biologe

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

Kategorie: Milbenforschung

Teaching: Ich als Naturalist – Me as a naturalist

Bumble bee Bombus sp. in Berlin, copyrights Stefan F. Wirth 2021/2022
Honey bee Apis mellifera in Berlin, copyrights Stefan F. Wirth 2021/2022
Deutonymphs of the microscopically tiny mite Schwiebea cf. eurynymphae (Acaridae, Astigmata) formally attached to beetle Phosphuga atrata under the bark of felled tree trunk of Tilia platyphyllos in urban park Rehberge in Berlin, copyrights Stefan F. Wirth, 2021/2022
Larvae of beetle Oryctes nasicornis from Italy with associated gamasid mites under studio light conditions, copyrights Stefan F. Wirth, Berlin 2016/2022
Land crab Metasesarma obesum under studio conditions, copyrights Stefan F. Wirth, Berlin 2017/2022

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Ich biete Unterricht, Förderkurse, Vorträge und Fortbildungskurse zu den Themen Naturkunde, Naturschutz, Artenvielfalt, Ökologie, Klimaschutz und Evolution an sowie Unterricht oder Vorträge zur Naturfotografie oder der Naturfilmerei. All dies entweder auf Honarbasis oder via Anstellung. Bitte entnehmen Sie weitere Informationen meinem Menüpunkt zum Thema Unterricht und Lehre. Selbstverständlich verfüge ich über Qualifikationsnachweise zu meinen diversen bisherigen Lehrtätigkeiten sowie meine fachliche Kompetenz. Bitte beachten Sie hierzu auch meinen Menüpunkt Curriculum Vitae.

Doch was sind eigentlich meine Themengebiete? Im Folgenden finden Sie interessante Fragestellungen aus meinen Kompetenzbereichen.

Was ist ein Ökosystem? Welche Ökosysteme sind gut untersucht, welche eher nicht? Wie gut kennt man die Artenvielfalt von Mikro-Lebensstätten in Deutschland, und was ist über deren biologische (ökologische) Zusammenhänge bekannt? Was ist denn eigentlich eine Art, was sind denn dann Zwillingsarten, und was versteht man gar unter einem Artenkomplex (kryptische Artengruppe)? Ist das Aussterben von Arten ein normaler Bestandteil der Evolution oder ist das Aussterben einer Art immer zwingend ein alamierender Hinweis auf eine (evtl. menschengemachte) Naturkatastrophe? Wieviele Arten aus allen Organismengruppen weltweit kennen wir, und wieviele in etwa kennen wir noch nicht? Warum kennen wir viele Arten, sogar in Deutschland, noch immer nicht? Wie erkennt man neue Arten, und wie ist eine sogenannte Artbeschreibung aufgebaut? Ist der Mensch eine Tierart, und wo im Stammbaum der Tiere ist er dann anzusiedeln?

Warum sind ein Wald, ein Teich oder eine Wiese Orte für interessante Entdeckungen, und zwar insbesondere auch für Kinder? Was lebt denn da, und wie ist es an seinen Lebensraum angepasst? Was haben unterschiedliche Arten in solchen Lebensräumen eigentlich miteinander zu tun? Und wie beobachtet man Tierverhalten am besten? Wie dokumentiert man es aussagekräftig, um sein Wissen später mit Freunden oder über soziale Netzwerke teilen zu können?

Wie kommt es zum sogenannten Global Warming, der globalen Klimaerwärmung? Wie können wir sie nachweisen? Warum ist sie zu einem beträchtlichen Teil menschengemacht? Und welche Auswirkungen haben Klimaerwärmung und die Ausbeutung natürlicher Ressourcen (Energiespeicher, Rohstoffe, wie zum Beispiel Tropenholz) für die Zukunft der Menschheit und die Artenvielfalt auf unserer Erde. Welche Auswege erhofft man sich? Woran wird derzeit gearbeitet?

Was benötigt man zur Naturfotografie, was, wenn man zusätzlich oder alternativ auch noch auf gutem Niveau filmen möchte? Was ist grundsätzlich wichtiger: Das Equipment oder das Bild, das zuvor im Kopf des Fotografen oder Filmers entsteht? Muss taugliches Equipment immer ultra-teuer sein? Welche Software eignet sich am besten zum Editieren? Was genügt dabei den Ansprüchen von Anfängern, was benötigen Fortgeschrittene und Profis? Wie filme oder fotografiere ich draußen in der Natur? Wie hole ich stattdessen die Natur in mein Fotostudio und inszeniere sie dort so, dass es aussieht, als habe man im Freien gearbeitet?

Dies sind alles mögliche Themen, die in meinem Unterricht, meinen Kursen oder Vorträgen vertieft werden können. Beliebige weitere Fragestellungen aus den Bereichen Naturkunde, Biologie, Ökologie und Evolution arbeite ich gerne für Sie aus.

