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Worldwide decline of the entomofauna: A review of its drivers
Abstract
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.
Supplementary resources (2)
... Although the ongoing mass extinction is mostly associated with the dramatic decline in vertebrate populations (Grooten and Almond, 2018), arthropods are affected as much, if not more, as vertebrates (Dirzo et al., 2014;Sánchez-Bayo and Wyckhuys, 2019). According to IUCN criteria, 41 % of insect species, including the ones we generally regard as "common", are currently declining, and an estimated 31 % of them are threatened with extinction (Sánchez-Bayo and Wyckhuys, 2019). ...
... Although the ongoing mass extinction is mostly associated with the dramatic decline in vertebrate populations (Grooten and Almond, 2018), arthropods are affected as much, if not more, as vertebrates (Dirzo et al., 2014;Sánchez-Bayo and Wyckhuys, 2019). According to IUCN criteria, 41 % of insect species, including the ones we generally regard as "common", are currently declining, and an estimated 31 % of them are threatened with extinction (Sánchez-Bayo and Wyckhuys, 2019). Surprisingly, of the thousands of estimated insect extinctions, only 394 have been documented (Hochkirch, 2016). ...
... Samways, 2019) dedicated to the subject. A few recent papers claiming or documenting serious declines in arthropod density and diversity (Hallmann et al., 2017;Sánchez-Bayo and Wyckhuys, 2019) have even made headlines in the public media. In light of these recent developments, it may be appropriate to look at the entomological practice with a critical eye. ...
... Larval forms of certain insect orders are classified as the group with the highest indicative value (so called EPT: Ephemeroptera, Trichoptera and Plecoptera). Many freshwater species of insects in Poland and Europe are endangered (Czachorowski and Buczyński 2000) and particularly sensitive to habitat change as flow alterations, habitat fragmentation and pollution being their main threats (Buczyńska and Buczyński 2019;Sánchez-Bayo and Wyckhuys 2019). Intensively studied the recent worldwide decline in the number and biomass of insects (Hallmann et al. 2017;Leather 2017), widely discussed by specialists (e.g. ...
... However, the impact on the populations of rare, local and sparse species seems to be worth considering. The discussions of specialists on the development of standards and good practices in insect sampling for the purposes of monitoring in the face of their global decline began only recently (Samways 2019;Montgomery et al. 2021). ...
During the analysis of the biomonitoring data of Polish watercourses, it was found that the vast majority of aquatic insects (83–95% of more than 8.8 million individuals collected between 2012 and 2019) die unnecessarily during sampling, as a result of the sub-sampling procedure. Great, in some cases 30-fold differences in the mortality of insects, including those belonging to protected taxa, were observed between the samples analyzed by various regional laboratories. The most important reason for these differences appears to be factors that can be collectively referred to as the ‘human factor’, related to removing insects from the sphere of ethical protection, makes their killing an activity ethically neutral. This kind of attitude, which does not attach any importance to the life and suffering of insects interacts with the lack of precise requirements for the sampling equipment used. Those factors seem to be the most important in explaining the causes of excessive mortality of aquatic insects during sampling and the huge differences between laboratories. Principal component analysis and the analysis of variability measures showed that ecological differences between sampling sites can only be considered as a secondary determinant.
Implications for insect conservation
Improperly planned and conducted monitoring procedures, through excessive mortality of free-living aquatic insects, have or may have a negative impact on the environment and biodiversity. Therefore, it seems very important to promote alternative solutions that reduce such mortality in biological monitoring, such as: non-lethal methods of animal sampling, the use of pre-sampling areas to estimate the density of animals before sampling and estimation of the maximum abundance of a sample necessary for a reliable estimate of taxonomic richness using rarefaction.
... While trends in vertebrate species have been easier to document and traditionally received more attention [e.g., [2][3][4], the importance of insects and threats towards them have garnered a broader interest in the past decade with the publication of alarming trends in insect decline. For example, Hallman et al. [5] estimated that there has been a 75% decline in flying insect biomass in Germany since the late 1980s, and Sánchez-Bayo and Wyckhuys [6] have predicted that 40% of insect species will be extinct in the next few decades. While there has been debate whether the decline will be as severe as Sánchez-Bayo and Wyckhuys [6] predicted [e.g., 7], it nevertheless remains clear that there is a consistent pattern of insect decline across a broad range of taxonomic groups and habitats in response to climate change and land use [8][9][10]. ...
... For example, Hallman et al. [5] estimated that there has been a 75% decline in flying insect biomass in Germany since the late 1980s, and Sánchez-Bayo and Wyckhuys [6] have predicted that 40% of insect species will be extinct in the next few decades. While there has been debate whether the decline will be as severe as Sánchez-Bayo and Wyckhuys [6] predicted [e.g., 7], it nevertheless remains clear that there is a consistent pattern of insect decline across a broad range of taxonomic groups and habitats in response to climate change and land use [8][9][10]. Freshwater habitats, such as streams, are particularly threatened by anthropogenic land use and climate change, despite their irreplaceable ecosystem services [11,12]. ...
Background
Freshwater ecosystems, such as streams, are facing increasing pressures from agricultural land use and recent literature stresses the importance of robust biomonitoring to detect trends in insect decline globally. Aquatic insects and other macroinvertebrates are often used as indicators of ecological condition in freshwater biomonitoring programs; however, these diverse groups can present challenges to morphological identification and coarse-level taxonomic resolution can mask patterns in community composition. Here, we incorporate molecular identification (DNA metabarcoding) into a stream biomonitoring sampling design to explore the diversity and variability of aquatic macroinvertebrate communities at small spatial scales. While individual stream reaches can be very heterogenous, most community ecology studies focus on larger, landscape-level patterns of community composition. A high degree of community variability at the local scale has important implications for both biomonitoring and ecological research, and the incorporation of DNA metabarcoding into local biodiversity assessments will inform future sampling protocols.
Results
We sampled twenty streams in southern Ontario, Canada, for aquatic macroinvertebrates across multiple time points and assessed local community variability by comparing field replicates taken ten meters apart within the same stream. Using bulk-tissue DNA metabarcoding, we revealed that aquatic macroinvertebrate communities are highly diverse at small spatial scales with unprecedented levels of local taxonomic turnover. We detected over 1600 Operational Taxonomic Units (OTUs) from 149 families, and a single insect family, the Chironomidae, contained over one third of the total number of OTUs detected in our study. Benthic communities were largely comprised of rare taxa detected only once per stream despite multiple biological replicates (24–94% rare taxa per site). In addition to numerous rare taxa, our species pool estimates indicated that there was a large proportion of taxa that remained undetected by our sampling regime (14–94% per site). Our sites were located across a gradient of agricultural activity, and while we predicted that increased land use would homogenize benthic communities, this was not supported as within-stream dissimilarity was unrelated to land use. Within-stream dissimilarity estimates were consistently high for all levels of taxonomic resolution (invertebrate families, invertebrate OTUs, chironomid OTUs), indicating stream communities are very dissimilar at small spatial scales.
... The consensus is that bee population decline is the product of multiple factors that can act singly or in combination, the most known being diseases and parasites, invasive species, intensive agriculture, climate change, and pesticides (i.e., insecticides, herbicides and fungicides) [12,13]. Among these factors, land use (i.e., agricultural intensification and its associated landscape simplification) is considered an important driver of pollinator decline [14][15][16]. ...
Intensive landscape modifications have led to the loss of floral resources, partly in early spring when bumble bee queens need suitable pollen to establish their brood. Adequate floral resources are also crucial to mitigate parasite infection, a stress compromising reproductive success. Among early blooming trees, willows represent an important and highly suitable pollen resource. Alas, riparian areas and their associated willows have been declining. In this study, we found that hedgerow and orchard pollen were at least as suitable as willow pollen for bumble bee survival and microcolony development. Moreover, orchard pollen seemed an interesting candidate to help reduce parasite infection, but unlikely due to its flavonoids. Such non-willow trees could then be favoured in agri-environmental schemes implemented in bee conservation strategies, but pollen chemicals underlying beneficial effects remain to be determined.
... A recognized problem for biodiversity is the fragmentation of and reduction in ecosystems as a result of human activity [7][8][9]. The main factors contributing to the decline in the number of insect species are considered to be: habitat loss and the transition to intensive agriculture and urbanization; pollution, mainly with synthetic pesticides and fertilizers; biological factors, including pathogens and introduced species; and climate change [10,11]. Various studies have shown that Scarabaeoidea species are sensitive to structural changes in the habitat caused by various anthropogenic disturbances. ...
(1) Background: Beetles in the superfamily Scarabaeoidea are one of the most important groups of Coleoptera. They are found in various ecosystems all over the world and belong to coprophagous, necrophagous, saproxylophagous, phyllophagous and rhizophagous types. The aim of the study is to describe the fauna and distribution of Scarabaeoidea in the Republic of Mordovia (central part of European Russia); (2) Methods: The study was conducted from 2003 to 2023. Collection material (specimens from 1972 and 1986) was also used. Specimens were collected using traditional Coleoptera collecting methods (manual collecting, light trap, collection of rotten remains and pitfall traps). For each observation, the coordinates, number of specimens and dates were recorded; (3) Results: The dataset contains 3198 occurrences. We examined 11,011 specimens of Scarabaeoidea. The dataset contains information on 88 species of Scarabaeoidea. Of these, five species (Aphodius pedellus, Nobius serotinus, Phaeaphodius rectus, Planolinus fasciatus and Onthophagus medius) are listed for the region for the first time. Another seven species are additionally known from others taken from the literature (but were not found during the present field survey); (4) Conclusions: Species diversity of Scarabaeoidea of Mordovia accounts for 95 species from 4 families (Geotrupidae, Trogidae, Lucanidae and Scarabaeidae). Ten species (Protaetia marmorata, Anoplotrupes stercorosus, Cetonia aurata, Protaetia cuprea volhyniensis, Oxythyrea funesta, Platycerus caraboides, Serica brunnea, Melolontha hippocastani, Trichius fasciatus and Protaetia fieberi) constitute the main population of Scarabaeoidea fauna given in the dataset. The species diversity of Scarabaeoidea of the Republic of Mordovia is roughly similar in number of species to that of neighboring or more northern regions.
... Their departures from these "roosts" are often visible in weather radar, from which it's possible to estimate their numbers [20][21][22]. The US "NEXRAD" weather radar network [23] has collected data for 30 years from 143+ stations and provides an unprecedented opportunity to study long-term and wide-scale biological phenomenon such as roosts [24,25]. However, the sheer volume of radar scans (>250M) prevents manual analysis and motivates computer vision approaches [26][27][28]3]. ...
Many modern applications use computer vision to detect and count objects in massive image collections. However, when the detection task is very difficult or in the presence of domain shifts, the counts may be inaccurate even with significant investments in training data and model development. We propose DISCount -- a detector-based importance sampling framework for counting in large image collections that integrates an imperfect detector with human-in-the-loop screening to produce unbiased estimates of counts. We propose techniques for solving counting problems over multiple spatial or temporal regions using a small number of screened samples and estimate confidence intervals. This enables end-users to stop screening when estimates are sufficiently accurate, which is often the goal in a scientific study. On the technical side we develop variance reduction techniques based on control variates and prove the (conditional) unbiasedness of the estimators. DISCount leads to a 9-12x reduction in the labeling costs over naive screening for tasks we consider, such as counting birds in radar imagery or estimating damaged buildings in satellite imagery, and also surpasses alternative covariate-based screening approaches in efficiency.
... Furthermore, arthropods are a key component of terrestrial food-webs and loss of arthropod communities have cascading impacts on higher taxa such as mammals and birds (Hallmann et al., 2014;Wagner et al., 2021). While multiple drivers appear responsible for the widespread arthropod decline, agricultural intensification has been pointed out as a key-stressor (Habel et al., 2019;Sánchez-Bayo and Wyckhuys, 2019;Raven and Wagner, 2021;Wagner et al., 2021). Intensified agricultural cropping landscapes are characterized by large homogeneously managed areas planted with a single genotype (van der Zanden et al., 2016), and field sizes that have increased over the past decades (Clough et al., 2020). ...
