Dung Beetle Assemblages Research Articles

Dung-beetle (Coleoptera: Scarabaeidae: Scarabaeinae) assemblage in two livestock production systems in a southern Mexican High Plateau semiarid ecosystem

AbstractIn this work, we used measures of diversity and biogeographic patterns to evaluate the response of dung-beetle assemblages (Coleoptera: Scarabaeidae: Scarabaeinae) at two cattle ranches with different management systems on the southern Mexican High Plateau. The number of individuals and biomass were used as the primary diversity attributes of the assemblage. The 1D and 2D true diversity indexes of these attributes were examined, and the attributes were classified according to Halffter’s biogeographical patterns. In total, 1375 Scarabaeinae adults were collected, representing 11 species and seven genera. Site management regime did not significantly affect species richness or assemblage structure when the number of individuals was considered. However, species diversity and biomass turnover were higher in the system with holistic management than in that with semitechnified management. The proportions of Halffter’s biogeographical patterns also differed between the two production systems. In conclusion, the location under holistic management, despite having cattle production, contained a significant proportion of the Scarabaeinae species that are typical of the Mexican High Plateau. In contrast, the semitechnified system negatively impacted beetle abundance, leading to half the individuals, the dominance of species with high biomass, and the absence of groups typical of the region.

Short- and long-term temporal changes in the assemblage structure of Amazonian dung beetles.

Species diversity varies in space and time. Temporal changes in the structure and dynamics of communities can occur at different scales. We investigated the temporal changes of dung beetle assemblages in the Amazonian region along seasons, years, and successional stages. We evaluated if assemblage structure changes between temporal scales and whether such changes affect the functional structure of communities. To achieve these goals, we sampled dung beetles using linear transects of baited pitfall traps during the dry and rainy seasons at two natural reserves in the Amazon region, each representing different time scales: one covering successional variations (80, 30, 5, and 1years of recovery from logging) and the other one encompassing three consecutive years at two successional stages (20 and 10years from logging). We used Generalized Linear Models to analyze interannual and successional changes in diversity, described assemblage structure with a NMDS, and examined compositional variation by partitioning beta diversity into its nestedness and turnover components. Abundance and richness decrease from the rainy to the dry season and towards earlier successional stages but do not differ between years. Assemblage diversity changes differently in interannual and successional scales. During succession, dung beetle assemblages change drastically, following a nested structure due to the appearance of species and functional groups in later successional stages. In contrast, functional group composition does not show consistent changes between years, displaying a turnover structure. This pattern supports non-deterministic changes in dung beetle assemblage structure along forest succession.

Between locality variations in the seasonal patterns of dung beetles: the role of phenology in mitigating global warming effects

1. Global warming may especially affect ectothermic insect species, making it necessary to forecast the capacity of these species to cope with climatic changes.2. In this study, we use circular statistics to examine the seasonal plasticity of 32 dung beetle species in 17 localities of a mountain Iberian assemblage. We assume that the high variability between localities in the seasonal patterns for the same species suggests that seasonal plasticity could minimise the demographic effects of climate change on local populations.3. Our results suggest that the populations of at least one‐third of the dung beetle species could partially adapt to the effects of climate change by modifying their phenological occurrence, and that the degree of concentration of the seasonal occurrences is generally maintained independently of the locality. However, we have not detected clear seasonal pattern variations or a clear effect of environmental temperature on seasonal variations in around two‐thirds of the studied species.4. The dung beetle assemblages of this mountain region will experience deep changes in the future. Plasticity in seasonal patterns does not seem to be associated with species characteristics such as high‐rank taxonomic identity, body weight, or geographical distribution. Only the general functional character of species would have some explanatory power. Endophagic Aphodiidae dung beetle species would be more capable than hypophagic species in mitigating the effects of climate change by modifying their phenological traits, whereas that Scarabaeidae hypophagic species may cope better with these climatic changes without having to change their seasonal activities.