I offer lessons, remedial courses, lectures and advanced training courses on the subjects of natural history, nature conservation, biodiversity, ecology, climate protection and evolution, as well as lessons or lectures on nature photography or nature filming. All this either on a fee basis or via employment. Please see my menu item on the subject of teaching for further information. Of course, I have proofs of qualifications for my various previous teaching activities as well as my professional competence. Please also note my menu item Curriculum Vitae. 

But what are my topics? In the following you will find interesting questions from my areas of competence:

What is an ecosystem? Which ecosystems have been well studied and which not? How well do you know the biodiversity of micro habitats in Germany and what is known about their biological (ecological) relationships? What is actually a species, what are sibling species, and what is meant by a species complex (cryptic species group)? Is the extinction of species a normal part of evolution or is the extinction of a species always an alarming indicator of a (possibly human-made) natural disaster? How many species from all groups of organisms worldwide do we know, and roughly how many do we not yet know? Why do we still not know many species, even in Germany? How do we recognize new species and how is a so-called species description structured? Are humans an animal species, and if so, where do they belong in the animal tree?

Why are a forest, a pond or a meadow places for interesting discoveries, especially for children? What lives there and how is it adapted to its habitat? What do different species actually have to do with each other in such habitats? And what is the best way to observe animal behavior? How can you document it meaningfully so that you can later share your knowledge with friends or via social networks? 

How does the global warming come about? How can we prove its existence? Why is it largely human-made? And what are the effects of global warming and the exploitation of natural resources (energy stores, raw materials such as tropical wood) on the future of humanity and biodiversity on our planet? What exits to avoid emergency situations are we hoping for? What are scientists currently working on to ensure a healthy human future? 

What do we need for nature photography, what if we also want to film at a good level in addition or as an alternative? What is fundamentally more important: the equipment or the image that is created in the head of the photographer or filmmaker? Does suitable equipment always have to be ultra-expensive? Which software is best for editing? What meets the requirements of beginners, what do advanced and professionals need? How do we film or take photos outdoors in nature? Instead, how do we bring nature into our photo studio and stage it there in such a way that it looks as if we were working outdoors? 

These are all possible topics that can be deepened in my teaching, courses or lectures. I would be happy to work out any other questions from the fields of natural history, biology, ecology and evolution for you. 



all copyrights Stefan F. Wirth Berlin 2022

Mate guarding of a juvenile female in mites of the Histiostomatidae (Astigmata, Acariformes)

Male of Histiostoma sp. guards a female tritonymph, copyrights Stefan F. Wirth 2005-2022

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A strategy to avoid male competition for females

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Some mites of the Histiostomatidae practice so-called mate guarding of subadult females in order to have an advantage in the intraspecific competition between males for adult females. My SEM image shows a male on top of a female, which is still inside its tritonymphal cuticle. Inside the tritonymphal cuticle, the adult female is already developed and shortly before hatching. Before hatching, the legs of the new instar are folded under the body side. The new second leg on the right side is visible in the SEM, because the weak cuticle of the old leg broke off. This strategy to avoid sexual competition is quite common with Histiostomatidae. Due to insufficient mite material and not longer available clear ecological data, I determine the long haired adults of my old SEM series with caution as Histiostoma sp., it seemingly was found around sap flux on a tree trunk in Berlin. The species is not identical with Seliea pulchrum (= Histiostoma pulchrum), typically known from sap flux. The distance between the male legs 1 and 2 in the photo is about 0.1 mm. These SEM objects were seemingly chemically dried for the scanning electron microscopic procedure. The photos were taken around 2005 with an older SEM at FU Berlin. © Stefan F. Wirth Berlin 2022

Mites, Biodiversity, evolution, species extinction, new species

More Specialists are needed to study our biodiversity: recognizing and describing new species, redescribing known ones, mapping their distribution and understanding their ecological role in an ecosystem.Thus we have to support our children and students to become fascinated by nature.

Also interested laypeople, hobby researchers and nature lovers can contribute to species preservation and nature conservation (and thus climate protection) and encourage their children or relatives to study biology or a similar subject.

Es werden mehr Spezialisten benötigt, um unsere Biodiversität zu studieren: neue Arten zu erkennen und zu beschreiben, schon bekannte Arten neu zu beschreiben, ihre Verbreitung zu kartieren und ihre ökologische Rolle in einem Ökosystem zu verstehen. Daher müssen wir unsere Kinder und Schüler dabei unterstützen, sich für die Natur zu begeistern.

Auch interessierte Laien, Hobbyforscher und Naturfreunde können einen Beitrag zum Arten- und Naturschutz (und damit zum Klimaschutz) leisten und ihre Kinder oder Angehörigen für ein Studium der Biologie oder eines ähnlichen Faches animieren.