Loss of arthropod biodiversity can impair the provision of ecosystem services in agricultural landscapes. Crop diversification strategies offer the possibility to support arthropod communities without putting aside agricultural land as conservation areas. Within-field crop diversification measures, such as strip cropping and crop mixtures, may provide arthropods with continuity and diversity in food, shelter and habitat at fine spatial and temporal resolutions. However, it is unclear how strip cropping and plant species diversity within strips influences aerial arthropod and weed communities in commercially sized arable fields. In this 2-year study we tested the effects of crop heterogeneity on aerial arthropod and plant communities in organically managed strip fields. We tested effects of configurational crop heterogeneity by comparing sole cropping (MONO) with strip cropping (STRIP), and compositional crop heterogeneity by comparing STRIP with flower-legume-grain crop mixtures grown in strips (STRIPMIX). Aerial arthropod communities were assessed in 138 sweep net transects and plant communities in 124 vegetation plots in cabbage, wheat, sugar beet and barley. Higher configurational crop heterogeneity by strip cropping reduced herbivore abundances and increased natural enemy species richness in organic cabbage strips. Cabbage in MONO had a significantly higher herbivore abundance (+11%) and a lower natural enemy species richness (− 57%) than cabbage in STRIP. Higher compositional crop heterogeneity by sowing additional plant species in strips (STRIPMIX) significantly increased plant abundance (+33%), plant species richness (+21%), total aerial arthropod abundance (+45%), and total aerial arthropod species richness (+21%) compared to STRIP. Our work shows that both configuration of crop areas (MONO vs. STRIP) and plant species diversity within strips (STRIP vs. STRIPMIX) can support arthropod biodiversity and natural pest suppression , but that arthropod responses differ between diversification strategies and crop combinations. Further optimization of design and management of within-field crop diversification strategies holds potential to attain biodiversity-based cropping systems which deliver multiple ecosystem services and have a reduced dependency on pesticides.
... However, despite this characteristic, we still observed distinct elevational variation in insect communities. Insect declines have been widespread both taxonomically and geographically (Hallmann et al., 2017;S anchez-Bayo & Wyckhuys, 2019;Wagner, 2020), including declines of Diptera in arctic habitats (Loboda et al., 2018) and Lepidoptera in mountains areas (Halsch et al., 2021). Coupled with these observations, our results further highlight that climate change likely will cause strong perturbations to insect communities in areas of high elevation and latitude. ...
Mountain topography gives rise to often dramatic climate-driven elevation gradients in primary productivity, which can generate substantial biodiversity variation. Therefore, mountain areas may be particularly useful for evaluating the ecological consequences of climate change. Arthropods are the most diverse animal phylum, which play important roles in most ecosystems. However, despite their ecological importance, we have limited information on how arthro-pods vary along elevation gradients. We investigated how taxonomic richness, taxonomic composition, and spatial structuring of spider and insect communities varied along elevation gradients and among three geographic locations in a mountain region of northern Sweden. The locations provided a latitude gradient spanning approximately 3 (from 62 N to 65 N), but were otherwise selected to contain similar environmental characteristics. Taxonomic richness of both spiders and insects declined monotonically with increasing elevation, and there were limited differences between the geographic locations in such declines. Taxonomic composition varied with elevation for both taxonomic groups, but also differed among the three sites. Linyphiid spiders were more widely distributed along the elevation gradients than other spider taxa, whereas a broad taxo-nomic range of insects occurred over almost all elevations. We observed nested as well as modular spatial distributions of both spider and insect communities along the elevation gradients. While the modular patterns suggest that species turnover has generated distinct communities at different elevations, some gener-alist species were still widespread throughout large parts of the gradients. Our results point to smaller differences among geographic locations than among tax-onomic groups in how taxonomic richness and community structuring varied with elevation. We interpret these results as support for taxonomically specific adaptations to environmental conditions being important for structuring arthro-pod communities. We also suggest that climate-driven changes to arthropod communities in mountain environments may be regulated by two not mutually exclusive processes, one in which generalist species may become more dominant and shift their ranges upward and one in which high-elevation specialists may go extinct because of increasingly fragmented habitats
... Anthropogenic disturbances (e.g., habitat destruction, industrialized agriculture, urbanization) are well-known to mediate the spread of invasive species, often imposing severe resource restrictions that limit productivity and niche space (Martínez-Meyer et al., 2013;Sánchez-Bayo and Wyckhuys, 2019). Here, niche expansion was found to be positively associated with higher disturbance in the native habitat accompanied by lower disturbance in the invaded range ( Figure 4C). ...
Coleoptera are key elements of terrestrial trophic interactions and generate significant economic and ecological benefits, but their representatives also represent severe pest species. Understanding how invasive species operate is indispensable to identify and anticipate potential invasion areas. However, few studies have explored niche dynamics and drivers of invasions in this group. Here we examined niche dynamics across 54 invasive beetle species native to Europe and assessed whether factors such as human influence index, feeding habits, body size, and niche breadth are associated with the degree of invasion. The realized niches had low similarity in invasive and native ranges (i.e., invaded areas are climatically dissimilar to native ranges). This included a high degree of niche expansion in invaded areas but also environments occupied in the native ranges but unoccupied in the invasive range (unfilling), suggesting that altered species–climate relationships during invasion processes are common. Niche expansions showed positive association with small native niche breadth sizes and movements from highly disturbed native areas to less disturbed invaded ranges; unfilling was associated with invaded niche breadth size and frequency of species occurrence. Both were related to dissimilar realized climatic niches in invaded ranges. Colonization of invaded areas might be triggered by low quality resources in native areas. Unfilling levels might be related to the year of introduction and loss of biotic constraints present in their native distribution, leading to the use of different climatic spaces in the invasive areas. This idea is reinforced by larger invasive climatic niche breadth. Our results provide insight into patterns of invasive species, and initial holistic exploration towards the understanding of invasive species dynamics.
... For example, Hallmann et al. (2017) reported a 76% insect biomass decline over 27 years in protected areas, and Seibold et al. (2019) reported a 68% decline in grassland insect biomass over 19 years. The global insect loss was recently estimated to be approximately 9% per decade (Sánchez-Bayo and Wyckhuys, 2019;Warren et al., 2021;Engelhardt et al., 2022). While some drivers of this ecological crisis are unknown, others like climate change, habitat loss driven by land-use change, and land-use intensification have been identified (Cardoso et al., 2020;Sohlström et al., 2022). ...
... Increase in global population drives growth in food demand and agricultural production (United Nations, 2019). The productive increment in intensive agricultural systems is based on expansive land use and recurrent chemical inputs (Evenson and Gollin, 2003), leading to landscape simplification and deterioration of insect-mediated ecosystem services (Dudley and Alexander, 2017;Sánchez-Bayo and Wyckhuys, 2019). More diverse agricultural systems potentially provide benefits for productivity and ecosystem services, such as biological control (Beaumelle et al., 2021;He et al., 2019;Lichtenberg et al., 2017;Tamburini et al., 2020). ...
Pest management in intensive crop production currently underutilizes natural biological control, and frequently results in pesticide application. Intercropping modifies physical and ecological conditions in the field and alters the predator-prey dynamics to potentially benefit generalist arthropod predators. We investigated the assemblages of ground-dwelling arthropod predators and crop pests of spring turnip rape (Brassica rapa L. ssp. oleifera) and faba bean (Vicia faba L.) in a replicated two-year field experiment. Pitfall traps and pan traps were used to sample arthropod predators and pests. Arthropod assemblages were compared between intercropping and monocropping systems to illustrate the changes. Intercropping was associated with lower abundance of turnip rape pests compared with monoculture. The total abundance of ground-dwelling predators did not differ between cropping systems. Carabid beetles (Coleoptera: Carabidae) and spiders (Araneae) were the dominant generalist predator taxa. Faba bean monoculture supported the highest abundance of harvestmen (Opiliones) and the lowest abundance of ants (Hymenoptera: Formicidae). The turnip rape monoculture had the highest abundance of spiders in the first year but not in the second. The abundance and species assemblage of carabids indicated a response to season progress but not to cropping system. The abundance of turnip rape pests reflected host crop proportions in each cropping system. Because the cropping method had no significant impact on predator abundance, intercropping potentially facilitated natural biological control resulting from a higher ratio of ground-dwelling predators to pests. Differential within-season dynamics among abundant predator taxa also implied a temporal shift in predation characteristics, and hence, vulnerability of crop production to pest injuries. To utilize natural biological control more effectively at the field scale, intercropping with no shared pests between crops, minimal chemical pest control, and heterogeneous agricultural landscapes are needed.
... Hallmann et al.'s (2017) ground-breaking study demonstrated a 75% decrease in insect abundance across 63 conservation areas over a 30-year span. Subsequent work has documented that this declining trend in insect abundance has been occurring across a wide variety of taxa and locations (Sanchez-Bayo & Wyckhuys, 2019;Seibold et al., 2019;Wagner, 2020). Drastic changes in arthropod population abundance and diversity have negative cascading effects on ecological stability and ecosystem resiliency (Borer et al., 2012;Kremen et al., 1993;Tscharntke et al., 2012). ...
Deep learning for computer vision has shown promising results in the field of entomology, however, there still remains untapped potential. Deep learning performance is enabled primarily by large quantities of annotated data which, outside of rare circumstances, are limited in ecological studies. Currently, to utilize deep learning systems, ecologists undergo extensive data collection efforts, or limit their problem to niche tasks. These solutions do not scale to region agnostic models. However, there are solutions that employ data augmentation, simulators, generative models, and self‐supervised learning that can supplement limited labelled data. Here, we highlight the success of deep learning for computer vision within entomology, discuss data collection efforts, provide methodologies for optimizing learning from limited annotations, and conclude with practical guidelines for how to achieve a foundation model for entomology capable of accessible automated ecological monitoring on a global scale.
... However, these measures demand a careful consideration of their repercussions regarding people, biodiversity and NCP in different landscape contexts [75][76][77][78] , which could not be examined here. In the past, the shift from low-input farming to intensive farming and concurrent landscape transitions have caused sharp species declines 35,79,80 and undermined essential NCP 2,4,8,9,13 . Promoting off-farm ecosystem management and multifunctionality within farmed landscapes therefore could not only offer decisive means for counteracting these negative trends 18,37,57,81,82 , but also reduce the use of external inputs in agricultural production, such as pesticides 83,84 . ...
Land conservation and increased carbon uptake on land are fundamental to achieving the ambitious targets of the climate and biodiversity conventions. Yet, it remains largely unknown how such ambitions, along with an increasing demand for agricultural products, could drive landscape-scale changes and affect other key regulating nature’s contributions to people (NCP) that sustain land productivity outside conservation priority areas. By using an integrated, globally consistent modelling approach, we show that ambitious carbon-focused land restoration action and the enlargement of protected areas alone may be insufficient to reverse negative trends in landscape heterogeneity, pollination supply, and soil loss. However, we also find that these actions could be combined with dedicated interventions that support critical NCP and biodiversity conservation outside of protected areas. In particular, our models indicate that conserving at least 20% semi-natural habitat within farmed landscapes could primarily be achieved by spatially relocating cropland outside conservation priority areas, without additional carbon losses from land-use change, primary land conversion or reductions in agricultural productivity.
... There is a general consensus that the stressors of global change (i.e., habitat loss or land degradation, agricultural intensification, invasive species, environmental pollutants, and the manifold impacts of climate change [8,11,14,[20][21][22]) create "winners" and "losers". However, information on the consequences of the undisputed reorganization of insect communities in ecological terms is still scarce [4,11,12,23]. ...
