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International scientists formulate a roadmap for
insect conservation and recovery
To the Editor — A growing number of
studies are providing evidence that a suite
of anthropogenic stressors — habitat loss
and fragmentation, pollution, invasive
species, climate change and overharvesting
— are seriously reducing insect and other
invertebrate abundance, diversity and
biomass across the biosphere18. These
declines affect all functional groups:
herbivores, detritivores, parasitoids,
predators and pollinators. Insects are
vitally important in a wide range of
ecosystem services9 of which some are
vitally important for food production and
security (for example, pollination and
pest control)10. There is now a strong
scientific consensus that the decline of
insects, other arthropods and biodiversity
as a whole, is a very real and serious threat
that society must urgently address1113. In
response to the increasing public awareness
of the problem, the German government is
committing funds to combat and reverse
declining insect numbers13. This funding
should act as a clarion call to other
nations across the world — especially
wealthier ones — to follow suit and
to respond proactively to the crisis by
addressing the known and suspected threats
and implementing solutions.
We hereby propose a global ‘roadmap’
for insect conservation and recovery
(Fig. 1). This entails the immediate
implementation of several ‘no-regret’
measures (Fig. 1, step 1) that will act
to slow or stop insect declines. Among the
initiatives we encourage are the following
immediate measures:
Taking aggressive steps to reduce
greenhouse gas emissions; reversing recent
trends in agricultural intensification
including reduced application of synthetic
pesticides and fertilizers and pursuing
their replacement with agro-ecological
measures; promoting the diversification
and maintenance of locally adapted land-
use techniques; increasing landscape
heterogeneity through the maintenance of
natural areas within the landscape matrix
and ensuring the retention and creation of
microhabitats within habitats which may be
increasingly important for insects during
extreme climatic events such as droughts or
heatwaves; reducing identified local threats
such as light, water or noise pollution,
invasive species and so on; prioritizing the
import of goods that are not produced at
the cost of healthy, species-rich ecosystems;
designing and deploying policies (for
example, subsidies and taxation) to induce
the innovation and adoption of insect-
friendly technologies; enforcing stricter
measures to reduce the introduction of alien
species, and prioritizing nature-based tactics
for their (long-term) mitigation; compiling
and implementing conservation strategies
for species that are vulnerable, threatened
or endangered; funding educational
and outreach programs, including those
tailored to the needs of the wider public,
farmers, land managers, decision makers
and conservation professionals; enhancing
citizen science’ or ‘community science’
as a way of obtaining more data on insect
diversity and abundance as well as engaging
the public, especially in areas where
academic or professional infrastructure is
lacking; devising and deploying measures
across agricultural and food value chains
that favour insect-friendly farming,
including tracking, labelling, certification
and insurance schemes or outcome-based
incentives that facilitate behavioural
changes, and investing in capacity building
to create a new generation of insect
conservationists and providing knowledge
and skills to existing professionals
(particularly in developing countries).
To better understand changes in insect
abundance and diversity, research should
aim to prioritize the following areas:
Quantifying temporal trends in insect
abundance, diversity and biomass by
extracting long-term datasets from existing
insect collections to inform new censuses;
exploring the relative contributions
of different anthropogenic stressors
causing insect declines within and across
different taxa; initiating long-term studies
comparing insect abundance and diversity
in different habitats and ecosystems along
a management-intensity gradient and at
the intersection of agricultural and natural
habitats; designing and validating insect-
friendly techniques that are effective,
locally relevant and economically sound in
agriculture, managed habitats and urban
environments; promoting and applying
standardized monitoring protocols globally
and establishing long-term monitoring plots
or sites based on such protocols, as well as
increasing support for existing monitoring
efforts; establishing an international
governing body under the auspices of
existing bodies (for example, the United
Nations Environment Programme (UNEP)
or the International Union for Conservation
of Nature (IUCN)) that is accountable for
documenting and monitoring the effects of
proposed solutions on insect biodiversity in
the longer term; launching public–private
partnerships and sustainable financing
initiatives with the aim of restoring,
protecting and creating new vital insect
habitats as well as managing key threats;
increasing exploration and research to
improve biodiversity assessments, with
a focus on regional capacity building in
understudied and neglected areas, and
performing large-scale assessments of the
conservation status of insect groups to help
define priority species, areas and issues.
