A trait-based framework for dung beetle functional ecology

Postfire Scenarios Shape Dung Beetle Communities in the Orinoquía Riparian Forest-Savannah Transition

The Orinoquía region of Colombia includes diverse ecosystems such as riparian forests and seasonal savannas, which play vital roles as biodiversity reservoirs. However, increased fire activity, driven by both natural and anthropogenic pressures, poses mounting threats to these ecosystems. Despite their importance, the effects of fire on faunal communities, especially in transitional habitats, are not well understood. Understanding biodiversity responses to fire across different recovery stages is essential for conservation planning. This study aimed to assess the effects of fire occurrence and recovery time on dung beetle communities as an indicator of ecosystem resilience. We analyzed taxonomic responses-including species richness, abundance, and Hill diversity indices (D0, D1, D2)-as well as functional traits such as guild richness, biomass, and food relocation behavior, across riparian forest-savanna ecotones under varying fire histories. Our results indicate that recent fires (≤1 year) and high fire frequencies (4-5 events) negatively affect species diversity and abundance. Dominance by a few disturbance-tolerant species, such as Digitonthophagus gazella, was observed in burned savannas, while forest habitats supported both rare and dominant taxa. Despite taxonomic declines, functional redundancy was maintained, largely due to the prevalence of small-bodied species. However, we observed a general resilience effect in which core species contributed to postfire community reassembly. Functional redundancy was maintained, with small dung beetles dominating the biomass and guild composition. The conservation status of transitional habitats, particularly the forest-savanna ecotone, played a critical role in postfire dung beetle community restructuring. The presence of resilient assemblages highlights the importance of dung beetles in sustaining key ecosystem functions following fire events. These findings underscore the potential of dung beetles as bioindicators for postfire monitoring and emphasize the need for improved fire management strategies in sensitive ecosystems.

Endozoochory by the cooperation between beetles and ants in the holoparasitic plant Cynomorium songaricum in the deserts of Northwest China

Cynomorium songaricum Rupr. first described by Carl Johann (Ivanovič) Ruprecht in 1840 is a desert parasitic plant that mainly parasitizes the roots of Nitraria L. (especially of Nitraria tangutorum Bobrov., Nitraria sibirica Pall.). During seed maturation, C. songaricum releases a distinct smell, and its seeds are round and dust-like. Previous studies indicated that most parasitic plants produce small seeds, which are primarily dispersed by the wind. Recent studies reveal the significant role of animals in the seed dispersal of parasitic plants. In this study, we combined (1) the direct observation of the seed dispersal of C. songaricum, and (2) the indoor breeding of beetles and ants to assess the viability of seeds, clarify the seed dispersal system, and explore the mechanisms by which the seeds attract dispersal agents. By a population study, we identified beetles (Mantichorula semenowi Reitter, 1888) and ants (Messor desertora He & Song, 2009) as the primary seed dispersal agents for the C. songaricum. These plants rely on the visits from these agents to transfer their seeds near the roots of the host plant, Nitraria L.. The release of a distinct volatile compound from C. songaricum seeds attracts M. semenowi and M. desertora to consume and/or transport the seeds. This study provides the first evidence of a multi-medium and inter-species seed dispersal system in the C. songaricum. This study elucidates the role of invertebrates in the seed dispersal of desert parasitic plants. We propose that the two seed dispersal agents play distinct roles in the sequential seed dispersal of C. songaricum, representing two key stages in the overall seed dispersal mechanism.

Spatial and temporal trends in dung beetle research

Dung beetles are one of the most charismatic animal taxa. Their familiarity as ecosystem service providers is clear, but they also play a range of roles in a variety of different ecosystems worldwide. Here, we give an overview of the current state of dung beetle research and the changes in the prevalence of topics in a collated corpus of 4,145 peer-reviewed articles of dung beetle research, spanning from 1930 until 2024. We used a range of text-analysis tools, including topic modelling, to assess how the peer-reviewed literature on dung beetles has changed over this period. Most of the literature is split into three distinct, but related discourses-the agri/biological topics, the ecological topics, and the taxonomic topics. Publications on the 'effect of veterinary chemicals' and 'nesting behaviour' showed the largest drop over time, whereas articles relating to 'ecosystem function' had a meteoric rise from a low presence before the 2000's to being the most prevelant topic of dung beetle research in the last two decades. Research into dung beetles is global, but is dominated by Europe and North America. However, the research from South America, Africa, and Australia ranges wider in topics. Research in temperate and tropical mixed forests, as well as grasslands, savanna and shrublands dominated the corpus, as would be expected from a group of species directly associated with large mammals. Our assessment of dung beetle research comes when ecosystem service provision is becoming more important and more dominant in the literature globally. This review therefore should be of direct interest to dung beetle researchers, as well as researchers working in agricultural, ecological, and taxonomic arenas globally. Research worldwide and across agri/biological, ecological, and taxonomic discourses is imperative for a continued understanding of how dung beetles and their ecosystem services are modified across rapidly changing natural and agricultural landscapes.