Simple Summary
Insect populations are facing unprecedented changes in many ecosystems worldwide. However, do these changes make insect communities more vulnerable? The study of interaction networks can help to answer this question. We assessed the adequacy of network tools to address the long-term variation (after 11 years) of diversity patterns of the saproxylic (wood-dependent) beetle communities that inhabit tree hollows in three representative Mediterranean woodland types. To explore saproxylic communities’ vulnerability to microhabitat loss, we simulated hollow extinctions and recreated feasible future threat scenarios based on decreasing microhabitat suitability. Contrasting responses in diversity patterns among woodland types were found, whereas interaction patterns generally showed substantial temporal variations in the way that saproxylic beetles interact with tree hollows (less interconnected and specialized networks). Network procedures evidenced increased saproxylic communities’ vulnerability, and this situation could worsen in potential future scenarios with decreased microhabitat suitability. The valuable information that ecological networks provide should be considered for improving management and conservation programs.
Abstract
Insect communities are facing contrasting responses due to global change. However, knowledge on impacts of communities’ reorganizations is scarce. Network approaches could help to envision community changes in different environmental scenarios. Saproxylic beetles were selected to examine long-term variations in insect interaction/diversity patterns and their vulnerability to global change. We evaluated interannual differences in network patterns in the tree hollow–saproxylic beetle interaction using absolute samplings over an 11-year interval in three Mediterranean woodland types. We explored saproxylic communities’ vulnerability to microhabitat loss via simulated extinctions and by recreating threat scenarios based on decreasing microhabitat suitability. Although temporal diversity patterns varied between woodland types, network descriptors showed an interaction decline. The temporal beta-diversity of interactions depended more on interaction than on species turnover. Interaction and diversity temporal shifts promoted less specialized and more vulnerable networks, which is particularly worrisome in the riparian woodland. Network procedures evidenced that saproxylic communities are more vulnerable today than 11 years ago irrespective of whether species richness increased or decreased, and the situation could worsen in the future depending on tree hollow suitability. Network approaches were useful for predicting saproxylic communities’ vulnerability across temporal scenarios and, thus, for providing valuable information for management and conservation programs.
... There have been concerning reports of declining insect biomass in different regions (Hallmann et al., 2017;Sánchez-Bayo & Wyckhuys, 2019). A variety of environmental factors such as habitat destruction, climate change, agricultural intensification and invasive species have been implicated (Wagner, 2020). ...
... Between 1970 and 2014, wildlife populations decreased by half and those of vertebrate species (mammals, birds, reptiles, amphibians, and fish), by on average 60% [39,62,63]. The proportion of insect species in decline is 41%, nearly twice that of vertebrates [64]. A global temperature increase of 1.5-2.5 • C (2.7-4.5 • F) would put an estimated 20-40% of assessed species at increased risk of extinction [65]. ...
Driven by increasing consumption and population numbers, human demands are depleting natural resources essential to support human life, causing damage to crop lands, fresh water supplies, fisheries, and forests, and driving climate change. Within this century, world population could increase by as little as 15% or by more than 50%, depending largely on how we respond. We must face the challenge of accommodating these additional people at the same time as virtually eliminating the use of fossil fuels and other activities that generate greenhouse gases, reversing environmental degradation and supporting improved living standards for billions of impoverished people. The response to this challenge is handicapped by a lack of common understanding and an integrated agenda among those contributing to the response. This report offers a strategy to protect natural systems and improve welfare through expansion of reproductive justice, a concept that includes family planning, reproductive health, and gender equity, and preservation of the environment and climate.
Odonata is an order of insects that comprises ~6500 species. They are among the earliest flying insects, and one of the first diverging lineages in the Pterygota. Odonate evolution has been a topic of research for over 100 years, with studies focusing primarily on their flight behavior, color, vision, and aquatic juvenile lifestyles. Recent genomics studies have provided new interpretations about the evolution of these traits. In this manuscript we look at how high throughput sequence data (i.e., subgenomic and genomic data) has been used to answer long standing questions in Odonata ranging from evolutionary relationships to vision evolution to flight behavior. Additionally, we evaluate these data at multiple taxonomic levels (i.e., ordinal, familial, generic, and population) and provide comparative analysis of genomes across Odonata, identifying features of these new data. Lastly, we discuss the next two years of Odonata genomic study, with context about what questions are currently being tackled.
Aim
To project the impact of climate change on dragonfly and damselfly diversity in West and Central Asia.
Location
West and Central Asia.
Time period
1900–2020 data used to predict distributions in 2070 and 2100.
Taxon studied
Odonata.
Methods
Based on 149,001 records, distribution models were created for 159 species using MaxEnt. Environmental variables consisted of climate variables taken from BIOCLIM, river data and soil data. The future climate data were obtained from CHELSA from CMIP6 climate models. The same variables were collected for three scenarios (SSP1‐2.6, SSP3‐7.0 and SSP5‐8.5) of shared socioeconomic pathways for the years 2050–2070 and 2080–2100. For each scenario and period, diversity maps were prepared for six species groups: all species, Lentic, Lotic, Oriental, Afrotropical and Palaearctic species.
Results
Strong declines in diversity are expected in western Turkey, the Levant and Azerbaijan, and to a lesser extent in parts of Iran and southern Central Asia. An increase is expected in eastern Turkey and at higher elevations in Central Asia with a limited increase throughout the Arabian Peninsula. In contrast to expectations, a decrease in areas with <15 species was found. Faunal composition is predicted to show strong shifts, with Palaearctic species declining and Oriental and Afrotropical species increasing. No clear difference between the trend of lentic and lotic species is found, although there are clear spatial differences in trend between these groups.
Main Conclusions
Climate change will result in strong changes in diversity and distribution of dragonflies and damselflies in West and Central Asia with regional declines and increases. None of the species are predicted to go extinct based on the impact of climate change only, however, the combined impact of climate change and anthropogenic forces is likely to push some of the species to near extinction by 2100.
Animals face many natural challenges, and humans have added to this burden by applying potentially harmful herbicides and unintentionally introducing competitors. We examine the recently introduced Velarifictorus micado Japanese burrowing cricket which shares the same microhabitat and mating season as the native Gryllus pennsylvanicus field cricket. In this study, we assess the combined effects of Roundup (glyphosate-based herbicide) and a lipopolysaccharide (LPS) immune challenge on both crickets. In both species, an immune challenge reduced the numbers of eggs that the female laid; however, this effect was much larger in G. pennsylvanicus. Conversely, Roundup caused both species to increase egg production, potentially representing a terminal investment strategy. When exposed to both an immune challenge and herbicide, G. pennsylvanicus fecundity was harmed more than V. micado fecundity. Furthermore, V. micado females laid significantly more eggs than G. pennsylvanicus, suggesting that introduced V. micado may have a competitive edge in fecundity over native G. pennsylvanicus. LPS and Roundup each had differing effects on male G. pennsylvanicus and V. micado calling effort. Overall, introduced male V. micado spent significantly more time calling than native G. pennsylvanicus, which could potentially facilitate the spread of this introduced species. Despite the population-level spread of introduced V. micado, in our study, this species did not outperform native G. pennsylvanicus in tolerating immune and chemical challenge. Although V. micado appears to possess traits that make this introduced species successful in colonizing new habitats, it may be less successful in traits that would allow it to outcompete a native species.
Solitary bees provide an important ecological and agricultural service by pollinating both wild plants and crops, often more effectively than honey bees. In the context of worldwide pollinators' declines, it is important to better understand the functioning of populations under multiple stressors at larger spatial and temporal scales. Here we propose building a detailed, spatially-explicit agent-based model of one of the best-studied species of solitary bees, Osmia bicornis L. In this Formal Model, we review various aspects of O. bicornis biology and ecology in detail and provide descriptions of their planned implementations in the model. We also discuss the model gaps and limitations, as well as inclusions and exclusions, allowing a dialogue with the reviewers about the model's design.
The ALMaSS model of O. bicornis aims to provide a realistic and detailed representation of O. bicornis populations in space and time in European agricultural landscapes. The model will be a part of the Animal, Landscape and Man Simulation System (ALMaSS); thus will be able to utilise a highly detailed, dynamic ALMaSS landscape model. It will consider the behaviour of all bee life stages daily and use state transitions to allow each individual to decide their behaviour. The development of egg-to-pupa stages in the nest will be temperature-driven. Adult bees, after they emerge from the nest in spring, will interact with the environment. They will be able to search for suitable nesting locations, provision their brood cells with pollen and reproduce. Modelled females will balance offspring size and number following the optimal allocation theory, but local environmental factors will modify their actual parental investment decisions. The model will include the daily mortality rate for the egg-to-pupa stages, overwintering mortality, and background mortality outside the nest. We will also consider the risk of open-cell parasitism as increasing with the time the brood cell is open.
With the level of detail suggested, the model will be able to simulate population-level dynamics in response to multiple factors at the landscape scale over long periods. The European Food Safety Authority (EFSA) has suggested O. bicornis as a model organism for non-Apis solitary bees in the pesticide risk assessment scheme. Therefore, we hope our model will be a first step in building future landscape risk assessments for solitary bees.
Aim: The aim was to develop tasar cultivation zones by introducing diverse tasar host plant species at mined out sites undergoing ecological restoration for generating sustainable livelihood option for local tribals. Methodology: The site selected for vanya sericulture was an integral part of ecologically restored 250 -acres limestone/dolomite mined out area of Steel Authority of India Limited (SAIL).Tasar cultivation zones were developed by planting saplings of host plant species viz, Terminalia tomentosa (Roxb.) ex DC., Terminalia arjuna Wright & Arn., Terminalia belerica (Gaertn) Roxb, Ziziphus mauritiana Lam., Terminalia chebula Retz. and Syzygium cumini (L.) Skeels. These cultivation zones are currently scattered among nine forest communities that were developed by growing saplings of more than 260 native species of trees and shrubs, besides ground vegetation, using ecosystem approach. Women self-help groups were formed and trained in rearing of tasar silkworms as well as making tasar-based products to ensure continuous practice of tasar silkworm culture at these novel cultivation zones. Results: During early ecological stages of ecosystem redevelopment through restoration of the habitat, it was observed that wild tasar moths laid eggs and silkworms spun cocoons, albeit in very small quantity, indicating suitability of foliage as food for larvae. In the year 2019-2020 alone, an estimated one lakh cocoons were produced from DFLs procured from CTRTI, Ranchi,and sent to the market/stored as seed cocoon. The average income per member of self-help group from sale of tasar cocoons was Rs 7, 855 (INR) annually. Interpretation: The restored ecosystems in the limestone/dolomite mined-out areas of SAIL at Purnapani serve as an excellent model for conservation of Tasar gene pools and sustainable livelihood development that can be replicated elsewhere. Hence, this practise can serve as an excellent model for replication elsewhere. Key words: Biodiversity, Ecological restoration, Livelihood, Mined out areas, Self-help group, Tasar silkworm
Budhathoki N, Dhakal S, Dyola U. 2021. Diversity of hoverflies (Diptera: Syrphidae) in Nagarjun, Shivapuri Nagarjun National Park, Nepal. Biodiversitas 22: 5382-5388. Hoverflies are recognized as potential pollinators of a wide range of wild plants. This study explored the abundance and diversity of hoverflies over three different seasons from October 2018 to April 2019 in two different study sites, i.e. forest and grassland at Nagarjun of Shivapuri Nagarjun National Park, Nepal. Each site of the study area was further divided into five sampling transect stations. Hoverflies were collected from each station by using two methods as pan trap sampling and transect sweeping sampling. Overall, a total of 373 specimens representing 13 species under nine genera of two subfamilies (Syrphinae and Eristalinae) were recorded. The abundance and diversity of hoverflies varied seasonally, the maximum number of individuals and diversity were recorded from the spring season, whereas the minimum number of individuals and diversity were found in the winter season. In addition, forest habitat consists of the highest abundance and diversity of hoverflies, whereas grassland consists of the lowest abundance and diversity. The analysis done by using generalized linear modeling (GLM) revealed climatic parameters such as temperature and humidity had a varying effect on the abundance of hoverflies. However, both these parameters had not any significant influence on the number of hoverfly species.
