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Lost and found: 160 years of Lepidoptera observations in Wuppertal (Germany)

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  • General Customs Authority, Cologne, Germany
  • Naturwissenschaftlicher Verein Wuppertal
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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.
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Journal of Insect Conservation (2021) 25:273–285
https://doi.org/10.1007/s10841-021-00296-w
ORIGINAL PAPER
Lost andfound: 160years ofLepidoptera observations inWuppertal
(Germany)
TimLaussmann1 · ArminDahl1· ArminRadtke1
Received: 11 June 2020 / Accepted: 19 January 2021 / Published online: 22 February 2021
© The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature 2021
Abstract
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 havebeen 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 last160 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 acomprehensive abundance list of all macrolepidoptera species observed in the study region. We
found that, from the mid-twentieth century onwards, the speciesrichness of butterfly and moths species decreased consider-
ably. In terms of the number of species evaluated (537), we see that 27% decreased within the last 160 yearswhile 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 indus-
trial 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.
Keywords Insect decline· Agriculture· Forestry· Moth· Butterfly
Introduction
In recent years there have been a number of scientifically
recognised studies in particular on the decline of butterfly
populations, e.g. Maes and van Dyck (2001), van Swaay
etal. (2006), van Dyck etal. (2009), Melero etal. (2016),
Fartmann (2017), Schmitt and Habel (2018), and Habel
etal. (2019a, 2019b). A decline in many moth species has
been shown as well, e.g. Conrad etal. (2006), Franzén and
Johannesson (2007), Groenendijk and Ellis (2011), Fox etal.
(2011, 2014), and Dennis etal. (2019). The ‘Krefeld study’
on the loss of biomass in flying insects received particu-
lar public attention (Hallmann etal. 2017). These findings
fueled a scientific debate on whether or not, or to which
extent, there is a global negative trend in insect populations
(Sánchez-Bayo and Wyckhuys 2019; Crossley etal. 2020).
There are indications that freshwater insect populations are
stable or recovering (van Klink etal. 2020a) while terrestrial
insect populations are declining (Seibold etal. 2019). Find-
ings on freshwater insect populations are still intensively
discussed (Desquilbet etal. 2020; van Klink etal. 2020b;
Jähnig etal. 2020).
Historical data of butterfly and, especially, moth abun-
dance is fragmented and often focussed on high-quality but-
terfly habitats or rare species. In this article, we describe
and interpret changes in the abundance of macrolepidop-
tera in Wuppertal (Germany, North Rhine-Westphalia) and
the surrounding area over the past 160years. Thanks to a
long tradition of mapping butterflies and moths in the study
region—which has never possessed an outstanding habitat
for butterflies and moths—we have access to data from the
mid-nineteenth century until today, collected by amateur
entomologists. The study region experienced a massive
* Tim Laussmann
tim.laussmann@t-online.de
1 Naturwissenschaftlicher Verein Wuppertal e.V. (Scientific
Association Wuppertal e.V.), Wuppertal, Germany
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Supplementary resource (1)

... 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. ...
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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). ...
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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]. ...
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