Effects of dung-pad conditions and density on coprophagous beetle assemblages in a Mediterranean rangeland

Dung beetles highly depend on the ephemeral microhabitat dung which is food resource and larval habitat at the same time. Environmental conditions surrounding a dung pad, such as vegetation structure, have an impact on dung beetle assemblages. We investigated the influence of dung conditions and surrounding habitat characteristics on Mediterranean dung beetle assemblages in a permanently grazed landscape in northern Sardinia. We sampled the dung beetle assemblages of donkey and horse dung in three different vegetation types and assessed species richness and abundance of dung beetles. Species richness was determined by dung and surrounding habitat conditions, whereas abundance was solely affected by dung conditions. However, species richness and abundance decreased with increasing dung density. The effect of dung density on species richness varied depending on vegetation type, with dry grassland exhibiting the highest number of dung beetles species at high dung density. Species composition in dung pads was influenced by abiotic factors with dwellers being negatively affected by increasing dung-pad temperature. Our results underline the importance of diverse vegetation, particularly with respect to the complexity of vegetation which interrelates with the microclimate. Furthermore, our findings illustrate the negative effect of high dung densities on dung beetle assemblages, suggesting that the degree of the intensity of use by grazing animals is important when considering measures for the conservation of dung beetles.     

Effects of Degradation and Replacement of Southern Brazilian Coastal Sandy Vegetation on the Dung Beetles (Coleoptera: Scarabaeidae)

In this paper we address the effects of anthropogenic disturbance and replacement of Brazilian Coastal sandy vegetation (restingas) on dung beetles communities. We sampled dung beetles in the four main vegetative physiognomies of Guriri Island, Espírito Santo State: forest restinga, restinga Clusia, disturbed restinga (from burning events), and pastures. We placed four sets of two pitfall traps (baited with horse and human dung) in four independent areas of each vegetation type, and collected 14,534 individuals of 13 dung beetle species. Neither log₁₀ of individuals nor log₁₀ of species richness were good predictors of restinga disturbance. However, a significant amount of variation in dung beetle abundance and richness could be explained by bait type. Ordination of these sites using hybrid multidimensional scaling revealed a gradient of habitat disturbance from undisturbed restinga samples to pasture. Dung beetle communities along this gradient demonstrated a complete turnover in species composition, from restinga‐specialists to invasive and generalists species respectively. This complete turnover signals the local extirpation of forest‐adapted species in disturbed and converted areas. Only a single dung beetle species in preserved restingas is protected by Brazilian law (Dichotomius schiffleri). Given the extent of the clearing of restinga habitat, the conservation status of dung beetles associated with restinga forest gives cause for concern.     

Dung Beetle Community and Functions along a Habitat-Disturbance Gradient in the Amazon: A Rapid Assessment of Ecological Functions Associated to Biodiversity

Although there is increasing interest in the effects of habitat disturbance on community attributes and the potential consequences for ecosystem functioning, objective approaches linking biodiversity loss to functional loss are uncommon. The objectives of this study were to implement simultaneous assessment of community attributes (richness, abundance and biomass, each calculated for total-beetle assemblages as well as small- and large-beetle assemblages) and three ecological functions of dung beetles (dung removal, soil perturbation and secondary seed dispersal), to compare the effects of habitat disturbance on both sets of response variables, and their relations. We studied dung beetle community attributes and functions in five land-use systems representing a disturbance gradient in the Brazilian Amazon: primary forest, secondary forest, agroforestry, agriculture and pasture. All response variables were affected negatively by the intensification of habitat disturbance regimes, but community attributes and ecological functions did not follow the same pattern of decline. A hierarchical partitioning analysis showed that, although all community attributes had a significant effect on the three ecological functions (except the abundance of small beetles on all three ecological functions and the biomass of small beetles on secondary dispersal of large seed mimics), species richness and abundance of large beetles were the community attributes with the highest explanatory value. Our results show the importance of measuring ecological function empirically instead of deducing it from community metrics.     