Most importantly, we should not wait
to act until we have addressed every key
knowledge gap. We currently have enough
information on some key causes of insect
decline to formulate no-regret solutions
whilst more data are compiled for lesser-
known taxa and regions and long-term data
are aggregated and assessed. Implementation
should be accompanied by research that
examines impacts, the results of which
can be used to modify and improve the
implementation of effective measures.
Furthermore, such a ‘learning-by-doing’
approach ensures that these conservation
strategies are robust to newly emerging
pressures and threats. We must act now.
Jerey A. Harvey  1*,
Robin Heinen  1, Inge Armbrecht  2,
Yves Basset3, James H. Baxter-Gilbert4,
T. Martijn Bezemer  1, Monika Böhm  5,
Riccardo Bommarco  6,
Paulo A. V. Borges  7, Pedro Cardoso8,
Viola Clausnitzer9, Tara Cornelisse10,
Elizabeth E. Crone11, Marcel Dicke  12,
Klaas-Douwe B. Dijkstra13, Lee Dyer14,
Jacintha Ellers  15, Thomas Fartmann16,
Mathew L. Forister14, Michael J. Furlong17,
Andres Garcia-Aguayo18, Justin Gerlach19,
Rieta Gols  12, Dave Goulson  20,
Jan-Christian Habel21, Nick M. Haddad  22,
Caspar A. Hallmann23, Sérgio Henriques  5,
Marie E. Herberstein24, Axel Hochkirch25,
Alice C. Hughes26, Sarina Jepsen27,
T. Hefin Jones28, Bora M. Kaydan29,
David Kleijn30, Alexandra-Maria Klein  31,
Tanya Latty32, Simon R. Leather  33,
Sara M. Lewis11, Bradford C. Lister34,
John E. Losey35, Elizabeth C. Lowe24,
Craig R. Macadam  36,
James Montoya-Lerma37,
Christopher D. Nagano10, Sophie Ogan25,
Michael C. Orr  38, Christina J. Painting39,
Thai-Hong Pham40, Simon G. Potts41,
Aunu Rauf42, Tomas L. Roslin6,
Michael J. Samways43,
Francisco Sanchez-Bayo44, Sim A. Sar45,
Cheryl B. Schultz  46, António O. Soares  7,
Anchana Thancharoen47, Teja Tscharntke48,
Jason M. Tylianakis  49,
Kate D. L. Umbers  50, Louise E. M. Vet1,
Marcel E. Visser  1, Ante Vujic51,
David L. Wagner52,
Michiel F. WallisDeVries  53,
1. No-regret solutions
3. New research
Avoid and mitigate
alien species
Phase out
pesticide use,
and replace
with ecological
restoration and
in agriculture
Phase out
pesticide use,
and replace
with ecological
in agriculture
Phase out
pesticide use,
and replace
with ecological
Education for
awareness, citizen
science and capacity
of threatened
Reduce light,
water and
noise pollution
Reduce imports
of ecologically
harmful products
2. Prioritization
Perform large-scale assessments
of the conservation status of insect
groups to define priority species,
areas and issues, for example increase
the number of insects with informative
IUCN Red List assessments.
Immediate action
Mid-term action
Conduct new research to disentangle the
contributions of different anthropogenic
stressors driving insect declines, within
and across different taxa. Perform field
studies along a management-intensity
gradient and at the intersects of agricultural
and natural habitats. Increase explorative
research to accelerate rate of knowledge
gain in understudied areas.
5. Partnerships
Long-term action
Launch public–private partnerships and
sustainable financing initiatives with the
aim of restoring, protecting and creating
new vital insect habitats, as well as
managing key threats.
4. Existing data
Analyse current data on insect diversity that
is present, such as in private, museum and
academic insect collections. This is important
to form new censuses of past insect diversity.
This is especially important in areas where
scientific data currently do not exist.
6. Global monitoring program
Promote and apply standardized monitoring
protocols at a global level under the auspices
of an existing international governing body
(for example, the UN or IUCN). Establish
standardized sites where monitoring is
conducted over longer terms. Ensure support
for existing monitoring efforts.
Fig. 1 | Roadmap to insect conservation and recovery, calling for action at short-, intermediate- and long-term timescales. No-regret measures for immediate
utilization in insect conservation refer to actions that should be implemented as soon as possible. These solutions will be beneficial to society and biodiversity
even if the direct effects on insects are not known as of yet (that is, no-regret solutions). This encompasses utilization of insect-friendly techniques that are
effective, locally relevant and economically sound, for example, in farming, habitat management and urban development.