© Stefan F. Wirth, Berlin 2022

I provide advices and information about the topics mites (in general, in your house or your company and in a hygiennic context), biodiversity, correlation biodiversity research and climate change, speciation processes, describing new species, species extinction, taxonomy for private people, educational institutions, e.g. schools or university students. Please see my menue item „Angebot biologische Beratung…“

Ich biete Beratung und Informationen zu den Themen Milben (allgemein, in Ihrem Haus oder Ihrem Unternehmen oder im hygienischen Kontext), Biodiversität, Korrelation Biodiversitätsforschung und Klimawandel, Artbildungsprozesse, Beschreibung neuer Arten, Artensterben, Taxonomie, für Privatpersonen, Bildungseinrichtungen, z.B. Schulen, oder Studenten. Bitte beachten Sie meinen Menüpunkt "Angebot biologische Beratung..."

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

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

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

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

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

 

Amsterdam_027

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

 

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

Mite Histiostoma 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

Mite Histiostoma sachsi (Astigmata): Juvenile dispersal instar deutonymph and its orientation behavior

Some animals live in environments, where there is (almost) no light available. It makes no sense to see in the dark, but it is important for a specimen to know, where it actually is, where it is going to, whether there is enough food and what the conspecifics are doing. Predators need to be recognized in time, and a sexual partner must be found. There is also need for an efficient communication between specimens of a species. How can all this be performed by mites of the Astigmata, which usually live inside decomposing soil habitats in a more or less permanent darkness?

 

Olfactory sense organs in mites of the Histiostomatidae

 

Histiostoma sachsi (Histiostomatidae, Astigmata) is such a mite, living inside cow dung or compost. It might have a rudimentary ability for a light perception, but has not visible or functional eyes. It cannot produce any sounds. It can only feel and smell. Seemingly very limited abilities, but the contrary is fact: Due to evolution this mite is perfectly adapted to its life-style. It can feel objects by touching on them using its body setation (= body hairs). And it smells by means of very specialized body hairs, which are called solenidia and appear in different types, shapes and functions. These mites don’t smell on the level of us humans, which would be very insufficient. If at all, it should be compared with a dog. I am always fascinated when seeing blind dogs and how perfectly they can interact with their environment, despite their handicap. That’s may be how the efficiency of olfactory perception abilities of such a mite must be imagined. They do not only perceive scent particles from other animals, plants and soil components. Even olfactory signals from their conspecifics will be correctly and differentiatedly interpreted. And that not only marginally.  Olfactory signals represent indeed the major mode of their intraspecific communication.

 

Chemical communication of mites of the Histiostomatidae

 

Communication always requires contributions from both sides, a signal and an answer. These mites smell the signal of a conspecific using their solenidia, and they answer by the secretion of biochemical components. For these purposes, they possess a huge and complex gland system located on the upperside of their backs. Volatile excretions aggregate inside a big and rounded reservoir and finally leak to the outside via a pore, called oilgland opening. These gland systems are located symmetrically on both sides, each with one reservoir and one pore.

The meaning of the sent volatile message simply depends on the composition of the correspondingbiochemical components. Even diffferent stereochemical configurations of the same molecule can have different meanings. Citral for instance is a major component and has in different stereoisomers different functions. Such cummunicative volatile signals are usually named pheromones. And mites of the Histiostomatidae can indeed produce different kinds of pheromnes via the same gland system. Aggregation pheromones inform specimens about a suitable place to stay together with their conspecifics, for example due to a sufficient amount of food resources. Alarm pheromones solicit mites nearby to flee from an unpleasant situation. Sexual pheromones attract adult partners to each other in order to perform the mating procedure. But the gland secretions can even more. As allomones, they communicate with specimens of other species. They function as defenses against predators or other dangerous cohabitants.

 

Deutonymphs need to find a carrier for dispersal

 

Another form of communicative interspecific interactions is performed by a specific juvenile instar, the deutonymph. It looks morphologically quite different from all other instars (heteromorphic situation), does not need or possess a functional mouth, has a thicker cuticle as protection against drying out and a complex sucker organ on its underside in order to attach itself to an insect or another bigger arthropod. Deutonymphs of the astigmatid mites search for bigger carrier-arthropods to get carried from one habitat to another (dispersal strategy  is calledphoresy). While doing so, they again use their specifically modified leg setation (hairs) on the first pairs of legs to perceive scents for the detection of a suitable and passing by carrier. Basically it is still unknown, whether the term „communication“ is indeed appropriate in this context as we don’t know yet about a mutual interaction between deutonymphs and their carriers, before the phoretic ride begins.

 

 

Olfactory orientation of the deutonymph of Histiostoma sachsi, copyrights Stefan F. Wirth, February 2019.

