Lost and found: 160 years of Lepidoptera observations in Wuppertal (Germany)
Abstract and Figures
In the light of the current discussion on reduced insect biomass and species decline, we would like to draw attention to the work of amateur entomologists who have been observing the moth and butterfly fauna for decades. Actually, the recording of butterflies and moths has a long tradition in Wuppertal and its surroundings (Germany, North Rhine-Westfalia, Bergisches Land). Therefore, we have access to rather detailed data of the local macrolepidoptera fauna collected over the last 160 years and are able to comment on the trends of moth and butterfly populations during this rather long period. We review historical and current data and provide a comprehensive abundance list of all macrolepidoptera species observed in the study region. We found that, from the mid-twentieth century onwards, the species richness of butterfly and moths species decreased considerably. In terms of the number of species evaluated (537), we see that 27% decreased within the last 160 years while 15% have already been lost. Additionally, 24% are apparently stable at a low level. Particularly affected are highly specialised species of heath, moor, grassland, scrub, coppice and orchard habitats. However, 15% of the evaluated species are observed more frequently. Some of these newly colonised the study region (2.4%). Since Wuppertal is a city that profited from the industrial revolution from the middle of the nineteenth century onwards, we think that our results could serve as a representative example of the loss of species richness due to industrialisation, urbanisation, intensive agriculture and forestry.
Implications for insect conservation
If we intend to increase species richness of butterflies and moths again, the focus must be on protecting, restoring and promoting low-nutrient open landscape habitats rather than forests.
Figures - available from: Journal of Insect Conservation
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Supplementary resource (1)
... Seibold et al. 2019) in European forests over the past decades are at least partly attributable to the abovementioned changes in forest management (e.g. Thorn et al. 2015;Roth et al. 2021;Laussmann et al. 2021;Habel et al. 2022). However, changes in forest management have rarely been discussed as drivers of long-term insect declines (e.g. ...
Coppice forests are socio-ecological systems especially rich in biodiversity. They have been transformed into high forest and abandoned across large areas of Europe over the past 200 years. Coppice loss is likely an important driver of insect declines. It is currently unclear whether habitat quality or decreasing connectivity of the remaining fragments is more important for the survival of insect populations. We related the abundance of two coppice-associated butterflies of conservation concern, Satyrium ilicis and Melitaea athalia, to indicators of habitat quality and habitat connectivity. We estimated butterfly densities using Distance Sampling along a successional gradient (time since last cut: 1–9 years; N = 130 plots) across one of the largest remaining simple oak-birch coppice landscapes in Central Europe. Both species reached abundance peaks within four to six years after the last cut, declining rapidly in abundance with subsequent succession. We found no evidence that coupe size, coppice availability and patch (= coupe) connectivity were related to the density of the species. Besides stand age, the cover of larval foodplants explained predicted butterfly densities well. Only Satyrium ilicis benefitted from high Red Deer densities.
Implications for insect conservation: Our results suggest that habitat quality and sufficient availability of coppice of suitable age matters more than coupe size and fragmentation within a traditional managed coppice landscape. Coppice restoration aiming at the study species should ensure a shifting mosaic of successional habitat to provide a large availability of resprouting oak stools and bilberry vegetation that holds dense Melampyrum pratense stands.
... 19 On the other hand, butterflies and moths provide economically critical pollination services, so it is important to avoid habitat destruction and the extensive use of nonspecific insecticides that reduce insect biodiversity. 20,21 In this context, M. sexta is used as a model in ecotoxicology and agricultural science to study and develop new insecticides. 12,16,19,[22][23][24][25] Lately, lepidopteran insects were also used as high-throughput preclinical models for diseases involving gut inflammation, including inflammatory bowel disease, which reflects the general homology of the innate immune system and the common epithelial organization of the alimentary tract in insects and mammals. ...
The tobacco hornworm is used extensively as a model system for ecotoxicology, immunology and gut physiology. Here, we established a micro-computed tomography approach based on the oral application of the clinical contrast agent iodixanol, allowing for a high-resolution quantitative analysis of the Manduca sexta gut. This technique permitted the identification of previously unknown and understudied structures, such as the crop or gastric ceca, and revealed the underlying complexity of the hindgut folding pattern, which is involved in fecal pellet formation. The acquired data enabled the volume rendering of all gut parts, the reliable calculation of their volumes, and the virtual endoscopy of the entire alimentary tract. It can provide information for accurate orientation in histology uses, enable quantitative anatomical phenotyping in three dimensions, and allow the calculation of locally effective midgut concentrations of applied chemicals. This atlas will provide critical insights into the evolution of the alimentary tract in lepidopterans.
