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The Global Decline of Dung Beetles
Abstract
The main threats to insects are the expansion and intensification of agriculture, resulting in the loss or degradation of their habitats; excessive chemical contamination; the spread of invasive species; and global climate change. In the tropics, massive deforestation and agricultural intensification and expansion play a major role in the loss of biodiversity. The same threats apply to the dung beetles which have co-evolved for many millions of years in close association with the vertebrates whose dung they exploit. The extinction or scarcity of dung producers, especially mammalian herbivores and omnivores, can result in significant, detrimental changes in the composition of dung beetle assemblages. By manipulating, redistributing and degrading feces, dung beetles play a major role in the functioning of ecosystems. Their contributions include the replenishment of soil nutrients through the burial of feces, soil bioturbation that facilitates plant growth, and also the secondary dispersal of seeds. These ecological functions render important ecosystem services to humans, such as the biological control of livestock pests, reduction of greenhouse gas emissions from livestock, and soil enrichment through nutrient replenishment and the boosting of soil organic matter levels.
Numerous studies have reported the decline of dung beetles in various parts of the world, especially in the last 30 years. The gradual abandonment of traditional mixed grazing in Europe has led to the depletion of the trophic resources available to dung beetles. This abandonment has led to the reforesting of the landscape, which is detrimental to species of open habitats. These environmental changes have coincided with the increased use of veterinary parasiticides, whose residues often retain their insecticidal properties after defecation. Some residues can cause the near-immediate death of dung beetles while other residues can cause a greater or lesser degree of paralysis of the muscles of adults. This reduces their ability to locate feces, as well as decreasing female fertility and causing significant mortality of larvae, leading to a gradual and sometimes rapid decline in the number of individuals. The routine use of these parasiticides over long periods results in the decimation of exposed dung beetle populations and a reduction in their overall functional efficiency, leading in the long term to the accumulation of dry dung on the ground. The same effects have been observed on dung beetles after the regular use of some selective herbicides to prevent the invasion of pastures by bushy vegetation and forest trees.
The massive destruction and degradation of tropical forests has badly impacted their particularly diverse dung beetle faunas. Many forest dwelling dung beetles are in a precarious situation as most species have been unable to adapt to the grossly simplified grassy pasture habitats or the remaining fragmented and/or degraded forest habitats. In addition, the elimination or population crashes of many large forest mammals due to intensive hunting have resulted in the loss or scarcity of their feces for exploitation by forest dung beetles. The newly pastured areas and other simplified ecosystems are home to a very impoverished fauna, partly made up of exotic species intentionally introduced to compensate for the deficiency of ecosystem services. However, these introduced species can become invasive and compete with native dung beetles.
... These beetles provide many ecological services in pastures by their use of large volumes of dung for feeding as adults and larvae. Among the most important services, are promotion of grass growth, reduction of nutrient loss, increase in soil fertility and productivity, reduction of pest fly populations, destruction of eggs and cysts of livestock intestinal parasites, and reduction in greenhouse gas emissions (Nichols et al. 2008;Lumaret et al. 2020). ...
... These localities have suffered serious environmental degradation, mainly due to changes in the traditional use of land and crops, illegal deforestation, as well as the shift from large, extensive farms to small ranches with intensive agriculture or livestock (Hoffmann 1993), combined with uncontrolled chemical applications to reduce pasture weeds and aggressive techniques to eliminate livestock parasites (Martínez & Cruz 2009). The negative effect on dung beetle populations of veterinary drugs (Lumaret et al. 2012) and herbicides ) must be taken into account (Lumaret et al. 2020). For example, in Cuiyachapa and Llano de las Flores, the pastures are located in rural areas where these chemicals were not applied, and the species richness and abundance of dung beetles were the highest recorded. ...
... Given the multiple ecosystem services provided by dung beetles in pastures (Lumaret et al. 2020), studies on phenology and reproductive cycles, as well as ecotoxicological studies, are essential tools for implementing their conservation. ...
The phenology and reproductive cycles of seven Mexican Aphodiini dung beetles are studied. The highest abundances of individuals occurred during the wet and warm season of the year, coinciding with the long summer. Their abundance is reduced or beetles are in diapause, depending on the species, during the dry and cold months that mainly corresponded to winter. Five species are univoltine, and females and males emerge mature after the first rains arrive, reproduce and then they enter diapause until the following year. One species is bivoltine and is found from the beginning of the wet season until the onset of winter. The other species is multivoltine and found almost all year round, although the highest abundances are found during the summer when generations overlap. The abundances of three of the species occurring at different localities are compared.
... As a consequence, spatial autocorrelation is a general property of ecological variables (Legendre, 1993) and natural distributions of species (Condit et al., 2000;McGill, 2010McGill, , 2011aMay et al., 2019). However, many of the statistical methods used in ecology often assume sample independence, for which reason spatial autocorrelation can be considered a source of noise in studies related to the estimation and monitoring of biological diversity (Lobo and Martín-et al., 2017;Giménez-Gómez et al., 2020;Lumaret et al., 2020). As a consequence, they often present a spatially structured distribution that is driven by the food resources they exploit (Cambefort, 1991;Hanski, 1991;Marsh et al., 2013;França et al., 2016França et al., , 2018Noriega et al., 2021). ...
... Furthermore, the Scarabaeinae dung beetles are recognized for their provision of key ecosystem services thanks to traits derived from their natural history, such as cleaning of the soil surface, bioturbation, nutrient recycling and soil fertilization, suppression and dispersion of parasites and pests, and mitigation of greenhouse gas emissions, among others (Nichols et al., 2008;Iwasa et al., 2015;deCastro-Arrazola et al., 2020;Lumaret et al., 2020). The environmental services derived from dung beetle activity have a high economic value for different productive sectors, but particularly for livestock production (Beynon et al., 2015;López-Collado et al., 2017;Lumaret et al., 2020). ...
... Furthermore, the Scarabaeinae dung beetles are recognized for their provision of key ecosystem services thanks to traits derived from their natural history, such as cleaning of the soil surface, bioturbation, nutrient recycling and soil fertilization, suppression and dispersion of parasites and pests, and mitigation of greenhouse gas emissions, among others (Nichols et al., 2008;Iwasa et al., 2015;deCastro-Arrazola et al., 2020;Lumaret et al., 2020). The environmental services derived from dung beetle activity have a high economic value for different productive sectors, but particularly for livestock production (Beynon et al., 2015;López-Collado et al., 2017;Lumaret et al., 2020). The use of the Scarabaeinae as an indicator group confers different advantages, particularly from a methodological point of view: their natural history is well known, their taxonomy is relatively accessible, they can be easily collected using standardized methods, they respond quickly to disturbance, they are correlated with other taxa (for example, terrestrial mammals) and their sampling is highly effective in terms of cost-benefit (Favila and Halffter, 1997;Spector, 2006;Gardner et al., 2008;Andrade et al., 2013;Raine et al., 2019;Ferreira et al., 2020). ...