The role of habitat and daily activity patterns in explaining the diversity of mountain Neotropical dung beetle assemblages

The interaction between land use and climate change is expected to strongly affect species distributions along high elevation landscapes. We aimed to test the effect of climatic variables on community metrics among five types of land use in a high elevation landscape. We described dung beetle spatial and temporal taxonomic and functional diversity patterns, and partitioned β‐diversity into turnover and nestedness components. The interaction between land use and daily period of activity mostly drives abundance, functional richness and functional diversity, but not dung beetle species richness. Unlike Neotropical lowlands, species richness and abundance in open environments are similar to those existing in forests. Temperature is an important predictor of abundance and functional divergence. There is a higher spatial component of the taxonomic β‐diversity, which is highly driven by species turnover. The temporal component of the taxonomic β‐diversity was strongly driven by nestedness, where night assemblages are sub‐sets, although not entirely, of diurnal assemblages. For functional diversity, the temporal β‐diversity was much higher than the spatial β‐diversity, but both were similarly represented by functional group turnover and nestedness. The composition of nocturnal and diurnal assemblages is clearly different, even more than the differences observed between habitats. However, taxonomic turnover is the dominant force between sampling sites while nestedness dominates the daily pattern. This means that forest habitats are unlikely to act as shelters for grassland species under a scenario of rising temperature.     

小兴安岭阔叶红松林地表甲虫Beta多样性

Beta多样性用来衡量集群内物种组成的变异性,可以被分解为空间物种转换和物种集群镶嵌两个组分,是揭示群落构建机制的重要基础。目前开展了较多的地上生态系统beta多样性研究,然而地下生态系统beta多样性进展缓慢。以小兴安岭凉水和丰林自然保护区为研究地区,于2015年8、10月采用陷阱法对阔叶红松林进行调查,揭示地表甲虫(步甲科、隐翅虫科、葬甲科)的beta多样性。结果表明:(1)凉水共发现39种、856只地表甲虫,丰林共发现43种、1182只地表甲虫。8月凉水明显具有较高的全部甲虫(三个科的总和)物种多样性和丰富度,10月正好相反。(2)凉水和丰林之间地表甲虫beta多样性的差异仅发现于8月的步甲科和葬甲科之间。(3)凉水和丰林地表甲虫的beta多样性主要由空间物种转换组成,物种集群镶嵌对beta多样性的贡献很小,说明地表甲虫物种组成变异主要由本地物种之间较高的转换引起。研究表明小兴安岭阔叶红松林地表甲虫的beta多样性主要由空间物种转换组成,在揭示群落构建机制过程中,其内部物种交换和环境调控不容忽视。     

Abrupt species loss of the Amazonian dung beetle in pastures adjacent to species-rich forests

Anthropogenic disturbances, such as conversion of forests to pastures, are considered one of the major causes of Amazonian biodiversity loss. Pastures are hostile environments for forest species that are not adapted to the adverse conditions of open areas. The aim of this study was to analyze the effects of forest replacement by cattle pastures in the north-eastern part of the Amazonian rainforest using dung beetles (Scarabaeidae: Scarabaeinae) as indicators. Therefore, we determined edge effects and differences in dung beetle species richness, composition, and abundance between forest and neighbouring cattle pastures. A total of 6723 individuals of 63 species of dung beetle were collected. In comparison to forests, adjacent pastures were sharply less rich and abundant in dung beetles. The forests had 6604 individuals and 59 species, while the pastures had 119 individuals and 12 species. The replacement of forests by pastures results in an increase of dung beetle species turnover. Only 12% of dung beetle species were shared by both forest and pasture environments. We highlight that most Amazonian dung beetles are forest species sensitive to abrupt human-driven modification of habitats and are only moderately affected by edge effects.     