Catrin Westphal54, Thomas E. White  32,
Vicky L. Wilkins55, Paul H. Williams56,
Kris A. G. Wyckhuys  57, Zeng-Rong Zhu58
and Hans de Kroon23
1Netherlands Institute of Ecology (NIOO-KNAW),
Wageningen, e Netherlands. 2Departamento de
Biología, Universidad del Valle, Cali, Colombia.
3ForestGEO, Smithsonian Tropical Research Institute,
Panama City, Panama. 4Centre for Invasion
Biology, Stellenbosch University, Matieland, South
Africa. 5Institute of Zoology, Zoological Society of
London, London, UK. 6Department of Ecology,
Swedish University of Agricultural Sciences,
Uppsala, Sweden. 7cE3c-Centre for Ecology,
Evolution and Environmental Changes / Azorean
Biodiversity Group, University of Azores, Lisbon,
Portugal. 8Laboratory for Integrative Biodiversity
Research (LIBRe), Finnish Museum of Natural
History, University of Helsinki, Helsinki, Finland.
9Senckenberg Research Institute, Goerlitz, Germany.
10Center for Biological Diversity, Portland, OR, USA.
11Department of Biology, Tus University, Medford,
MA, USA. 12Laboratory of Entomology, Wageningen
University, Wageningen, e Netherlands. 13IUCN
SSC Freshwater Conservation Committee, Naturalis
Biodiversity Center, Leiden, e Netherlands.
14Biology Department, University of Nevada, Reno,
NV, USA. 15Department of Ecological Sciences,
Vrije University, Amsterdam, e Netherlands.
16Department of Biodiversity and Landscape Ecology,
Osnabrück University, Osnabrück, Germany. 17School
of Biological Sciences, e University of Queensland,
St Lucia, Queensland, Australia. 18Estacion de
Biología Chamela, Instituto de Biología, Chamela,
Jalisco, Mexico. 19IUCN SSC Terrestrial Invertebrate
Red List Authority, Cambridge, UK. 20School of
Life Sciences, University of Sussex, Brighton, UK.
21Evolutionary Zoology, Department of Biosciences,
University of Salzburg, Salzburg, Austria. 22Kellogg
Biological Station and Department of Integrative
Biology, Michigan State University, Hickory Corners,
MI, USA. 23Institute for Water and Wetland Research,
Radboud University, Nijmegen, e Netherlands.
24Department of Biological Sciences, Macquarie
University, Sydney, New South Wales, Australia.
25Department of Biogeography, Trier University, Trier,
Germany. 26Centre for Integrative Conservation,
Xishuangbanna Tropical Botanical Garden, Chinese
Academy of Sciences, Menglun, Yunnan, China.
27e Xerces Society for Invertebrate Conservation,
Portland, OR, USA. 28School of Biosciences, Cardi
University, Cardi, UK. 29Biotechnology Application
and Research Centre, Çukurova University, Balcalı,
Adana, Turkey. 30Plant Ecology and Nature
Conservation Group, Wageningen University,
Wageningen, e Netherlands. 31Albert Ludwigs
University of Freiburg, Freiburg, Germany. 32School
of Life and Environmental Science, Sydney Institute
of Agriculture, University of Sydney, Sydney, New
South Wales, Australia. 33Crop & Environment
Science, Harper Adams University, Newport, UK.
34Department of Biological Sciences, Rensselaer
Polytechnic Institute, Troy, NY, USA. 35Entomology
Department, Cornell University, Ithaca, NY, USA.
36Buglife - e Invertebrate Conservation Trust,
Peterborough, UK. 37Departamento de Biología,
Universidad del Valle, Cali, Colombia. 38Key
Laboratory for Zoological Systematics and Evolution,
Institute of Zoology, Chinese Academy of Sciences,
Beijing, China. 39School of Science, University
of Waikato, Hamilton, New Zealand. 40Vietnam
National Museum of Nature & Graduate School
of Science and Technology, Vietnam Academy of
Science and Technology, Hanoi, Vietnam. 41Centre for
Agri-Environmental Research, School of Agriculture,
Policy and Development, Reading University,
Reading, UK. 42Department of Plant Protection,
IPB University, Bogor, Indonesia. 43Department of
Conservation Ecology and Entomology, Stellenbosch
University, Matieland, South Africa. 44Department
of Environment and Energy, Canberra, Australian
Capital Territory, Australia. 45National Agricultural
Research Institute, Lae, Papua New Guinea. 46School
of Biological Sciences, Washington State University,
Vancouver, British Columbia, USA. 47Department
of Entomology, Faculty of Agriculture, Kasetsart
University, Bangkok, ailand. 48Agroecology,
Department of Crop Sciences, University of
Göttingen, Göttingen, Germany. 49Bio-protection
Centre, School of Biological Sciences, University
of Canterbury, Christchurch, New Zealand.
