Food ingestion by Dicyphus errans Wolff (Heteroptera, Miridae, Bryocorinae) : range of food, potential and behaviour

Die paläarktische Weichwanze Dicyphus errans zeichnet sich unter anderem durch ihr sehr breites Spektrum von Beutetieren, (Wirts-)Pflanzen, Habitaten und besiedelten Klimabereichen aus. Die omnivore Lebensweise befähigt das Insekt zum „Switching“, dem Wechsel zwischen zwei trophischen Ebenen (COLL & GUERSHON 2002), und somit zum langfristigen Überleben in Pflanzenbeständen, auch unter Beutetiermangel oder –abwesenheit. Hervorzuheben ist die ausgesprochene Präferenz von D. errans für (glandulär) behaarte Pflanzen, die auf andere natürliche Gegenspieler, wie diverse Parasitoide, Vertreter der Coccinellidae und Syrphidae als physikalische und chemische Barrieren wirken (CORTESERO ET AL. 2000). Die räuberische Leistungsfähigkeit von D. errans fiel im Februar 2000 im Botanischen Garten der TU Dresden bei Schnittmaßnahmen an der Vitaceae Cissus njegerre GILG. auf. Neben D. errans war die Pflanze mit unzähligen ausgesaugten Planococcus citri RISSO besetzt. Seitdem wurde die Wanze hinsichtlich ihrer bionomischen Parameter beobachtet und experimentell untersucht (VOIGT 2005). Ein Teilaspekt der Forschungsarbeiten galt der Nahrungsaufnahme von D. errans. Es erfolgten Videodokumentationen zum spezifischen Verhalten und Experimente zur Verzehrleistung in Abhängigkeit von verschiedenen Beutetieren und Wirtspflanzen sowie von der Verfügbarkeit ergänzender Wasserquellen.The omnivorous mirid bug Dicyphus errans needs food of two trophic levels. It is able to prey on a wide range of small phytophagous arthropods and therefore may play a role as a biocontrol agent. In order to assess its biocontrol potential, D. errans was observed at the botanical garden of the Technical University of Dresden over a period of five years. Its behaviour was studied and analysed in more detail by means of video film recordings. D. errans searches for prey by repeatedly probing the leaf surface with its rostrum. Prey is located coincidentally when it is hit by the tip of the rostrum or touched by the tips of the tarsi. Prey contacted in this way is pierced by the rostrum stylets and then the body fluids are sucked out by repeated extra-oral digestion (regurgitations). In many cases prey is only partially consumed. Attacks are usually followed by prolonged resting periods during which the bug cleans itself intensively. Experiments with 9 different plant and 8 different prey species showed that the number of preyed individuals varies according to the host and prey species. D. errans consumes more phytophagous arthropods on plants covered with trichomes than on plants with a smooth surface or with a chrystalline epicuticular wax layer. The uptake of plant sap seems to serve as an additional water source. However, noticeable damage of the plant tissue could not be observed. The results of an experiment testing the two variants a) only prey without plants and b) only prey without plants but with moistened dental cotton rolls showed that the bugs consumed considerably more prey when provided with an additional water source

Untersuchungen zur Morphologie, Biologie und Ökologie der räuberischen Weichwanze Dicyphus errans Wolff (Heteroptera, Miridae, Bryocorinae)