The Impact of Eucalyptus and Pine Plantations on the Taxonomic and Functional Diversity of Dung Beetles (Coleoptera: Scarabaeidae) in the Southern Region of Ecuador

This study sheds light on the complex relationship between land use, biodiversity, and the functional traits of dung beetles in Ecuador. The results indicate that the richness and abundance of dung beetles vary across different land uses and regions, with forests generally having a positive impact, while eucalyptus and pine plantations have a negative effect in certain areas. Specific indicator species, such as Homocopris buckleyi for forest areas and Onthophagus curvicornis for eucalyptus plantations, were identified. This study also found that functional diversity analysis, based on morphological traits, revealed that certain traits, such as biomass, pronotum width, head width, and elytra length, were significant contributors to differences in dung beetle communities across various land uses and regions. This study highlights the potential conservation value of certain modified habitats and emphasizes the importance of considering both taxonomic and functional diversity when assessing the impact of land use on the ecosystem services provided by dung beetles. It underscores the potential value of plantations as refuges for dung beetle communities and the need for long-term assessments to better understand biodiversity changes over time.

The impact of dung beetles on the free-living stages of ruminant parasites in faeces and their role as biological control agents in grazing livestock

Dung beetles provide a variety of ecosystem services in both natural and farmed landscapes. Amongst these services, reductions in the abundance of the free-living stages of pests and parasites that develop in faeces is considered to be of great importance. There is evidence from Australia that enhanced dung beetle populations can reduce populations of pest fly species, particularly the bush fly, however, there is little empirical evidence for reductions in the incidence and impact of nematode parasitism in grazing ruminants. There are two main pathways whereby beetles can disrupt worm life-cycles: predaceous species that feed on eggs or larvae can directly reduce populations in dung whereas coprophagous species can affect parasite development, survival and translocation by altering the location, microclimate and infrastructure of dung deposits. In addition, predaceous mites that are phoretic on dung beetles, can also prey on larval stages in the faeces. To date, reductions in both larval survival and the acquisition of gastrointestinal nematode burdens in ruminants on pasture has been reported only in association with the activity of large tunnelers that bury dung 15 cm or more below ground. The activity of dwellers, rollers and shallow tunnelers can either limit or enhance larval development and translocation, depending on the influence of other factors, notably rainfall. Currently, the scientific evidence for dung beetles playing a major role in the control of gastrointestinal nematodes in domestic ruminants is very limited and may have been overestimated in assessments of their ecosystem services.

Functional redundancy of weed seed predation is reduced by intensified agriculture

Intensified agriculture, a driver of biodiversity loss, can diminish ecosystem functions and their stability. Biodiversity can increase functional redundancy and is expected to stabilize ecosystem functions. Few studies, however, have explored how agricultural intensity affects functional redundancy and its link with ecosystem function stability. Here, within a continental-wide study, we assess how functional redundancy of seed predation is affected by agricultural intensity and landscape simplification. By combining carabid abundances with molecular gut content data, functional redundancy of seed predation was quantified for 65 weed genera across 60 fields in four European countries. Across weed genera, functional redundancy was reduced with high field management intensity and simplified crop rotations. Moreover, functional redundancy increased the spatial stability of weed seed predation at the field scale. We found that ecosystem functions are vulnerable to disturbances in intensively managed agroecosystems, providing empirical evidence of the importance of biodiversity for stable ecosystem functions across space.

Isopod mouthpart traits respond to a tropical forest recovery gradient

Functional trait ecology has the potential to provide generalizable and mechanistic predictions of ecosystem function from data of species distributions and traits. The traits that are selected should both respond to environmental factors and influence ecosystem functioning. Invertebrate mouthpart traits fulfill these criteria, but are seldom collected, lack standardized measurement protocols, and have infrequently been investigated in response to environmental factors. We surveyed isopod species that consume plant detritus, and tree communities in 58 plots across primary and secondary forests in Singapore. We measured body dimensions (body size traits), pereopod and antennae lengths (locomotory traits), dimensions of mandible structures (morphological mouthpart traits), and mechanical advantages generated by mandible shape (mechanical mouthpart traits) for six isopod species found in these plots and investigated if these traits respond to changes in tree community composition, tree diversity, and forest structure. Morphological mouthpart traits responded to a tree compositional gradient reflecting forest recovery degree. Mouthpart features associated with greater consumption of litter (broader but less serrated/rugose lacinia mobilis [an important cutting and chewing structure on the mandible]) were most prevalent in abandoned plantation and young secondary forests containing disturbance-associated tree species. Feeding strategies associated with fungi grazing (narrower and more serrated/rugose lacinia mobilis) were most prevalent in late secondary forests containing later successional tree species. Since morphological mouthpart traits likely also predict consumption and excretion rates of isopods, these traits advance our understanding of environment-trait-ecosystem functioning relationships across contrasting tropical forest plots that vary in composition, disturbance history, and post-disturbance recovery.