50School of Science and Health, Western Sydney
University, Penrith, New South Wales, Australia.
51Department of Biology and Ecology, Faculty of
Sciences, University of Novi Sad, Novi Sad, Serbia.
52Ecology and Evolutionary Biology, University of
Connecticut, Storrs, CT, USA. 53De Vlinderstichting
(Dutch Buttery Conservation) & Plant Ecology and
Nature Conservation Group, Wageningen University,
Wageningen, e Netherlands. 54Functional
Agrobiodiversity, Department of Crop Sciences,
University of Göttingen, Göttingen, Germany.
55IUCN SSC Mid Atlantic Island Invertebrate
Specialist Group, IUCN, Cambridge, UK. 56Natural
History Museum, London, UK. 57Chrysalis
Consulting, Hanoi, Vietnam. 58Zhejiang Provincial
Key Laboratory of Crop Insect Pests and Diseases,
Hangzhou, Zhejiang, China.
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Competing interests
The authors declare no competing interests.
... Some authors state that we already know enough to act in order to halt or reverse insect decline [22], whereas others suggest that investment in basic science is warranted to better understand the phenomenon [23][24][25], to inform more targeted and effective countermeasures. However, both positions are not necessarily in contradiction, since research into the causes of insect decline does not preclude action where this is already possible and should not be seen as a justification to delay action [26,27]. Being aware of this, many of the recent publications aim to identify the potential causes behind these trends [8,[28][29][30]. ...
... Both aspects are crucial for the interpretation of the resulting datasets. Moreover, to analyse the development of biodiversity over time and to assess changes, it is important to consider historical data like some of those analysed in this review [27]. Only by comparison of historical with recent data, the scale of change in terms of quality and quantity can be assessed, and typical pitfalls of missing out gradual shifts due to a different perception over generations can be avoided (shifting baseline syndrome [77]). ...
Full-text available
Insect declines have been discussed intensively among experts, policymakers, and the public. Albeit, decreasing trends have been reported for a long time for various regions in Europe and North America, but the controversial discussion over the role of specific drivers and pressures still remains. A reason for these uncertainties lies within the complex networks of inter-dependent biotic and abiotic factors as well as anthropogenic activities that influence habitats, communities, populations, and individual organisms. Many recent publications aim to identify both the extent of the observed declines and potential drivers. With this literature analysis, we provide an overview of the drivers and pressures and their inter-relationships, which were concluded in the scientific literature, using some of the best-studied insect groups as examples. We conducted a detailed literature evaluation of publications on Carabidae (Coleoptera) and Lepidoptera trends with data for at least 6 years in countries of Central and Western Europe, with a focus on agricultural landscapes. From the 82 publications identified as relevant, we extracted all reported trends and classified the respective factors described according to the DPSIR model. Further, we analysed the level of scientific verification (presumed vs correlated vs examined) within these papers for these cited stressors. The extracted trends for both species groups underline the reported overall declining trend. Whether negative or positive trends were reported in the papers, our semi-quantitative analysis shows that changes in insect populations are primarily anthropogenically driven by agriculture, climate change, nature conservation activities, urbanisation, and other anthropogenic activities. Most of the identified pressures were found to act on habitat level, only a fraction attributed to direct effects to the insects. While our analysis gives an overview of existing research concerning abundance and biodiversity trends of carabids and lepidopterans, it also shows gaps in scientific data in this area, in particular in monitoring the pressures along with the monitoring of abundance trends. The scientific basis for assessing biodiversity changes in the landscape is essential to help all stakeholders involved to shape, e.g. agriculture and other human activities, in a more sustainable way, balancing human needs such as food production with conservation of nature.