In temperate and tropical rivers, macroinvertebrates are commonly utilised for biological monitoring. Therefore, it is important to understand their functional feeding guilds and assemblage structure. However, there have been few studies in high-altitude rivers in East Africa aimed at assessing macroinvertebrate functional guilds. In this study, we examined the macroinvertebrate assemblage characteristics using abundance/di-versity metrics and the functional feeding groups (FFGs). We collected physicochemi-cal data and macroinvertebrate samples at seven sites along the Gura River and three sites on the Sagana River. Dissolved oxygen concentration, water temperature, electrical conductivity, pH, turbidity, ammonia, and soluble reactive phosphorus showed significant differences among the sites (p < 0.05). A total of 32 families belonging to 11 orders of macroinvertebrates were collected during the study period. Overall, scrapers were the most abundant FFG, dominated by Heptageniidae (Afronurus). Collector filters and collector gatherers were the second most abundant, while shredders and predators exhibited the least relative abundance. Across all the dominant orders, macroinvertebrate abundance decreased from upstream to downstream sites, with upstream sites exhibiting high diversity and abundance of Ephemeroptera, Diptera, Coleoptera, and Trichoptera taxa. Furthermore, the FFGs in this study differed widely from the River Continuum Concept predictions. Our findings provide crucial understanding of macroinvertebrate assemblage characteristics in high-altitude rivers. Thus, this study provides additional evidence on the high abundance and diversity of Ephemeroptera and Trichoptera taxa in tropical rivers.
The decline of insect diversity is a much discussed yet understudied phenomenon, particularly in the tropics, where the majority of insect abundance, diversity and biomass is found. Integrated approaches, involving traditional taxonomic methods, new molecular approaches, and novel monitoring and identification tools and applications are needed to address related and challenging questions regarding how many species of tropical insects exist, their distributions and natural history, the relative impacts of global change drivers on insect diversity across complex tropical landscapes, and the effects of insect declines on ecosystem functions and services. The main barriers to addressing these challenges are a lack of capacity and funding for research on insects in tropical countries, and a lack of recognition of their importance for ecosystem functioning and human wellbeing. Insects must be brought into policy agendas, local capacity and funding through cross-boundary collaborations and equitable scientific practices increased, and their importance emphasized.
In the face of global biodiversity declines, surveys of beneficial and antagonistic arthropod diversity as well as the ecological services that they provide are increasingly important in both natural and agro-ecosystems. Conventional survey methods used to monitor these communities often require extensive taxonomic expertise and are time-intensive, potentially limiting their application in industries such as agriculture, where arthropods often play a critical role in productivity (e.g. pollinators, pests and predators). Environmental DNA (eDNA) metabarcoding of a novel substrate, crop flowers, may offer an accurate and high throughput alternative to aid in the detection of these managed and unmanaged taxa. Here, we compared the arthropod communities detected with eDNA metabarcoding of flowers, from an agricultural species (Persea americana-'Hass' avocado), with two conventional survey techniques: digital video recording (DVR) devices and pan traps. In total, 80 eDNA flower samples, 96 h of DVRs and 48 pan trap samples were collected. Across the three methods, 49 arthropod families were identified, of which 12 were unique to the eDNA dataset. Environmental DNA metabarcoding from flowers revealed potential arthropod pollinators, as well as plant pests and parasites. Alpha diversity levels did not differ across the three survey methods although taxonomic composition varied significantly, with only 12% of arthropod families found to be common across all three methods. eDNA metabarcoding of flowers has the potential to revolutionize the way arthropod communities are monitored in natural and agro-ecosystems, potentially detecting the response of pollinators and pests to climate change, diseases, habitat loss and other disturbances.
The current study was conducted to investigate the variety of Odonata in Kashmir from November 2020 to November 2022. The study revealed the existence of 24 species, which includes 18 species of Anisoptera (dragonflies) under eight genera & two families and six species of Zygoptera (damselflies) in five genera & three families. New records of four species Orthetrum sabina (Drury, 1770), O. internum McLachlan, 1894, Aeshna petalura Martin, 1906, and Anax guttatus (Burmeister, 1839) from the region are provided herewith. Libellulidae (12 spp.) followed by Aeshnidae (six spp.) were recorded as two dominant families. This study provides some important baseline information on the odonates of Kashmir, Jammu & Kashmir, India.
Dung beetles (Coleoptera: Scarabaeinae) frequently traverse agricultural matrices in search of ephemeral dung resources and spend extended periods of time burrowing in soil. Neonicotinoids are among the most heavily applied and widely detected insecticides used in conventional agriculture with formulated products designed for row crop and livestock pest suppression. Here, we determined the comparative toxicity of two neonicotinoids (imidacloprid and thiamethoxam) on dung beetles, Canthon spp., under two exposure profiles: direct topical application (acute) and sustained contact with treated-soil (chronic). Imidacloprid was significantly more toxic than thiamethoxam under each exposure scenario. Topical application LD50 values (95% CI) for imidacloprid and thiamethoxam were 19.1 (14.5–25.3) and 378.9 (200.3–716.5) ng/beetle, respectively. After the 10-day soil exposure, the measured percent mortality in the 3 and 9 µg/kg nominal imidacloprid treatments was 35 ± 7% and 39 ± 6%, respectively. Observed mortality in the 9 µg/kg imidacloprid treatment was significantly greater than the control (p = 0.04); however, the 3 µg/kg imidacloprid dose response may be biologically relevant (p = 0.07). Thiamethoxam treatments had similar mortality as the controls (p > 0.8). Environmentally relevant concentrations of imidacloprid measured in airborne particulate matter and non-target soils pose a potential risk to coprophagous scarabs.
There have been reports in the media of an insect Armageddon, a sixth mass extinction or a collapse of nature, which tend to fit more with a sudden “Catastrophian Age” rather than a prolonged “Anthropocene Epoch”. The decline of insect populations and the diversity of species is being witnessed worldwide, with reports from all continents such as a 76% decline over 26 years in Germany or estimates of up to a staggering 98% over 35 years in Puerto Rica. The 2019 IPBES report suggests a tentative value of 10% insects globally face extinction, although it recognises that there are gaps in knowledge of the exact numbers of endangered insect species. In another 2019 review there are claims that a third of North American and European insects are at risk of extinction. Significantly, many of these insects such as bees and hoverflies provide an essential role in crop pollination. Neonicotinoids in particular are extensively used across the globe and residues have been found in 75% of honey samples.
There are various causes of this insect decline including pesticide use, habitat loss and climate change. However, there are several knowledge gaps relating to insect abundance overlap with other drivers of reductions in biodiversity generally and more broadly with planetary health. Therefore, it is vital to continually bear in mind that although concern over pollinator insect populations is important it is part of a much wider picture. For example, allowing careful management of a small group of pesticides on non-insect pollinated crops may have short term benefits it does not aid ecosystem restoration that is much more important in the long run. This opinion piece outlines answers to some of the UK House of Commons select committee questions relating to the use of insecticides and insect decline in the UK. Some recommendations include promoting further citizen science research to gain much wider data, extending nature education within school curriculum, promoting more hedgerow replanting as part of habitat restoration and much more interdepartmental communication and collaboration within government to help reach biodiversity, carbon emissions and restoring nature targets.... thereby increasing planetary health.
Organic pollutants in aquatic environment could have important implications on pollution stress on aquatic organisms and even on the risk of human exposure. Thus, revealing their occurrence in aquatic environment is essential for water quality monitoring and ecological risk purposes. In this study, a comprehensive two-dimensional gas chromatography connected with time-of-flight mass spectrometry (GC × GC-TOF-MS) was applied, to enable non-target and target analysis of pollutants in the Yongding River Basin. Based on the isotopic patterns, accurate masses and standard substances, certain environmental contaminants were tentatively identified which including polycyclic aromatic hydrocarbon (PAHs), organochlorine pesticides (OCPs), phenols, amines, etc. The compounds with the highest concentration were naphthalene (109.0 ng/L), 2,3-benzofuran (51.5 ng/L) and 1,4-dichlorobenzene (35.9 ng/L) in Guishui River. Wastewater treatment plants (WWTPs) discharges were a main source of pollutants in Yongding River Basin, as the types of compounds screened in the downstream river were relatively similar to those from WWTPs. According to the target analysis, a number of pollutants were selected due to the acute toxicity and cumulative discharge from WWTPs and downstream rivers. Three PAHs (naphthalene, Benzo(b)fluoranthene and pyrene) homologues showed moderate risk to fish and H. Azteca in Yongding River Basin, while the rest of the measured chemicals showed low ecological impact across the entire study area based on the risk assessment. The results are helpful for understanding the necessity of high-throughput screening analysis for assessing water quality of rivers and the discharge emissions of pollutants from WWTPs to the river environment.
The full-scale war in Ukraine negatively impacted populations of urban and semi-urban animals. This study examines the effects of war-related damages on urban populations of bats in Kharkiv city (NE Ukraine) during 2022. Our findings suggest that 45.1% of buildings used as wintering roosts for N. noctula were either partially damaged or completely destroyed by shellings, which may have led to the direct killing of approximately 7,000 bats. Additionally, the war-damaged urban environments in Kharkiv serve as a deadly trap for bats during the period of autumn migration or swarming. Bats flew into buildings’ interiors through windows that were left open or broken by blast waves, resulting in entrapment. The total number of N. noctula trapped inside buildings damaged by shelling was 2,836 individuals, with a death rate of approximately 30%. The group size of trapped bats was more numerous than in previous years, and the main findings were concentrated in war-damaged districts of the city.
The purpose of the current study was to document the variety of predatory spider species present in the cotton fields of two major cotton-producing districts in Punjab, Pakistan, as well as the population dynamics of those spiders. The research was carried out between May and October 2018 and 2019. Manual picking, visual counting, pitfall traps, and sweep netting were the procedures used to collect samples on a biweekly basis. A total of 10,684 spiders comprising 39 species, 28 genera, and 12 families were documented. Araneidae and Lycosidae families contributed a major share to the overall catch of spiders, accounting for 58.55 percent of the total. The Araneidae family's Neoscona theisi ) was the most dominating species, accounting for 12.80% of the total catch and being the dominant species. The estimated spider species diversity was 95%. Their densities were changed over time in the study, but they were highest in the second half of September and the first half of October of both years. The cluster analysis distinguished the two districts and the sites chosen. There was a relationship between humidity and rainfall and the active density of spiders; however, this association was not statistically significant. It is possible to increase the population of spiders in an area by reducing the number of activities detrimental to spiders and other useful arachnids. Spiders are considered effective agents of biological control throughout the world. The findings of the current study will help in the formulation of pest management techniques that can be implemented in cotton growing regions all over the world.