Communities of Dung Beetles (Coleoptera: Scarabaeoidea) in the Steppe of Mongolia

We studied the community structure of dung beetles in livestock dung within the steppe ecosystem of Mongolia. We found 15 species of dung beetles belonging to three families and representing two functional guilds, namely paracoprids and endocoprids. All species were found in the horse dung, but only 11 species inhabited cow dung, and except Geotrupes koltzei none of these species seemed linked exclusively to one kind of dung. A few species dominated the communities, specifically Aphodius comma, Aphodius altaicus and Aphodius antiquus. Among these, Aphodius comma was the predominant species, occupying 44.4% of total surveyed dungs. Species richness, biomass, and abundance of beetles per dung were significantly higher in horse dung than cow dung. Abundance of beetles was significantly higher in the middle of summer than in late summer, but species richness was not significantly different between the middle of and late summer. This study constitutes one of the first efforts to systematically understand dung beetle assemblages in the steppe of Mongolia, including the effects of dung types and environmental gradients on beetle communities.

Wood Pastures: A Transitional Habitat between Forests and Pastures for Dung Beetle Assemblages

Wood pastures are home to a variety of species, including the dung beetle. Dung beetles are an important functional group in decomposition. Specifically, in terms of livestock manure, they not only contribute to nutrient cycling but are key players in supporting human and animal health. Dung beetles, however, are declining in population, and urgent recommendations are needed to reverse this trend. Recommendations need to be based on solid evidence and specific habitats. Herein, we aimed to investigate the role of an intermediate habitat type between forests and pastures. Wood pastures are key areas for dung beetle conservation. For this reason, we compared dung beetle assemblages among forests, wood pastures, and grasslands. We complemented this with studies on the effects of dung type and season at three Hungarian locations. Pitfall traps baited with cattle, sheep, or horse dung were used in forests, wood pastures, and pasture habitats in spring, summer, and autumn. Dung beetle assemblages of wood pastures showed transient characteristics between forests and pastures regarding their abundance, species richness, Shannon diversity, assemblage composition, and indicator species. We identified a strong effect of season and a weak of dung type. Assemblage composition proved to be the most sensitive measure of differences among habitats. The conservation of dung beetles, and the decomposition services they provide, need continuous livestock grazing to provide fresh dung, as well as the maintenance of wood pastures where dung beetle assemblages typical of forests and pastures can both survive.

Dung beetle trophic ecology: are we misunderstanding resources attraction?

Trophic ecology of dung beetles has been widely studied because of the important ecological role of these taxa. However, previous studies have focused on a limited number of potential food items (mainly vertebrate dung and carrion) and have used only one approach (either field or laboratory). Moreover, recent studies showed high abundance of dung beetles in defaunated areas with a low abundance of these resources. In this study, we combined a field and laboratory approach to explore dung beetle trophic attraction to different potential native resources in the Atlantic forest; and we evaluated whether results can explain the high abundance of dung beetles in defaunated areas. Through laboratory olfactometry experiments, we first exposed individuals to vertebrate carrion, omnivorous dung, and decomposing fungi. Then, we exposed species that exhibited a preference for dung to monkey, tapir, and feline dung; and those that preferred carrion and decomposing fungi to chicken, cow meat, and arthropod carcasses. We compared trophic attractions in the field and laboratory conditions with generalised additive models. We found that coprophagous species preferred monkey dung, and all necrophagous and sapro‐necrophagous species preferred arthropod carcasses. These results suggest that the importance of arthropods carcasses as an important resource for dung beetles has been largely underestimated. The results of this study might provide an explanation for the high abundance of necrophagous and sapro‐necrophagous dung beetles in defaunated areas. In addition, the use of omnivorous dung and arthropod carcasses could be an effective sampling method for dung beetle assemblages.

Quantifying responses of dung beetle assemblages to cattle grazing removal over a short-term in introduced Brazilian pastures

Pasture management techniques may affect the biodiversity of insects beneficial to pastures, such as dung beetles. Cattle grazing removal over a short-term is widely used in introduced Brazilian pastures. However, the impact of this management on dung beetles is still unknown. This study evaluated the taxonomic (species richness, abundance, biomass, species composition, Shannon, and Simpson indexes) and functional (functional richness FRic, functional dispersion FDis, functional evenness FEve, and community-weighted means of trait values CWMs) dung beetle assemblages response to cattle grazing removal over a short-in introduced pastures. We sampled dung beetles, with pitfall traps baited with cattle dung and carrion, simultaneously in pastures with constant cattle grazing (control), and one, three, and five months after cattle grazing removal in Aquidauana, Mato Grosso do Sul, Brazil. Taxonomic metrics and FRic, FDis, and FEve did not differ among control and pasture treatments. We found that pastures with one month of cattle removal maintain the same CWM coprophagous diet from the control, and higher CWM biomass in relation to control. Although cattle grazing removal, at least over the short-term, does not cause a negative impact on dung beetle taxonomic metrics and functional diversity indexes, two important traits associated to dung removal are negatively affected after three months of cattle removal. Thus, we suggest that one month of cattle removal to grazing rotational management in introduced Brazilian pastures can be a useful strategy to, besides conserving the grass, also conserving dung beetle diversity, and consequently the ecological functions performed by them.