Spatial autocorrelation is a general property of ecological variables. Since many of the statistical methods used in ecology often assume sample independence, spatial clustering is considered a source of noise in studies related to the estimation and monitoring of biological diversity. Spatial autocorrelation was assessed herein in a Mexican Scarabaeinae dung beetle ensemble. Dung beetles where sampled using 1,240 pitfall traps baited with human feces. Response variables such as Hill numbers and abundance (number of individuals by trap) were analyzed using the Moran's I. A total of 3,198 dung beetles were collected, belonging to 67 species. Sample coverage suggested that the dung beetle survey was close to capture the true diversity of the ensemble, providing robust statistical inferences for subsequent analyses. All the ensemble level metrics (species richness, Shannon-Wiener diversity, Simpson diversity and abundance) were spatially autocorrelated. The species level analyses suggested that the number of individuals for 22 Scarabaeinae species was spatially clustered, while 33 dung beetle species were randomly distributed. Therefore, the patterns of spatial autocorrelation at ensemble level are suggested to mask the inherent patterns of autocorrelation of the individual species. Since spatial clustering in dung beetles is thought to be promoted by several dung beetle individuals co-occurring to exploit similar food resources, the bait type used to collect Scarabaeinae is proposed to have a considerable influence on the patterns of spatial autocorrelation. Consequently, trap spacing design could be irrelevant to ensure the avoidance of spatial autocorrelation in Scarabaeinae, while the use of methodologies that guarantee adequate representation of the different trophic guilds of Scarabaeinae could be of greater importance for biodiversity assessment and monitoring.
... Según Sánchez-Bayo y Wyckhuys (2019) y Lumaret et al. (2022), los principales factores de la disminución de los insectos son la pérdida de hábitat, debido en particular al desarrollo de la agricultura intensiva, la contaminación relacionada principalmente con el uso de medicamentos y plaguicidas, y la introducción de especies invasoras que compiten con las especies locales y el cambio climático. ...
... La magnitud de la perturbación depende del tamaño de los fragmentos y de su posición en la matriz del paisaje, que podría permitir una recolonización posterior más o menos fácil (Audino et al. 2014, Sullivan et al. 2018. Dada la magnitud de la deforestación en grandes áreas del Amazonas y otras regiones tropicales, y considerando la alta especificidad de este hábitat, la supervivencia de la fauna de escarabajos estercoleros asociada a la selva tropical está dramáticamente amenazada (Lumaret et al. 2022). ...
En el presente libro se ha recopilado la mayor cantidad posible de información publicada sobre los aspectos más importantes de la biología reproductiva y su regulación ambientaly fisiológica de los escarabajos estercoleros. En los primeros cuatro capítulos se describe el comportamiento reproductor, los sistemas re- productivos de las hembras y de los machos, el desarrollo preimaginal y el desarrollo imaginal. En los dos siguientes capítulos se abordan la regulación ambiental y fisiológica de la reproducción, y la comunica- ción química. En los dos capítulos finales se tratan las funciones y los servicios ecosistémicos que brindan estos escarabajos, y los riesgos y las amenazas que representan para ellos las alteraciones del medio ambiente.
... In the case of dung beetles, a decline in their populations has recently been observed Lumaret et al., 2022;Tonelli et al., 2018) as a consequence of the abandonment of extensive livestock farming and the use of anti-parasitic treatments in livestock, which are excreted unaltered and poison the beetles . However, the close link between these species and the livestock practices in the Mediterranean since the Neolithic (Ethier et al., 2017) must have promoted the expansion of the populations of some species (Kang et al., 2018), but not the disappearance of native dung beetle fauna. ...
Aim: Different hypothesis have been proposed to explain differences in species richness among islands. However, few studies have attempted to compare the explanatory power of multiple hypotheses using a large data set. Here, we analyse how different types of predictors (energetic/climatic, environmental heterogeneity, island biogeography and anthropogenic) affect variation in dung beetle species richness on Mediterranean and Macaronesian islands.
Location: Mediterranean and Macaronesian islands.
Taxon: Dung beetles.
Methods: Using a large data set of islands (n = 147), we extracted the species richness of dung beetles on each island using 362 bibliographic reference sources. We performed GLMs to analyse the relationship between the species richness of dung beetles and 11 explanatory variables (temperature, evapotranspiration, aridity, area, maximum elevation, connection to continent during LGM, geological origin, distance from continent, nearest continent, years since first human colonization and human density) representing four types of causal hypotheses. We also included as a covariate the number of published papers studying dung beetles as a surrogate of the survey/study effort carried out in each island.
Results: GLMs suggest that the years since first human colonization, the number of published papers and island area were the predictors with a higher explanatory capacity. The volcanic character of the islands and the distance from the mainland
had some relevance in the case of Scarabaeinae and Geotrupinae, and maximum
elevation appeared relevant in the species richness of Scarabaeinae and Aphodiidae. The anthropogenic and island biogeography hypotheses on the variation in species richness were the ones that have the strongest explanatory capacity, regardless of the inclusion of the surrogate of survey effort as a covariate in the models.
Main conclusions: The long history of human movements and agricultural activities
has facilitated the colonization of dung beetles and provided trophic resources for their persistence, leading to increased species richness. Thus, the importance of anthropogenic factors in shaping the biodiversity patterns of island biogeography cannot be ignored. These human-induced influences may play a fundamental role in altering the biogeographic patterns of islands, even overriding the importance of other variables. Consequently, our findings underline the profound impact of historical human actions on islands biodiversity.
... La disminución o la extinción local de los escarabajos estercoleros podría tener importantes consecuencias, a corto y largo plazo, sobre el mantenimiento de los procesos ecosistémicos descritos anteriormente (Nichols et al. 2008, Lumaret et al. 2022. Por tal motivo, la conservación de estos escarabajos para el mantenimiento de los servicios ecosistémicos debería ser un objetivo prioritario en la gestión de los pastizales. ...
En el presente libro se ha recopilado la mayor cantidad posible de información publicada sobre los aspectos más importantes de la biología reproductiva y su regulación ambientaly fisiológica de los escarabajos estercoleros. En los primeros cuatro capítulos se describe el comportamiento reproductor, los sistemas re- productivos de las hembras y de los machos, el desarrollo preimaginal y el desarrollo imaginal. En los dos siguientes capítulos se abordan la regulación ambiental y fisiológica de la reproducción, y la comunica- ción química. En los dos capítulos finales se tratan las funciones y los servicios ecosistémicos que brindan estos escarabajos, y los riesgos y las amenazas que representan para ellos las alteraciones del medio ambiente.
... The impact of broad-spectrum insecticides and pesticides on populations of beneficial dung beetle species is firmly established, for example , but the indirect effects of veterinary drugs on provisioning functions such as dung degradation has to date been less well explored (Tonelli et al., 2020). Due to their increased interactions with dung during manipulation on the surface, and during burial, tunnellers are known to be more susceptible to the effects of veterinary endectocides (e.g., Macrocyclic lactones) and ectocides (e.g., insect growth regulators) (Lumaret et al., 2020 We would also like to thank Gene Lollis and Dr. Elizabeth Boughton of Buck Island Ranch for providing helpful comments which contributed to the formation of this manuscript. We are also grateful for the help rendered by Daniel Bonsignore who aided data collection efforts in both the field and laboratory. ...