Space-for-time substitution reveals a hump-shaped distribution of dung beetles

Unraveling how climate change impacts the diversity and distribution patterns of organisms is a major concern in ecology, especially with climate-sensitive species, such as dung beetles. Often found in warmer weather conditions, beetles are used as bio-indicators of environmental conditions. By using an altitudinal gradient as a proxy for climate change (i.e., space-for-time substitution), we assessed how changes in climatic variables, such as temperature and precipitation, impact patterns of dung beetle diversity and distribution in the Peruvian Andes. We recorded dung beetle diversity using three different types of baits, feces, carrion, and fruits, distributed in 18 pitfall traps in five different altitudinal sites (from 900 to 2500 m, 400 m apart from each other) in the rainy and dry season. We found that (i) dung beetle richness and abundance were influenced by the climate gradient, (ii) seasonality influenced beetle richness, which was high in the wet season, but did not influence abundance, (iii) dung beetle richness and abundance fit to a hump-shaped distribution pattern along the altitudinal gradient, and (iv) species richness is the beta-diversity component that best describes the composition of dung beetle species along the altitudinal gradient. Our data show that the distribution and diversity of dung beetles are different at larger scales, with different patterns resulting from the response of species to both abiotic and biotic factors.     

Is microclimate-driven turnover of dung beetle assemblage structure in regenerating coastal vegetation a precursor to re-establishment of a forest fauna?

We questioned the capability of post-mining rehabilitation and successional changes in coastal vegetation to achieve restoration of dune forest, dung beetle assemblages in the Maputaland Centre of Endemism, South Africa. A repeat 2010 study of structural turnover between dung beetle assemblages across a 33 year successional sere of rehabilitating vegetation and old-growth forest (>73 years) produced comparable results to an earlier study across the 23 year chronosequence of 2000. Despite overlap, three structural patterns along the 33 year chronosequence were associated with specific stages of vegetation succession and their characteristic microclimates as in 2000. Although species biased to unshaded habitat dominated the earliest succession, there was rapid re-establishment of dominance by shade-associated forest species. In concert with progression from unshaded, post-mining vegetation to strongly shaded, early successional, Acacia shrub-woodland, there was an initial increase in similarity of the dung beetle fauna (species-poor, low abundance) to that in strongly-shaded forest (also species-poor, low abundance). However, in concert with decreasing shade cover in late successional woodland, the dung beetle fauna became species-rich with high abundance so that the early successional trajectory of increasing similarity to forest fauna either levelled off to a plateau (species in 2000; abundance in 2010) or declined (species in 2010, abundance in 2000). It remains to be seen if gaps forming in the oldest Acacia woodland permit forest tree saplings of the exposed understorey to recreate a forest canopy that would be tracked by dung beetles to re-establish a typically species-poor, deep shade, forest assemblage with low abundance.     

Habitat heterogeneity, richness and structure of assemblages of dung beetles (Scarabaeidae: Scarabaeinae) in areas of cerrado in the Chapada dos Parecis, Mato Grosso state, Brazil

Ecological theory of habitat heterogeneity and limited niche-similarity assumes that more heterogeneous environments provide a greater amount and diversity of resources than simple environments, resulting in a greater diversity of species. This study aimed to evaluate the effect of the habitat heterogeneity on the richness of dung beetles and to examine the spatial patterns of assemblage structure in relation to patterns of habitat heterogeneity. Dung beetles were collected using pitfall traps without bait in 30 points distributed in an area of cerrado sensu lato, in the region of Tangará da Serra, MT, Brazil, including areas of cerrado sensu stricto, campo sujo, cerrad?o and gallery forest. A total of 1,291 dung beetles were collected, distributed in 16 genera and 29 species. Overall habitat heterogeneity exerted a negative effect on patterns of dung beetles richness. Higher levels of species richness were observed in areas of cerrado campo sujo, while the areas of gallery forest were the most species poor. Regarding assembly structure, it was found that the dung beetles were separated into two major groups, one formed by the presence of specialized species in forest areas and other composed of species that occurred predominantly in cerrado. In conclusion, it was found that habitat complexity influenced the distribution of dung beetles, but the level of turnover in species composition along the heterogeneity gradient was relatively weak.     

