Thomas Hörren

• Chairman at Entomological Society Krefeld

Auf Augenhöhe mit heimischen Insekten. In diesem Buch werden eindrucksvolle Porträts heimischer Insekten auf Augenhöhe präsentiert, wodurch wir ihre Schönheit neu entdecken. Die preisgekrönten Fotos von Thorben Danke, ergänzt durch Thomas Hörrens wissenschaftliches Wissen und Dominik Eulbergs künstlerische Perspektive, verändern unseren Blick auf d...

In Germany, the decline of insect biomass was observed in nature conservation areas in agricultural landscapes. One of the main causal factors discussed is the use of synthetic pesticides in conventional agriculture. In a Germany-wide field study, we collected flying insects using Malaise traps in nature conservation areas adjacent to agricultural...

Global declines in insects have sparked wide interest among scientists, politicians, and the general public. Loss of insect diversity and abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services. Our understanding of the extent and underlying causes of this decline is based on the abundance of single spec...

Beaver activities modify floodplains of small streams fundamentally. Prevailing lotic sections are supplemented with several additional habitats (e.g., ponds, dams and side channels). While there are several investigations into the invertebrate fauna of single beaver‐induced habitats, the ways beavers modify aquatic invertebrate assemblages of enti...

Insekten bestimmen war nie einfacher! Bekannt vom Instagram-Kanal @totholz-thomas bringt Insektenforscher Thomas Hörren mit diesem Insektenbestimmungsbuch aus der neuen KOSMOS-Reihe 'Nature Guide' frischen Wind in die Naturführer-Community. Locker, modern und leicht verständlich stellt er die Welt der Insekten genauer vor und garantiert mit seinen...

Recent observations of winter-active Taeniopterygidae in mid-sized Central European rivers reveal that these large-river stonefly species, previously thought to have been extirpated by severe water pollution, have persisted in hidden refugia. During February and March 2024, we conducted a comprehensive survey along a 300-km section of the lower Riv...

Zusammenfassung Im Rahmen des Kurses „Netzflügler – eine wenig beachtete Insektengruppe“ im Auftrag des Rote-Liste-Zentrums Bonn wurden vom 11.-14. Juli 2024 Netzflüglerartige im Umland des Gustav-Stresemann-Instituts in Bad Bevensen erfasst und bearbeitet. Ein Schwerpunkt des Kurses galt der Determination der Neuropterida, um die Kenntnisse in den...

Totholz – kaum etwas ist so vielfältig. Ein Formenreichtum, der selbst so viel mehr ist als nur der umgefallene tote Baum im Wald, bildet Lebensräume für Insekten und andere Organismen. Egal ob tote Wurzeln unter Wasser oder Holzsärge unter der Erde in unseren Städten – überall finden wir ein enges Zusammenspiel von Verfall und neuem Leben. Das gen...

The ichneumonine Darwin wasp Ctenochares bicolorus (Linnaeus, 1767) is reported for the first time from Germany based on a female photographed in May 2023 in a Cologne supermarket and a male caught in December 2023 in a living room in Mönchengladbach.

Insects are declining in both species richness and abundance. Conservation areas are expected to mitigate this diversity loss, as they typically sustain higher species richness across various insect taxa compared with non‐conservation areas. However, there is growing evidence that the rates of decline are similar in both area types. This indicates...

Widespread insect losses are a critical global problem. Mitigating this problem requires identifying the principal drivers across different taxa and determining which insects are covered by protected areas. However, doing so is hindered by missing information on most species owing to extremely high insect diversity and difficulties in morphological...

Mitigating ongoing losses of insects and their key functions (e.g. pollination) requires tracking large‐scale and long‐term community changes. However, doing so has been hindered by the high diversity of insect species that requires prohibitively high investments of time, funding and taxonomic expertise when addressed with conventional tools. Here,...

Although microhymenoptera are highly abundant in all terrestrial ecosystems, they are overlooked in most of insect monitoring studies due to their small-size and demanding identification linked with lack of taxonomic experts. Until now, it is unclear to what extent microhymenoptera are affected by insect decline, as there is a huge knowledge gap on...