Climate change is expected to exert a large impact on the spatial distribution of insects, yet limited analyses are available for assessing the influences of climate change on the distribution of Libellula angelina (Odonata: Libellulidae), which hindered the development of conservation strategies for this critically threatened dragonfly species. Here, a consensus model (BIOCLIM, GAM, MaxEnt and Random Forest) and niche analysis approach were applied to predict the dynamic change of potential distribution areas and ecological niche for L. angelina under future climate change. Meanwhile, the important environmental variables affecting the potential distribution of L. angelina were identified. The results demonstrated that the potential distribution pattern and ecological niche of L. angelina will not shift significantly in face of future climate change, but its highly suitable area in southern Beijing (China), the western and southern South Korea, and the southern Honshu Island (Japan) will decrease constantly. Further analyses indicated that the human influence index (32.3% of variation) is the second highest factor in predicting the potential distribution of L . angelina , following the precipitation of warmest quarter (42.6% of variation). Based on the obtained results, we suggest that extensive cooperation among the countries (China, South Korea and Japan) be advocated to formulate the international conservation strategies, especially more attention and conservation efforts should be paid in those high-suitability areas of L. angelina to gain better protection efficiency, and proper artificial ecological restoration measures should also be exerted. Implication for insect conservation : Our results show that although the critically endangered dragonfly L. angelina will still stay the current niche under climate change, its suitable area (especially highly suitable area) will decrease significantly. Therefore, we suggest that more attention and conservation efforts should be implemented in those high-suitability areas to reduce the extinction risk of L. angelina .
The Po Plain (Northern Italy) is one of the most urbanized areas in Europe. In such a territory, where ecosystem degradation reached critical levels and the agricultural matrix is prevailingly intensive, small fragments of hilly oak-hornbeam forests still persist. Examples of well preserved forests of the Po Plain are those of the Monte Netto Regional Park that represents irreplaceable refuges for both sedentary and migratory species. In this paper we present a preliminary list of Coleoptera inhabiting the Park collected during 10 years of field surveys using several sampling techniques (hand netting, beating tray, sight-collecting and collecting under bark; water nets; litter reducers, light traps; aerial sweet-bait trap; cross-vane panel trap, pitfall traps, Malaise traps, window traps, and walking transects). Specific samplings were also made in tree hollows and by car-netting. To date we have identified 834 species belonging to 531 genera and 71 families (several specimens and some families are still undetermined). Among all the species identified, 31 were non-native while 202 were included in the Red List of Italian saproxylic beetles, 12 of which were in threatened category. The high beetle richness and the presence of many endangered species recorded during this survey, emphasises the conservation value of Monte Netto. Moreover, the discovery of species linked to old and stable forest systems, such as Osmoderma eremita, Oxylaemus cylindricus, Pycnomerus terebrans or Xylotrechus antilope suggests how, despite their small size and the fact that they are surrounded by agricultural land, the remaining forest patches of Monte Netto still possess a fair level of naturalness, especially in the internal areas of the larger plots. Future targeted research, also intended to cover other parts of Monte Netto, could increase our present knowledge; however, and at least in the number of families, we do not expect a substantial increase in species richness.
Damselflies and dragonflies (Order: Odonata) play important roles in both aquatic and terrestrial food webs and can serve as sentinels of ecosystem health and predictors of population trends in other taxa. The habitat requirements and limited dispersal of lotic damselflies make them especially sensitive to habitat loss and fragmentation. As such, landscape genomic studies of these taxa can help focus conservation efforts on watersheds with high levels of genetic diversity, local adaptation, and even cryptic endemism. Here, as part of the California Conservation Genomics Project (CCGP), we report the first reference genome for the American rubyspot damselfly, Hetaerina americana, a species associated with springs, streams and rivers throughout California. Following the CCGP assembly pipeline, we produced two de novo genome assemblies. The primary assembly includes 1,630,044,487 base pairs, with a contig N50 of 5.4 Mb, a scaffold N50 of 86.2 Mb, and a BUSCO completeness score of 97.6%. This is the seventh Odonata genome to be made publicly available and the first for the subfamily Hetaerininae. This reference genome fills an important phylogenetic gap in our understanding of Odonata genome evolution, and provides a genomic resource for a host of interesting ecological, evolutionary, and conservation questions for which the rubyspot damselfly genus Hetaerina is an important model system.
In recent decades, forest fires in the Mediterranean basin have been increasing in frequency, intensity, and the area burnt. Simultaneously, insects, a group with extraordinary biodiversity that provides vital ecosystem services such as pollination and decomposition, are undergoing a precipitous decline. Unfortunately, the impact of fire on arthropod communities has been poorly addressed despite the high diversity of taxonomic and functional arthropod groups. Responses to fire can differ considerably, depending on the life history and functional traits of the species. In the present study, we investigate the short-term impact of fire (three years after a blaze) on the abundance and species composition of soil arthropods in a burnt pine forest located in Ceuta (Spain, northwestern Africa). Soil arthropods were collected from pitfall traps in burnt and unburnt pine forest sampling points. In terms of total abundance per taxonomic order, Blattodea and Diptera were the only orders seemingly affected by the fire, whereas other arthropod groups (e.g., Araneae, Coleoptera, and Isopoda) showed no differences. In terms of species composition, Coleoptera and Formicidae (Hymenoptera) communities differed between burnt and unburnt sampling points, having more species associated with burnt areas than with unburnt ones. In burnt areas, some species from open areas built nests, fed in/on the ground, and dispersed over longer distances. Within the unburnt plots, we found more species in vegetated habitats, particularly those with shorter dispersal distances. We conclude that arthropod communities differ between burnt and unburnt sites and that the response of each taxon appears to be related to particular functional traits such as habitat preference (from open to forested landscapes) and ecological specialization (from generalist to specialist species).
The global-scale decline of animal biodiversity ('defaunation') represents one of the most alarming consequences of human impacts on the planet. The quantification of this extinction crisis has traditionally relied on the use of IUCN Red List conservation categories assigned to each assessed species. This approach reveals that a quarter of the world's animal species are currently threatened with extinction, and 1% have been declared extinct. However, extinctions are preceded by progressive population declines through time that leave demographic 'footprints' that can alert us about the trajectories of species towards extinction. Therefore, an exclusive focus on IUCN conservation categories, without consideration of dynamic population trends, may underestimate the true extent of the processes of ongoing extinctions across nature. In fact, emerging evidence (e.g. the Living Planet Report), reveals a widespread tendency for sustained demographic declines (an average 69% decline in population abundances) of species globally. Yet, animal species are not only declining. Many species worldwide exhibit stable populations, while others are even thriving. Here, using population trend data for >71,000 animal species spanning all five groups of vertebrates (mammals, birds, reptiles, amphibians and fishes) and insects, we provide a comprehensive global-scale assessment of the diversity of population trends across species undergoing not only declines, but also population stability and increases. We show a widespread global erosion of species, with 48% undergoing declines, while 49% and 3% of species currently remain stable or are increasing, respectively. Geographically, we reveal an intriguing pattern similar to that of threatened species, whereby declines tend to concentrate around tropical regions, whereas stability and increases show a tendency to expand towards temperate climates. Importantly, we find that for species currently classed by the IUCN Red List as 'non-threatened', 33% are declining. Critically, in contrast with previous mass extinction events, our assessment shows that the Anthropocene extinction crisis is undergoing a rapid biodiversity imbalance, with levels of declines (a symptom of extinction) greatly exceeding levels of increases (a symptom of ecological expansion and potentially of evolution) for all groups. Our study contributes a further signal indicating that global biodiversity is entering a mass extinction, with ecosystem heterogeneity and functioning, biodiversity persistence, and human well-being under increasing threat.
Records of 24 Curculionoidea species new for the Biebrza Basin in Northeastern Poland, including the Biebrza National Park and its buffer zone, are provided as a result of field studies in 2021-2022. Three more weevil species, unique or rare in Poland, were rediscovered in the Biebrza Basin after nearly 20 years, including Anthonomus rubripes GYLLENHAL previously thought to be extinct. The fauna of the Biebrza Basin comprises currently 505 species of Curculionoidea (Scolytinae excluded), being among the richest documented for protected areas in Northeastern Poland. Noteworthy and alarming is a great decrease in abundance of practically all hygrophilous weevil species observed in the Lower Biebrza, compared to results of previous surveys conducted in 1999-2004.
Behavioral manipulation (BM) is a multimodal control approach based on the interference with the stimuli mediating insect perception and interaction with the surroundings. BM could represent a win–win strategy for the management of vector-borne plant pathogens as the bacterium Xylella fastidiosa, since it could reduce the number of vectors alighting on host plants and, consequently, the chances for transmission to occur. In this review, we summarized current knowledge and highlighted gaps in information on (i) how insect vectors of X. fastidiosa in general, and more specifically the meadow spittlebug Philaenus spumarius, locate and accept the host plant; and (ii) how behavioral manipulation techniques could be applied to disrupt the vector–host plant interaction. Finally, we discussed how diverse BM strategies could be combined with other integrated pest management tools to protect olive groves from inoculation with the fastidious bacterium.
Los traspatios son relevantes para el humano ya que proveen alimento y pueden ser reservorios de biodiversidad. Sin embargo, estos agroecosistemas han sido poco estudiados debido a la enorme variación de tamaño, forma y manejo que presentan. El objetivo de este trabajo fue evaluar la abundancia y riqueza de artrópodos asociados a traspatios con dominancia de durazno Prunus persica (L.) Stokes en el centro de México, a lo largo de dos temporadas climáticas (lluvias y seca). Se muestrearon cinco traspatios dentro de una misma comunidad humana mediante trampas de caída (pitfall), las cuales fueron monitoreadas mensualmente durante 12 meses (mayo 2017–mayo 2018). Se colectaron 3,263 individuos pertenecientes a nueve órdenes identificados para 175 morfoespecies. Los órdenes más abundantes y con mayor riqueza en ambas temporadas fueron consistentemente Diptera, Coleoptera e Hymenoptera. La abundancia de individuos no presentó diferencias significativas entre traspatios ni entre temporadas. En el traspatio con densidades intermedias de árboles de duraznos, se presentó una menor diversidad, pero la riqueza de especies no fue significativamente diferente entre traspatios. La diversidad estimada en el presente estudio es más alta comparada con otros estudios en cultivos extensivos de durazno. Los traspatios son importantes para la conservación, no solo de especies apreciadas por el ser humano, sino que también funcionan como refugios de artrópodos, manteniendo abundancias parecidas incluso en épocas de estiaje como lo encontrado en este estudio. Esto sin contraponer la producción a pequeña escala de árboles frutales como lo son los duraznos criollos.
Biodiversity loss is a main challenge for agricultural sustainability. Major drivers include local management and landscape simplification. Therefore, conservation measures aim to increase organic agriculture, reduce pesticide use, and increase the proportion of semi-natural habitats (SNH). Yet, it is important to understand the effects of such measures. We investigate how arthropod biomass, taxa richness, and community composition in Malaise trap samples are affected by organic management, pesticide use, and SNH in the landscape. The 32 studied vineyards were chosen in a crossed design of management (organic vs. conventional) and pesticide use (regular vs. reduced) along a gradient of landscape composition. Pesticide reduction by 55% was obtained by including half of the vineyards with fungus-resistant grape (FRG) varieties. Malaise trap samples were weighed and arthropods identified using metabarcoding. Surprisingly, biomass was almost one-third higher in conventionally managed vineyards compared to organic ones. Taxa richness increased by more than one third when the proportion of SNH in a radius of 1,000 m in the surrounding landscape increased from zero to 50%. Diptera richness tended to be 4% higher in conventionally managed vineyards and the richness of Hymenoptera was 9% higher in FRG varieties. Community composition changed with the proportion of SNH and differed between organic and conventional management. Overall, organic viticulture was not effective to enhance the arthropod community, which was dominated by flying insects in our study. Agricultural policies should therefore rather preserve and promote SNH in the surrounding in order to promote arthropod biodiversity in viticultural landscapes.
Orthopterans are commonly encountered in rural, suburban, and urban landscapes and have charismatic songs that attract the public’s attention. These are ideal organisms for connecting the public with science and critical concepts in ecology and evolution, such as habitat conservation and climate change. In this review, we provide an overview of community science and review community science in orthopterans. Best practices for orthopteran community science are provided, with a focus on audio recordings and highlighting new ways in which scientists who study orthopterans can engage in community science.