Die paläarktische omnivore Weichwanze Dicyphus errans Wolff (Heteroptera, Miridae, Bryocorinae) zeichnet sich durch ein ausgesprochen breites Spektrum an besetzten Wirtspflanzen und konsumierten Beutetieren aus. Über 150 von D. errans akzeptierte Pflanzenarten sind erstmalig belegt worden. Der erfolgreiche Verzehr von 15 Beute-tierarten wurde quantitativ nachgewiesen. Eine weitere Besonderheit der Wanze besteht in der Präferenz für glandulär behaarte Pflanzen. Die Weichwanze besetzt somit von vielen anderen Insekten gemiedene Nischen. Untersuchungen im Botanischen Garten der Technischen Universität Dresden (2000 bis 2002) ließen auf eine bemerkenswerte räuberische Aktivität und Anpassungsfähigkeit an unterschiedliche Habitate, Beutetiere und Klimabedingungen schließen. Die fortführenden Studien im Rahmen der vorliegenden Dissertation (2002 bis 2005) erbrachten umfassende Erkenntnisse über die Art D. errans im Hinblick auf deren Morphologie, Vermehrung und Haltung, Bionomie und Ökologie (Fekundität und Ontogenese in Abhängigkeit von ausgewählten Einflussfaktoren, Dormanz), Aufenthalt und Fortbewegung (räumliche Orientierung und strukturanalytische Studien zu den Interaktionen zwischen Wanze und Pflanzenoberflächen), den Nahrungserwerb (Verzehrleistung und Omnivorie) sowie Videodokumentationen der Lebensweise und des Verhaltens. Der Generalist und Opportunist D. errans integriert sich als Pflanzensaftsauger regulierendes Kompartiment neben echten Räubern und Parasitoiden in Biozönosen. Als omnivores Insekt übernimmt die Wanze eine intermediäre und supplementäre Position in Nahrungsnetzen. Die Lebensweise dieser Weichwanzenart erscheint sehr komplex. Die enge Assoziation mit Pflanzen tritt stark in den Vordergrund. Sie ist in jeglichen Betrachtungen von D. errans unbedingt zu berücksichtigen und bietet außerdem als ein Modellsystem ein spannendes Forschungsfeld im Hinblick auf die Adaptation partiell räuberisch lebender Insekten an behaarte Pflanzen.The omnivorous mirid bug Dicyphus errans Wolff (Heteroptera, Miridae, Bryocorinae) lives on a wide range of host plants and feeds on various preys. Over 150 plant species accepted by the mirid bug have been identified. It was experimentally shown that 15 prey species are efficiently consumed. Another characteristical features of D. errans is that it preferes hairy plants. Thus, the mirid bug occupies unique niches avoided by many other insects. Investigations, carried out at the Botanical Garden of the Technical University of Dresden (2000-2002) gave evidence for a remarkable predatory activity and ability to adaptation to different habitats, preys and climate conditions. The studies presented in the dissertation (2002-2005) gave the comprehensive knowledge about the species D. errans, especially its morphology, rearing, bionomy and ecology (fecundity and ontogenesis depending on selected factors, dormancy), habitat preference and locomotion (spatial orientation and structural-analytical studies of the interactions between the bug and plant surfaces), foraging and food ingestion (predatory capacity and omnivory). In addition, video documentation of the modus vivendi and the behavior was performed. The generalist and opportunist D. errans lives together with predators and parasitoids and takes part in a biological control of phytophagous insects in biocenoses. The life history of this bug species appeared to be very complex. The close association to plants has to be considered. Dicyphus errans offers a model system for further research on omnivorous predatory insects connected with hairy plants

Cuticular Hydrocarbon Trails Released by Host Larvae Lose their Kairomonal Activity for Parasitoids by Solidification

Successful host search by parasitic wasps is often mediated by host-associated chemical cues. The ectoparasitoid Holepyris sylvanidis is known to follow chemical trails released by host larvae of the confused flour beetle, Tribolium confusum, for short-range host location. Although the hexane-extractable trails consist of stable, long-chain cuticular hydrocarbons (CHCs) with low volatility, the kairomonal activity of a trail is lost two days after release. Here, we studied whether this loss of kairomonal activity is due to changes in the chemical trail composition induced by microbial activity. We chemically analyzed trails consisting of hexane extracts of T. confusum larvae after different time intervals past deposition under sterile and non-sterile conditions. GC-MS analyses revealed that the qualitative and quantitative pattern of the long-chain CHCs of larval trails did not significantly change over time, neither under non-sterile nor sterile conditions. Hence, our results show that the loss of kairomonal activity of host trails is not due to microbially induced changes of the CHC pattern of a trail. Interestingly, the kairomonal activity of trails consisting of host larval CHC extracts was recoverable after two days by applying hexane to them. After hexane evaporation, the parasitoids followed the reactivated host trails as they followed freshly laid ones. Cryo-scanning electron microscopy showed that the trails gradually formed filament-shaped microstructures within two days. This self-assemblage of CHCs was reversible by hexane application. Our study suggests that the long-chain CHCs of a host trail slowly undergo solidification by a self-assembling process, which reduces the accessibility of CHCs to the parasitoid’s receptors as such that the trail is no longer eliciting trail-following behavior