Five years after a German study on insect biomass described a multi-decade decline in nature protected habitats, the DINA (Diversity of Insects in Nature protected Areas) project has investigated the status of insects in 21 selected nature reserves across Germany in the years 2020 and 2021. We used the same methods and protocols for trapping and me...

Das in Nordrhein-Westfalen durch den Entomologischen Verein Krefeld (EVK) durchgeführte Monitoring der Biodiversität flugaktiver Insekten ist bundesweit wegweisend. Es wurde an Untersuchungsstandorten innerhalb der Kulisse der Ökologischen Flächenstichprobe NRW sowie in verschiedenen Schutzgebieten durchgeführt. Damit sind sowohl Flächen mit hoher...

The decline of insect abundance and richness has been documented for decades and has received increased attention in recent years. In 2017, a study by Hallmann and colleagues on insect biomasses in German nature protected areas received a great deal of attention and provided the impetus for the creation of the project Diversity of Insects in Nature...

Schon im Jahr 2014 hat das LANUV Untersuchungen des Entomologischen Vereins Krefeld gefördert, um die Biomasse flugaktiver Insekten in verschiedenen Schutzgebieten zu erheben. Diese Daten flossen auch in die Publikation zu Rückgängen der Insektenbiomassen ein (Hallmann et al. 2017). In der Folge hat das LANUV ein groß angelegtes Projekt unterstützt...

Five years after the well-known study on insect biomass decline in nature protected habitats in Germany over three decades, the project DINA (Diversity of Insects in Nature protected Areas) has investigated the status of insects in 21 selected nature reserves across Germany in the years 2020 and 2021. We used the same methods and protocols for trap...

Zusammenfassung Die stark gefährdete Honigwespe Celonites abbreviatus (Villers, 1789) ist die einzige Vertreterin der Unterfamilie Masarinae in Deutschland. Die Revision der Entomologischen Sammlungen der Stadt Krefeld erbrachte nach einem Hinweis des Kurators einen historischen Beleg aus Nordrhein-Westfalen aus dem Jahr 1918. Der Beleg ist seit e...

Insects are unique in terms of their high species diversity and deliver key ecological functions. Despite this importance, we know little about true species numbers and biodiversity trends for most insect orders. A key limitation is a lack of time, funding and taxonomic expertise needed to identify the huge number of often small species, of which m...

Nature reserves are one of the most important instruments for biodiversity protection and to limit regional species extinctions. However, these functions can only be fulfilled if environmental influences from the surroundings , such as agrochemical inputs do not negatively affect the protected habitats. Here, we compare the effectiveness of conserv...

Beavers and their dams, once common in small streams throughout Eurasia and North America, are returning to their original range. Beaver dams are special habitats in the aquatic-terrestrial interface, but their macroinvertebrate fauna is hardly known. This study aims to qualify and quantify the invertebrate fauna of beaver dams, taking into account...

Zusammenfassung. In ausgewählten FFH-Gebieten werden im Rahmen des F+E-Projektes „Biodiversitätsschäden in FFH-Lebensraumtypen des Offenlandes“ Insektenrückgänge untersucht und jüngere Untersuchungen im Vergleich zu historischen für ausgewählte Taxa ausgewertet. Die Bearbeitung von Käfern aus Malaisefallen-Proben aus dem Jahr 2014 ergab mehrere Nac...

Red lists represent an important instrument for evaluating the decline of species in space and time, for improving decision-making and for guiding conservation planning. However, globally, only a fraction of species has been categorized according to a red list, even in countries where insects are relatively well-studied. Such large knowledge gaps h...

In recent years, the decline of insect biodiversity and the imminent loss of provided ecosystem functions and services has received public attention and raised the demand for political action. The complex, multi-causal contributors to insect decline require a broad interdisciplinary and cross-sectoral approach that addresses ecological and social a...

With increased application of DNA metabarcoding in biodiversity assessment, various laboratory protocols have been optimized, and their further evaluation is subject of current research. Homogenization of bulk samples and subsequent DNA extraction from a subsample of destructed tissue is a common first stage of the metabarcoding process. This can e...