 

Specific way of walking in deutonymphs

 

In detail, different kinds of behaviors can be observed in deutonymphs, when searching a carrier. The detailed behavioral patterns in this context can slightly differ between even closer related species. Deutonymphs of Histiostoma sachsi as all deutonymphs show a characteristic mode of walking, in which especially the first pair of legs plays an important role. During each step, performed by four pairs of legs, the first legs are lifted up much higher than all other hind legs. While doing so, they slightly tremble up and down. A behavior that mostly supports a better basic orientation inside a „jungle-„micro-landscape, being filled up with soil particles and decomposing plant tissues. But what H. sachsi deutonymphs additionally need in order to find their carriers is repeatedly to rest between the walking activities. Thus the first legs, which normally are still walking legs, are made free and that way available for the perception of carrier-scent-components only. These  namely are the legs that bear the highest densiy of solenidia.

 

Two different behavioral modes for an efficient orientation towards a carrier

 

Two different modes of resting with olfactory searching activities could be observed: In periodic intervals the deutonymph attached to the ground by using its sucking structures. They were then more or less laying on their entire undersides with only their forebodies slightly lifted up. By alternating moving the first legs up and down, olfactory information could be perceived from all directions without having the own body as a barrier to backwards. To improve its orientation situation, the deutonymph additionally turned on its own axis around, being stabilized by its sucking structures, which are flexible enough to follow these movements. When the deutonymph intended to continue its walk, it first needed to detach from the ground, which happened via muscle contractions that caused an abrupt detachment of the corresponding suckers. But main aim of the deutonymph is to find an elevated place, where the probability of a passing by carrier is especially high and from where a bigger insect (or other arthropod) can easier be ascended. There the second behavioral mode was performed. The deutonymph only fixed the edge of its hind body to the ground, again using the suckers on its underside, which are located close to this edge. This time the entire mite body stood in an upright position. The first legs again „waved“ alternating up and down and could under these especially elevated conditions even perceive scents from bigger distances. By occasionally slightly and alternating turning their upright bodies to both sides, olfactory information could be easier detected from all directions.

 

Carrier of H. sachsi still unknown

 

The frequency of such movements in mites increases typically as closer a suitable carrier approaches. But this was not yet observed or documented for Histiostoma sachsi. Its carrier inside the compost substrate is still unknown, which is why I so far could’t perform corresponding experiments. The species‘ describer, Scheucher (1957), found her mite specimens in cow dung and also didn’t identify the corresponding carriers there.

The observations presented in my video are part of my research project about morphologies and behaviors of deutonymphs in the Histiostomatidae.

 

Berlin, February 2019. All copyrights Stefan F. Wirth.

 

Months passing, but where has all the life gone?

I am standing in Berlin. The sky is a grey monotony. And while tiny waves gently wash around the little sandy beaches, tree skeletons surround the hidden bays on the Havel river. A semi-lucid vapor is covering the branchage of leafless treetops, already early in the afternoon. It is December in Berlin. The entire spectrum of bright summer colors is overlaid by muddy shades. Only larger groups of pine trees gleam in a greenish-black out of a giant cemetery of seemingly inanimate bodies of beeches, oaks, birches and maples. The cry of a heron in a far distance, but where has all the colorful and manifold life gone?

T. S. Eliot (1888-1965) wrote („Journey of the Magi“):

„A cold coming we had of it, just the worst time of the year  For a journey, and such a long journey: the ways deep and the weather sharp, The very dead of winter…“

Shakespeare (1564-1616) on Sonnet  97:

„…What freezings have I felt, what dark days seen! What old December’s bareness everywhere!…“

Seeming emptyness of a Forest-waterside landscape in winter, copyrights Stefan F. Wirth, Berlin December 2018. Please like my video also on Youtube, in case you really like it.

 

Bareness, emptyness, death, attributes being combined with winter since mankind exists. From the evolutionary point of view a serious problem that early humans  had to master. The seemingly emptyness was for them a very real lack of sources. They needed to prepare the winter time, food needed to be stored and protecting clothes to be stiched. There was no well organized international trade of goods, no fresh apples and pears in winter, no cheap winter jackets made in China. Winter meant to fear for the basic survival.

Today we live a different life, being independent from the seasons. Life today means for us to fear for the basic survival of our environment. What are the effects of a global climatic change? What the effects of our environmental pollution? What changes are independent from all that and just represent natural processess as they happened again and again since about 470 millions of years, when the first plants appeared on shore?

 

Most life does not disappear in winter, it just hibernates – alive!

 

The Berlin nature refuges around the forest Grunewald-terrain are interesting due to their complex mosaics of different habitats close to each other. Forest Grunewald in Berlin and the sandy beaches and bays along the Havel river offer space for lizards, an interstitial insect fauna, dry grassland visitors such as butterflies, wetland animals like frogs and newts, aquatic inhabitants like river lampreys, numerous bird species and inhabitants of wood in all kinds of decomposition stages such as bark beetles, longhorn beetles or hermit beetles.