An important service in many ecosystems is the turnover and degradation of dung deposited by cattle. Dung beetles are the primary group of insects responsible for dung turnover, and factors affecting their abundance and distribution thus impact dung degradation. Lands lost to grazing due to dung buildup and pasture contamination total millions of acres per year in US pastures.
We evaluated the structural differences in dung beetle assemblages in natural grasslands versus a managed agroecosystem in subtropical southeastern Florida (USA). We measured the direct effect of dung longevity when dung beetle fauna normally inhabiting dung pats were excluded.
Our results indicate dung beetle abundance, functional diversity, and species richness have a substantial impact on the rate of dung turnover in subtropical pastoral lands with ~70% of dung removed from the soil surface after three months. Functional diversity and evenness did not have a significant positive effect on dung removal in managed, versus natural grasslands demonstrating a strong relationship between dung beetle assemblage composition and delivery of a key ecological process, dung degradation.
We suggest the importance of trees, which provide a thermal refuge for beetles, should be dispersed within matrixes of open pasture areas and within proximity to adjacent closed‐canopy hammocks to facilitate the exchange of dung beetles between habitats and therefore maintain the provisioning of dung degradation services by dung beetle assemblages.
... Onthophagus es considerado como un género cuasi cosmopolita, estando ausente únicamente en la Antártida, y pudiéndose encontrar en todos los ecosistemas desde el nivel del mar hasta los 5000 m.s.n.m.; siendo típicamente moradores del suelo, frecuentando ocasionalmente el dosel, o incluso siendo habitantes de madrigueras y cuevas (Cambefort 1991;Pulido-Herrera y Zunino 2007;Zunino y Halffter 2007;Moctezuma y Halffter 2021). Los Onthophagus son usualmente reconocidos por sus hábitos coprófagos, aunque numerosas especies pueden recurrir a la necrofagia, saprofagia o micofagia (Halffter y Matthews 1966;Anduaga 2000;Halffter y Halffter 2009;Moretto 2010;Moctezuma et al. 2016a;Joaqui et al. 2019), por lo que proveen servicios ambientales clave a los ecosistemas naturales y antropizados, y son ampliamente recomendados como indicadores biológicos (Nichols et al. 2007;2008;Lumaret et al. 2020). ...
ABSTRACT
Data from literature was gathered to compile the checklist of the fauna of Onthophagus of Mexico. A total amount of 120 species was found, with 85 endemics to Mexico. The distributional pattern as originally proposed by Halffter (1964) and commentaries of the majority of the species are provided. Records of species were found for all the Mexican States, except for Baja California. Mexico is the diversification center of Onthophagus in America, with ca. 62% of the described species of the continent. Oaxaca is the richest state and the only one with the greater number of endemisms. The factors that drove the diversification of Onthophagus in Mexico are discussed. Onthophagus mesoamericanus Zunino y Halffter, 1988 is resurrected from previous synonymy.
Key words: Scarabaeinae, Onthophagini, dung beetles, Mexican Transition Zone, Paleoamerican, Boreotropical, endemism, mountains.
RESUMEN
Se utilizó información proveniente de literatura para compilar el listado de la fauna de Onthophagus de México. Se encontraron un total de 120 especies, de las cuales 85 son endémicas de México. Se incluyen los patrones de distribución originalmente propuestos por Halffter (1964) y comentarios adicionales para la mayoría de las especies. Se encontraron registros de especies para todos los estados de la República Mexicana, con excepción de Baja California. México es el centro de diversificación de Onthophagus de América, con aproximadamente el 62% de las especies descritas para el continente. Oaxaca es el estado con mayor riqueza de especies y mayor número de endemismos. Se discuten los factores que promovieron la diversificación de Onthophagus en México. Onthophagus mesoamericanus Zunino y Halffter, 1988 es resucitado de la sinonimia previa.
Palabras clave: Scarabaeinae, Onthophagini, escarabajos del estiércol, Zona de Transición Mexicana, Paleoamericano, Boreotropical, endemismo, montañas.
Background: Efforts to alleviate the negative effects of oil spills in the Ecuadorian Amazon include remediation activities such as cleaning, reshaping, and revegetation of polluted areas. However, studies of the diversity of biological communities in these hydrocarbon-degraded ecosystems have never been carried out. Here, we evaluated the diversity of dung beetles on remediated soil ecosystems (Agricultural Soils and Sensitive Ecosystems) and on non-contaminated soils (Natural Forests and Palm Plantations).
Methodology: The study was conducted in Sucumbíos and Orellana provinces, in the Ecuadorian Amazon at four sampling sites per ecosystem type (a total of 16 sites). At each sampling site, six pitfall traps remained active for 120 consecutive h per month for 1 year.
Results: We collected 37 species and 7,506 individuals of dung beetles. We observed significant differences in mean species abundance, richness, and diversity between non-contaminated soil ecosystems and remediated soil ecosystems, with Natural Forests presenting the highest values, and Agricultural Soils the lowest values. Regarding sampling month, we also found significant differences among ecosystems, which were also higher in Natural Forests.
Discussion: The results suggest that hydrocarbon-degraded ecosystems tend to conserve lower beetle diversity one year after remediation highlighting the importance of Natural Forests for the conservation of tropical biodiversity. Therefore, dung beetle diversity could be used for future landscape management of these hydrocarbon-degraded ecosystems.
Draa oases are declared as a part of the biosphere reserve of Moroccan oases. These oases are agro-ecosystem dominated by the palm and fed by Draa Wadi, the longest in Morocco. Outside the oasis, the acacia trees and many pre-Saharan herbaceous species expand along the flooded areas and at the edges of temporary waterways. This desert vegetation creates a microclimate that favors the proliferation of a vast invertebrate diversity including Coleopteran species (beetles) that support the soil and flora-fauna ecosystem services. These insects play a very important role in the health of this environment. Indeed, they can perform the functions of ecosystems such as pollination, purification, biological control, and soil fertilization. In this chapter, the authors provide new information and update the list of the Coleopteran species in the Draa Valley. Thirty-one species and 15 families were observed through several entomological trips.
Dryland cattle pastures often yield sub-optimal economic returns while it intervenes with natural ecosystems functioning. Dung beetles improve soil conditions but little is known about how their functioning changes with different land management intensities. We assessed the role of the telecoprid dung beetle Canthon humectus in soil nutrient mobilization and commercial crop growth in arid grasslands with contrasting cattle managements. We set up a mesocosm experiment where we monitored dung beetle activity in containers filled with dung and soil from sites with three different cattle managements. Dung removal rates due to beetle burial activity were 10% higher than due to dehydration alone but was not affected by cattle management. After 60 days of beetle activity nitrates and ammonium levels increased significantly as compared with control pots without beetles.
Additionally, we monitored corn plant growth in pots with soil with and without beetle activity. Plants significantly increased their biomass due to beetle activity in the substrate with the highest and lowest pasture management intensity. In the latter case, more biomass was allocated to shoots. The ability of C. humectus to increase soil nutrients and enhance plant growth is affected by local cattle management.
