more time, the rebellious stream needed to be crossed as it was a firm component of a natural daily routine, an essential component for a successful coping of a fox’s future. A careful first step with his left paw, and he crossed the left log until the end of its third quarter, where he with a fluid movement switched to the right.

In the moment the fox had decided for inexplicable reasons to balance along the standing upright edge of the small branch instead of crossing the much bigger rounded trunk, the moon lost its last cover behind the skeleton of a dead pine and all of a sudden illuminating the entire night sky in its full splendor.

The fox, almost blind with viscous droplets of blood in his eyes, tipped slightly sideways to the left, an almost invisible and very subtle movement, when a thin somehow diffuse, but bright light beam was reflected from the seething water on his right side and disabled the fox’s sight completely for about two seconds. Two seconds with remarkable consequences, because his slight weight shift in combination with unpredictable water movements, his short sightlessness and the wounded ear resulted in a total disruption of his entire equilibrium sense.

As if the branch under his feet had perceived the loss of control of the fox’s body and as if this seemingly dead piece of wood suddenly acquired a spiteful liking for even more instability, it followed the left-side motion of the fox and rolled against the big log, which due to this friction in turn got on motion and turned in a clockwise direction against the adjacent branch.

When the two unequally sized remnants of the dead birch had decided to release a brisk impulse of new signs of life, centrifugal forces threw the fox’s body in the air, from where he roughly landed in a 90 degrees angle to the subjacent branch with his head directed towards the waterside. And his head, unfortunately not lighter than the moving crazy water surface, was submersed, while water immediately invaded all his facial cavities, even washing around his right drumhead, which lacked its external auditory canal almost entirely, a cold pain, which the fox tried to ignore. He only cumbersomely could lift up his head, gasping for breath, when his hind legs, pointing towards the big log, all of a sudden were pulled between the two unequally sized, still incessantly grinding against each other. A clearly audible crackling on both sides, followed by several further grating sounds, made the fox remark the smashing of all his leg bones. At the end, courageous natatory movements with his forelegs released him from this awkward situation. He slowly crawled with all his remaining powers to the opposite stream bank. And there, he rested for a felt eternity, being completely exhausted.

The fox felt no pain any more, but only indescribable weakness. Surrounded by an unreal silence, he licked his wounds.

END OF PART I

Berlin, 10June 2020, copyrights Stefan F. Wirth

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

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.

SARS-CoV-2_without_background

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.

Varroamilbe

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.

Demodex

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

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