Dung beetle persistence in human-modified landscapes: Combining indicator species with anthropogenic land use and fragmentation-related effects

Identifying and making use of ecological indicators becomes an essential task in the conservation of tropical systems, mainly in fragmented landscapes where land use intensification and habitat loss are confounding factors in the detection of species’ responses to human-caused disturbance. We aimed to analyze the importance of anthropogenic land use and fragmentation-related effects on dung beetle (Coleoptera: Scarabaeinae) persistence according to the interior–exterior non-linear gradient (forest + matrix) in a fragmented Atlantic Forest landscape used to sugar cane production and cattle ranching/farming. We offer scores for a comprehensive set of community-level attributes, from beetle abundance to taxonomic and ecological composition (i.e. species body size), including a list of indicator species of different forest habitats and adjacent matrix. Dung beetles were surveyed by traps across forest interiors (i.e. core forest areas) and edges of a primary forest, small fragments, sugar cane fields and pastures in a total of 60 sites. Indicator analyses were conducted across the landscape, using two well-established methods (IndVal and SIMPER). Our results suggest that (1) cross-habitat taxonomic distinctness is associated with the presence of indicator species, (2) some species benefit or are dependent of open habitats created by human-disturbances, such as forest edges (e.g. Canthon nigripennis) and matrices (e.g. Canthon aff. piluliformis, Dichotomius nisus and Trichilum externepunctatum), (3) although landscape habitats exhibit reduced beta diversity, dung beetle assemblages are spatially organized in response to the presence of both forest habitats and matrix and fragment area, (4) forest interior supports beetle assemblages biased toward large-bodied species, (5) accordingly forest interior, forest edges and matrix support taxonomically distinct assemblages, both contributing to the bulk of species richness at landscape level, (6) the response of dung beetles to the interior–exterior non-linear gradient (i.e. forest edge + matrix) reveals a similar pattern regardless of the nature of the matrix, and (7) there is no within-habitat variation in beetle abundance and species richness associated with distance from forest edge. Given that there is a high number of forest-dependent or forest-interior specialist species (e.g. Aphengium aff. sordidum, Ateuchus aff. alipioi, Dichotomius mormon, Ontherus aff. erosus and Onthophagus aff. clypeatus) dung beetle persistence in human-modified landscape is highly dependent on the presence of core areas, although edge-affected and matrix habitats may be complementary. This information is essential to permit a better prospect for dung beetle persistence in human-modified landscapes as they continue to move toward edge-dominated landscapes with intensively managed matrices.     

Dung Beetle Assemblages and Seasonality in Primary Forest and Forest Fragments on Agricultural Landscapes in Budongo, Uganda

Very little is known about the diversity of arthropods in the fast-disappearing fragments of natural forests in sub-Saharan Africa. This study investigated: (1) the influence of forest fragment characteristics on dung beetle species richness, composition, abundance, and diversity; and (2) the relationship between dung beetle assemblages and rainfall pattern. Beetles were sampled through 12 mo using dung baited pitfall traps. A total of 18,073 dung beetles belonging to three subfamilies and 45 species were captured. The subfamily Scarabaeinae was the most abundant (99%) and species rich (89%). Fast-burying tunnellers (paracoprids) were the most dominant functional group. Catharsius sesostris, Copris nepos , and Heliocopris punctiventris were the three most abundant species, and had the highest contributions to dissimilarities between forests. With few exceptions, dung beetle abundance, species richness, and diversity were generally higher in larger forest fragments (100–150 ha) than in smaller ones (10–50 ha) and the nature reserve (1042 ha). Forest fragment size had a highly significant positive relationship with beetle abundance, but only when the nature reserve is excluded in the analysis. Dung beetle abundance and species richness showed direct weak relationships with litter depth (positive) and groundcover (negative) but not tree density, tree species richness, and fragment isolation distance. Dung beetle abundance and species richness were strongly correlated with monthly changes in rainfall. Results of this study indicate that forest fragments on agricultural lands in the Budongo landscape, especially medium-sized (100–150 ha) ones, represent important conservation areas for dung beetles.     

Does natural reforestation represent a potential threat to dung beetle diversity in the Alps?