... However, Saunders et al. (2020) reject this "apocalyptic" view of the current insect conservation, which they attribute to the biased consideration of certain studies and their subsequent highlighting by the media (but see Chapter 3) and call for action to be taken instead of mourning the loss of insects. Current researchers' advice focus on the development and improvement of conservation actions (especially for those threated insects); the increase of landscape heterogeny in agriculture; the prevention and control of alien introductions (see below and Chapters 5e9); the reduction of light, water, and noise pollution; the replacement of pesticides by ecological treatments; the reduction of harmful products for the environment; and the improvement of education programs for ecological awareness Harvey et al., 2020). These researchers also encourage the development studies focused on unraveling the anthropogenic stressors causing insect decline considering (i) the existent data stored in private, museum, and academic collections and (ii) standardized data from global monitoring programs. ...
... For example, insects pollinate plants, provide food to other organisms, including humans, and act as decomposers of organic matter (Grimaldi & Engel, 2005;Samways et al., 2020). However, the diversity of insects is rapidly declining, and their conservation is threatened by several components of global change (Harvey et al., 2020;van der Sluijs, 2020). In fact, the current global insect decline is often referred to as the "Insect Decline Syndrome", which is a complex, multifactorial, nonlinear, and context-dependent phenomenon (see Chapter 3). ...
Globalization is accelerating the intentional and unintentional introductions of species beyond their natural biogeographic boundaries. Of all introduced species, only a small proportion become invasive, causing a wide variety of negative impacts. Some of them have detrimental consequences for native insects. In this chapter, which serves as an introduction to this book, we discuss the role of biological invasions as a driver of the current global decline in insect diversity, as well as the importance of considering biological invasions when planning insect conservation actions.
... The decline in abundance and distribution of many insects has raised widespread public and political awareness on their biological value (Harvey et al. 2020;Didham et al. 2020;Wagner et al. 2021;Welti et al. 2021). As habitat loss and fragmentation have been identified as major drivers of this insect decline, a focus on connectivity conservation for (meta) population persistence is essential and justified (Hanski et al. 1996;Hanski and Ovaskainen 2002;Haddad et al. 2015;Cardoso et al. 2020). ...
Full-text available
Connectivity is a species- and landscape-specific measure that is key to species conservation in fragmented landscapes. However, information on connectivity is often lacking, especially for insects which are known to be severely declining. Patterns of gene flow constitute an indirect measure of functional landscape connectivity. We studied the population genetic structure of the rare digger wasp Bembix rostrata in coastal and inland regions in and near Belgium. The species is restricted to sandy pioneer vegetations for nesting and is well known for its philopatry as it does not easily colonize vacant habitat. It has markedly declined in the last century, especially in the inland region where open sand habitat has decreased in area and became highly fragmented. To assess within and between region connectivity, we used mating system independent population genetic methods suitable for haplodiploid species. We found more pronounced genetic structure in the small and isolated inland populations as compared to the well-connected coastal region. We also found a pattern of asymmetrical gene flow from coast to inland, including a few rare dispersal distances of potentially up to 200 to 300 km, based on assignment tests. We point to demography, wind and difference in dispersal capacities as possible underlying factors that can explain the discrepancy in connectivity and asymmetrical gene flow between the different regions. Overall, gene flow between existing populations appeared not highly restricted, especially at the coast. Therefore, to improve the conservation status of B. rostrata, the primary focus should be to preserve and create sufficient habitat for this species to increase the number and quality of (meta) populations, rather than focusing on landscape connectivity itself.
Pollination plays a very crucial role in the sustainability of agricultural and natural ecosystems. Insect pollinators are thought to be the most efficient pollinators. Beetles have been pollinating plants since the early Cretaceous period and have contributed significantly to the evolution and diversity of angiosperms. Despite this, beetles are often overlooked as pollinators compared to bees and butterflies. We explore the evolution of beetle pollination, the beetle pollination syndrome, and the impact of current stressors on their populations. Moreover, we identify research gaps on beetle pollination and trigger awareness of beetles as pollinators. Beetle-pollinated plants have evolved certain characteristics that attract beetles and facilitate effective pollination while the beetles have developed adaptations to enhance their effectiveness as pollinators. We identified different plant functional traits of beetle pollination syndromes across 8 plant families including Annonaceae, Arecaceae, Areceae, Cyclanthaceae, Proteaceae, Magnoliaceae, Myristicaceae, Sterculiaceae, and Dipterocarpaceae; which involve 28 beetle families. Our literature synthesis revealed that beetles have a crucial long evolutionary niche as pollinators, with enormous potential to shape future pollination systems in the Anthropocene and beyond. More research is needed to understand beetle pollinators’ visual, sensory, and chemical preferences as well as their responses to anthropogenic factors. Strategic conservation efforts must be implemented to safeguard and protect beetles for their essential role in the ecosystem.