Before the modern era, scientific discovery was commonly made by people who were not scientists by profession (Brenna 2011, Miller-Rushing et al. 2012). This began to change in the middle of the nineteenth century when science became highly academic, with greater “gatekeeping” of knowledge, and data collection became increasingly expensive. As a result, much of the knowledge gained during that time has been effectively withheld from non-scientists in difficult-to-obtain scientific journals, and there were few opportunities for the public to directly engage with scientific research. In recent years, there has been a concerted effort from the scientific community to change the way we engage with the public. These “citizen” or “community” science projects are filling gaps in the modern approach to scientific inquiry (Jordan et al. 2012, Toomey and Domroese 2013, Johnson et al. 2014). Here, we provide an overview of community science and highlight the exciting and unique role that community science can play in orthopteran research. We focus on how acoustic surveys can be used to study orthopteran biodiversity, provide best practices for orthopteran community science, and suggest future avenues for research.
Environmental transport and deposition of particulate matter (PM) associated with toxic chemicals has begun to receive attention as a source of risk to pollinators. For example, dust arising from manipulations of insecticide-treated seed has potential to exert toxic effects among non-target insects. Similarly, synthetic steroid growth promoters, antibiotics and multiple insecticides and parasiticides detected in fugitive beef cattle feedyard PM may also negatively impact pollinators since many of these chemicals have been detected on wildflowers and pollinators collected near beef cattle feedyards. Therefore, there is a need to assess risk to pollinators posed by deposition of agrochemical-laden PM, both in the field and the laboratory. Unfortunately, established laboratory methods for simulating PM exposure or toxicity associated with contaminated PM are few and highly situation-specific. Herein we describe development and use of a PM circulation system that can be employed to evaluate toxicity of agrochemical-contaminated PM in the laboratory under controlled conditions. Two model organisms (honeybees (Apis mellifera) and mason bees (Osmia lignaria)) were exposed to agrochemical-free PM in the circulator system, and post-exposure mortality was compared with controls. No significant differences in mortality between exposed and control bees were observed. Next, honeybees and mason bees were exposed to PM spiked with an insecticide known to exert toxic effects to pollinators (thiamethoxam). Bees experienced significantly higher mortality when exposed to thiamethoxam-laden PM at environmentally relevant concentrations as compared to bees exposed to agrochemical-free PM. These results confirm the validity of these methods for use in controlled laboratory PM toxicity tests and offer a source of positive and negative control groups for laboratory and field experiments examining exposure of pollinators to potentially toxic agrochemical-laden PM. This method facilitates generation of more realistic toxicity data than standard contact toxicity tests when pollinator exposure scenarios involve particulate-based agrochemicals or other toxic chemicals.
Pollinating insects are essential for food production. Both bee and non-bee pollinators are undergoing dramatic declines due to land use intensification and its consequences on native ecosystems. While interactions between crops and bee pollinators are well studied, our understanding of the pollination service provided by non-bee flower visitors including flies, ants, beetles and others is still limited. Moreover, the effects of landscape urbanization and changes in floral and nesting resource availability on the network structure of pollinators with both cultivated and wild plants have been poorly studied. We assessed which common bee and non-bee flower visitor groups dominate the interactions with both wild (e.g. Trifolium pratense, Taraxacum officinales) and cultivated plants (e.g. Fragaria ananassa, Cucurbita pepo) in urban community gardens in Berlin and Munich and explored how these interactions between flower visitor groups and plants change over the growing season. We further investigated the effect of changes in urbanization surrounding community gardens, and the availability of floral and nesting resources within gardens on the complexity (i.e. nestedness, linkage density, connectance) of interaction networks. We observed 20 focal plant species and 13 common bee and non-bee flower visitor groups in 30 urban community gardens. We found that dominant plant visitors changed over the growing season, with non-bee flower visitors including ants and flies as dominant early season visitors, and bee pollinators as important visitors later in the season. Nestedness of the flower visitor network increased with increases in floral richness in community gardens, while neither floral abundance nor the impervious surface surrounding the community gardens, garden size or the availability of nesting resources in gardens strongly influenced the flower visitor networks. Our findings suggest that high floral richness in community gardens may ensure the complexity and, thus, the stability of flower visitor networks. Findings further suggest that the role of non-bee flower visitors should be considered for pollination service provision especially in the shoulder seasons. Finally, our results emphasize that urban gardeners play a key role in mediating flower visitor interactions through their gardening practices.
Fighting insect pests is a major challenge for agriculture worldwide, and biological control and integrated pest management constitute well-recognised, cost-effective ways to prevent and overcome this problem. Bats are important arthropod predators globally and, in recent decades, an increasing number of studies have focused on the role of bats as natural enemies of agricultural pests. This review assesses the state of knowledge of the ecosystem services provided by bats as pest consumers at a global level and provides recommendations that may favour the efficiency of pest predation by bats. Through a systematic review, we assess evidence for predation, the top-down effect of bats on crops and the economic value of ecosystem services these mammals provide, describing the different methodological approaches used in a total of 66 reviewed articles and 18 agroecosystem types. We also provide a list of detailed conservation measures and management recommendations found in the scientific literature that may favour the delivery of this important ecosystem service , including actions aimed at restoring bat populations in agroecosystems. The most frequent recommendations include increasing habitat heterogeneity, providing additional roosts, and implementing laws to protect bats and reduce agrochemical use. However, very little evidence is available on the direct consequences of these practices on bat insectiv-ory in farmland. Additionally, through a second in-depth systematic review of scientific articles focused on bat diet and, as part of the ongoing European Cost Action project CA18107, we provide a complete list of 2308 documented interactions between bat species and their respective insect pest prey. These pertain to 81 bat species belonging to 36 different genera preying upon 760 insect pests from 14 orders in agroecosystems and other habitats such as forest or urban areas. The data set is publicly available and updatable.
Though often perceived as an environmentally-risky practice, biological control of invasive species can restore crop yields, ease land pressure and thus contribute to forest conservation. Here, we show how biological control against the mealybug Phenacoccus manihoti (Hemiptera) slows deforestation across Southeast Asia. In Thailand, this newly-arrived mealybug caused an 18% decline in cassava yields over 2009–2010 and an escalation in prices of cassava products. This spurred an expansion of cassava cropping in neighboring countries from 713,000 ha in 2009 to > 1 million ha by 2011: satellite imagery reveals 388%, 330%, 185% and 608% increases in peak deforestation rates in Cambodia, Lao PDR, Myanmar and Vietnam focused in cassava crop expansion areas. Following release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera) in 2010, mealybug outbreaks were reduced, cropping area contracted and deforestation slowed by 31–95% in individual countries. Hence, when judiciously implemented, insect biological control can deliver substantial environmental benefits.
Neonicotinoids and fipronil are the most widely used insecticides in the world. Previous studies showed that these compounds have high toxicity to a wide taxonomic range of non-target invertebrates. In rice cultivation, they are frequently used for nursery-box treatment of rice seedlings. The use of fipronil and neonicotinoid imidacloprid is suspected to be the main cause of population declines of red dragonflies, in particular Sympetrum frequens, because they have high lethal toxicity to dragonfly nymphs and the timing of the insecticides’ introduction in Japan (i.e., the late 1990s) overlapped with the sharp population declines. However, a causal link between application of these insecticides and population declines of the dragonflies remains unclear. Therefore, we estimated the amount of the insecticides applied for nursery-box treatment of rice seedlings and analyzed currently available information to evaluate the causality between fipronil and imidacloprid usage and population decline of S. frequens using Hill’s causality criteria. Based on our scoring of Hill’s nine criteria, the strongest lines of evidence were strength, plausibility, and coherence, whereas the weakest were temporality and biological gradient. We conclude that the use of these insecticides, particularly fipronil, was a major cause of the declines of S. frequens in Japan in the 1990s, with a high degree of certainty. The existing information and our analyses, however, do not allow us to exclude the possibility that some agronomic practices (e.g., midsummer drainage or crop rotation) that can severely limit the survival of aquatic nymphs also played a role in the dragonfly’s decline.
Electronic supplementary material
The online version of this article (10.1007/s11356-018-3440-x) contains supplementary material, which is available to authorized users.
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.
Insects provide critical ecosystem services to humanity, including biological control of pests. Particularly for invasive pests, biological control constitutes an environmentally sound and cost-effective management option. Following its 2008 invasion of Southeast Asia, biological control was implemented against the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) through the introduction and subsequent release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) in Thailand. In this study, we quantify yield benefits of mealybug biological control in Thailand’s cassava crop by using two different types of manipulative field trials: i.e., ‘physical exclusion’ cage trials and field-level ‘chemical exclusion’ assays. In cage trials with two popular cassava varieties, root yield and total dry matter (or ‘biological yield’) were a respective 4.0–4.2 times and 3.5–3.9 times higher in the presence of biological control. Extrapolating results from cage trials, biological control thus ensured an approximate yield gain of 5.3–10.0 T/ha for either variety. Under chemical exclusion trials, P. manihoti populations attained levels of 3266 ± 1021 cumulative mealybug-days (CMD) over a 10-month time period, and no longer impact yields. Moreover, under effective P. manihoti control, both root yield and biological yield increased with season-long CMD measures, and pest management interventions-including insecticide sprays-led to notable reductions in yield. This study is the first to show how biological control effectively downgrades the globally invasive P. manihoti to non-economic status and restores yields in Thailand’s cassava crop. Our work emphasizes the economic value of biological control, reveals how current P. manihoti populations do not necessarily cause yield penalties, and underlines the central importance of nature-based approaches in intensifying global agricultural production.
In order to study the in situ effects of the agricultural landscape and exposure to pesticides on honey bee health, sixteen honey bee colonies were placed in four different agricultural landscapes. Those landscapes were three agricultural areas with varying levels of agricultural intensity (AG areas) and one non-agricultural area (NAG area). Colonies were monitored for different pathogen prevalence and pesticide residues over a period of one year. RT-qPCR was used to study the prevalence of seven different honey bee viruses as well as Nosema apis in colonies located in different agricultural systems with various intensities of soybean, corn, sorghum and cotton production. Populations of the parasitic mite Varroa destructor were also extensively monitored. Comprehensive MS-LC pesticide residue analyses were performed on samples of wax, honey, foragers, winter bees, dead bees and crop flowers for each apiary and location. Significantly higher level of varroa loads were recorded in colonies of the AG areas, but this at least partly correlated with increased colony size and did not necessarily result from exposure to pesticides. Infections of two viruses (DWVa, ABPV) and Nosema apis varied among the four studied locations. The urban location significantly elevated colony pathogen loads, while AG locations significantly benefited and increased the colony weight gain. Cotton and sorghum flowers contained high concentrations of insecticide including neonicotinoids, while soybean and corn had less pesticide residues. Several events of pesticide toxicity were recorded in the AG areas, and high concentrations of neonicotinoid insecticides were detected in dead bees.
Varroa destructor is one of the most common parasites of honey bee colonies and is considered as a possible co-factor for honey bee decline. At the same time, the use of pesticides in intensive agriculture is still the most effective method of pest control. There is limited information about the effects of pesticide exposure on parasitized honey bees. Larval ingestion of certain pesticides could have effects on honey bee immune defense mechanisms, development and metabolic pathways. Europe and America face the disturbing phenomenon of the disappearance of honey bee colonies, termed Colony Collapse Disorder (CCD). One reason discussed is the possible suppression of honey bee immune system as a consequence of prolonged exposure to chemicals. In this study, the effects of the neonicotinoid thiamethoxam on honey bee, Apis mellifera carnica, pupae infested with Varroa destructor mites were analyzed at the molecular level. Varroa-infested and non-infested honey bee colonies received protein cakes with or without thiamethoxam. Nurse bees used these cakes as a feed for developing larvae. Samples of white-eyed and brown-eyed pupae were collected. Expression of 17 immune-related genes was analyzed by real-time PCR. Relative gene expression in samples exposed only to Varroa or to thiamethoxam or simultaneously to both Varroa and thiamethoxam was compared. The impact from the consumption of thiamethoxam during the larval stage on honey bee immune related gene expression in Varroa-infested white-eyed pupae was reflected as down-regulation of spaetzle, AMPs abaecin and defensin-1 and up-regulation of lysozyme-2. In brown-eyed pupae up-regulation of PPOact, spaetzle, hopscotch and basket genes was detected. Moreover, we observed a major difference in immune response to Varroa infestation between white-eyed pupae and brown-eyed pupae. The majority of tested immune-related genes were upregulated only in brown-eyed pupae, while in white-eyed pupae they were downregulated.