... In contrast to habitat specialists, they might still be found on transects at low-quality sites because of immigration from neighbouring high-quality habitats. Accordingly, a decrease in grassland quality can be assumed to particularly affect habitat specialists that have already experienced much more pronounced declines in the past decades than generalists (Eskildsen et al., 2015;Habel et al., 2019b;Laussmann et al., 2021). ...
Extensively managed grasslands are globally recognized for their high biodiversity value. Over the past century, a continuous loss and degradation of grassland habitats has been observed across Europe that is mainly attributable to agricultural intensification and land abandonment. Particularly insects have suffered from the loss of grassland habitats due to land-use change and the decrease in habitat quality, either due to an increase in livestock density, higher mowing frequency, and an increase in nitrogen fertilization, or by abandonment. However, only a few studies have used nationwide datasets to analyse the effects of land cover and land-use intensity on insects. It further remains largely unexplored how these effects are modulated by species traits, i.e. habitat specialisation and mobility. Using nationwide butterfly data originating from the German Butterfly Monitoring Scheme, we investigated the effect of three indicators related to land cover and agricultural land-use intensity on species richness as well as trait composition of butterfly communities. Based on agricultural census data at the municipality scale, we calculated the share of permanent grasslands (measure of habitat availability), the total livestock density (proxy for organic fertilization) and the livestock density of domestic herbivores (proxy for management intensity in grasslands) within a 2 km buffer surrounding each butterfly transect. To analyse the relationships between butterflies and indicators of land cover and land-use intensity, we applied generalised linear mixed effect models. We found a negative relationship between butterfly species richness and the livestock density of domestic herbivores. Further, the ratio of butterfly generalist to specialist species shifted towards generalists and the size of butterflies increased with higher herbivore livestock density, indicating a shift in communities towards mobile habitat generalists. Our results are in accordance with previous studies carried out across smaller geographic extents, highlighting the importance of low herbivore livestock densities to halt the loss of pollinating insects and safeguard biodiversity and associated ecosystem services in agricultural landscapes. We here demonstrate that indicators based on livestock distribution data at the municipality scale can provide insights into processes and spatial diversity patterns of butterflies at the national level. Further, we highlight potentials and limitations of using agricultural census data to quantify and assess effects of land cover and land-use intensity on butterflies, and make recommendations for further research needs.
... In NW Europe, butterfly diversity loss is probably among the strongest globally (Maes et al., 2012;van Strien et al., 2019;Laussmann et al., 2021). This is due to the very high anthropogenic impact (intensive agriculture and industry, high population density and dense road and infrastructure network) on the landscape which converted (semi-)natural habitat into other land uses and lowered the quality of the remaining fragmented (semi-)natural areas. ...
The recent decline in insect diversity and abundance and the consequences for associated ecosystem functioning and services have attracted growing attention. Especially highly anthropogenic regions are affected by rapid biodiversity changes including significant losses. Two decades ago, we suggested that Flanders (northern Belgium) was Europe's worst case scenario for butterfly diversity loss with habitat destruction, fragmentation and nitrogen deposition as major causes (Maes and Van Dyck, 2001). To analyse changes since the second half of the 20th century, we used >2.5 million distribution records to calculate trends in distribution during the last three decades. By linking these trends to the species' ecology using multi-species indicators for a set of ecological and life-history traits, we determined the most important drivers policy makers and nature managers should focus on. Species showing the strongest expansion are woodland specialists and polyphagous species. On the other hand, sedentary species of nutrient-poor biotopes such as heathlands and semi-natural grasslands showed a decreasing trend, despite the ongoing policy focus and conservation efforts. We discuss our results with regard to challenges and bottlenecks for the conservation of butterflies and other insects in anthropogenic regions.
... One reason is that NHCs offer the unique opportunity to study long periods of time, e.g. a century or more, thus potentially allowing to study phenomena before massive anthropogenic effects started taking a considerable toll on nature (e.g. Bakker et al., 2020;Bozzuto, 2020;Laussmann et al., 2021;Lister, 2011;Shaffer et al., 1998;Theng et al., 2020). ...
