biologe

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

Tag: footage

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

Oribatida mites: Fast runners and slow crawlers

Microhabitats often consist of a complexity of organism species. Under suitable conditions, samples can be kept „alive“ for months and even for years by regularly adding moisture and organic tissue, in case of my sample of this footage: patato pieces.

 

 

Mites of the Oribatida and their different ways of locomotion. Copyrights: Stefan F. Wirth, Berlin April 2019. Please give the video a like on youtube too.

 

Soil samples from island Norderney

 

This soil sample was collected in summer 2018 on the North Sea island Usedom during my participation at the „Geo Tag der Natur“. It contained several specimens of the predatory chilopode Lithobius sp. and pieces of rotting wood, moss and forestground, everything collected under rotting treetrunks and tree branches. The samples additionally contained the carabid beetle Pterosticus cf. niger and ants of genus Lasius. Samples were collected in a small forest area with wetland aspects. The soil quality was rather moist.

 

Astigmatid mites

 

I later added potato pieces and regularly some water droplets to the sample with still living big arthropods/ insects. After some weeks, specimens of the astigmatid mite Acodyledon cf. schmitzi developed on dryer areas of the potato pieces. These mites were presumably phoretic associates of the carabid beetles. They died out after several months, after the sample had dried out a little bit and may be due to changes of the room temperature during winter time.

 

Oribatida

 

Now, almost a year later, the micro habitat is inhabited by mites of the Oribatida in greater numbers of specimens of at least three species: Nothrus sp. (genus not yet clarified), Nothrus palustris (already found for the first time shortly after the sample collection) and a species of Phthiracarida.

 

Locomotion and biodiversity

 

Purpose of the short film is to show different organisms, cultured after about a year in this sample: mites, nematodes, collembolans and microorganisms, fungae and bacteria. Of the bigger arthropods/insects, only one Lithobius species survived until now.  Also the diversity of ways of locomotion in different oribatid species is emphasized: There are slow crawlers (Nothrus) and fast runners (Phthiracarida).

 

Berlin, April 2019, Copyrights Stefan F. Wirth

Agriculture, natural countryside and stream pasture landscape north of Berlin

Berlin as a green city

 

 

Berlin is an unusually green metropolis. Besides numerous urban park landscapes and the huge forest area Grunewald, there is a unique countryside north of Berlin, including the area of the old village Lübars, being surrounded by numerous fields (Lübarser Felder) and a stream pasture landscape, named Tegeler Fließ, with bog meadows.

 

 

Nature sites Lübarser Felder, Arkenberge, Schönerlinder Teiche in 4K, copyrights Stefan F. Wirth. Please also like my video on Youtube.

 

Mounts Arkenberge and pondlandscape Schönerlinder Teiche

 

In the northeast, around the urban village Blankenfelde, the currently highest elevation of Berlin can be found, the Arkenberge. Originally, they represented a chain of smaller mounts as natural remnants of the Weichselian glacier. One of these mounts is especially conspicuous and is acually prepared to become accessible for people and forms with a height of 122 m over NHN the highest mountain of Berlin. It represents despite of its natural origin a rubble landfill site, which was formed beginning in 1984.
Adjacent to the Arkenberge, several wetland areas attract nature enthusiasts for hiking tours: the pond landscape „Schönerlinder Teiche“ (Brandenburg) and the lake Kiessee Arkenberge.

 

Lowland area of the stream Tegeler Fließ as remnants of the Weichselian glacier and adjacent calcareous tufa area

 

The stream Tegeler Fließ is a wetland nature site with a high biodiversity of plants and animals. It is surrounded by different types of bog meadows. The Tegeler Fließ lowland is also a result of the last glacier period.

The stream lowland is additionally adjacent to a calcareous tufa area, which is well visible from top of the Arkenberge. Calcareous springs and calcareous tufas created here calcareous rush- marshes with an interesting biodiversity of for example species of mosses and snails.

 

https://www.instagram.com/p/BuZUYu3FVJK/

Video footage

 

The footage was captured from localities around the village Lübars in the area of Lübarser Felder and additionally around Arkenberge. Some above mentioned nature sites are only visible in a distance.

 

Berlin, March 2019, 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

Round-leaved sundew: How a fly can die

The round-leaved sundew Drosera rotundifolia is a carnivorous plant. It digests mostly small arthropods in order to gain additional nitrogen on floor coverings with a lack of sufficiant mineral nutriment.

 

Sundew and its digestive secretions

 

Along the edges of the rounded leaves, tentacles are arranged, which produce sticky secretions, consisting of enzymes and formic acid. Attracted by a fragrant smell, small animals approach this deadly plant.

Please like my videos also on youtube, in case you like them. Copyrights Stefan F. Wirth

 

The secretions trap them finally to the leave. After some hours the tentacles move towards the leaf-inside due to growth „movements“, where digestive glands are located. Later even the whole leaf rolls that way that more glands get into a contact with the prey. The whole digestive procedure then needs several days. My video only shows the effect of sticky tentakles to a fly, which finally is unable to flee.

 

Fly on a sundew leaf, independent evolution of carnivorous plants

 

The fly specimen might have represented a too large prey, which is why it at first resisted against the slimy and sticky secretions. However later, its body is thus covered with threads of adhesive that it remains fixed to the sundew leaf. Carnivorous plants evolved several times independently within the Angiosperma. That means that pitcher plants, as for example Sarracenia or Nepenthes, systematically do not represent close relatives of the sundew or even between each other. Under comparable ecological conditions, selective pressures caused options for plants to enrich their nutrients by the ability to digest smaller animals using specific organs, usually being homologous to leaves. The way carnivorous traps develop, differs in the various groups of carnivorous plants.

 

Micro-habitats for mites or nematodes

 

Decaying remnants of partly digested arthropods can especially in Sarracenia or Nepenthes become micro-habitats, in which mites or nematodes might find suitable living conditions. Some of them can even be resistant against digestive enzymes of these plants. Whether microorganisms ,such as mites, also can occur on sundew, is unknown to me. Common inhabitants of pitchers of Sarracenia or Nepenthes are represented by mites of the Astigmata, e.g. of the family Histiostomatidae.

 

Distribution of the round-leaved sundew

 

The round-leaved sundew is native to the whole northern hemisphere in bogs and wetlands.

 

Copyrights for film and text: Stefan F. Wirth, October 2017/ November 2018