Full-text available
Projects promoting bees in urban areas are initiated in cities around the world but evidence-based conservation concepts at a city-wide scale are scarce. We developed a holistic approach for assessment of bee and flowering plant diversity in a medium-sized city. In addition to standard mapping approaches in bee hotspots, we initiated citizen science projects for participative urban bee research to be able to collect comprehensive bee data across the entire city. We identified 22 hotspots of bee diversity, analyzed connectivity between those hotspots and evaluated the impact of flower patches planted in collaboration with the municipal gardens department as stepping stones for oligolectic bee species throughout the city. Participation by urban citizens in bee identification trainings was high (c. 630 persons) but their subsequent contribution through observation reports was relatively low (1,165 records by 140 observers). However, we identified a total of 139 bee taxa, seven of them only discovered by citizen scientists. Total species richness was higher in extensively managed orchards than in semi-natural and wasteland areas. Half of the stepping stone flower patches were occupied by the target oligolectic bee species in the year of planting. After 3 years, all but two species could be confirmed. We suggest a 5-step concept for bee management in cities: (1) identification of bee hotspots combined with standardized surveys, especially of rare species; (2) training of citizen scientists at two different levels for comprehensive surveys in all parts of the city: (a) half-day introductions to wild bee diversity, ecology and conservation in order to create more awareness and (b) 2-weeks workshops for in-depth training of a small number of dedicated citizen scientists; (3) extensive management of existing habitats and special conservation programs for very rare species; (4) creation of high-value habitats which take into account the varied resource needs of bees within flight ranges of only a few hundred meters; (5) creation of stepping stone habitats as floral and nesting resources, integrating educative and participative aspects.
Full-text available
Insects are of increasing conservation concern as a severe decline of both biomass and biodiversity have been reported. At the same time, data on where and when they occur in the airspace is still sparse, and we currently do not know whether their density is linked to the type of landscape above which they occur. Here, we combined data of high-flying insect abundance from six locations across Switzerland representing rural, urban and mountainous landscapes, which was recorded using vertical-looking radar devices. We analysed the abundance of high-flying insects in relation to meteorological factors, daytime, and type of landscape. Air pressure was positively related to insect abundance, wind speed showed an optimum, and temperature and wind direction did not show a clear relationship. Mountainous landscapes showed a higher insect abundance than the other two landscape types. Insect abundance increased in the morning, decreased in the afternoon, had a peak after sunset, and then declined again, though the extent of this general pattern slightly differed between landscape types. We conclude that the abundance of high-flying insects is not only related to abiotic parameters, but also to the type of landscapes and its characteristics, which, on a long-term, should be taken into account for when designing conservation measures for insects.
Full-text available
Climate change is forcing species to migrate to cooler temperatures at higher elevations, yet many taxa are dispersing slower than necessary. One yet-to-be-tested explanation for inadequate migration rates is that high-elevation environments pose physiological barriers to dispersal, particularly in species with high metabolic demands. By synthesizing across >800 species, we find evidence for metabolic constraints: upslope migration is slower in insects that rely on nature's most expensive locomotor strategy--flight.
Many people, especially those living in developed countries, exhibit irrational negative feelings (e.g., fear, disgust, and aversion) toward insects. This so-called "entomophobia" has often been suggested as a key contributing factor to the ongoing global decline in insects. However, this topic has not been well investigated. From this point of view, we discuss the formation processes of entomophobia and its consequences from an evolutionary psychological perspective. Adopting the concept of the behavioral immune system, we suggest that the negative responses toward insects exhibited by modern people are driven by a series of emotional, cognitive, and behavioral traits that evolved to avoid infectious diseases. We then provide several strategic recommendations for mitigating the prevalence of entomophobia and a roadmap for better understanding how individual-level entomophobia can influence insect conservation. Understanding the human psychological dimension behind the ongoing decline of insects will provide useful insight on how best to mitigate this decline.