Dung beetle introduction programmes were designed to accelerate exotic livestock dung degradation and to control dung breeding pestiferous flies and livestock parasites. The introduction programmes provided exotic dung beetle species with an opportunity to cross natural barriers and spread beyond their native range. There are no reports that explain what probable adaptation mechanisms enable particular dung beetle species to be the most successful invader. Here we identify the morphological, biological, physiological, ecological and behavioural attributes of the four most widespread and successful dung beetle species in introduced areas on a global scale in relation to the assumption that these species are different from other exotic and native dung beetles. We have recognised Digitonthophagus gazella (Fabricius), Onthophagus taurus (Schreber), Euoniticellus intermedius (Reiche) and Aphodius fimetarius (Linnaeus) as the most successful invaders based on their spread, predominance, distribution range and the reports of invasion. Each of these four species has different natural history traits that increase their fitness making them successful invaders. D. gazella has high fecundity and spreading ability, can instantly locate and colonise fresh and nutritious dung, and has a broad thermal window. O. taurus has morphological plasticity, high fecundity, high brood survival rate due to bi-parenting, and is adapted to extreme thermal and moisture conditions. E. intermedius has remnant-dung feeding abilities, a wide thermal window, functioning best at upper-temperature levels, and successful breeding and survival abilities at extremely low soil moisture conditions. A. fimetarius is small-sized, has high breeding and dispersal abilities, and is adapted to lower thermal and upper moisture extremes and variable soil conditions. Discussed here are perspectives on adaptive attributes of dung beetle species that are important to consider during their selection for redistributions. We have elaborated on the fitness and success characteristics of the four species individually. Further, we recommend a prior-introduction baseline monitoring of native dung beetle assemblages so as to evaluate the future impact of exotic dung beetle introductions on the recipient ecosystem.
A terrestrial test system to investigate the biomagnification potential and tissue-specific distribution of ivermectin, a widely used parasiticide, in the non-target dung beetle Thorectes lusitanicus (Jekel) was developed and validated. Biomagnification kinetics of ivermectin in T. lusitanicus was investigated by following uptake, elimination, and distribution of the compound in dung beetles feeding on contaminated faeces. Results showed that ivermectin was biomagnified in adults of T. lusitanicus when exposed to non-lethal doses via food uptake. Ivermectin was quickly transferred from the gut to the haemolymph, generating a biomagnification factor (BMFk) three times higher in the haemolymph than in the gut after an uptake period of 12 days. The fat body appeared to exert a major role on the biomagnification of ivermectin in the insect body, showing a BMFk 1.6 times higher than in the haemolymph. The results of this study highlight that the biomagnification of ivermectin should be investigated from a global dung-based food web perspective and that the use of these antiparasitic substances should be monitored and controlled on a precautionary basis. Thus, we suggest that an additional effort be made in the development of standardised regulatory recommendations to guide biomagnification studies in terrestrial organisms, but also that it is necessary to adapt existing methods to assess the effects of such veterinary medical products.
Knowing how recent environmental changes may have affected species diversity is a major objective to estimate the consequences of habitat alteration and climate change. In this study two dung beetle inventories made in the same locality of the Sierra de Guadarrama (Madrid, Spain) 34 years apart (1983–2017) are compared. Changes in diversity, species richness, abundances and composition were analysed and species replacements described considering the three main functional dung beetle groups: large paracoprids, small paracoprids and small endocoprids. In addition, changes in vegetation cover and climate between the two periods were also analysed to examine their association with the detected faunistic changes. Both the vegetation and climatic data show that the surveyed locality would have experienced an increase in the area covered by bushes and forest and an increase in temperature and warm conditions during the 34 years. These changes are associated with a probable increase in species richness and species dominance, a decrease in diversity and an important change in composition that would have positively affected small paracoprids but negatively affected large paracoprids.
The ongoing down‐sizing of the global mammal communities is assumed to have subsequent effects on mutualistic species communities. Dung beetles co‐evolved with large‐sized animals since millennia and depend on the megafauna feces of an appropriate size. Mammal community down‐sizing as a result of past and ongoing megafauna losses is therefore likely to result in a down‐sizing of dung beetle communities. However, empirical evidence for this co‐down‐sizing is lacking especially on larger spatial scales and over extended periods of time.
Here we show a significant down‐sizing of European dung beetle assemblages over the last ~53 000 years by relating Quaternary fossil records with trait information on body size of beetles. This significant down‐sizing of dung beetle communities was thereby not linear, but characterized by a weak decrease until the early Holocene but a strong acceleration in the recent pre‐history, from 6‐7000 years BP onwards. This acceleration of down‐sizing coincides with the completion of the Quaternary megafauna extinction and the start of major shifts in human agricultural land‐use. In contrast, assemblage mean body size of non‐coprophagous scarabids as well as ground beetles – two groups of beetles with no or weak relations to megafauna – was observed to increase towards the present with an acceleration of body size increase coinciding with the onset of late‐glacial warming (14 200 years BP).
In summary, the observed late‐Quaternary down‐sizing of European dung beetle communities is consistent with an effect of pre‐historic megafauna losses, and not with the coincident general warming. Ongoing down‐sizing of mammal communities is therefore likely to result in further down‐sizing of dung beetle assemblages, with potential effects on their important role for nutrient cycling and secondary seed dispersal in natural and extensive agro‐ecosystems. Future nature management initiatives could halt or even reverse this functional diversity loss via effective protection or restoration of megafauna communities.
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Global declines in insects have sparked wide interest among scientists, politicians, and the general public. Loss of insect diversity and abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services. Our understanding of the extent and underlying causes of this decline is based on the abundance of single species or taxo-nomic groups only, rather than changes in insect biomass which is more relevant for ecological functioning. Here, we used a standardized protocol to measure total insect biomass using Malaise traps, deployed over 27 years in 63 nature protection areas in Germany (96 unique location-year combinations) to infer on the status and trend of local entomofauna. Our analysis estimates a seasonal decline of 76%, and midsummer decline of 82% in flying insect biomass over the 27 years of study. We show that this decline is apparent regardless of habitat type, while changes in weather, land use, and habitat characteristics cannot explain this overall decline. This yet unrecognized loss of insect biomass must be taken into account in evaluating declines in abundance of species depending on insects as a food source, and ecosystem functioning in the European landscape.
Although there are nearly 500 species of native dung beetles in Australia, most are adapted to small, hard, dry, pelletised marsupial droppings and not to dealing with the large, moist deposits of cattle. In 1788, Governor Arthur Phillip arrived at Botany Bay with five cows, two bulls, 44 sheep and seven horses: this signalled major changes in Australia. Now there are about 27 million cattle whose annual dung production has a dry matter content of about 42 million tonnes. Until CSIRO introduced exotic dung beetles in the 1960s, the dung of these herbivores sat on the soil surface, sometimes for years, locking up organic matter, smothering pasture and polluting waterways. CSIRO introduced 53 exotic dung beetle species, of which 43 were released to the Australian mainland between 1965 and 1985. Twenty-three of these have become established, many of which have reached the natural limits of their distribution. I consider the reason for the failure of the other 30 species to establish and briefly review previous contributions to examining the role of dung beetles in delivering ecosystem services, noting that much of the published literature concerns laboratory studies. New field data are then examined on the way in which introduced species are transforming dung communities and the ecosystem services they provide. The capacity of deep-tunnelling dung beetles to transform the soil profile is examined along with their effects on pasture production and the flow of nutrients from dung on pasture. The biocontrol capacity of dung beetle activity is considered in relation to the native bush fly, Musca vetustissima, the introduced buffalo fly, Haematobia irritans exigua, and dung-borne intestinal parasites (helminths and Cryptosporidium). The rationale for introducing additional species to Australia is considered.