Impacts of Exotic Pasture Establishment on Dung Beetle Assemblages (Coleoptera: Scarabaeidae: Scarabaeinae) in the Brazilian Cerrado.

The Brazilian Cerrado is the second largest Neotropical biome and an important hotspot of biodiversity. However, land use change in this ecosystem is producing landscapes with modified natural environments and anthropogenic environments, such as exotic pastures. In this study, we evaluated how conversion of native Cerrado vegetation to exotic pastures affects the dung beetle assemblages (Coleoptera: Scarabaeidae: Scarabaeinae). We sampled dung beetles in four areas of Cerrado (sensu stricto) and in four areas of exotic pastures (Urochloa spp.) in Aquidauana, Mato Grosso do Sul, Brazil. In all, 7,544 individuals from 43 species of dung beetles were collected, and 19 species were found in both the Cerrado and exotic pastures. The abundance and species richness of dung beetles were higher in Cerrado remnants. Species composition differed between Cerrado and exotic pastures, where 11 species were classified as specialists of Cerrado, 10 species were considered specialists of exotic pastures, and 6 species were habitat generalists. Roller beetles were most negatively affected by exotic pasture establishment. We demonstrated that exotic pasture establishment has a negative impact on dung beetle assemblages in Brazilian Cerrado. The decline in abundance and richness of roller beetles has important implications for the understanding of ecosystem functioning because it can reduce the ecological functions performed by dung beetle assemblages in exotic pastures. Finally, the high number of dung beetle species shared between Cerrado and exotic pastures suggests that the Cerrado remnants is a fundamental requirement for the conservation of biodiversity of dung beetles in exotic pastures in the Brazilian Cerrado.

Intermediate disturbance promotes diversity and the conservation of dung beetles (Scarabaeoidea: Scarabaeidae and Aphodiidae) in the Eastern Cape, South Africa

Environmental fluctuations, such as changes in climate, agricultural management and anthropogenic land-use patterns can affect the diversity of organisms inhabiting an area. Losses of biodiversity alter ecosystems processes, eroding their capacity to deliver ecosystem services. Dung beetles are critical ecosystem service providers, making them an ideal ecological indicator to explore the effects of land-use change on biodiversity. Dung beetles were sampled across three land-use types, in the summers of 2015 and 2016 in the Eastern Cape province, South Africa. Game ranching is regarded as a relatively low-intensity land use type. It was compared with cattle ranching (medium intensity) and dairy farming (high intensity) to examine their effect on dung beetle assemblage metrics (abundance, species richness and true Shannon diversity index), guild diversity (as nesting guilds) and spatial turnover. The intermediate grazing intensity of cattle ranching supported a higher abundance and diversity of both whole dung beetle assemblage and the nesting guilds, followed by the game ranches and then dairy farms. Differences between the sampling years were dependent on the beetle nesting guild, and largely correlated with rainfall and temperature. Cattle and game ranches shared a higher number of species than either shared with dairy farms. Whittaker's Beta-diversity index showed the highest species turnover between game ranches and dairy farms. A mix of game and cattle ranching, minimising dairy farming or restricting it to already ecological degraded sites, appears the best alternative for maintenance of dung beetle diversity and their ecosystem services. The year-to-year trends of the data were in general consistent, confirming that dung beetles are reliable ecological indicators; but also suggest that climate change that affects rainfall will result in the reduction of the abundance and diversity of this key ecological group.