 

Migration

 

Some animal inhabitants of the Grunewald/ Havel-area in summer migrate during the winter season, but most species stay. They hibernate and are even now in December still there.

 

Birds

 

Many birds show a strict migration behavior to avoid northern winters, others migrate in greater numbers, while some specimens stay, and some migrate only over smaller distances. Which of those migration behaviors is exactly performed by which bird species might depend on climatic conditions and is object of scientific research. NABU for example regularly starts projects, to which the general public can contribute with own observations. One of them takes place in early January and is named „Stunde der Wintervögel“ („the moment of winter birds“).

Common cranes Grus grus and greylag geese Anser anser normally migrate over bigger distances and numerous bigger routes towards southern winter refuges. Especially cranes are in summer for examples inhabitants of the Havelland Luch, thus prefer areas more western of Berlin. A trend was observed by ornithologists that more and more often, obviously corresponding with a global warming, troops of crane specimens stay instead of migrating southward.

Migration behavior of common cranes and greylag geese in Linum, autumn 2018, copyrights Stefan F. Wirth

Female of the red-backed shrike in Berlin (Köppchensee). The bird is a typical long-distance migrating animal. Copyrights Stefan F. Wirth, 2018

 

Butterflies

 

The red admiral butterfly Vanessa atalanta is known as a migrating insect. The „normal“ case is that migration from Southern Europe towards Central Europe is performed in spring. There, a summer generation develops and in autumn either tries to migrate back southward or to hibernate as adult butterfly, where it hatched, for example in Germany. But specimens mostly do not survive their tries to hibernate during our cold winters. This makes the admiral to a rare example of our summer-fauna, which over here partly indeed dies out before winter begins. The migration routes of populations throughout Europe is still topic of research. The migration behaviors seem to change corresponding to a global warming.

Admiral butterfly in Berlin, copyrights Stefan F. Wirth, 2018

 

River lamprey

 

Also the river lamprey Lampetra fluviatilis obligatory needs migrations over bigger distances. But these migrations do not correspond primarily with our cold seasons, but instead with the complexity of its life cycle. Larvae, which differ morphologically from adults, hatch in our freshwaters and develop as filter feeders within about three years, in which they  hibernate inside their aquatic freshwater habitats. They then migrate after a morphological metamorphosis towards the Sea. There they live as ectoparasites on fishes until they reach sexual maturity and then return into freshwater-rivers to reproduce and finally die. It is still subject of research, whether they return for their reproduction to the areas of their original larval development.

 

Hibernation

 

Sand lizard

 

The sand lizard Lacerta agilis  hibernates in hideaways, which are able to hold a temperature around 5°C. There they fall into winter numbness due to their unability to regulate their body temperature independently from the environment. Juveniles and adult genders start their hibernations  at different times.

Sand lizard juvenile, found in Berlin Grunewald/ Teufelsberg, copyrights Stefan F. Wirth

 

Frogs

 

Toads and frogs hibernate after finishing their metamorphosis, juvenile and mature specimens spent a diapause as a total numbness such as in lizards. Amphibians and lizards are poikilotherm, thus their body temperature corresponds to their environment (some monitor lizards Varanus were found to have physiological abilities for a limited self regulation of their temperature, which is an exception within the taxon big Squamata).

Marsh frog Pelophylax ridibundus, pool frog Pelophylax lessonae and edible frog Pelophylax kl. esculentus survive the cold season in hideaways, which maintain acceptable environmental temperatures. While pool and edible frog hibernate on land, the marsh frog spends its diapause in aquatic habitats. Skin respiration then plays an even more imortant role, which is why these frogs require a high availability of oxygene. The edible frog is even from the evolutionary point of interest, as it represents a hybride between two closely related species, namely marsh and pool frog. It is in many of its populations non reproductive with other hybrides and needs one of the parental species to reproduce. But interestingly triploid specimens of the edible frog sometimes develop in populations and bear the complete genomic information of one of the parental species. These edible frogs can reproduce with other hybrides They can be found throughout Berlin. Such specimens are difficult to be determined morphologically, as they resemble in their outer appearance either to the marsh or the pool frog.

 

Sand wasps

 

Insects hibernate in different developmental instars, if holometabolic, egg, larva, pupa and adults are options, if hemimetabilic eggs, nymphs or adults perform the winter diapause. Some insects can even hibernate in all of their developmental instars.