Forest canopies are highly diverse ecosystems, but despite several decades of intense research, there remain substantial gaps in our knowledge of their biodiversity and ecological interactions. One fundamental challenge in canopy research is the limited accessibility of the ecosystem. Consequently, previous studies have relied on the application of...

We describe a new mechanical tool for dividing mixed insects and other invertebrate samples into subsamples. The device enables the division to equal parts by means of a movable hemispherical bowl and a separating disc. Due to the complete stainless steel manufacturing, the sample divider is sterilizable by using chemicals or heating and thus suita...

The worldwide rapid declines in insect and plant abundance and diversity that have occurred in the past decades have gained public attention and demand for political actions to counteract these declines are growing. Rapid large-scale biomonitoring can aid in observing these changes and provide information for decisions for land management and speci...

Im Kontext des Insektenrückgangs und landwirtschaftlicher Nutzung als einem bedeutenden Verursacher kommt Naturschutzgebieten und den FFH-Gebieten des europäischen Natura-2000-Netzes eine wach- sende Bedeutung zum Erhalt der lokalen Biodiversität zu, die sich auch auf Ackerbiotope bezieht. Eine Raumanalyse im Rahmen des Forschungs- projektes DINA (...

1. Forest canopies are a highly diverse ecosystem, but despite several decades of intense research, there remain substantial gaps in our knowledge of their biodiversity and ecological interactions. One fundamental challenge in canopy research is the limited accessibility of the ecosystem. Consequently, previous studies have relied on the applicatio...

Im Jahr 1905 wurde der Entomologische Verein in Krefeld (EVK) als eine klassische, wissenschaftlich orientierte Fachgesellschaft gegründet. Der EVK betreut international bedeutende Sammlungs- und Archivbestände zur Entomologie (Entomologica, entomologica.org) in Krefeld. Zu den Mitgliedern zählen seitdem sowohl Entomologen und Entomologinnen mit un...

We present a unique data set of trait information for 586 insect families in Central Europe, covering the largest known part of described species (over 34,000 species). Life history information and major functional traits were evaluated with fuzzy coding and weighted according to the number of known species in Germany. An overall analysis of the Ge...

With increased application of DNA metabarcoding in fast and high-resolution biodiversity assessment, various laboratory protocols have been optimised in recent years and their further evaluation is subject of current research. Homogenisation of bulk samples and subsequent DNA extraction from destructed tissue is one way of starting the metabarcodin...

The declines observed in insect abundance and diversity in the past decades has also been observed in plants, and these events are most certainly correlated. Rapid largescale biomonitoring of both plants and insects can help monitor these changes and inform decisions for land management and species protection. Malaise traps have been used for nearl...

Background Small and rare specimens can remain undetected when metabarcoding is applied on bulk samples with a high specimen size heterogeneity. This is especially critical for Malaise trap samples, where most of the biodiversity is contributed by small taxa with low biomass. The separation of samples in different size fractions for downstream anal...

Insect declines and biodiversity loss have attracted much attention in recent years, but lack of comprehensive data, conflicting interests among stakeholders and insufficient policy guidance hinder progress in preserving biodiversity. The project DINA (Diversity of Insects in Nature protected Areas) investigates insect communities in 21 nature rese...

The pathways of introduction of non-native amphibians are diverse, as historically amphibians were used as pest control agents, food stock, or were introduced to perform research. Today, the pet trade is the main source for amphibian introductions into novel ranges. However, these introductions mainly concern anurans, whereas cases involving urodel...

The species composition of a community is driven by the dispersal capacity of the species forming that community and their ecological niche. While the ecological niches of EPTs (Ephemeroptera, Plecoptera and Trichoptera) are well-studied due to their wide use as indicators for the ecological status of freshwater ecosystems, their dispersal capacity...

Here we present new records of the rare weevil Bagous diglyptus (Curculionidae). The species is rediscovered in the German federal state North Rhine-Westphalia after almost 85 years, while two new record in Rhineland-Palatinate are the first ones after roughly 50 years. The collecting method and the circumstances of the records are discussed. It is...

Zwei Krefelder Entomologen trugen maßgeblich zum heutigen Kenntnisstand der artenreichen Insektenordnung der Zweiflügler (Diptera) bei. Im Jahr 2020 möchten wir an ihre runden Geburtstage erinnern und bislang unveröffentlichte Einblicke in ihr Leben geben. Jean Jean Winnertz (1800- 1890) war Kaufmann und bearbeitete als Entomologe ver- schiedene Mü...