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.
Several anthropogenic contaminants, including pesticides and heavy metals, can affect honey bee health. The effects of mixtures of heavy metals and pesticides are rarely studied in bees, even though bees are likely to be exposed to these contaminants in both agricultural and urban environments. In this study, the lethal toxicity of Cr alone and in combination with the neonicotinoid insecticide clothianidin and the ergosterol-biosynthesis-inhibiting fungicide propiconazole was assessed in Apis mellifera adults. The LD50 and lowest benchmark dose of Cr as Cr(NO3)3, revealed a low acute oral toxicity on honey bee foragers (2049 and 379 mg L(-1), respectively) and the Cr retention (i.e. bee ability to retain the heavy metal in the body) was generally low compared to other metals. A modified method based on the binomial proportion test was developed to analyse synergistic and antagonistic interactions between the three tested contaminants. The combination of an ecologically-relevant field concentration of chromium with clothianidin and propiconazole did not increase bee mortality. On the contrary, the presence of Cr in mixture with propiconazole elicited a slight antagonistic effect.
Global demands for agricultural and forestry products provide economic incentives for deforestation across the tropics. Much of this deforestation occurs with a lack of information on the spatial distribution of benefits and costs of deforestation. To inform global sustainable land-use policies, we combine geographic information systems (GIS) with a meta-analysis of ecosystem services (ES) studies to perform a spatially explicit analysis of the trade-offs between agricultural benefits, carbon emissions, and losses of multiple ecosystem services because of tropical deforestation from 2000 to 2012. Even though the value of ecosystem services presents large inherent uncertainties, we find a pattern supporting the argument that the externalities of destroying tropical forests are greater than the current direct economic benefits derived from agriculture in all cases bar one: when yield and rent potentials of high-value crops could be realized in the future. Our analysis identifies the Atlantic Forest, areas around the Gulf of Guinea, and Thailand as areas where agricultural conversion appears economically efficient, indicating a major impediment to the long-term financial sustainability of Reducing Emissions from Deforestation and forest Degradation (REDD+) schemes in those countries. By contrast, Latin America, insular Southeast Asia, and Madagascar present areas with low agricultural rents (ARs) and high values in carbon stocks and ES, suggesting that they are economically viable conservation targets. Our study helps identify optimal areas for conservation and agriculture together with their associated uncertainties, which could enhance the efficiency and sustainability of pantropical land-use policies and help direct future research efforts.
Significance
The strong focus on species extinctions, a critical aspect of the contemporary pulse of biological extinction, leads to a common misimpression that Earth’s biota is not immediately threatened, just slowly entering an episode of major biodiversity loss. This view overlooks the current trends of population declines and extinctions. Using a sample of 27,600 terrestrial vertebrate species, and a more detailed analysis of 177 mammal species, we show the extremely high degree of population decay in vertebrates, even in common “species of low concern.” Dwindling population sizes and range shrinkages amount to a massive anthropogenic erosion of biodiversity and of the ecosystem services essential to civilization. This “biological annihilation” underlines the seriousness for humanity of Earth’s ongoing sixth mass extinction event.
Managed honey bee colony losses are of concern in the USA and globally. This survey, which documents the rate of colony loss in the USA during the 2015–2016 season, is the tenth report of winter losses, and the fifth of summer and annual losses. Our results summarize the responses of 5725 valid survey respondents, who collectively managed 427,652 colonies on 1 October 2015, an estimated 16.1% of all managed colonies in the USA. Responding beekeepers reported a total annual colony loss of 40.5% [95% CI 39.8–41.1%] between 1 April 2015 and 1 April 2016. Total winter colony loss was 26.9% [95% CI 26.4–27.4%] while total summer colony loss was 23.6% [95% CI 23.0–24.1%], making this the third consecutive year when summer losses have approximated to winter losses. Across all operation types, 32.3% of responding beekeepers reported no winter losses. Whilst the loss rate in the winter of 2015–2016 was amongst the lowest winter losses recorded over the ten years this survey has been conducted, 59.0% (n = 3378) of responding beekeepers had higher losses than they deemed acceptable.
Queen health is crucial to colony survival of honeybees, since reproduction and colony growth rely solely on the queen. Queen failure is considered a relevant cause of colony losses, yet few data exist concerning effects of environmental stressors on queens. Here we demonstrate for the first time that exposure to field-realistic concentrations of neonicotinoid pesticides can severely affect the immunocompetence of queens of western honeybees (Apis mellifera L.). In young queens exposed to thiacloprid (200 µg/l or 2000 µg/l) or clothianidin (10 µg/l or 50 µg/l), the total hemocyte number and the proportion of active, differentiated hemocytes was significantly reduced. Moreover, functional aspects of the immune defence namely the wound healing/melanisation response, as well as the antimicrobial activity of the hemolymph were impaired. Our results demonstrate that neonicotinoid insecticides can negatively affect the immunocompetence of queens, possibly leading to an impaired disease resistance capacity.
Colony losses of managed honeybees have raised a major concern, and surveys of colony losses were conducted around the globe to understand the apicultural situation. Up to now, most studies have focused on the mortality of the Western honeybee (Apis mellifera); however, little is known about the mortality of its eastern counterpart—the Eastern honeybee (Apis cerana). Here, we report the survey results of A. cerana colony losses in three consecutive years (2011–2012, 2012–2013, and 2013–2014) in China. Colony losses were low overall (12.8%, 95% CI 11.9–13.7%) but varied among years, provinces, and types of apiaries. We used generalized linear mixed effects models to estimate the effects of possible risk factors and found that queen problems (queenless or drone-laying queens) were associated with colony losses. Further analyses showed that differences in mortality among different types of apiaries may be contributable to the differences in queen problems. This is the first survey of colony losses of A. cerana.
Safeguarding crop productivity by protecting crops from pest attacks entails the wide use of plant protection products that provide a quick, easy and cheap solution. The objective of this study is to understand the effects of insecticides used in agriculture on non-target butterflies, specifically on the families Lycaenidae, Nymphalidae, Hesperiidae, and Papilionidae. To achieve this goal, a formal systematic review was performed according to European Food Safety Authority (EFSA) guidelines, by entering a combination of keywords on 3 online databases. Three reviewers independently extracted information on study characteristics and quality. The main results were collected and grouped by the insecticide used, butterflies species and family, and endpoints. The output was valuable but heterogeneous as the endpoints and methodologies of the studies reviewed were different. Few experimental studies on the effects of insecticides on the most common butterfly families have been published. Naled and permethrin are the most commonly used insecticides in the experiments, whilst the target organisms of these studies are Vanessa cardui, Danaus plexippus, Heliconius charitonius, belonging to the Nymphalidae family, and Eumaeus atala, belonging to the Lycaenidae family; the effects were evaluated on all developmental stages, with special attention to the larval phase. This systematic review highlights the need for more studies on the effects of chemical insecticides on non-target Lepidoptera in light of their ecological importance and the extensive use of these chemical products.
The use of biological control agents to control pests is an alternative to pesticides and a tool to manage invasive alien species. However, biocontrol agents can themselves become invasive species under certain conditions. The harlequin ladybird ( Harmonia axyridis ) is a native Asian biocontrol agent that has become a successful invader. We reviewed articles containing “ Harmonia axyridis ” to gather information on its presence and surveyed entomologists researching Coccinellidae around the world to investigate further insights about the current distribution, vectors of introduction, habitat use and threats this species pose. The harlequin ladybird has established populations in at least 59 countries outside its native range. Twenty six percent of the surveyed scientists considered it a potential threat to native Coccinellidae. Published studies and scientists suggest Adalia bipunctata , native to Europe, is under the highest risk of population declines. Strict policies should be incorporated to prevent its arrival to non-invaded areas and to prevent further expansion range. Managing invasive species is a key priority to prevent biodiversity loss and promote ecosystem services.
Achieving sustainable crop production while feeding an increasing world population is one of the most ambitious challenges of this century1. Meeting this challenge will necessarily imply a drastic reduction of adverse environmental effects arising from agricultural activities2. The reduction of pesticide use is one of the critical drivers to preserve the environment and human health. Pesticide use could be reduced through the adoption of new production strategies3, 4, 5; however, whether substantial reductions of pesticide use are possible without impacting crop productivity and profitability is debatable6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17. Here, we demonstrated that low pesticide use rarely decreases productivity and profitability in arable farms. We analysed the potential conflicts between pesticide use and productivity or profitability with data from 946 non-organic arable commercial farms showing contrasting levels of pesticide use and covering a wide range of production situations in France. We failed to detect any conflict between low pesticide use and both high productivity and high profitability in 77% of the farms. We estimated that total pesticide use could be reduced by 42% without any negative effects on both productivity and profitability in 59% of farms from our national network. This corresponded to an average reduction of 37, 47 and 60% of herbicide, fungicide and insecticide use, respectively. The potential for reducing pesticide use appeared higher in farms with currently high pesticide use than in farms with low pesticide use. Our results demonstrate that pesticide reduction is already accessible to farmers in most production situations. This would imply profound changes in market organization and trade balance.
The widespread use of systemic neonicotinoid insecticides in agriculture results first in contamination of the soil of the treated crops, and secondly in the transfer of residues to the aquatic environment. The high toxicity of these insecticides to aquatic insects and other arthropods has been recognized, but there is little awareness of the impacts these chemicals have on aquatic environments and the ecosystem at large. Recent monitoring studies in several countries, however, have revealed a worldwide contamination of creeks, rivers and lakes with these insecticides, with residue levels in the low µg/L (ppb) range. The current extent of aquatic contamination by neonicotinoids is reviewed first, and the findings contrasted with the known acute and chronic toxicity of neonicotinoids to various aquatic organisms. Impacts on populations and aquatic communities, mostly using mesocosms, are reviewed next to identify the communities most at risk from those that undergo little or no impact. Finally, the ecological links between aquatic and terrestrial organisms are considered. The consequences for terrestrial vertebrate species that depend mainly on this food source are discussed together with impacts on ecosystem function. Gaps in knowledge stem from difficulties in obtaining long-term experimental data that relates the effects on individual organisms to impacts on populations and ecosystems. The paper concludes with a summary of findings and the implications they have for the larger ecosystem.
The butterfly fauna of lowland Northern California has exhibited a marked decline in recent years that previous studies have attributed in part to altered climatic conditions and changes in land use. Here, we ask if a shift in insecticide use towards neonicotinoids is associated with butterfly declines at four sites in the region that have been monitored for four decades. A negative association between butterfly populations and increasing neonicotinoid application is detectable while controlling for land use and other factors, and appears to be more severe for smaller-bodied species. These results suggest that neonicotinoids could influence non-target insect populations occurring in proximity to application locations, and highlights the need for mechanistic work to complement long-term observational data.
The threats of old are still the dominant drivers of current species loss, indicates an analysis of IUCN Red List data by Sean Maxwell and colleagues.
We calculated a Living Planet Index (LPI) for the Netherlands, based on 361 animal species from seven taxonomic groups occurring in terrestrial and freshwater habitats. Our assessment is basically similar to the global LPI, but the latter includes vertebrate species and trends in population abundance only. To achieve inferences on trends in biodiversity more generally, we added two insect groups (butterflies and dragonflies) and added occupancy trends for species for which we had no abundance trends available.