Over the last two decades, many studies have emphasized the value of natural history collections (NHCs) for ecological and evolutionary research. Furthermore, with the current biodiversity crisis worsening by the day, these specimens offer invaluable insights into past changes, directly helping researchers to understand the current status and to propose apt measures to halt the decline of species and communities. In parallel, the digitization of collections continues being an on-going and pressing endeavor at the global scale. Several achievements are already impressive, with global databases meanwhile offering online access to many millions of specimen data. Unfortunately, especially the use of regional data for regional-scale studies is partly hampered by small- to medium-size natural history museums (NHMs) still awaiting digitalization. But even with completed digitization, many NHC data continue being only available by request. As an incentive for NHMs to more actively and rapidly share their data, in this study we present simple spatio-temporal analyses and visualizations helpful to display NHC data in a research-oriented way. The aim is to allow researchers a rapid online assessment of NHC data for their purposes. To this end, we propose the use – alone and combined – of (i) well-known indices from biodiversity research, (ii) cumulative and/or parametric representations of temporal data, and (iii) Voronoi tessellations and Delaunay triangulations for spatial data. As an illustrative example, we analyze butterfly collection data from a Swiss NHM. With today’s possibilities to quickly set up web applications and with the modest attribute requirements per specimen for our methods, we believe the implementation of these ideas will be affordable and quickly realizable, all the more – to the benefit of research – if NHMs share forces. The ideas and methods will also appeal to global initiatives ultimately aiming at offering access to the majority of NHCs. For the time being, our study may serve as a regional incentive encouraging NHMs to aid researchers generating much-needed knowledge on a rapidly changing natural world.
... For example, the 160-year data set of Lepidoptera observations in Wuppertal, Germany, which clearly shows a decline in http://www.cabi.org/cabreviews those species with specialised habitat requirements [88]. Similarly, analysing natural history collections using Bayesian occupancy models has enabled researchers to create a 116-year data set on wasps and hornets in the UK [89]. ...
Reports of declines in abundance of a number of insect species have been increasing over the last two decades. These have variously been attributed to climate change, urbanisation, deforestation, agricultural intensification, habitat fragmentation and pesticide usage. The picture has been complicated by the fact that not all insect groups have shown the drastic declines reported for others, flawed methodology, paucity of long-term studies, the lack of data from the tropics with most long-term studies emanating from Europe and North America. In addition, the number of insect groups studied has largely been restricted to charismatic species such as Hymenoptera, Lepidoptera, Coleoptera and Odonata. Despite this, the evidence for long-term declines in insect abundance is incontrovertible. To aid in our understanding of the problem we need to set up more globally coordinated studies, use past data in innovative ways and convince policy makers and governments to support these studies.
Coppice forests are socio-ecological systems especially rich in biodiversity. They have been transformed into high forest and abandoned across large areas of Europe over the past 200 years. Coppice loss is likely an important driver of insect declines. It is currently unclear whether habitat quality or decreasing connectivity of the remaining fragments is more important for the survival of insect populations. We related the abundance of two coppice-attached butterflies of conservation concern, Satyrium ilicis and Melitaea athalia, to indicators of habitat quality and habitat connectivity. We estimated butterfly densities using Distance Sampling along a successional gradient (time since last cut: 1-9 years; N = 130 plots) across one of the largest remaining simple oak-birch coppice landscapes in Central Europe. Both species reached abundance peaks within four to six years after the last cut, declining rapidly in abundance with subsequent succession. We found no evidence that coupe size, coppice availability and patch (= coupe) connectivity were related to the density of the species. Besides stand age, the cover of larval foodplants explained predicted butterfly densities well. Only Satyrium ilicis benefitted from high Red Deer densities.
Implications for insect conservation: Our results suggest that habitat quality and sufficient availability of coppice of suitable age matters more than coupe size and fragmentation within a traditional managed coppice landscape. Coppice restoration aiming at the study species should ensure a shifting mosaic of successional habitat to provide a large availability of resprouting oak stools and blueberry vegetation that holds dense Melampyrum pratense stands.
Declines and losses of insects throughout the world have wide ramifications for the sustainability of terrestrial and inland water ecosystems, and for humanity. Recent accounts and estimates of declines in insect richness and abundance in many parts of the world pose serious concerns for the future of global biodiversity. Some have been claimed to be sensationalistic and many such claims are difficult to validate. This summary of concerns demonstrates difficulties of interpreting data against insecure historical baselines and incomplete taxonomic and ecological information, features that introduce ambiguities and uncertainties in interpreting observed changes and may reduce credibility.
Context
Biodiversity is severely decreasing at a global scale since several decades. There are significant changes in species community compositions, reductions of species richness and abundances of arthropods, as well as of arthropod biomass. Land use intensification and climate change are assumed to be main drivers causing biodiversity change and loss. However, proximate effects of land use, landscape configuration, topography and climate on species richness and species community composition were only rarely analysed.