Traditional agro-pastoral practices are in decline over much of the Alps, resulting in the complete elimination of livestock grazing in some areas. Natural reforestation following pastoral abandonment may represent a significant threat to alpine biodiversity, especially that associated with open habitats. This study presents the first assessment of the potential effects of natural reforestation on dung beetles by exploring the relationships between the beetle community (abundance, diversity, species turnover and assemblage structure) and the vegetation stages of ecological succession following pastoral abandonment. A hierarchical sampling design was used in the montane belt of the Sessera Valley (north-western Italian Alps). Dung beetles were sampled across 16 sampling sites set in four habitat types corresponding to four different successional stages (pasture, shrub, pioneer forest and beech forest) at two altitudinal levels. The two habitats at the extremes of the ecological succession, i.e. pasture and beech forest, had the greatest effect on the structure of local dung beetle assemblages. Overall, dung beetle abundance was greater in beech forest, whereas species richness, Shannon diversity and taxonomic diversity were significantly higher in pasture, hence suggesting this latter habitat can be considered as a key conservation habitat. Forests and pastures shared a lower number of species than the other pairs of habitats (i.e. species turnover between these two habitats was the highest). The two intermediate seral stages, i.e. shrub and pioneer forest, showed low dung beetle abundance and diversity values. Local dung beetle assemblages were also dependent on season and altitude; early-arriving species were typical of pastures of high elevation, whereas late-arriving species were typical of beech forests. It is likely that grazing in the Alps will continue to decrease in the future leading to replacement of open habitats by forest. This study suggests therefore that, at least in the montane belt, reforestation may have potentially profound and negative effects on dung beetle diversity. Maintaining traditional pastoral activities appears to be the most promising approach to preserve open habitats and adjacent beech forests, resulting in the conservation of species of both habitats.     

Co‐declining mammal–dung beetle faunas throughout the Atlantic Forest biome of South America

The millennial–scale evolutionary relationships between mammals and dung beetles have been eroded due to several drivers of contemporary biodiversity loss. Although some evidence of co‐decline has been shown for mammals and dung beetles at some Neotropical sites, a biome‐scale analysis for the entire Atlantic Forest of South America would strengthen our understanding of how relictual sets of mammal species can affect dung beetle co‐occurrences and co‐declines. We therefore collated hundreds of assemblages of both dung beetles and medium‐ to large‐bodied mammals throughout the world's longest tropical forest latitudinal gradient to examine to what extent mammal assemblages may exert a positive influence on dung beetle species composition and functional assembly, and whether this relationship is scale dependent. We also collated several climatic and other environmental variables to examine the degree to which they shape mammal–dung beetle relationships. The relationships between local mammal and dung beetle faunas were examined using regression models, variation partitioning, dissimilarity indices and ecological networks. We found a clear positive relationship between mammal and dung beetle species richness across this forest biome, indicating an ongoing process of mammal–dung beetle niche‐mediated co‐decline. We found a strong relationship between the species composition of both taxa, in which dung beetle species dissimilarity apparently track changes in mammalian dissimilarity, typically in 80% of all cases. Co‐variables such as phytomass and climatic variables also influenced mammal–dung beetle patterns of co‐decline along the Atlantic Forest. We conclude that dung beetle diversity and community assembly are shaped by the remaining co‐occurring mammal assemblages and their functional traits, and both groups were governed by environmental features. We emphasize that ecosystem‐wide effects of mammal population declines remain poorly understood both quantitatively and qualitatively, and curbing large vertebrate defaunation will ensure the persistence of co‐dependent species.     

Dung beetle assemblages on tropical land‐bridge islands: small island effect and vulnerable species