Full-text available
Recent reports of local extinctions of arthropod species 1 , and of massive declines in arthropod biomass 2 , point to land-use intensification as a major driver of decreasing biodiversity. However, to our knowledge, there are no multisite time series of arthropod occurrences across gradients of land-use intensity with which to confirm causal relationships. Moreover, it remains unclear which land-use types and arthropod groups are affected, and whether the observed declines in biomass and diversity are linked to one another. Here we analyse data from more than 1 million individual arthropods (about 2,700 species), from standardized inventories taken between 2008 and 2017 at 150 grassland and 140 forest sites in 3 regions of Germany. Overall gamma diversity in grasslands and forests decreased over time, indicating loss of species across sites and regions. In annually sampled grasslands, biomass, abundance and number of species declined by 67%, 78% and 34%, respectively. The decline was consistent across trophic levels and mainly affected rare species; its magnitude was independent of local land-use intensity. However, sites embedded in landscapes with a higher cover of agricultural land showed a stronger temporal decline. In 30 forest sites with annual inventories, biomass and species number-but not abundance-decreased by 41% and 36%, respectively. This was supported by analyses of all forest sites sampled in three-year intervals. The decline affected rare and abundant species, and trends differed across trophic levels. Our results show that there are widespread declines in arthropod biomass, abundance and the number of species across trophic levels. Arthropod declines in forests demonstrate that loss is not restricted to open habitats. Our results suggest that major drivers of arthropod decline act at larger spatial scales, and are (at least for grasslands) associated with agriculture at the landscape level. This implies that policies need to address the landscape scale to mitigate the negative effects of land-use practices.
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Insects make up the bulk of terrestrial diversity (1). Reports of insect declines, best documented in Europe and North America, suggest that 40% of insect species in temperate countries may face extinction over the next few decades (2), although this figure is probably inflated (3). Other studies have highlighted falling insect biomass in Germany and Puerto Rico (4, 5), as well as threats to many insect taxa in Europe (5) and insect pollinators worldwide (6) that support food production (7). To protect insects, it is crucial that they are considered as separate species with distinct responses to threats, with particular attention to tropical insects and their habitats. Bees and butterflies may serve as an initial focus, but conservation efforts must go far beyond these iconic species. Halting habitat loss and fragmentation, reducing pesticide use, and limiting climate change are all required if insect populations are to be preserved.
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Significance Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance. We compared arthropod biomass in Puerto Rico’s Luquillo rainforest with data taken during the 1970s and found that biomass had fallen 10 to 60 times. Our analyses revealed synchronous declines in the lizards, frogs, and birds that eat arthropods. Over the past 30 years, forest temperatures have risen 2.0 °C, and our study indicates that climate warming is the driving force behind the collapse of the forest’s food web. If supported by further research, the impact of climate change on tropical ecosystems may be much greater than currently anticipated.
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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 species or taxo-nomic groups only, rather than changes in insect biomass which is more relevant for ecological functioning. Here, we used a standardized protocol to measure total insect biomass using Malaise traps, deployed over 27 years in 63 nature protection areas in Germany (96 unique location-year combinations) to infer on the status and trend of local entomofauna. Our analysis estimates a seasonal decline of 76%, and midsummer decline of 82% in flying insect biomass over the 27 years of study. We show that this decline is apparent regardless of habitat type, while changes in weather, land use, and habitat characteristics cannot explain this overall decline. This yet unrecognized loss of insect biomass must be taken into account in evaluating declines in abundance of species depending on insects as a food source, and ecosystem functioning in the European landscape.
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We must start an ambitious and professional global programme to explore and preserve invertebrate biodiversity, says Axel Hochkirch.
Government deal adds €17 billion through 2030.
Biodiversity of insects is threatened worldwide. Here, we present a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assess the underlying drivers. Our work reveals dramatic rates of decline that may lead to the extinction of 40% of the world's insect species over the next few decades. In terrestrial ecosystems, Lepidoptera, Hymenoptera and dung beetles (Coleoptera) appear to be the taxa most affected, whereas four major aquatic taxa (Odonata, Plecoptera, Trichoptera and Ephemeroptera) have already lost a considerable proportion of species. Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species. Concurrently, the abundance of a small number of species is increasing; these are all adaptable, generalist species that are occupying the vacant niches left by the ones declining. Among aquatic insects, habitat and dietary generalists, and pollutant-tolerant species are replacing the large biodiversity losses experienced in waters within agricultural and urban settings. The main drivers of species declines appear to be in order of importance: i) habitat loss and conversion to intensive agriculture and urbanisation; ii) pollution, mainly that by synthetic pesticides and fertilisers; iii) biological factors, including pathogens and introduced species; and iv) climate change. The latter factor is particularly important in tropical regions, but only affects a minority of species in colder climes and mountain settings of temperate zones. A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.