Objective
We study the effects of current land cover, landscape structures and climate on butterfly and burnet moth species diversity and community composition across northern Austria (i.e. the federal state of Salzburg).
Methods
We compiled observation data of butterflies and burnet moths for the past 40 years. We divided faunal data, land cover data and data on climate into 5 × 5 km ² grid cells. We classified all lepidopterans assessed into groups according to their distribution, behaviour, ecology and life-history.
Results
We found higher species richness and temporal community shifts in higher elevations, and where topographic heterogeneity is high. Habitat connectivity has a positive impact on ecologically specialised, sedentary, and endangered species. Mean temperature and precipitation positively influenced species richness.
Conclusions
Both, land-use and climate strongly shape biodiversity structures. In particular, landscape heterogeneity promotes the diversity of ecological niches, which subsequently accelerates species diversity, including specialist species. Agricultural intensification in higher elevations and at steep slopes is more difficult and therefore less attractive, and thus the level of biodiversity is still high. In addition, climate warming might lead to the accumulation of species in higher elevations. Our study further underlines the relevance of habitat conservation at lower elevations, where not all habitat types are conserved sufficiently.
Nach der Datenbank des LÖBBECKE-Museum Düssseldorf und zusätzlichen Daten aus der Literatur kamen um 1900 mindestens 64 Tagfalterarten im Gebiet der heutigen Landeshauptstadt Düsseldorf vor. Davon wurden in den Jahren von 2000 bis 2004 mindestens 27 Arten in Düsseldorf beobachtet, ein Artenverlust von 58 %. Wichtige Ursachen für die Artenverarmung wie der Verlust von Freiflächen und das Verschwinden der Futterpflanzen der Raupen werden diskutiert, auf die Bedeutung der Dauerbeobachtung von Tagfaltern wird hingewiesen.
In North Rhine-Westphalia last observations of the Short-tailed Blue Cupido argiades date back to 1930. In 2011 and 2012 there were again numerous reports, also from neighbouring areas in the Benelux states as well as in Hesse and Lower Saxony. The Short-tailed Blue has, in a few years, advanced its distribution area several hundred kilometres northwards.
The recording of butterflies has a long tradition in the area of Wuppertal (Germany, North Rhine-Westfalia). Therefore, we have access to rather detailed data of the local moth and butterfly fauna collected over the last 150 years and are able to comment on the development of their populations during this quite long period of time. Unsurprisingly, the diversity of butterfly species decreased considerably during the rapid industrialisation at the end of the 19th century and the intensive large-scale farming that was propagated from the middle of the 20th century. Today, about 20 % of moth species have been lost and the number of diurnal butterflies has decreased by 30 % compared to the situation 50 to 60 years ago. Highly specialised species of open woodland, shrubland and heath are particularly affected. On the other hand, some species can be found “new” in our region or in greater abundance. Some of these moths benefit from industrial fallows, others are spreading from Western and South-Western Europe to the East. This article summarises the results of a comprehensive study on this issue (Laussmann et al. 2009) and we discuss the development of butterfly and moths populations in relation to changes of landscape and climate.
Desquilbet al. take issue with our data inclusion criteria and make several other dubious claims regarding data processing, analysis, and interpretation. Most of their concerns stem from disagreement on data inclusion criteria and analysis, misunderstanding of our goals, and unrealistic expectations. We maintain that our synthesis provides a state-of-the-art analysis of patterns of trends in insect abundances.
The full-text of this article is also available at the journal website: https://science.sciencemag.org/content/370/6523/eabe0760
A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta‐analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta‐analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems.
This article is categorized under:
• Water and Life > Conservation, Management, and Awareness
Abstract
Relying on abundance or biomass and examining nonrepresentative datasets limits our ability to infer the condition of freshwater insect communities globally. Photo by Jeremy Monroe, Freshwaters Illustrated: a caddisfly larva from an Oregon Coastal stream, USA (Limnephilidae: Dicosmoecus sp.).
Van Klink et al. (Reports, 24 April 2020, p. 417) argue for a more nuanced view of insect decline, and of human responsibility for this decline, than previously suggested. However, shortcomings in data selection and methodology raise questions about their conclusions on trends and drivers. We call for more rigorous methodology to be applied in meta-analyses of ecological data.