According to the LPI, the state of biodiversity has slightly increased from 1990 to 2014. However, large differences exist between habitat types. We found a considerable increase in freshwater animal populations, probably because of improvement of chemical water quality and rehabilitation of marshland habitats. We found no trend in the LPI for woodland populations. In contrast, populations in farmland and open semi-natural habitats (coastal dunes, heathland and semi-natural grassland) declined, which we attribute to intensive agricultural practices and nitrogen deposition, respectively. The LPI shows that, even in a densely populated western European country, ongoing loss of animal biodiversity is not inevitable and may even be reversed if adequate measures are taken. Our approach enabled us to produce summary statistics beyond the level of species groups to monitor the state of biodiversity in a clear and consistent way.
The decline of pollinators worldwide is of growing concern and has been related to the use of plant protecting chemicals. Most studies have focused on three neonicotinoid insecticides, clothianidin, imidacloprid and thiamethoxam, currently subject to a moratorium in the EU. Here we focus on thiacloprid, a widely used cyano-substituted neonicotinoid thought to be less toxic to honey bees and of which use has increased in the last years. Honey bees (Apis mellifera carnica) were exposed chronically to thiacloprid in the field for several weeks at a sublethal concentration. Foraging behavior, homing success, navigation performance, and social communication were impaired, and thiacloprid residue levels increased both in the foragers and the nest mates over time. The effects observed in the field were not due to a repellent taste of the substance. For the first time, we present the necessary data for the risk evaluation of thiacloprid taken up chronically by honey bees in field conditions.
Recent efforts to evaluate the contribution of neonicotinoid insecticides to worldwide pollinator declines have focused on honey bees and the chronic levels of exposure experienced when foraging on crops grown from neonicotinoid-treated seeds. However, few studies address non-crop plants as a potential route of pollinator exposure to neonicotinoid and other insecticides. Here we show that pollen collected by honey bee foragers in maize- and soybean-dominated landscapes is contaminated throughout the growing season with multiple agricultural pesticides, including the neonicotinoids used as seed treatments. Notably, however, the highest levels of contamination in pollen are pyrethroid insecticides targeting mosquitoes and other nuisance pests. Furthermore, pollen from crop plants represents only a tiny fraction of the total diversity of pollen resources used by honey bees in these landscapes, with the principle sources of pollen originating from non-cultivated plants. These findings provide fundamental information about the foraging habits of honey bees in these landscapes.
Distribution in France and Corsica of species belonging to families Scarabaeidae, Aphodiidae, Aegialiidae, Hybosoridae, Ochodaeidae, Trogidae, Geotrupidae and Pachypodidae.
For each species is given: taxonomy, size of individuals, distribution in France, distribution in the world, biology, and phenology. Each species with a distribution map.
We previously characterized and quantified the influence of land use on survival and productivity of colonies positioned in six apiaries and found that colonies in apiaries surrounded by more land in uncultivated forage experienced greater annual survival, and generally more honey production. Here, detailed metrics of honey bee health were assessed over three years in colonies positioned in the same six apiaries. The colonies were located in North Dakota during the summer months and were transported to California for almond pollination every winter. Our aim was to identify relationships among measures of colony and individual bee health that impacted and predicted overwintering survival of colonies. We tested the hypothesis that colonies in apiaries surrounded by more favorable land use conditions would experience improved health. We modeled colony and individual bee health indices at a critical time point (autumn, prior to overwintering) and related them to eventual spring survival for California almond pollination. Colony measures that predicted overwintering apiary survival included the amount of pollen collected, brood production, and Varroa destructor mite levels. At the individual bee level, expression of vitellogenin, defensin1, and lysozyme2 were important markers of overwinter survival. This study is a novel first step toward identifying pertinent physiological responses in honey bees that result from their positioning near varying landscape features in intensive agricultural environments.
Several reports suggested that rice seedling nursery-box application of some systemic insecticides (neonicotinoids and fipronil) is the cause of the decline in dragonfly species noted since the 1990s in Japan. We conducted paddy mesocosm experiments to investigate the effect of the systemic insecticides clothianidin, fipronil and chlorantraniliprole on rice paddy field biological communities. Concentrations of all insecticides in the paddy water were reduced to the limit of detection within 3 months after application. However, residuals of these insecticides in the paddy soil were detected throughout the experimental period. Plankton species were affected by clothianidin and chlorantraniliprole right after the applications, but they recovered after the concentrations decreased. On the other hand, the effects of fipronil treatment, especially on Odonata, were larger than those of any other treatment. The number of adult dragonflies completing eclosion was severely decreased in the fipronil treatment. These results suggest that the accumulation of these insecticides in paddy soil reduces biodiversity by eliminating dragonfly nymphs, which occupy a high trophic level in paddy fields.
Biological control is a valuable and effective strategy for controlling arthropod pests and has been used extensively against invasive arthropods. As one approach for control of invasives, exotic natural enemies from the native range of a pest are introduced to areas where control is needed. Classical biological control began to be used in the late 1800s and its use increased until, beginning in 1983, scientists began raising significant concerns and questions about nontarget and indirect effects that can be caused by these introductions. In recent years, similar issues have been raised about augmentative use of exotic natural enemies. Subsequently, international guidelines, national regulations and scientific methods being used for exotic natural enemies in biological control have changed to require appropriate specificity testing, risk assessment and regulatory oversight before exotic natural enemies can be released. National and international standards aimed at minimizing risk have increased awareness and promoted more careful consideration of the costs and benefits associated with biological control. The barriers to the implementation of classical and augmentative biological control with exotic natural enemies now are sometimes difficult and, as a consequence, the numbers of classical biological control programs and releases have decreased significantly. Based in part on this new, more careful approach, classical biological control programs more recently undertaken are increasingly aimed at controlling especially damaging invasive arthropod pests that otherwise cannot be controlled. We examine evidence for these revised procedures and regulations aimed at increasing success and minimizing risk. We also discuss limitations linked to the apparent paucity of post-introduction monitoring and inherent unpredictability of indirect effects.
Queen health is closely linked to colony performance in honey bees as a single queen is normally responsible for all egg laying and brood production within the colony. In the U. S. in recent years, queens have been failing at a high rate; with 50% or greater of queens replaced in colonies within 6 months when historically a queen might live one to two years. This high rate of queen failure coincides with the high mortality rates of colonies in the US, some years with >50% of colonies dying. In the current study, surveys of sperm viability in US queens were made to determine if sperm viability plays a role in queen or colony failure. Wide variation was observed in sperm viability from four sets of queens removed from colonies that beekeepers rated as in good health (n = 12; average viability = 92%), were replacing as part of normal management (n = 28; 57%), or where rated as failing (n = 18 and 19; 54% and 55%). Two additional paired set of queens showed a statistically significant difference in viability between colonies rated by the beekeeper as failing or in good health from the same apiaries. Queens removed from colonies rated in good health averaged high viability (ca. 85%) while those rated as failing or in poor health had significantly lower viability (ca. 50%). Thus low sperm viability was indicative of, or linked to, colony performance. To explore the source of low sperm viability, six commercial queen breeders were surveyed and wide variation in viability (range 60-90%) was documented between breeders. This variability could originate from the drones the queens mate with or temperature extremes that queens are exposed to during shipment. The role of shipping temperature as a possible explanation for low sperm viability was explored. We documented that during shipment queens are exposed to temperature spikes (<8 and > 40°C) and these spikes can kill 50% or more of the sperm stored in queen spermathecae in live queens. Clearly low sperm viability is linked to colony performance and laboratory and field data provide evidence that temperature extremes are a potential causative factor.
Minimizing the impact of invasive alien species (IAS) on islands and elsewhere requires researchers to provide cogent information on the environmental and socioeconomic consequences of IAS to the public and policy makers. Unfortunately, this information has not been readily available owing to a paucity of scientific research and the failure of the scientific community to make their findings readily available to decision makers. This review explores the vulnerability of islands to biological invasion, reports on environmental and socioeconomic impacts of IAS on islands and provides guidance and information on technical resources that can help minimize the effects of IAS in island ecosystems. This assessment is intended to provide a holistic perspective on islandIAS dynamics, enable biologists and social scientists to identify information gaps that warrant further research and serve as a primer for policy makers seeking to minimize the impact of IAS on island systems. Case studies have been selected to reflect the most scientifically-reliable information on the impacts of IAS on islands. Sufficient evidence has emerged to conclude that IAS are the most significant drivers of population declines and species extinctions in island ecosystems worldwide. Clearly, IAS can also have significant socioeconomic impacts directly (for example human health) and indirectly through their effects on ecosystem goods and services.These impacts are manifest at all ecological levels and affect the poorest, as well as richest, island nations.The measures needed to prevent and minimize the impacts of IAS on island ecosystems are generally known. However, many island nations and territories lack the scientific and technical information, infrastructure and human and financial resources necessary to adequately address the problems caused by IAS. Because every nation is an exporter and importer of goods and services, every nation is also a facilitator and victim of the invasion of alien species. Wealthy nations therefore need to help raise the capacity of island nations and territories to minimize the spread and impact of IAS.
Significance
In 2014, a presidential memorandum called for an assessment of the nation’s pollinators, in response to growing awareness of their economic importance and recent declines. We assess, for the first time to our knowledge, the status and trends of wild bee abundance and their potential impacts on pollination services across the United States. We develop national maps of wild bee abundance, report land-use–driven changes over time, and relate them to trends in agricultural demand for pollination. We estimate uncertainty in the findings, so future research can target the least-understood regions and topics. Our findings can also help focus conservation efforts where declines in bee abundance are most certain, especially where agricultural demand for pollination services is growing.
Concerns about the rapid and severe declines of many bumble bee (Bombus spp.) species in Europe, and more recently North America, have spurred research into the extent and possible causes for these losses. Drawing conclusions has been difficult due to a lack of long-term data, especially for specific regions that may have different factors at play than the global trend. In this study, 150 years of Bombus records in the state of New Hampshire from the University of New Hampshire Insect Collection were examined. This allowed for changes in abundance and distribution to be tracked over time, with focus on species designated of greatest conservation need by NH Fish & Game Department. Floral records also provided insight into the diet breadth of these species, which may affect their vulnerability. Evidence of drastic decline was found in Bombus affinis, Bombus fervidus, and Bombus terricola, as well as significant decline in Bombus vagans with data suggesting it has been ecologically replaced by Bombus impatiens over time. We suggest Bombus vagans receive future conservation consideration. Our analyses found a severe constriction of the geographic range of Bombus terricola to high elevation regions in the latter half of the 20th century, and its role as pollinator of several alpine plants necessitates immediate conservation action.
Classical biological control using insects has led to the partial or complete control of at least 226 invasive insect and 57 invasive weed species worldwide since 1888. However, at least ten introductions of biological control agents have led to unintended negative consequences and these cases have led to a focus on risk that came to dominate the science and practice of classical biological control by the 1990s. Based upon historical developments in the field we consider that the era of focus on benefits began in 1888 and that it was supplanted by an era in which the focus was on risks during the 1990s. This paradigm shift greatly improved the safety of biological control releases but also led to a decline in the number of introductions, probably resulting in opportunity costs. We note here the development of a third paradigm: one in which the benefits and risks of biological control are clearly and explicitly balanced so that decisions can be made that maximize benefits while minimizing risks.
Agriculture is the largest contributor to biodiversity loss with expanding impacts due to changing consumption patterns and growing populations. Agriculture destroys biodiversity by converting natural habitats to intensely managed systems and by releasing pollutants, including greenhouses gases. Food value chains further amplify impacts including through energy use, transport and waste. Reducing the food system’s toll on biodiversity is a critical challenge. The ‘sparing or sharing’ debate contrasts two response pathways: inte