The quite common red-banded sand wasp Ammophila sabulosa for example is part of the insect interstitial fauna and does not practise brood care, but maternal care. Females built up several single nests up to 20 centimeters into the soil, each of them containing only one cell for the deposition of always one egg. As food supply they hunt caterpillars preferrably of Noctuidae, stun them with a sting and carry them to their nests, which will be closed with soil particles afterwards. The last brood hibernates as pupa or larva inside the nest.

Sand wasp Ammophila sabulosa in Berlin, copyrights Stefan F. Wirth, 2018

 

 

Grasshoppers

 

The grasshopper Sphingonotus caerulans is a thermophilic species, which is a typical inhabitant of sandy areas in Southern Europe. It also appears in Berlin. Its eggs are deposited into deeper soil layers and hibernate there.

Grasshopper Sphingonotus caerulans, male, found in Berlin (Köppchensee). Copyrights Stefan F. Wirth, 2018

 

terrestrial Isopods

 

The common woodlouse Oniscus asellus for example hibernates as nymph or mature adult in hideaways inside deeper soil layers, dead wood or compost. These terrestrial curustaceans become inactive, when colder temperatures appear. Specimens can live over several years (usually about two years).

An example for a woodlouse, in this case a mediterranean species of genus Porcellio, copyrights Stefan F. Wirth, 2018

 

Hibernating animal communities

 

Communities of different animal species often hibernate altogether. I focus here on inhabitants of micro habitats. Especially long living insect nests can bear greater numbers of cohabitants. But also deadwood or compost bear many different animal species side by side.

 

Ant nests

 

Nests of the red wood ant Formica rufa represent complex animal communities, as it is typical for ant nests generally. Besides ants and their brood noumerous nematode and mite species inhabit nest mounts of F. rufa. Additionally different larvae of other insect taxa can be members of the ant community, I even discovered the larvae of the green rose chafer sometimes inside red wood ant nests in the area of the Berlin forest Grunewald. Also several species of pseudoscorpions are known to science to be adapted for a survival in nests of F. rufa in Europe: commonly found are for example the species Allochernes wideri and Pselaphochernes scorpioides. Pseudoscorpion species of genus Allochernes are known to practice a dispersal strategy named phoresy. They use bigger and better motile insects as carriers and that way are transferred to new habitats. Besides ants, their suitable phoretic carriers seem to be dipterans. Also different mite and nematode taxa inside nests of the wood ant perform phoresy. A mite example is the species Histiostoma myrmicarum (Acariformes, Histiostomatidae), which seems to be carried by ants and eventually additionally also by other arthropodes.

The larva of the green rose chafer inside a nest of Formica rufa, copyrights Stefan F. Wirth, 2011

Mite Histiostoma myrmicarum (Astigmata) collected from its hibernation habitat in the soil underneath an old oak in Berlin forest Grunewald, copyrights Stefan F. Wirth, 2018

 

Formica rufa itself hibernates inside its nest in absence of eggs, larvae or pupae. Only the queen and workers remain during the cold season. Not much is known about other nest inhabitants. More research is needed.

Typical ant cohabitants (with Formica rufa) do not necessarily need to hibernate inside their ant nests. I collected deutonymphs of the mite Histiostoma myrmicarum in winter 2017/18 from soil (some centimeters deep) underneath an old oak in the absence of ants and their nest. The well scleotized deutonymph (phoretic dispersal juvenile stage) might represent the hibernation stage.

The advantage for organisms, living in ant nests, is a higher and constant temperature due to the ant worker’s nest-care-activities. Additionally the defensive behaviors of ants offer protection for those organisms being adapted (based on evolution) to survive inside ant nests.

Due to suitable temperatures, many organisms inside nests of the red wood ant might stay even active in winter. Interactions between ant nest-cohabitants can be very complex. An example is the Alcon large blue butterfly Phengaris alcon, being adapted to other ant species: Myrmica rudinodis and M. rubra. The caterpillar resembles an ant worker due to the morphology of its cuticle and the production of ant-similar pheromones. Ant workers fail for this imitation, carry the caterpillar into their nests and feed it. The butterfly’s larva hibernates inside the ant nest as larva, molts into pupa in the subsequent spring season and finally leaves the nest as adult butterfly. Still inside the ant nest, the caterpillar can become a victim of the parasitic wasp Ichneumon eumerus. Its female invades the ant nest, only after recognizing that caterpillars of the blue butterfly are indeed inside. It then confuses the antworkers due to the release of different chemicals and then attaches its eggs to the caterpillar. The wasp’s larva hibernates there and molts into its pupa inside the host’s pupa. The adult wasp afterwards leaves the ant nest.