Sexual Dimorphism in the Attachment Ability of Leptinotarsa decemlineata Say (Coleoptera, Chrysomelidae) on Rough Substrata

Leptinotarsa decemlineata lebt oligophag ausschließlich auf Vertretern der Solanaceae, insbesondere Solanum spp. (Radcliffe 1982). Die herbivore Spezies ist fähig, erfolgreich auf den unbehaarten, behaarten und glandulär behaarten Blattoberflächen der Nachtschattengewächse zu haften, sich fortzubewegen und zu leben. Dazu verhelfen paarige Krallen und Hafthaarkissen an den Tarsen (Rivnay 1928). Das ausgesprochen gute Haftvermögen und die Substratanpassungsfähigkeit haariger Haftsysteme von Insekten sind für verschiedene Vertreter der Diptera und Coleoptera experimentell belegt (siehe Review von Gorb 2001). Stork (1980 a, b) beobachtete insbesondere bei Käfern der Familien Chrysomelidae und Coccinellidae einen ausgeprägten Sexualdimorphismus der tarsalen Hafthaare. Schanz (1953) beschreibt für L. decemlineata drei verschiedene Hafthaartypen: (1) Haare mit sich asymmetrisch verjüngenden Spitzen, (2) spatelförmige Gebilde und (3) Haare mit Haftsohlen, welche nur die Männchen besitzen. Hinsichtlich der geschlechterspezifischen Unterschiede der Haftkraft auf verschieden rauen Oberflächen existieren bislang wenige quantitative Nachweise. Pelletier & Smilowitz (1987) wiesen für Männchen von L. decemlineata in Inversionsexperimenten ein außerordentliches Haftvermögen auf Glas- und Kunststoffoberflächen nach, wobei sie dessen Gründe in den maskulin-spezifischen Hafthaaren mit scheibenförmig verbreiterten Enden vermuteten. Die Fähigkeit der Männchen, an glatten Oberflächen besonders gut zu haften, wurde als eine Anpassung an die Haftung auf den glatten Oberflächen der Weibchenelytren während der Kopulation erklärt. Die meisten natürlichen Oberflächen (insbesondere Pflanzenoberflächen) sind jedoch rau. Somit besteht die Frage, ob beide Geschlechter auch eine unterschiedliche Spezialisierung der Haftsysteme für die Haftung auf rauen Substraten besitzen. Um den Einfluss unterschiedlicher Oberflächenrauhigkeiten auf die Haftsystemfunktionalität der Weibchen und Männchen von L. decemlineata zu prüfen, wurden in der vorliegenden Studie Kraftmessungen mit einzelnen Individuen auf Oberflächen mit exakt definierter Rauheit durchgeführt.The remarkable attachment ability and the adaptability to different substrates of insects‘ hairy attachment systems have been experimentally demonstrated in representatives of Diptera and Coleoptera. Many representatives from the family Chrysomelidae exhibit a distinctive sexual dimorphism in the structure of adhesive tarsal hairs. Differences in attachment ability between sexes have been previously reported for smooth substrata. In L. decemlineata, a very strong attachment ability on smooth glass and plastic surfaces has been described in males, and explained by the action of specialised mushroom-like tarsal hairs. The present study demonstrates the influence of different surface roughnesses on the attachment forces of L. decemlineata males and females. The maximum attachment force of individual beetles was measured on epoxy resin surfaces (0-12 μm surface roughness) using a centrifugal force tester. On the smooth surface, no considerable differences between males and females were found, whereas, on rough surfaces, adherence of females was significantly stronger, up to twice that of males. The results indicate that the main functional trait of the adhesive system of females is its stronger specialization to rough plant surfaces

Open-Access-Strategie für Berlin: wissenschaftliche Publikationen für jedermann zugänglich und nutzbar machen : Nachbereitung einer Veranstaltung und Desiderata