This study assesses the effects of the veterinary medical product ivermectin (IVM) in a range of concentrations on adult reproductive physiology and larval mortality of the dung beetle Euoniticellus intermedius (Reiche) (Coleoptera: Scarabaeidae). The ecotoxicological tests comprised eight treatments, including two controls and six increasing ivermectina concentrations (3.16, 10.0, 31.6, 63.2, 100, and 316 µg IVM/kg fresh dung). After 10 days of exposure, the females were dissected and the brood balls counted (fecundity). The brood balls were opened 15 days later and live larvae were counted to estimate larval mortality. Ivermectin altered the morphology of the ovary and stopped vitellogenesis, causing oocyte resorption and thus decreasing fecundity. The 30% threshold of decline in fecundity was reached at 115.9 µg IVM/kg dung, with no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) values of 10.0 and 31.6 µg IVM/kg dung, respectively. Larval sensitivity to ivermectin was higher, with a lethal concentration required to kill 50% of the population of 85.9 μg IVM/kg dung, and NOEC and LOEC of 3.16 and 10.0 µg IVM/kg dung, respectively. After cattle were treated with ivermectin at the recommended dose, the ivermectin concentration in their dung during the two first weeks after administration far exceeded the thresholds determined for E. intermedius.
Ivermectin is a veterinary pharmaceutical generally used to control the ecto- and endoparasites of livestock, but its use has resulted in adverse effects on coprophilous insects, causing population decline and biodiversity loss. There is currently no information regarding the direct effects of ivermectin on dung beetle physiology and behaviour. Here, based on electroantennography and spontaneous muscle force tests, we show sub-lethal disorders caused by ivermectin in sensory and locomotor systems of Scarabaeus cicatricosus, a key dung beetle species in Mediterranean ecosystems. Our findings show that ivermectin decreases the olfactory and locomotor capacity of dung beetles, preventing them from performing basic biological activities. These effects are observed at concentrations lower than those usually measured in the dung of treated livestock. Taking into account that ivermectin acts on both glutamate-gated and GABA-gated chloride ion channels of nerve and muscle cells, we predict that ivermectin's effects at the physiological level could influence many members of the dung pat community. The results indicate that the decline of dung beetle populations could be related to the harmful effects of chemical contamination in the dung.
1. The DEFRA ecosystem services framework was implemented in an entomological context to provide preliminary estimates of the economic value of four key ecosystem service benefits delivered by dung beetles ( C oleoptera: S carabaeidae, G eotrupidae) to the U.K. cattle industry and individual cattle farmers. These benefits included (i) reduced pest flies; (ii) reduced gastrointestinal parasites; (iii) reduced pasture fouling and (iv) increased soil nutrients.
2. A mesocosm experiment was carried out to quantify the impacts of anthelmintic treatment on dung removal by dung beetles when (i) cattle were excreting anthelmintics (which affect dung beetles) in a sufficient concentration to impact dung beetles and (ii) when cattle were not excreting dung containing anthelmintics (which affect dung beetles) in a sufficient concentration to impact dung beetles.
3. Inferring from our mesocosm experiment and existing data, the value of the benefits of dung beetles under current farming practices (and current anthelmintic usage) was estimated. We estimated the potential economic benefits if dung beetles were protected (i) under all entry‐level agri‐environment schemes; (ii) under organic schemes; or (iii) if farmers stopped treating adult cattle with anthelmintics during the grazing season.
4. While these estimates are preliminary, and should not be treated as definitive values, we suggest that dung beetles may be currently saving the U.K. cattle industry c. £367 million each year: c . £354 million in conventional systems and c. £13 million in organic systems. Annual benefits per cow are greater in organic systems (£43.47) compared with conventional systems (£37.42).
5. Protecting dung beetles under agri‐environment schemes could save the U.K. cattle industry an additional £40.2 million year ⁻¹ (£4.36 per cow), while protecting dung beetles under organic schemes could save £378 k year ⁻¹ (£1.26 per cow). The cessation of, largely unnecessary, treatment of adult cattle with anthelmintics could save the U.K. cattle industry an additional £6.2 million year ⁻¹ (£1.40 per cow) in addition to savings on the anthelmintics themselves.
6. These estimates are based on a large number of underlying assumptions and, thus, may be overestimating or underestimating the economic value of ecosystem services delivered by dung beetles.
7. The potential for using the DEFRA ecosystem services framework in an entomological context is highlighted. These estimates emphasise the contribution of dung beetles as key E cosystem S ervice P roviders ( ESP 's) within the U.K. cattle sector and, by extension, emphasise the importance of valuing supporting ecosystem services derived from invertebrates.
We live amid a global wave of anthropogenically driven biodiversity loss: species and population extirpations and, critically,
declines in local species abundance. Particularly, human impacts on animal biodiversity are an under-recognized form of global
environmental change. Among terrestrial vertebrates, 322 species have become extinct since 1500, and populations of the remaining
species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45%
mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown
about this “Anthropocene defaunation”; these knowledge gaps hinder our capacity to predict and limit defaunation impacts.
Clearly, however, defaunation is both a pervasive component of the planet’s sixth mass extinction and also a major driver
of global ecological change.
Biodiversity loss can precipitate extinction cascades and impair ecological processes. These 'downstream' effects will be exacerbated if functionally important taxa are tightly linked with species threatened by extinction or population decline. We review the current evidence that such a scenario is currently playing out in the linked declines of persistently hunted mammal populations and the dung beetles communities (Coleoptera: Scarabaeidae: Scarabaeinae) that depend on them for adult and larval food resources. Through a close evolutionary association, mammal assemblages have played a fundamental role in structuring extant dung beetle communities. Today many game mammal species' populations are severely depleted by subsistence or commercial hunting, especially in tropical forest systems. Multiple lines of evidence from temperate and tropical systems indicate that the regional-scale decline or extirpation of medium and large bodied mammal faunas can severely disrupt the diversity and abundance of dung beetle communities through alterations in the composition and availability of dung resources. These observed community disassemblies have significant short- and long-term implications for the maintenance of key ecosystem processes including nutrient recycling and secondary seed dispersal. Identifying the species- and community-level traits that buffer or exacerbate these species and functional responses is essential if we are to develop a better understanding of the cascading ecological consequences of hunting in tropical forests.