Phoretic mites of the taxon Astigmata inside a nest of Myrmica rudinodis, found on island Usedom, copyrights Stefan F. Wirth

 

Bark beetle galleries

 

Numerous mite and nematode species live inside the galleries of bark beetles. Such a complex fauna is known for many bark beetle species. Additionally the larvae of different other insects can be cohabitants. Depending on the species, they can perform all kinds of life-strategies: being predators of adult bark beetles or their offspring or of other gallery cohabitants, they can also be microorganism feeders and prefer the bark beetle galleries due to its ideal warmth-isolation or due to the specific micro-climate that is created there by the activities of all different inhabitant activities. Besides animals, also fungi and bacteria contribute to that climate.

Bark beetle Hylurgops ligniperda and phoretic mites, copyrights Stefan F. Wirth, 2016

Wood associated nematode Diplogaster sp. found in the tree fungus Laetiporus sulphureus in Berlin, copyrights Stefan F. Wirth, 2016

Mite deutonymphs of the Histiostomatidae mites inside the galleries of the bark beetle Tomicus destruens in Italy, Vesuvio National Forest, copyrights Stefan F. Wirth, 2016

Bark beetle Ips typographus with some of its gallery-cohabitants, such as phoretic mites, found in SW-Germany (Saarland), copyrights Stefan F. Wirth, 2015

 

Furthermore the composition of species in a bark beetle gallery changes with an increasing age of a gallery. Secondary infections are often performed by other wood parasiting beetles, after the bark beetle brood finished its development and left the gallery. A secondary parasitism can for example be performed by longhorned beetles.

The bark beetle Dendroctonus micans for example infests several conifer species: Picea, Abies, Larix and Pinus. This bark beetle can hibernate in all its instars: eggs, larvae or adults. Adults can in spring sometimes be found in specific hibernation-chambers. In a research project with russian collegues, I isolated beetles of that species in the early spring season in Siberia (Russia) out of such a chamber on Pinus silvestris. Adjacent to attached substrate particles, I found nymphal stages of the phoretic mite Bonomoia opuniae, a species of the Histiostomatidae (Astigmata), which was even new to science at that time. I described this species, which I so far only know from those siberian samples. It is still unknown, whether it also appears in Central Europe.

The nymphal stages (protonymphs and tritonymphs) of that mite species might represent the hibernating instars. They were not fallen into a numbness after the collection and even remained active in a refrigerator, where my samples were stored subsequently for a while. I doubt that the mite in winter can pass through different generations as it would happen in a warmer climate, because the found mite nymphs appeared -also active- still rather weak in their cold environment. Thus I assume these nymphs to hibernate throughout the winter season. But there is still much research missing about the ecology/biology of bark inhabiting mites.

Adult beetles of Dendroctonus micans with deutonymphs of Bonomoia sibirica, Tyumen/ Siberia, copyrights Stefan F. Wirth, 2017

 

 

Berlin, December 2018. Copyrights Stefan F. Wirth

 

 

 

 

 

Male and female of Histiostoma sachsi and unsuccessful mating with a „stranger“

Mites of the Acariformes vary in very different forms and life-strategies. One taxon of very tiny and soft-skinned mites is named Astigmata. Within them the familiy Histiostomatidae is especially rich of species, most of them surely not yet described or discovered.

 

Modyfied mouthparts and a specific mode of dispersal

 

These mites feed on microorganisms using a complex mouthpart-apparatus with multifunctional abilities. They can be found in habitats, which dry out quickly. When it’s getting too dry, a specific instar of the mites takes a ride on insects or other bigger arthropods for dispersal to a new and fresh habitat ( strategy called Phoresy).

Histiostoma sachsi is one of numerous (often closely related) long haired (in females) species. It was originally in 1957 described from cattle-dung. I found it in compost.

 

Long upper-setation in females and tactile camouflage (mimesis)

 

Adult females are characterized by a long setation on their uppersides. They use them to hold parts of the old nymphal cuticle and soil particles on their backs. This seems to be due to a strategy named mimesis or camouflage. It’s a tactile camouflage as an optical sense in this kind of microhabitats plays almost no role.

 

Normal and unusual copulation position, trial of an interspecific copulation

 

Males mate their females via a dorsal copulation opening and thus need to ride on them. In H. sachsi, that copulation opening is located very close to the hind-edge of the body. That way it is even despite of the camouflage cover accessible. It seems even slightly being elevated out of the body surface in order to surmount adjacent soil particles. This is an adaptation of this particular species. It might share such morphological characters only with very closely related (not yet described) species In other members of genus Histiostoma, the copulation opening is usually more centered related to the hind body.

The copulation position requires that males insert their aedeagus („penis“) into the copulation opening. They additionally use their legs to grasp into the females body. That kind of leg arrangement and thus the whole copulation position can differ from species to species.