Am 13.10.2014 kamen Vertreter_innen verschiedener Universitäten, Hochschulen, Kulturerbe- und Forschungseinrichtungen sowie Open-Access-Initiativen zu der Veranstaltung "Open-Access-Strategie für Berlin" zusammen, die auf Initiative des Berliner Open-Access-Netzwerks durchgeführt wurde, um den Status quo von Open Access in Berlin darzustellen, Lücken aufzuzeigen und Bedarfe zu erörtern. Im vorliegenden Beitrag werden der Hintergrund und die wesentlichen Ergebnisse der Veranstaltung knapp zusammengefasst sowie Desiderata für eine künftige Berliner Open-Access-Strategie formuliert

“Push and Pull”: Biomechanics of the Pollination Apparatus of Oncidium spp.

Comprising ca. 28,000, species the Orchidaceae constitute one of the most species-rich plant families. Orchids differ from other monocotyledons i.a., in the formation of so-called pollinaria, which are entities consisting of pollen grains aggregated into compact pollinia and accessory structures, a viscidium and mostly also a pollinium stalk. The viscidium releases an adhesive material that attaches the pollinarium to a pollinator. Pollinaria are part of a complex pollination apparatus that enables the orchids to colonize niches in which only a few individuals of the respective pollinator occur infrequently. Because the aggregated pollen grains are removed from the flower at once, the development of a mechanical barrier ensuring that only suitable pollinators are able to access the flowers and more importantly to remove the pollen are important selective traits. In this paper we describe the functional morphology of the pollination apparatus in two orchid species, Oncidium wentworthianum and O. otogaya, by experimentally mimicking the pollination process. Furthermore, we analyzed the mechanical resistance of this apparatus by means of force measurements and showed that it most probably constitutes a hierarchical two-stage barrier. The first stage consists of the presence of the anther cap that not only protects the pollinia, but also serves to prevent premature removal of young and unripe pollinaria from the flower. As soon as the pollinaria are ripe, the anther cap sheds and the second stage of the mechanical barrier takes effect, a severable bond between pollinarium and rostellum. This bond can be overcome by a potential pollinator, applying a load of at least 10.8 mN (O. otogaya) or 12.6 mN (O. wentworthianum), respectively, on the viscidium which at the same time disengages the pollinarium from its anchorage. The adhesive material produced by the viscidium creates sufficient adhesive contact between pollinarium and pollinator. Potential pollinators, such as Centris spp. or Trigona spp. bees, should be well able to exert such forces by pushing their head/forebody into the orchid flowers. Thus, whether a pollinator is able to detach the pollinarium depends on both how forcefully it can push and how strongly it can pull the orchid pollination apparatus

Open-Access-Projekte wissenschaftlicher Einrichtungen aus Berlin und Brandenburg 2016

Im Spätsommer 2016 begannen die Planungen der Open-Access-Teams der Freien Universität, der Humboldt-Universität und der Technischen Universität Berlin für die internationale Open Access Week 2016. In einem Call for Posters wurden Berliner und Brandenburger Open-Access-Projekte dazu aufgerufen, ihre Aktivitäten in einer Ausstellung vorzustellen. Die Publikation dokumentiert die Posterausstellung und Podiumsdiskussion zur Open Access Week 2016. Sie enthält 30 Poster inklusive Beschreibungen und Links zu den Originalversionen in Druckqualität, ergänzt um Fotos einer Abendveranstaltung bei Wikimedia Deutschland.In late summer 2016 the open access teams of the Freie Universität, the Humboldt-Universität and the Technische Universität Berlin started their plans for the international Open Access Week 2016. In a call for posters, open access projects from Berlin and Brandenburg were requested to present their activities in a poster exhibition. The publication documents the poster exhibition and panel discussion during the Open Access Week 2016. It contains all posters including abstracts and links to the original versions in print quality, supplemented by photos from the Wikimedia event

Extensive collection of femtoliter pad secretion droplets in beetle Leptinotarsa decemlineata allows nanoliter microrheology