Abstract. Stenochrus portoricensis new to North Rhine-Westphalia (Germany), with notes on distribution and habitats of other alien short-tailed whipscorpion species in Europe (Arachnida: Schizomida). Records of the short-tailed whipscorpion Stenochrus portoricensis Chamberlin, 1922 (Schizomida: Hubbardiidae) from greenhouses in North Rhine-Westphal...

Small and rare specimens can remain undetected when metabarcoding bulk samples with a high size heterogeneity of specimens. This is especially critical for malaise trap samples, where most of the biodiversity is often contributed by small specimens. How to size sort and in which proportions to pool these samples has not been widely explored. We set...

Abstract The pseudoscorpion Mesochelifer ressli Mahnert, 1981 is a mainly Central European species that lives as a subcortical species in the bark of conifers. Regarding the taxonomy of Central European pseudoscorpions, it was described relatively late as a distinct species from Chelifer cancroides (Linnaeus, 1758). Specific investigations were ca...

Abstract. The seed beetle Bruchidius siliquastri Delobel, 2007 was described with specimens from southern France, the original range is probably in East Asia. In Europe, the species behaves invasively and develops oligophagous in the seeds of Judas trees, Cercis spp. (Fabaceae). The species is known from Germany since 2011 with only a few published...

Abstract. Suitable oviposition sites and embryogenesis are important factors for the spatial distribution of grasshoppers within habitats, and they determine a binding to habitats significantly. Documented observations of oviposition sites and successful hatching are rare and often based on random observations. In February 2019, older oak marble ga...

Abstract. The sycamore seed bug Belonochilus numenius (Say, 1831) is native to North America. It has been recorded in Europe since 2008 and spread within a few years. We classify the species as an invasive neozoon. In Germany it has been documented since 2012. A first occurrence in North Rhine-Westphalia was documented in October 2019. In January 2...

Die Große Heuschreckensandwespe Sphex funerarius Gussakovskij 1934 (Hymenoptera: Sphecidae) konnte im Jahr 2019 in den nördlichen Bundesländern auffällig häufig nachgewiesen werden. Für Niedersachsen, Schleswig-Holstein und, nach aktueller Einordung historischer Meldungen, Mecklenburg-Vorpommern handelt es sich dabei um Erstnachweise für das jeweil...

Zusammenfassung. Die Kreiselwespe Bembix rostrata (Linnaeus 1758) (Crabronidae) konnte im Jahr 2018 seit 1970 in Nordrhein-Westfalen wiedergefunden werden. Historische Daten wurden zusammengetragen und es wird erstmals eine landesweite Übersicht der Art präsentiert und diskutiert. Summary. Rediscovery of Bembix rostrata (Linnaeus 1758) in North Rh...

The authors compiled their records of arachnids in the city of Essen and neighbouring areas placed in the Ruhr Metropolitan Area. Data were supplemented with regional records according to the online atlas of arachnids in Europe and some unpublished records. 208 species of spiders (Araneae), 18 species of harvestmen (Opiliones) and 4 species of pseu...

Abstract: The sycamore lace bug Corythucha ciliata (Say, 1832) is a species of the family Tingidae. It was recorded for the first time in Germany in 1983 in Baden-Wuerttemberg and is an established neozoon nowadays. While the first records in North Rhine-Westphalia were made in the early 2000s in the Cologne Bonn region, a larger range expansion di...

Kurzfassung: Die Ameisengrille Myrmecophilus acervorum (Panzer, 1799) wurde in den vergangenen Jahren in Nordrhein-Westfalen zunehmend häufiger nachgewiesen. Im Ballungsraum Ruhrgebiet erfolgten dabei mehrfach Funde auf Industriebrachen. Gezielte Kartierungen in den Jahren 2017 bis 2019 ergaben zahlreiche neue Nachweise von M. acervorum für die Reg...