Aim Using dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in a tropical land‐bridge island system, we test for the small island effect (SIE) in the species–area relationship and evaluate its effects on species richness and community composition. We also examine the determinants of species richness across island size and investigate the traits of dung beetle species in relation to their local extinction vulnerability following forest fragmentation. Location Lake Kenyir, a hydroelectric reservoir in north‐eastern Peninsular Malaysia. Methods We sampled dung beetles using human dung baited pitfall traps on 24 land‐bridge islands and three mainland sites. We used regression tree analyses to test for the SIE, as well as species traits related to local rarity, as an indication of extinction vulnerability. We employed generalized linear models (GLMs) to examine determinants for species richness at different scales and compared the results with those from conventional linear and breakpoint regressions. Community analyses included non‐metric multidimensional scaling, partial Mantel tests, nestedness analysis and abundance spectra. Results Regression tree analysis revealed an area threshold at 35.8 ha indicating an SIE. Tree basal area was the most important predictor of species richness on small islands (<35.8 ha). Results from GLMs supported these findings, with isolation and edge index also being important for small islands. The SIE also manifested in patterns of dung beetle community composition where communities on small islands (<35.8 ha) departed from those on the mainland and larger islands, and were highly variable with no significant nestedness, probably as a result of unexpected species occurrences on several small islands. The communities exhibited a low degree of spatial autocorrelation, suggesting that dispersal limitation plays a part in structuring dung beetle assemblages. Species with lower baseline density and an inability to forage on the forest edge were found to be rarer among sites and hence more prone to local extinction. Main conclusions We highlight the stochastic nature of dung beetle community composition on small islands and argue that this results in reduced ecosystem functionality. A better understanding of the minimum fragment size required for retaining functional ecological communities will be important for effective conservation management and the maintenance of tropical forest ecosystem stability.     

The Old and Young Amazon: Dung Beetle Biomass, Abundance, and Species Diversity

The Amazon Basin can be divided into two geomorphological regions based on the age of its soils: young (< 30 mya) and old (> 300 mya). We tested the effects of soil age on dung beetle communities by comparing biomass, abundance, and species between reserves in Ecuador on young soils and reserves in Brazil on old soils. Beetle biomass in the old Amazon was one-third that in the young Amazon, and beetle abundance in the old Amazon was one-fourth that in the young Amazon. Species richness, rarefied to equal sample sizes, was not significantly different between old and young soils. These data suggest young soils of the Amazon support a significantly greater biomass and abundance of dung beetles than old soils, but that species richness across the Basin is similar. As dung beetles are bio-indicators of mammals, our data support previous studies indicating a greater biomass of mammals on young versus old Amazon soils.     

Dung beetle community composition affects dung turnover in subtropical US grasslands

1. 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.
2. 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.
3. 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.
4. 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.

     

Invasion and retreat: shifting assemblages of dung beetles amidst changing agricultural landscapes in central Peru

This study examines the effects of deforestation, and the habitat value of coffee and regenerated forest for tropical dung beetles, a functionally significant insect group. Pitfall trapping was conducted at 22 sites in a montane region of central Peru during April and November/December of 2002. Sites included primary and secondary forest, shade-coffee, regenerated forest and open farms (mainly with banana, yuca, and corn). Ordination techniques indicated that beetle assemblages in forests, regenerated forest and coffee were relatively similar. However, assemblage compositions in forested areas differed even at similar altitudes under the influence of biogeographical factors, and the assemblages at disturbed sites (farms/coffee) were influenced by beetle dispersal from adjacent forests. During dry months, when beetle activity is low, communities at all habitat types tended to converge because fewer unique species were recorded in forests at that time and habitat/season generalists were dominant. Preliminary results also indicate that beetles in shady crops such as bananas responded to plant growth: as the banana canopy closed-in, producing more shade, open-habitat specialists retreated and forest/shade specialists invaded the sites. Chronosequence data at two of the sites demonstrate the rapid and dramatic changes in species richness and assemblage composition caused by deforestation. As forests become increasingly fragmented, and open farms continue to expand, dung beetles will become more restricted to the remaining fragments and reserves. In the mosaic landscape studied here, shade crops, like coffee, act as habitat and corridors for many dung beetle species. Small farm size and the consequent magnitude of edge effects, likely contributed to beetle movement between habitat types and determined the apparent generalist nature of many of the dung beetle species in this study.     

Are Dung Beetles Driving Dung-Fly Abundance in Traditional Agricultural Areas in the Amazon?