Clear understanding of the links between ecological functions and biodiversity is needed to assess and predict the true environmental consequences of human activities. Several key ecosystem functions are provided by coprophagous beetles in the subfamily Scarabaeinae (Coleoptera: Scarabaeidae), which feed on animal excreta as both adults and larvae. Through manipulating feces during the feeding process, dung beetles instigate a series of ecosystem functions ranging from secondary seed dispersal to nutrient cycling and parasite suppression. Many of these ecological functions provide valuable ecosystem services such as biological pest control and soil fertilization. Here we summarize the contributions of dung beetles to nutrient cycling, bioturbation, plant growth enhancement, secondary seed dispersal and parasite control, as well as highlight their more limited role in pollination and trophic regulation. We discuss where these ecosystem functions clearly translate into ecosystem services, outline areas in critical need of additional research and describe a research agenda to fill those gaps. Due to the high sensitivity of dung beetles to habitat modification and changing dung resources, many of these ecological processes have already been disrupted or may be affected in the future. Prediction of the functional consequences of dung beetle decline demands functional studies conducted with naturally assembled beetle communities, which broaden the geographic scope of existing work, assess the spatio-temporal distribution of multiple functions, and link these ecosystem processes more clearly to ecosystem services.
This paper addresses the association between use of a herbicide and anecdotal reports of reduced dung degradation and dung beetle populations. Dung beetles were monthly collected at two adjacent ranches in Mexico. Ranches were similar in area, elevation, exposition, soil, and vegetation, but differed in weed control. Ranch A controlled weeds manually, and ranch B controlled unwanted vegetation with applications of the herbicide Tordon 101M. The main species recovered on each ranch (Ataenius apicalis) was significantly more abundant at ranch A than at ranch B. Conversely, similar numbers of a second species, Ataenius sculptor, were recovered from both ranches. Three lines of evidence support the tentative conclusion that herbicide applications may be causing a decline in populations of A. apicalis on ranch B. First, the greatest reductions of A. apicalis were observed during periods of herbicide application. Second, A. sculptor, apparently little affected by these same herbicide applications, is active primarily during months without herbicide applications. Third, preliminary results of laboratory studies show that exposure to herbicide can impair reproductive function of the dung beetle Canthon cyanellus.
Considering the recent discovery of veterinary pharmaceutical aerial transport from industrial cattle feeding operations via particulate matter, the objective of this study was to determine the extent to which insecticides are also transported into the environment by total suspended particulates emanating from beef cattle feed yards. Of sixteen different pesticides quantified in particulate matter samples collected from beef cattle feed yards, permethrin was detected most frequently at >67% of particulate matter samples and at a mean concentration of 1,211.7 ± 781.0 (SE) ng/m3. Imidacloprid was detected at a mean concentration of 62.8 ± 38.2 (SE) ng/m3, or equivalent to published concentrations in dust from treated seed planting activities. When insecticide concentrations observed in this study are projected to all United States of America feed yards, resulting particulate matter (669,000 kg) could contain enough insecticides (active ingredient mass basis) to kill over a billion honey bees daily. Further, a novel transport pathway for macrocyclic lactone entry into the environment was identified. These data raise concern that non-target organisms may be exposed to potentially toxic levels of pesticides from beef cattle feed yards.
Local drivers of decline matter
Recent studies have reported alarming declines in insect populations, but questions persist about the breadth and pattern of such declines. van Klink et al. compiled data from 166 long-term surveys across 1676 globally distributed sites and confirmed declines in terrestrial insects, albeit at lower rates than some other studies have reported (see the Perspective by Dornelas and Daskalova). However, they found that freshwater insect populations have increased overall, perhaps owing to clean water efforts and climate change. Patterns of variation suggest that local-scale drivers are likely responsible for many changes in population trends, providing hope for directed conservation actions.
Science , this issue p. 417 ; see also p. 368
Insect declines are being reported worldwide for flying, ground, and aquatic lineages. Most reports come from western and northern Europe, where the insect fauna is well-studied and there are considerable demographic data for many taxonomically disparate lineages. Additional cases of faunal losses have been noted from Asia, North America, the Arctic, the Neotropics, and elsewhere. While this review addresses both species loss and population declines, its emphasis is on the latter. Declines of abundant species can be especially worrisome, given that they anchor trophic interactions and shoulder many of essential ecosystem services of their respective communities. A review of the factors believed to be responsible for observed collapses and those perceived to be especially threatening to insects form the core of this treatment. In addition to widely recognized threats to insect biodiversity, e.g., habitat destruction, agricultural intensification (including pesticide use), climate change, and invasive species, this assessment highlights a few less commonly considered factors such as atmospheric nitrification from the burning of fossil fuels and the effects of droughts and changing precipitation patterns. Because the geographic extent and magnitude of insect declines are largely unknown, there is an urgent need for monitoring efforts, especially across ecological gradients, which will help to identify important causal factors in declines. This review also considers the status of vertebrate insectivores, reporting bias, challenges inherent in collecting and interpreting insect demographic data, and cases of increasing insect abundance.
Expected final online publication date for the Annual Review of Entomology, Volume 65 is January 7, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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.
The Logic of Deforestation in-Southeast Asia. Throughout Southeast Asia, where most countries are involved in a race for economic growth, the forest cover is receding very rapidly. In some ways, the magnitude of the retreat of the forest is reminiscent of what has occurred in the past in the now industrialized countries. For, in Europe as well as in North America and in Japan (although somewhat less in the latter case), forests were taken to task during the various phases of demographic and economic growth, agricultural expansion and overall state territorial formation and consolidation. But this «logic of deforestation» was tamed, even reversed, firstly in Europe, thanks on the one hand to the globalization of trade and the contribution of the colonies to the metropolitan needs, and, on the other, to vigourous protection, management and reforestation policies. While such policies are applied throughout most of the industrial world, deforestation rates are increasing in Southeast Asia, including in Vietnam. Here, current agricultural expansion is carried out mostly at the expense of the minority peoples and forests of the Central Highlands, notably in the province of Lam Dong. However, the conditions, whether demographic, economic or environmental, whether local or global, which had prevailed during the economic expansion phases of the now industrial countries do not apply to contemporary Southeast Asia, where the logic of deforestation seems to have run out of control.
Ivermectin is the most common endectocide used to control parasites affecting livestock. Short-term physiological and behavioural effects of ivermectin on dung beetles may have long-term consequences for beetle populations and ecosystemfunctioning. Long-term effects of the use of ivermectin can be estimated by comparing dung assemblages and ecosystem functions in areas with conventional ivermectin-treated livestock and environmentally similar areas in which livestock are not treated with veterinary medical products (organic farming). In this study, we investigated both short-term and long-term effects of the administration of ivermectin on the characteristics of dung beetle assemblages and the services they provided in a protected area (Doñana National Park, SWSpain). We examined short-term dung colonization, dwelling, relocation, and disaggregation rates and the associations between these processes and the key assemblage parameters of species richness, abundance, biomass and functional diversity. Furthermore, we analysed changes in soil physical-chemical properties and processes. Short-term differences were observed in the total amount of dung relocated by dung beetles at different colonization vs. emigration stages, suggesting that dung beetles in this areawere affected by the recent treatments of livestockwith ivermectin. Moreover, short-term effects could also be responsible for the significant differences in dung spreading rates between sites. Conventional use of ivermectin disrupted ecosystemfunctioning by affecting species richness, abundance and biomass. The decrease in diversity parameters was related to a reduction in the functional efficiency, which resulted in the long-termaccumulation of dung on the ground and considerable changes in soil functionality.