Dung removal increases under higher dung beetle functional diversity regardless of grazing intensification

Dung removal by macrofauna such as dung beetles is an important process for nutrient cycling in pasturelands. Intensification of farming practices generally reduces species and functional diversity of terrestrial invertebrates, which may negatively affect ecosystem services. Here, we investigate the effects of cattle-grazing intensification on dung removal by dung beetles in field experiments replicated in 38 pastures around the world. Within each study site, we measured dung removal in pastures managed with low- and high-intensity regimes to assess between-regime differences in dung beetle diversity and dung removal, whilst also considering climate and regional variations. The impacts of intensification were heterogeneous, either diminishing or increasing dung beetle species richness, functional diversity, and dung removal rates. The effects of beetle diversity on dung removal were more variable across sites than within sites. Dung removal increased with species richness across sites, while functional diversity consistently enhanced dung removal within sites, independently of cattle grazing intensity or climate. Our findings indicate that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a functionally diverse dung beetle community inhabits the human-modified landscape.

Population structure of Phanaeus vindex (Coleoptera: Scarabaeidae) in SE Michigan

Until now, little is known about the population structure and mobility of temperate dung beetles including the rainbow scarab, Phanaeus vindex (MacLeay 1819), although this knowledge is essential for their conservation as pastures become increasingly rare and the landscape fragmented by monocultures and urbanization. Here, we estimated population size, longevity, and dispersal within and between pastures. For 3 yr, we life-trapped beetles every week on 2 adjacent farms in SE Michigan, determined their sex, male morph, and size, and marked their elytra with individual tattoo patterns before releasing them. We marked a total of 470 rainbow scarabs of which 14 were recaptured once and 2 were recaptured twice. The sex ratio was not significantly sex-biased but fluctuated between months with no apparent uniformity between years. While the minor to major male ratios were unbiased in 2019 and 2020, they were marginally minor-biased in 2021. The gross population estimates for the 2 farms were 458-491 and 217 rainbow scarabs, respectively. Beetles traveled distances of up to 178 m within farms. No beetles dispersed between farms. One large female was recaptured after 338 days documenting the first cold hardiness and long lifespan of a cold-temperate dung beetle species in the wild. The low population estimates on both farms indicate 2 vulnerable populations with no or extremely limited connectivity. Supplementary funding for the land stewardship of small-scale cattle farmers could stabilize populations of native dung beetles and maintain their ecosystem services.

Metagenomics reveals that dung beetles (Coleoptera: Scarabaeinae) broadly feed on reptile dung. Did they also feed on that of dinosaurs?

The origin of the dung-feeding habits in dung beetles (Coleoptera: Scarabaeinae) is debatable. According to traditional views, the evolution of dung beetles (Coleoptera: Scarabaeinae) and their feeding habits are largely attributed to mammal dung. In this paper, we challenge this view and provide evidence that many dung beetle communities are actually attracted to the dung of reptiles and birds (= Sauropsida). In turn, this indicates that sauropsid dung may have played a crucial evolutionary role that was previously underestimated. We argue that it is physiologically realistic to consider that coprophagy in dung beetles could have evolved during the Cretaceous in response to the dung produced by dinosaurs. Furthermore, we demonstrate that sauropsid dung may be one of the major factors driving the emergence of insular dung beetle communities across the globe. We support our findings with amplicon-metagenomic analyses, field observations, and meta-analysis of the published literature.

The role of dung beetle species in nitrous oxide emission, ammonia volatilization, and nutrient cycling

This study evaluated the role of dung beetle species alone or associated under different species on nitrous oxide (N₂O) emission, ammonia volatilization, and the performance of pearl millet [Pennisetum glaucum (L.)]. There were seven treatments, including two controls (soil and soil + dung without beetles), single species of Onthophagus taurus [Shreber, 1759] (1), Digitonthophagus gazella [Fabricius, 1787] (2), or Phanaeus vindex [MacLeay, 1819] (3); and their assemblages (1 + 2 and 1 + 2 + 3). Nitrous oxide emission was estimated for 24 days, when pearl millet was planted in sequence to assess growth, nitrogen yield (NY), and dung beetle activity. Dung beetle species presented greater N₂O flow of dung on the 6th day (80 g N₂O-N ha^-1 day^-1) compared to soil and dung (2.6 g N₂O-N ha^-1 day^-1). Ammonia emissions varied with the presence of dung beetles (P < 0.05), and D. gazella had less NH₃^-N on days 1, 6, and 12 with averages of 2061, 1526, and 1048 g ha^-1 day^-1, respectively. The soil N content increased with dung + beetle application. Dung application affected pearl millet herbage accumulation (HA) regardless of dung beetle presence, and averages ranged from 5 to 8 g DM bucket^-1. A PCA analysis was applied to analyze variation and correlation to each variable, but it indicated a low principal component explanation (less than 80%), not enough to explain the variation in findings. Despite the greater dung removal, the largest species, P. vindex and their species combination, need to be more studied to get a better understanding about their contribution on greenhouse gases. The presence of dung beetles prior to planting improved pearl millet production by enhancing N cycling, although assemblages with the three beetle species enhanced N losses to the environment via denitrification.