Sheep herding in small grasslands promotes dung beetle diversity in a mountain forest landscape

It is assumed that the transformation of native forest into agricultural fields and grazing grasslands negatively affects biological diversity, and there are multiple cases documenting this pattern. For example, when lowland tropical forests are transformed into extensive cattle pastures, dung beetle richness, abundance and diversity decrease. However, in some cases, biodiversity may respond in the opposite direction. We describe dung beetle assemblages in a mountainous landscape where small grasslands (less than 7.5 ha) with sheep pastoralism are imbedded in a pine-oak forest matrix at the Mexican Transition Zone. We captured 14 species (1058 beetles) in 10 forest sites, and 20 species (2591 beetles) in 10 grassland sites. Generalized linear mixed models showed significantly higher values of species richness, diversity and abundance in grazing grasslands. We found 10 shared beetle species between forests and grassland sites, and a PERMANOVA revealed significant differences in species composition between habitats. Generalized linear models showed that dung beetle richness, abundance and diversity are related to dung availability, soil moisture and altitude, but not to soil hardness nor land use heterogeneity. Similarly, we did not find significant correlations between compositional dissimilarity (beta diversity) and dung availability nor land use heterogeneity. Our results document how traditional sheep herding in small grassland patches embedded in a forest matrix promotes the diversity of dung beetle assemblages, showing that biodiversity can be enhanced by human activities. The results of this study indicate that grassland patches embedded in the forest matrix where traditional small herds of sheep graze, contribute to increasing landscape complexity by providing a mosaic of environmental conditions that promote a high diversity of dung beetles on a regional scale.

Dung beetle species introductions: when an ecosystem service provider transforms into an invasive species.

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.

Mechanisms of diversity maintenance in dung beetle assemblages in a heterogeneous tropical landscape.

Background Anthropized landscapes play a crucial role in biodiversity conservation, as they encompass about 90% of the remaining tropical forest. Effective conservation strategies require a deep understanding of how anthropic disturbances determine diversity patterns across these landscapes. Here, we evaluated how attributes and assembly mechanisms of dung beetle communities vary across the Selva El Ocote Biosphere Reserve (REBISO) landscape.MethodsCommunity attributes (species diversity, abundance, and biomass) were assessed at the landscape scale, using spatial windows and vegetation classes. Windows were categorized as intact, variegated, or fragmented based on their percent cover of tropical forest. The vegetation classes analyzed were tropical forest, second-growth forest, and pastures.ResultsWe collected 15,457 individuals and 55 species. Variegated windows, tropical forests, and second-growth forests showed the highest diversity values, while the lowest values were found in intact windows and pastures. Landscape fragmentation was positively and strongly related to dung beetle diversity and negatively related to their abundance; biomass was positively associated with forest cover. Beta diversity was the primary driver of the high dung beetle diversity in the landscape analyzed.DiscussionThe landscape heterogeneity and its biodiversity-friendly matrix facilitate the complementarity of dung beetle assemblages in the Selva El Ocote Biosphere Reserve. Random processes govern beta diversity patterns in intact and variegated windows. Therefore, vegetation cover in the region is sufficient to maintain a continuous flow of dung beetles between forested landscape segments. However, intense anthropic disturbances acted as deterministic environmental filters in fragmented windows and pastures sites, leading to biotic homogenization processes. Our results suggest that increasing habitat variegation in highly fragmented sites is an effective strategy to prevent or buffer homogenization processes in the REBISO landscape.

Dung beetles and the conservation of diversity in an agricultural landscape with maize fields and Atlantic Forest remnants

Land use change is a global threat to biodiversity. Besides converting natural landscapes into monocultures, the use of genetically modified organisms is increasing, even though their effects on natural assemblages are still poorly known. The possible effects of transgenic crops on ecosystems can be studied using ecological indicators, such as dung beetles. We assessed the effect of creole, conventional, and transgenic maize crops on dung beetle assemblages in a landscape that also contained forest fragments in southern Brazil. We established 15 blocks, five on each type of maize fields. Each block consisted of a landscape with native forests and maize fields. A total of 2126 dung beetles were captured, belonging to 38 species. The forest-crop landscape associated with creole maize had a greater richness of dung beetle species. Conversely, an impoverished assemblage was detected in the transgenic maize crop landscape. The reduction of indicator insect diversity in landscapes influenced by transgenic crops suggests that the type of maize fields influences biodiversity conservation. In addition, the negative effects of transgenic crops went beyond maize fields, reaching native forest fragments adjacent to crops.