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Abstract
Succession in local dung beetle assemblages influences their delivery of ecological functions in natural and modified environments globally. Short-term changes in dung beetle (Coleoptera: Scarabaeidae) species richness, abundance, and biomass were investigated in standardized dung pads in northern, coastal Turkey. For mean tunneling guild abundance, dung deposition time, dung exposure period, and their interaction were significant, and for mean dung dwelling guild abundance, dung exposure period was significant, as was the interaction with dung deposition time, which collectively evidenced temporal resource partitioning, based principally on differences in diel activity. Succession was highly compressed, with maximum abundance at 12 h and maximum species richness at 24 h. A large ball roller and small- to medium-sized tunnelers dominated different periods in the first 24 h but were superseded by dwellers. Regression analysis demonstrated a significant, positive relationship between species richness and the evenness of abundance for both dung deposition times. Correlation analysis generally showed strong, positive correlations between tunneling species, low correlations between tunneling and dwelling species, and low correlations between dwelling species. Niche partitioning based on size difference appears to have acted on the environmental filtering of tunneling species along the temporal gradient of declining moisture, thereby limiting the number of abundant, concurrent species. The aggregation of tunneling species provided opportunities for the less competitive dwelling species to occupy less densely populated zones termed probability refuges. The network of strong, positive correlations between tunneling species may indicate that their collective functionality is vulnerable to loss of efficiency if species are lost.
Key words: Aphodiinae, coexistence, ecosystem service, Kizilirmak Delta, Scarabaeinae
The subfamily Scarabaeinae (Coleoptera: Scarabaeidae) may have originated in Gondwanaland, through Mesozoic vicariance or dispersal in association with dinosaur dung, or through Cenozoic dispersal in association with mammal dung. We review evidence from age-calibrated phylogenies, fossil records, biogeographical patterns, and ecological associations. Fossil calibrated phylogenies for Scarabaeoidea predict a Cretaceous origin for Scarabaeinae, although age estimates would rely on other scarabaeoid groups given the doubtful validity of Mesozoic ?scarabaeine? fossils. Molecular clock calibrated phylogenies for Scarabaeinae predict an early Cenozoic origin coeval with modern mammal diversification. Trace fossil evidence suggests the exploitation of dinosaur dung by fossorial insects, although scarabaeine fossils are only validated for the Cenozoic. Although we discuss fossil evidence for dinosaur dung as a faunal resource, the origin of modern scarabaeines from an earlier Mesozoic vicariant or dispersal fauna remains unsupported. Although clock-constrained, phylogram topography is consistent with early Cenozoic palaeoclimatic and palaeoecological events, Eocene marine barriers would demand dispersal to explain the distributional origins of Scarabaeinae. Inconsistencies between classification and phylogeny complicate biogeographical analysis, although earlier southern radiation of basally-derived tribes has probably been followed by later diversification and the global dispersal of both basally and terminally-derived taxa, primarily via restored land links.
Cattle treated with the veterinary parasiticide ivermectin (IVM) fecally excrete residues. Here we report the exposition and dissipation characteristics of these residues in dung of IVM-treated cattle, and in soil beneath this dung, on pastures including Canada, France, Switzerland, and The Netherlands. Residues were quantified for dung collected from cattle after 3, 7, 14, and 28 d post- treatment, and subsequently exposed in the field for up to 13 months. We first optimized a high performance liquid chromatography - fluorescence detection method to detect IVM residues in dung and soil matrices. We showed that a solid phase extraction and purification step generally can be eliminated to reduce the time and cost of these analyses. We also found that the addition of water to relatively dry samples improves the extraction efficiency of residues. We then analyzed the field samples to document differences in IVM dissipation in cattle dung among sites, with DT50 values of up to 32 d and DT90 values >396 d (DT50/DT90: dissipation time of 50%/90%). We further showed that the dissipation characteristics of residues are comparable between dung of IVM-treated cattle and in dung to which IVM has been added directly. Lastly, we report the first use of a desorption electrospray ionization - high resolution - mass spectrometry method to detect residues of metabolites in a dung matrix. This article is protected by copyright. All rights reserved.
The distribution and occurrence, with the time-factor taken into consideration, were monitored in Finland for the mainly dung-living histerid genera Margarinotus, Hister, and Atholus (all predators), and for the Scarabaeidae genera Onthophagus and Aphodius, in which almost all species are dung-feeders. All available records from Finland of the 54 species studied were gathered and distribution maps based on the UTM grid are provided for each species with brief comments on the occurrence of the species today. Within the Histeridae the following species showed a decline in their occunence: Margarinotus purpurascens, M. neglectus, Hister funestus, H. bissexstrinatus and Atholus bimaculatus, and within the Scarabaeidae: Onthophagus nuchicornis,O. gibbulus, O. fracticornis, O. similis, Aphodius subterraneus, A. sphacelatus and A. merdarius. The four Onthophagus species and A. sphacelatus disappeared in the 1950s and 1960s and are at present probably extinct in Finland. Changes in the agricultural ecosystems, caused by different kinds of changes in the traditional husbandry, are suggested as a reason for the decline in the occurrence of certain vulnerable species.
Surveys of dung beetles establish the dominance of exotic taxa associated with cattle dung on native grasslands in southern Alberta, Canada. Of the 12 species recovered, eight were of European origin and comprised 92.2% of the total catch of 187 963 beetles. Most common were Chilothorax distinctus (Müller), Onthophagus nuchicornis (Linnaeus), and Colobopterus erraticus (Linnaeus) (Coleoptera: Scarabaeidae). The abundance of C. distinctus has been known in the region since the 1920s, whereas that of O. nuchicornis only was first reported in the 1990s. The abundance of C. erraticus has not previously been observed in the region and identifies the species as the newest addition to the endemic fauna. The diversity of native species on pastures in southern Canada and adjacent states is depauperate, such that the establishment of European taxa has appreciably increased levels of bioturbation in pasture ecosystems. The success of these exotic species on northern pastures may reflect a level of cold-tolerance greater than that of most native species.
In this article we focus on the vital ecological services provided by insects. We restrict our focus to services provided
by “wild” insects; we do not include services from domesticated or mass-reared insect species. The four insect services for
which we provide value estimates—dung burial, pest control, pollination, and wildlife nutrition—were chosen not because of
their importance but because of the availability of data and an algorithm for their estimation. We base our estimations of
the value of each service on projections of losses that would accrue if insects were not functioning at their current level.
We estimate the annual value of these ecological services provided in the United States to be at least $57 billion, an amount
that justifies greater investment in the conservation of these services.