This is why copulations between members of different species already fail, because the right copulation setting does not fit, nor does the shape of the aedeagous. Nevertheless the phenomenon of unsuccessful trials for interspecific copulations can sometimes be observed in laboratory cultures. Such a trial is also visible in this video, where a male of Histiostoma feroniarum (also appears in my compost samples regularly) tries to mate a female of H. sachsi. It cannot even almost get in a proper copulation position and seems to hold on to the dorsal camouflage cover of the female. it could only remain in a transverse position related to the female body and thus not get access to the copulation opening, normal would be a longitudinal position with the sameame orientation of female and male.

Adult mites of the family Histiostomatidae (Astigmata) and a „false“ copulation. Copyrights Stefan F. Wirth, Berlin December 2018. Please like my video also at Youtube, in case you like it.

 

Chemical communication and chemo-sensitive leg setation

 

Mites of the Astigmata communicate and find their general orientation due to chemo-sensitive setae, mostly on legs I and II, which are named solenidia. They are even on the magnification level of my footage well visible on the male’s legs. Although a direct body contact is not necessary for a innerspecific communication by chemically interpreting scents produced from mite glands, the observed male in my video repeatedly was seeking for intense body-contacts and obviously „observed“ his conspecific while doing so with its first two legs. This might have intensified the perception of pheromones.

It showed this behavior also, when passing by the „false copulation-pair“ described above. It additionally seemed to invest power in its leg movements as if it would try to remove the „competitor“ on the female, in this case even belonging to another species.

 

Competitive fights between males

 

That mites of the Histiostomatidae can use their strongly sclerotized first legs to fight under each other for an access to a female is known to me from my older observations about the species Histiostoma palustre and Histiostoma feroniarum.

 

Origin of the compost samples

 

The compost samples were collected in SW-Germany (Saarland in October 2018). The footage was recorded in December 2018 in Berlin.

 

Berlin December 2018, copyrights Stefan F. Wirth

Habitat compost: Mite Histiostoma sachsi carries old cuticle and dirt as camouflage

My parents have a compost area in their backyards. I use it as reference habitat for two mite species of the family Histiostomatidae (Astigmata): Since I began my research in 2000, the compost regularly contained Histiostoma feroniarum with its typical male dimorphism. Since summer 2017 another species appears additionally regularly: Histiostoma sachsi. Both species do not appear under the same conditions. While H. feroniarum prefers fresher decaying material, H. sachsi on visibly older decomposed tissue. There mite be even more mites of the Histiostomatidae exist in this complex compost habitat, but under my laboratory conditions, only the two named species were so far successfully reared out of samles always again. Regarding the determination of H. sachsi on a species level, I was more careful in my comments to a former video (June 17), in which I named it Histiostoma cf. sachsi due to doubts about a correct identification. Meanwhile, also due to the morphology of the deutonymph, I determine „my“ compost mite as Histiostoma sachsi Scheucher, 1957. But it is still to emphasize that Scheucher described H. sachsi from cattle dung, not from compost. But generally, both habitats can sometimes share the same inhabitants.

 

Adult females carry their old cuticles and „dirt“ on their backs as tactile comouflage

 

Biologically conspicuous is darkish material, which especially adult females carry on their backs. Unlike males, females posses elongated setae on their backsides. These setae support the holding of material such as old cuticle and soil particles. In slide preparations, this cover usually appears amorphic and contains substrate from the mite’s environment. My video footage indicates that the basis of this cover is a retained old cuticle from the former nymphal instar . That this cannot easily be proven with the light microscope is due to the very soft and fine character of the cuticles in these mites. Remnants might become decomposed by microorganisms after a while.

Compost: the habitat of the mite Histiostoma sachsi Scheucher, 1957 (Acariformes, Astigmata, Histiostomatidae). Copyrights Stefan F. Wirth, please like my video also on youtube, in case you like it.

 

The phoretic dispersal instar, named deutonymph, in mites of the Astigmata controls its body position due to sticky leg endings and suckers on their undersides

 

Deutonymphs of H. sachsi represent one of my resent models to study mite-dispersal behavior. My research focus since a while concerns ultrastructure and function morphology of the deutonympal suckerplates and other structures to attach to insects for dispersal (this dispersal strategy is called phoresie). The anterior front-suckers on the suckerplate of the mite’s underside is extendable and very flexible, not only to find a suitable position on the insect carrier. When falling, the deutonymphs use it to lift their bodies up into a proper position again. Additionally they will try to get hold using „sticky“ lobe-shaped setae on the endings of legs I and II. Both is visible in my footage. The forelegs seem generally to make the first contact, when trying to get on a suitable carrier.

 

Deutonymphs of Histiostoma sachsi take a ride on other mites (Oribatida)

 

The suitable carrier of H. sachsi is unknown to me. Some astigmatid species have even a range of carrier-„hosts“. In my samples, deutonymphs at least attach to other mites, especially to mites of the Oribatida. This is in a very short scene visible in my video too.

 

Copyrights Stefan F. Wirth, Berlin December 2018