札幌市の林齢・樹種の異なる小面積林分における腐肉食性シデムシ・糞虫群集の初歩的研究

札幌市の林齢・樹種の異なる小面積林分における腐肉食性シデムシ・糞虫群集の初歩的研究

Does ecotourism impact biodiversity? An assessment using dung beetles (Coleoptera: Scarabaeinae) as bioindicators in a tropical dry forest natural park

Abstract Ecotourism can be defined as an environmental activity that takes place in well-preserved areas for recreation and with the responsibility of promoting their conservation. Nowadays, ecotourism is seen as a friendly pastime, but it can potentially affect negatively community diversity and structure by a number of processes such as soil compaction, erosion, and habitat alteration, among many others. Nonetheless, there is hardly any information on the impact of ecotourism in the Tropical Dry Forests and protected areas of the Neotropical region. In an attempt to fill this knowledge gap, the effect of ecotourism was evaluated in a study of a Tropical Dry Forest in the Tayrona National Natural Park of Colombia using dung beetles as bioindicators. A large-scale sampling of three sites with different levels of tourism intensity (no tourism – NT, low tourism – LT, and high tourism – HT) was performed using pitfall tramps baited with human/pig dung during two climatic seasons (rainy and dry). A total of 3238 individuals belonging to nine genera and 15 species were collected. Significant differences in abundances, richness, and the Shannon Wiener diversity index were observed between areas with tourism and those without. These differences disappeared during the dry season in response to the strong reduction in species abundance and richness associated to that time of year. All areas maintained a homogeneous beetle structure in terms of functional groups present irrelevant of the intensity level of tourism. Beta diversity analysis shows that the dung beetle assemblage has a nested structure, indicating that the pressure exerted by tourism entails the loss of particular species. Our results advocate that it is necessary to implement conservation strategies in order to reduce the negative impact of tourism on the National Park’s biodiversity.

Diversity of Scarabaeinae (Coleoptera: Scarabaeidae) in an urban fragment of Cerrado in Central Brazil

The diversity of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) is affected by urbanization, habitat fragmentation and disappearance of native mammals, which result in changes in the quality and availability of food, and resources for nesting. We evaluated the diversity, distribution of species in different trophic guilds and foraging strategies, and temporal variation in abundance of dung beetles in an urban fragment of Cerrado in a Federal District of Brazil. This study was conducted at the Experimental Station of Biology (EEB) of the University of Brasilia (UnB), Federal District, Brazil. Fortnightly, between October 2012 and September 2013, Scarabaeinae were collected using baited (human faeces, pig meat, or banana) and unbaited pitfall traps. Aspects of the dung beetle assemblage were evaluated, including species richness and abundance, feeding habits and foraging strategies. A total of 614 individuals were collected, which included eight species belonging to seven genera and four tribes. Dichotomius carbonarius (Mannerheim, 1829), a generalist species, dominated the assemblage, indicating that it is adapted to living in fragmented and urbanized areas. As regards feeding habits, Eurysternus caribaeus (Jablonsky & Herbst, 1789) was considered to be strictly coprophagous, Coprophanaeus cyanescens (d'Olsoufieff, 1924) copronecrophagous and D. carbonarius a generalist. Most species were classified as paracoprids, which accounted for 75% of the species collected. Regarding the attractiveness of the bait, the highest numbers of individuals and species were recorded in pitfall traps baited with human faeces. A high abundance of Scarabaeinae was recorded in the first half of the rainy season (October-December) with 98.2% of the individuals collected in this period. The urban area studied harboured a low number of species with high abundance of a few species.

A first step to evaluate the impact of ecotourism on biodiversity in El Salvador: a case study using dung beetles in a National Park

ABSTRACT Ecotourism involves visiting natural areas without adversely affecting biodiversity, an objective that is often not reached. Although ecotourism in El Salvador is currently under-developed, it has been proposed for the conservation of forests that remain within the territory. To this respect, National Park El Imposible is the largest natural protected area in the nation, with 23% of its extension designated for ecotourism. The objective of this study was to evaluate the impact of ecological disturbances produced by ecotourism, using dung beetles as biological indicators in the park. Three zones differing in tourism intensity: conservation, extensive, and intensive, were evaluated. Six samplings using pitfall traps were carried out from June–November, 2013 in each zone. We recorded a significantly lower beetle abundance in the intensive-use zone, even though biomass tended to increase with ecotourism intensity due to proportional increase in large-sized species. There were differences in composition, diversity, and evenness of the dung beetle assemblage, evidencing ecological disturbances in the intensive-use zone. Ecotourism in the park has caused a negative impact on the dung beetle assemblage structure due to the loss of habitat specialists in favor of widespread generalists. Consequently, ecotourism should be regulated to minimize its effects in the site.