Pads of beetles are covered with long, deformable setae, each ending in a micrometric terminal plate coated with secretory fluid. It was recently shown that the layer of the pad secretion covering the terminal plates is responsible for the generation of strong attractive forces. However, less is known about the fluid itself because it is produced in extremely small quantity. We here present a first experimental investigation of the rheological properties of the pad secretion in the Colorado potato beetle {\it Leptinotarsa decemlineata}. Because the secretion is produced in an extremely small amount at the level of the terminal plate, we first develop a procedure based on capillary effects to collect the secretion. We then manage to incorporate micrometric beads, initially in the form of a dry powder, and record their thermal motion to determine the mechanical properties of the surrounding medium. We achieve such a quantitative measurement within the collected volume, much smaller than the $1 {\rm \mu}$l sample volume usually required for this technique. Surprisingly, the beetle secretion was found to behave as a purely viscous liquid, of high viscosity. This suggests that no specific complex fluid behaviour is needed during beetle locomotion. We build a scenario for the contact formation between the spatula at the setal tip and a substrate, during the insect walk. We show that the attachment dynamics of the insect pad computed from the high measured viscosity is in good agreement with observed insect pace. We finally discuss the consequences of the secretion viscosity on the insect adhesion

Mobility enhancement among older adults 75 + in rural areas: Study protocol of the MOBILE randomized controlled trial

Background: Maintaining mobility in old age is crucial for healthy ageing including delaying the onset and progress of frailty. However, the extent of an individuals' mobility relies largely on their personal, social, and environmental resources as outlined in the Life-Space Constriction Model. Recent studies mainly focus on facilitating habitual out-of-home mobility by fostering one type of resources only. The MOBILE trial aims at testing whether tablet-assisted motivational counselling enhances the mobility of community-dwelling older adults by addressing personal, social, and environmental resources. Methods: In the MOBILE randomized controlled trial, we plan to enrol 254 community-dwelling older adults aged 75 and older from Havelland, a rural area in Germany. The intervention group will receive a tablet-assisted motivational counselling at the participant's home and two follow-up telephone sessions. Main focus of the counselling sessions lays on setting and adapting individual mobility goals and applying action planning and habit formation strategies by incorporating the personal social network and regional opportunities for engaging in mobility related activities. The control group will receive postal general health information. The primary mobility outcome is time out-of-home assessed by GPS (GPS.Rec2.0-App) at three points in time (baseline, after one month, and after three months for seven consecutive days each). Secondary outcomes are the size of the GPS-derived life-space convex hull, self-reported life-space mobility (LSA-D), physical activity (IPAQ), depressive symptoms (GDS), frailty phenotype, and health status (SF-12). Discussion: The MOBILE trial will test the effect of a motivational counselling intervention on out-of-home mobility in community-dwelling older adults. Novel aspects of the MOBILE trial include the preventive multi-level intervention approach in combination with easy-to-use technology. The ecological approach ensures low-threshold implementation, which increases the benefit for the people in the region

Open in Action in Berlin-Brandenburg

Im Spätsommer 2016 begannen die Planungen der Open-Access-Teams der Freien Universität, der Humboldt-Universität und der Technischen Universität Berlin für die internationale Open Access Week 2016. In einem Call for Posters wurden Berliner und Brandenburger Open-Access-Projekte dazu aufgerufen, ihre Aktivitäten in einer Ausstellung vorzustellen. Die Publikation dokumentiert die Posterausstellung und Podiumsdiskussion zur Open Access Week 2016. Sie enthält 30 Poster inklusive Beschreibungen und Links zu den Originalversionen in Druckqualität, ergänzt um Fotos einer Abendveranstaltung bei Wikimedia Deutschland.In late summer 2016 the open access teams of the Freie Universität, the Humboldt-Universität and the Technische Universität Berlin started their plans for the international Open Access Week 2016. In a call for posters, open access projects from Berlin and Brandenburg were requested to present their activities in a poster exhibition. The publication documents the poster exhibition and panel discussion during the Open Access Week 2016. It contains all posters including abstracts and links to the original versions in print quality, supplemented by photos from the Wikimedia event.Not Reviewe