We evaluated the effects of different land-use systems on the ability of dung beetles to control the population of detritus-feeding flies. We tested the hypotheses that intensification of land use will reduce dung beetles richness, abundance and biomass and, consequently, their dung burial ability, affecting the interaction between dung beetles and flies and reducing its effectiveness as a natural biological control. In the Brazilian Amazon we sampled dung beetles, fly larvae and adults; and recorded the rate of dung removal by dung beetles across a gradient of land-use intensity from primary forest, secondary forest, agroforestry, agriculture to pasture. Our results provide evidence that land-use intensification results in a reduction of the richness, abundance and biomass of dung beetles, and this in turn results in lower rates of dung removal in the most simplified systems. We found no significant differences in the abundance of fly larvae between the different systems of land use. However, the number of adult flies differed significantly between land-use systems, presenting higher abundance in those sites with greater intensity of use (pasture and agriculture) and a lower abundance of adult flies in forested systems (primary and secondary forests, and agroforestry). Information-theoretic model selection based on AICc revealed strong support for the influence of land-use systems, dung removal rates and dung beetle abundance, biomass and richness on adult dung-fly abundance. Our results also reveal that dung beetles are not solely responsible for fly control and that other factors linked to land use are influencing the populations of these detritus-feeding insects.     

El Niño impacts on human-modified tropical forests: Consequences for dung beetle diversity and associated ecological processes

Our knowledge of how tropical forest biodiversity and functioning respond to anthropogenic and climate-associated stressors is limited. Research exploring El Niño impacts are scarce or based on single post-disturbance assessments, and few studies assess forests previously affected by anthropogenic disturbance. Focusing on dung beetles and associated ecological functions, we assessed (a) the ecological effects of a strong El Niño, (b) if post-El Niño beetle responses were influenced by previous forest disturbance, and (c) how these responses compare between forests impacted only by drought and those affected by both drought and fires. We sampled 30 Amazonian forest plots distributed across a gradient of human disturbance in 2010, 2016, and 2017—approximately 5 years before, and 3–6 and 15–18 months after the 2015–16 El Niño. We found 14,451 beetles from 98 species and quantified the beetle-mediated dispersal of >8,600 seed mimics and the removal of c. 30 kg of dung. All dung beetle responses (species richness, abundance, biomass, compositional similarity to pre-El Niño condition, and rates of dung removal and seed dispersal) declined after the 2015–16 El Niño, but the greatest immediate losses (i.e., in 2016) were observed within fire-affected forests. Previous forest disturbance also influenced post-El Niño dung beetle species richness, abundance, and species composition. We demonstrate that dung beetles and their ecological functions are negatively affected by climate-associated disturbances in human-modified Amazonian forests and suggest that the interaction between local anthropogenic and climate-related stressors merits further investigation.     

The diversity of beetle assemblages in different habitat types in Sabah, Malaysia

The diversity of beetle assemblages in different habitat types (primary forest, logged forest, acacia plantation and oil palm plantation) in Sabah, Malaysia was investigated using three different methods based on habitat levels (Winkler sampling, flight-interception-trapping and mist-blowing). The overall diversity was extremely high, with 1711 species recorded from only 8028 individuals and 81 families (115 family and subfamily groups). Different degrees of environmental changes had varying effects on the beetle species richness and abundance, with oil palm plantation assemblage being most severely affected, followed by acacia plantation and then logged forest. A few species became numerically dominant in the oil palm plantation. In terms of beetle species composition, the acacia fauna showed much similarity with the logged forest fauna, and the oil palm fauna was very different from the rest. The effects of environmental variables (number of plant species, sapling and tree densities, amount of leaf litter, ground cover, canopy cover, soil pH and compaction) on the beetle assemblage were also investigated. Leaf litter correlated with species richness, abundance and composition of subterranean beetles. Plant species richness, tree and sapling densities correlated with species richness, abundance and composition of understorey beetles while ground cover correlated only with the species richness and abundance of these beetles. Canopy cover correlated only with arboreal beetles. In trophic structure, predators represented more than 40% of the species and individuals. Environmental changes affected the trophic structure with proportionally more herbivores (abundance) but fewer predators (species richness and abundance) in the oil palm plantation. Biodiversity, conservation and practical aspects of pest management were also highlighted in this study.