Abstract. The willowherb hawkmoth (Proserpinus proserpina) (Pallas, 1772) is a moth in the family Sphingidae which is strictly protected in the European Union listed in Annex IV of the Habitats Directive. As a mediterranean faunal element, it was rarely recorded north of the Alps but showed a larger range expansion in the recent years, especially i...

Die Amerikanische Büffelzikade Stictocephala bisonia Kopp & Yonke, 1977 ist eine von drei Arten der Membracidae in Deutschland. Nachdem die aus den USA stammende Art im Jahr 1966 erstmals in Deutschland nachgewiesen wurde, breitete sie sich in den vergangenen Jahrzehnten stark aus und ist mittlerweile ein etabliertes Neozoon bzw. Agriozoon. Im Jahr...

Aus bereits vorliegenden Zwischenergebnissen eines laufenden Forschungs-und Entwicklungsprojekts des Entomologischen Vereins Krefeld (EVK) sind u.a. gravierende Veränderungen in den Insektenzönosen an vielen Standorten in Schutzgebieten Deutschlands ableitbar, die auch die Gesamtheit der Insekten betreffen. Dies zeigt die Notwendigkeit, lokale Inse...

Malaise trap permissions. (PDF)

Posterior parameter estimates of the mixed effects model including land use variables and interactions. For each included variable, the corresponding coefficient posterior mean, standard deviation and 95% credible intervals are given. P-values are calculated empirically based on posterior distributions of coefficients. (PDF)

Temporal variation in weather variables. Annual means (A-C), daily means (D-F), and mean daily residual values (G-I) of temperature, precipitation and wind speed respectively. In all panels, black lines depict data while blue and red lines represent long term and seasonal fitted means of the variables, respectively. (PDF)

Land use and plant species richness changes. Mean land use in 1989–1994 (A) and 2012–2014 (B), based on aerial photograph analysis at 63 protected areas show a decrease of arable land and an increase in forested area over the past 25 years. (C) Changes in plants species richness for herbs (black) shrubs (red) and trees (blue). Annual means as well...

Seasonal profiles of daily biomass across 26 locations. For each location, different colors represent different years, with time color-coded from green (1989) to red (2016). X-axis represents day number (January 1 = 0). (PDF)

Daily biomass of insects over time for two habitat clusters. Boxplots depict the distribution of insect biomass pooled over all traps and catches in each year at trap locations in nutrient-poor heathland, sandy grassland, and dunes (A), and in nutrient-rich grasslands, margins and wasteland (B). Grey lines depict the fitted mean (+95% posterior cre...

Posterior parameter estimates of the mixed effects model including weather variables. For each included variable, the corresponding coefficient posterior mean, standard deviation and 95% credible intervals are given. P-values are calculated empirically based on posterior distributions of coefficients. (PDF)

Posterior parameter estimates of the mixed effects model including habitat variables. For each included variable, the corresponding coefficient posterior mean, standard deviation and 95% credible intervals are given. P-values are calculated empirically based on posterior distributions of coefficients. (PDF)

Map of study area. Insect trap locations (yellow points) in Nordrhein-Westfalen (n = 57), Rheinland-Pfalz (n = 1) and Brandenburg (n = 5), as well as weather stations (crosses) used in the present analysis. (TIFF)

Abstract. Chalcis sispes (Linnaeus, 1761), to date known as a parasitoid of the soldier fly genus Stratiomys Geof­froy, 1762 has been recorded in North Rhine­Westphalia, Germany. This paper presents and documents presence, evi­dence and insights obtained from the field observations into habitat and some possible host flies. Zusammenfassung. Chalci...

In recent years, large‐scale DNA barcoding campaigns have generated an enormous amount of COI barcodes, which are usually stored in NCBI 's GenBank and the official Barcode of Life database ( BOLD ). BOLD data are generally associated with more detailed and better curated meta‐data, because a great proportion is based on expert‐verified and voucher...

The redneck long-horned beetle Aromia bungii (Faldermann, 1835) was recorded in Upper Bavaria (Germany) again. At least four adult specimens and an indication for its larval development were recorded in July and August 2016 in Rosenheim. A detailed description of the record and some remarks are presented and discussed.