Recent reports of dramatic declines in insect abundance suggest grave consequences for global ecosystems and human society. Most evidence comes from Europe, however, leaving uncertainty about insect population trends worldwide. We used >5,300 time series for insects and other arthropods, collected over 4–36 years at monitoring sites representing 68 different natural and managed areas, to search for evidence of declines across the United States. Some taxa and sites showed decreases in abundance and diversity while others increased or were unchanged, yielding net abundance and biodiversity trends generally indistinguishable from zero. This lack of overall increase or decline was consistent across arthropod feeding groups and was similar for heavily disturbed versus relatively natural sites. The apparent robustness of US arthropod populations is reassuring. Yet, this result does not diminish the need for continued monitoring and could mask subtler changes in species composition that nonetheless endanger insect-provided ecosystem services.
The fate of humans and insects intertwine, especially through the medium of plants. Global environmental change, including land transformation and contamination, is causing concerning insect diversity loss, articulated in the companion review Scientists' warning to humanity on insect extinctions. Yet, despite a sound philosophical foundation, recognized ethical values, and scientific evidence, globally we are performing poorly at instigating effective insect conservation. As insects are a major component of the tapestry of life, insect conservation would do well to integrate better with overall biodiversity conservation and climate change mitigation. This also involves popularizing insects, especially through use of iconic species, through more media coverage, and more inclusive education. Insect conservationists need to liaise better with decision makers, stakeholders, and land managers, especially at the conceptually familiar scale of the landscape. Enough evidence is now available, and synthesized here, which illustrates that multiple strategies work at local levels towards saving insects. We now need to expand these locally-crafted strategies globally. Tangible actions include ensuring maintenance of biotic complexity, especially through improving temporal and spatial heterogeneity, functional connectivity, and metapopulation dynamics, while maintaining unique habitats, across landscape mosaics, as well as instigating better communication. Key is to have more expansive sustainable agriculture and forestry, improved regulation and prevention of environmental risks, and greater recognition of protected areas alongside agro-ecology in novel landscapes. Future-proofing insect diversity is now critical, with the benefits far reaching, including continued provision of valuable ecosystem services and the conservation of a rich and impressive component of Earth's biodiversity.
Here we build on the manifesto 'World Scientists' Warning to Humanity, issued by the Alliance of World Scientists. As a group of conservation biologists deeply concerned about the decline of insect populations, we here review what we know about the drivers of insect extinctions, their consequences, and how extinctions can negatively impact humanity. We are causing insect extinctions by driving habitat loss, degradation, and fragmentation, use of polluting and harmful substances, the spread of invasive species, global climate change, direct overexploitation, and co-extinction of species dependent on other species. With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits, and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends. From pollination and decomposition, to being resources for new medicines, habitat quality indication and many others, insects provide essential and irreplaceable services. We appeal for urgent action to close key knowledge gaps and curb insect extinctions. An investment in research
Aim
Occurrence data are fundamental to macroecology, but accuracy is often compromised when multiple units are lumped together (e.g., in recently separated cryptic species or in citizen science records). Using amalgamated data leads to inaccuracy in species mapping, to biased beta‐diversity assessments and to potentially erroneously predicted responses to climate change. We provide a set of R functions (biodecrypt) to objectively attribute unidentified occurrences to the most probable taxon based on a subset of identified records.
Innovation
Biodecrypt assumes that unidentified occurrences can only be attributed at certain distances from areas of sympatry. The function draws concave hulls based on the subset of identified records; subsequently, based on hull geometry, it attributes (or not) unidientified records to a given taxon. Concavity can be imposed with an alpha value and sea or land areas can be excluded. A cross‐validation function tests attribution reliability and another function optimises the parameters (alpha, buffer, distance ratio between hulls). We applied the procedure to 16 European butterfly complexes recently separated into 33 cryptic species for which most records were amalgamated. We compared niche similarity and divergence between cryptic taxa, and re‐calculated and contributed updated climatic niche characteristics of the butterflies in Europe (CLIMBER).
Main conclusions
Biodecrypt showed a cross‐validated correct attribution of known records always ≥ 98% and attributed more than 80% of unidientified records to the most likely taxon in parapatric species. The functions determined where records can be assigned even for largely sympatric species, and highlighted areas where further sampling is required. All the cryptic taxa showed significantly diverging climatic niches, reflected in different values of mean temperature and precipitation compared to the values originally provided in the CLIMBER database. The substantial fraction of cryptic taxa existing across different taxonomic groups and their divergence in climatic niches highlight the importance of using reliably assigned occurrence data in macroecology.