The Mediterranean region as a whole has the highest dung beetle species richness within Europe. Natural coastal habitats in this region are among those which have suffered severe human disturbance. We studied dung beetle diversity and distinctiveness within one of the most important coastal protected areas in the west Euro-Mediterranean region (the regional Park of Camargue, southern France) and made comparisons of dung beetle assemblages with other nearby Mediterranean localities, as well as with other coastal protected area (Doñana National Park, Spain). Our finding showed that: (1) The species richness of coastal habitats in the Camargue is low and only grasslands showed a similar level of species richness and abundance to inland habitats of other Mediterranean localities. The unique habitats of the coastal area (beaches, dunes and marshes) are largely colonized by species widely distributed in the hinterland. (2) In spite of their low general distinctiveness, dune and marsh edges are characterized by the occurrence of two rare, vulnerable, specialized and large roller dung beetle species of the genus Scarabaeus. As with other Mediterranean localities, current findings suggest a recent decline of Scarabaeus populations and the general loss of coastal dung beetle communities in Camargue. (3) The comparison of dung beetle assemblages between the Camargue and Doñana shows that, in spite of the low local dung beetle species richness in the Camargue, the regional dung beetle diversity is similar between both protected areas. Unique historical and geographical factors can explain the convergence in regional diversity as well as the striking divergence in the composition of dung beetle assemblages between both territories.
There is increasing concern about the conservation of dung beetles which are threatened by several peculiar dangers world-wide, both at the population and community level. A noticeable threat in Europe is the dramatic reduction in the number of cattle and sheep grazing in the open, which is associated with both intensive agriculture and the progressive reforestation of previously pastured areas. We studied dung beetle habitat and resource preferences at La Mandria Park (north-west Italy) which is a mosaic of open and wooded patches where domestic (cows and horses) and wild ungulates (deer and wild boar) co-exist. Scarabaeidae were numerically dominant, accounting for 61.5% of the approximately 3000 individuals sampled (Aphodiidae accounted for 32.5% and Geotrupidae for only 6%). However, when species richness was considered, Aphodiidae were dominant, with 17 of the 27 species found (Scarabaeidae with eight and Geotrupidae with two). Assuming a null hypothesis of equal probability of colonizing any habitat or faeces, we found that most species were significantly associated with one of the four dung types or with one of the two habitats considered. On average, Scarabaeidae preferred cattle dung and open habitats whereas most Aphodiidae used deer lumps and wooded habitats. In spite of the precise ecological choices observed at La Mandria, surveys from other European areas suggest that both habitat and food selection are quite flexible. From a conservation viewpoint, the ability of coprophagous beetles to choose herbivore faeces according to their availability and to select habitats that satisfy their own microclimate requirements may certainly be useful in preserving biodiversity. Agroecology, which implies some woodland and hedgerow management practices associated with pastoralism, could be the right approach to the management of the agricultural landscape. Conversely, in reforested areas, while wild ungulate populations should be preserved, some form of human disturbance, particularly clearings used for pastoralism, should also be maintained.
A historical compilation of data on roller dung beetle occurrence in the Iberian peninsula was examined for temporal changes between the first and second half of the 20th century. Analysis of changes in the relative frequency of database records, individuals and 10-km UTM cells where the beetles occurred showed a decline in the occurrence of nine of the eleven species. A comparison of latitudinal and longitudinal mid-points of the 10-km UTM cells where each species occurs indicated that the range of most roller dung beetles in the Iberian peninsula has also contracted. Before 1950 a significant, positive and curvilinear relationship was found between the number of roller dung beetles and the area of coastal environments (sea, dunes, beaches and marshes); while in the second half of the 20th century the number of “roller” species is positively correlated with artificial pastureland and scrub areas. It is suggested that urban development of the coastal zones for tourism since 1950 has probably contributed greatly to the disappearance of many roller populations. It is recommended that some of the more affected species of roller dung beetles should be considered for inclusion among protected invertebrates.
The decline of roller dung beetles (Coleoptera, Scarabaeidae) in Italy, at national and
regional level, was described using a database of both literature and unpublished
data, since the late of 19th century. The probability of finding roller species was assessed for each decade of the 20th century in order to detect changes in their distribution and status. An analysis of decline was performed using a complementary approach of different extinction indexes, according to IUCN criteria. During the 20th century, both the absolute number of records and the UTM cells where roller beetles were found increased clearly as a consequence of the escalation of entomological surveys. Nevertheless, comparing R species (rollers) with all the scarab dung beetles from the first to the last quarter of the 20th century, the relative frequency of roller records decreased by 31%, while the relative number of occupied UTM cells dropped by 23%. Six roller species showed a significant decline in Italy from the first to the second part of the 20th century, and nine in the last 30years. Other two species disappeared from the majority of the northern regions. Finally, the values of all the extinction indexes were strongly correlated and detected a high risk of extinction in Italy for six species. A gradual change in land use during the last three decades, consisting of a reduced extension of grasslands in favour of either intensive agriculture or reforestation after abandonment of livestock raising, was likely the main factor inducing decline and local extinction of roller species.
In Neotropical rain forests, fresh mammal dung, especially that of howler monkeys, constitutes an important resource used by dung beetles as food and for oviposition and further feeding by their larvae. Tropical rain forest destruction, fragmentation, and subsequent isolation causing reductions in numbers of and the disappearance of howler monkeys may result in decreasing numbers of dung beetles, but this has not been documented. In this study, we present information on the presence of howlers and dung beetles in 38 isolated forest fragments and 15 agricultural habitats. Howler monkeys were censused by visual means, while dung beetles were sampled with traps baited with a mixture of howler, cow, horse, and dog dung. Results indicated that loss of area and isolation of forest fragments result in significant decrements in howlers and dung beetles. However, dung beetle abundance was found to be closely related to the presence of howler monkeys at the sites and habitats investigated. Scenarios of land management designed to reduce isolation among forest fragments may help sustain populations of howler monkeys and dung beetles, which may have positive consequences for rain forest regeneration.
Changes in resources: Consequences for the dynamics of dung beetle communities
- J.-P Lumaret
- N Kadiri
- M Bertrand
Lumaret, J.-P., Kadiri, N., Bertrand, M., 1992. Changes in resources: Consequences for the dynamics of dung beetle communities. Journal of Applied Ecology 29, 349-356.
Suspected side effects of a herbicide on dung beetle populations (Coleoptera: Scarabaeidae). Comptes rendus de l'Académie des Sciences, Sciences de la vie
- M I Martínez
- J-P Lumaret
- Cruz Mr
Martínez MI, Lumaret J-P, and Cruz MR (2001) Suspected side effects of a herbicide on dung beetle populations (Coleoptera: Scarabaeidae). Comptes rendus de l'Académie des
Sciences, Sciences de la vie/Life Sciences 324: 989-994.
Dung beetles and the epidemiology of parasitic nematodes: Patterns, mechanisms and questions
- E Nichols
- A Gómez
Nichols, E., Gómez, A., 2014. Dung beetles and the epidemiology of parasitic nematodes: Patterns, mechanisms and questions. Parasitology 141, 614-623.
Les médicaments vétérinaires et leurs résidus: Quels risques pour les organismes non cibles et le fonctionnement des écosystèmes?
- Lumaret
Co-declining mammals and dung beetles: An impending ecological cascade
- Nichols
The economic value of ecological services provided by insects
- Losey