Patterns of alimentary resource use by dung beetles in introduced Brazilian pastures: Cattle versus sheep dung

AbstractDung beetles (Coleoptera: Scarabaeidae) perform essential ecological functions in pastures, such as dung removal, nutrient recycling and parasite control. However, the patterns of alimentary use by dung beetles in introduced Brazilian pastures are poorly known. Here, we compared dung beetle species richness, abundance and species composition in cattle and sheep dung, and identified the dung beetle species preference by each dung type. In January 2019, dung beetles were sampled with pitfall traps baited with cattle and sheep dung in 12 introduced pastures (Urochloa spp.), in Aquidauana, Mato Grosso do Sul, Brazil. A total of 592 individuals belonging to 14 species of dung beetles were collected. Of the 14 species sampled, nine were recorded in both dung types, five were found exclusively in sheep dung and no species was exclusive to cattle dung. Species richness and abundance were higher in sheep dung. Species composition was different between the dung types. Dichotomius bos (Blanchard), Genieridium bidens (Balthasar), Onthophagus aeneus Blanchard and Trichillum externepunctatum Preudhomme de Borre were associated with sheep dung. Our results provide evidence that sheep dung is more attractive to dung beetles with a distinct community species between the two dung types, although the studied pastures have never been used before for sheep breeding. Thus, our data shows that the introduction of a new alimentary resource (e.g. sheep dung) can be an important strategy to help to obtain a more diverse dung beetle assemblage in introduced Brazilian pastures.

Habitat patch size and isolation drive the near-complete collapse of Amazonian dung beetle assemblages in a 30-year-old forest archipelago

The creation of mega-hydropower dams inundates vast lowland areas, causing widespread environmental impacts in tropical forest regions. Few studies, however, have taken advantage of these newly fragmented landscapes to examine the effects of habitat insularization on arthropod faunas. Here, we assess how dung beetle assemblages respond to 30 years of post-isolation history in forest islands within a major hydroelectric reservoir in Central Amazonia. We sampled 30 of the 3546 islands created by this reservoir, and three neighbouring forest sites. We collected a total of 865 individuals representing 34 dung beetle species and 15 genera. Remarkably, one third of all islands had been entirely defaunated of dung beetles in terms of overall occupancy. Isolation was the single best predictor of dung beetle species richness, followed by the interaction between isolation and island area, and these variables were key determinants of the relict species composition. Isolation was the most important predictor of dung beetle abundance, but area alone was the main predictor of abundance when the dominant species was excluded. We predicted species richness across all 3546 islands, indicating that 61.5% of all islands likely retain only a single ‘super-tramp’ species (Onthophagus osculatii). These community disassembly patterns were likely aggravated by the marked hostility of the open-water matrix combined with the poor flight dispersal capacity of dung beetles over wide gaps between insular forests. As such, the overwhelming number of small, isolated islands created by major dams has profound effects on regional forest biodiversity, including wholesale local extinctions in detritivore assemblages and their ecosystem functions.

Dung beetles collected using flight intercept traps in an Amazon rainforest fragment and adjacent agroecosystems

Dung beetles present a high specificity degree to certain habitat types and they are widely used as bioindicators of environmental changes. Pitfall traps usually baited with human feces are the main method for collecting these insects. However, despite dung beetles being good flyers and actively move in the environment, collections with flight intercept traps have been little used in inventories of these insects in the wild. The fact that the intercept trap usually does not use any attractants, randomly capturing individuals can minimize sampling artifacts related with bait, light or other attractive methods. Here, we use flight intercept traps to analyze the dung beetle assemblages in different habitats in the Amazon rainforest. Dung beetles were sampled weekly from March 2017 to February 2018 in an Amazon forest fragment under anthropic pressure, cupuacu orchard, and exotic pasture in Porto Velho, Rondonia, Brazil. A total of 1041 individuals belonging to 35 species of dung beetles were collected. The species accumulation curve showed no significant difference in the number of species among the three different habitats. The dung beetle species composition found in the forest fragment and cupuacu orchard was similar, but the community of these two habitats was different from the exotic pasture. Our study provides a list of dung beetle species sampled using a method that is still little used in ecological studies using dung beetles as a study model. Finally, the flight intercept trap is a useful tool for dung beetle inventories in different habitats in the Amazon rainforest.