The flat bark beetle Cucujus cinnaberinus (Scopoli, 1763) which shows an actual range expansion has been recorded in April 2016 in Hamburg (Schleswig-Holstein, Germany) for the first time. Photographs and remarks relating to this record are presented and discussed.

The return of a strictly protected species: The wolf spider Arctosa cinerea (Fabricius, 1777) (Araneae: Lycosidae) in the Lippe floodplain in Wesel, North-Rhine Westphalia. The wolf spider Arctosa cinerea (Fabricius, 1777) is one of the biggest spiders in Germany and specialized on dynamic sand and gravel bars in riparian areas of rivers, lakes and...

The Oriental Wood Borer Heterobostrychus aequalis (C. O. Water­house, 1884) has been recorded from Saarland (Germany) for the first time. The record and a determination key to the species of the genus Heterobostrychus Lesne, 1898 so far introduced to Germany are presented and discussed.

Der Erstnachweis des Schnellkäfers Ampedus sinuatus GERMAR, 1844 für das Rheinland, sowie weitere bemerkenswerte Käfernachweise auf einer Exkursion am 5. Mai 2013 auf den Felsenberg bei Schloßböckelheim im Nahetal werden präsentiert und diskutiert. Der Bockkäfer Poecilium pusillum (FABRICIUS, 1787) wird erstmals für das Saar-Nahe-Bergland gemeldet....

Kurzfassung: Marolia variegata (BOSC D'ANTIC, 1791) wurde erstmals in Deutschland festgestellt. Zwei Nachweise aus dem Mai 2012 am Aussichtspunkt "Blumslay" im Unteren Moseltal bei Winningen (Rheinland- Pfalz) werden gemeldet und diskutiert. Abstract: Marolia variegata (BOSC D'ANTIC, 1791) was recorded for the first time in Germany. Two records fr...

Kurzfassung: Coproporus immigrans SCHÜLKE, 2007, Phacophallus pallidipennis (MOTSCHULSKY, 1858) und Mycetina cruciata (SCHALLER, 1783) werden erstmals für die Region Nordrhein gemeldet. Die Bedeutung der Funde wird diskutiert.

Die vorliegende Publikation ist Teil einer eröffentlichungsreihe die sich mit der Darstellung der Ergebnisse dieser Untersuchungen befasst. Der Bericht zur Waldstrukturaufnahme im Naturwaldreservat „Grouf“ wurde 2009 herausgegeben. Das Ziel dieses Bandes besteht darin, eine zusammenfassende Darstellung und Analyse der Befunde aus der ersten faunist...

Nach einem Hinweis des Besucherzentrums der Teufelsschlucht in Ernzen, Landkreis Bitburg-Prüm, Rheinland-Pfalz, erhielt JONAS BELLER im Juni 2012 vom Naturparkzentrum vor Ort eine kleine Schausammlung, welche von Hans G. METTLACH zwischen 1962 und 1970 aufgestellt wurde. Die Sammlung besteht aus drei Insektenkästen (Abb. 1) mit Belegen aus Rheinlan...

Kurzfassung: Der Bausenberg bei Niederzissen, ein xerothermer Schlackenvulkan in der Eifel (Rheinland-Pfalz), wurde in den 1960er und 1970er Jahren intensiv zoologisch erforscht. Dabei wurde von der Arbeitsgemeinschaft Rheinischer Koleopterologen und dem Zoologischen Institut der Universität Köln eine besonders schützenswerte Käferfauna mit 1.259 A...

Seit 2004 werden in Luxemburg Naturwaldreservate ausgewiesen, die dem Erhalt und der Förderung der Artenvielfalt in Wäldern dienen. In diesen nationalen Schutzgebieten führt die Abteilung für Wald der Naturverwaltung Luxemburg ein umfangreiches Monitoring durch, das sowohl waldwachstumskundliche als auch ökologische Fragestellungen behandelt. Dabei...

Am 1. Mai 2010 wurden drei Exemplare des Erdnussplattkäfers Oryzaephilus mercator in einer stark vermüllten Wohnung im Kölner Stadtteil Porz-Westhoven (MTB 5008) nachgewiesen.

The lady beetle Adalia conglomerata (L., 1758) has been firstly recorded for the Rhineland, Germany. A German up-to-date distribution map is presented.