Beyond Coprinisphaera: fossil nests of dung beetles

Forty‐two remains of fossil nests of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), which were recorded in four formations of the Cenozoic of South America, are described herein for the first time. Most of them are represented by nesting chambers containing a fossil brood ball (Coprinisphaera). However, in the most remarkable cases, parts of the burrows constructed by the parents and/or the vertical emergence burrows constructed by the offspring are preserved too. The preservation of the dung beetle nests is very unusual but more recurrent in younger formations probably because of the short‐term action of the diagenetic processes. Considering that the construction of brood balls always involves the construction of nests, the ichnotaxonomical proposal is that the remains of fossil nests should be considered as ‘structures associated with Coprinisphaera’ and added to the diagnosis to avoid the proliferation of names. The study of the fossil nests provides new palaeoetological inferences for dung beetles, such as the Nesting Pattern of the trace makers of Coprinisphaera tonnii and Coprinisphaera akatanka, and how phylogenetically related were they with the extant necrophagous species of the genera Coprophanaeus and Canthon, respectively. Additionally, the fossil evidence suggests that simple nests of dung beetles predate compound nests.     

Discontinuous gas exchange in dung beetles: patterns and ecological implications

This study correlates a distinctive pattern of external gas exchange, referred to as the discontinuous gas exchange cycle (DGC), observed in the laboratory, with habitat associations of five species of telecoprid dung beetles. The beetles were chosen from a variety of habitats that would be expected to present different amounts of water stress. All five species exhibited DGC. Sisyphus fasciculatus has been recorded only in woodland areas, and does not have strict spiracular control during its DGC. Anachalcos convexus and Scarabaeus rusticus are associated with open mesic habitats. Both species exhibit a distinct DGC, previously found in some other insect species, but intermediate within this study group. Sc. flavicornis and Circellium bacchus are typically found in arid regions, and have the most unusual form of DGC, with spiracular fluttering during the burst phase. These results support the hypothesis that spiracular fluttering reduces respiratory water loss. From this study we conclude that the DGC is an ancestral adaptation, most probably as a result of anoxic environments in underground burrows, but that spiracular control is enhanced to reduce respiratory water loss in beetle species that live in arid habitats. Received 4 August 1999 / Accepted: 7 October 1999     

The finely defined shift work schedule of dung beetles and their eye morphology

In nature, nothing is wasted, not even waste. Dung, composed of metabolic trash and leftovers of food, is a high‐quality resource and the object of fierce competition. Over 800 dung beetle species (Scarabaeinae) compete in the South African dung habitat and more than 100 species can colonize a single dung pat. To coexist in the same space, using the same food, beetles divide the day between them. However, detailed diel activity periods and associated morphological adaptations have been largely overlooked in these dung‐loving insects. To address this, we used a high‐frequency trapping design to establish the diel activity period of 44 dung beetle species in their South Africa communities. This allowed us to conclude that the dung beetles show a highly refined temporal partitioning strategy, with differences in peak of activity even within the diurnal, crepuscular, and nocturnal guilds, independent of nesting behavior and taxonomic classification. We further analyzed differences in eye and body size of our 44 model species and describe their variability in external eye morphology. In general, nocturnal species are bigger than crepuscular and diurnal species, and as expected, the absolute and relative eye size is greatest in nocturnal species, followed by crepuscular and then diurnal species. A more surprising finding was that corneal structure (smooth or facetted) is influenced by the activity period of the species, appearing flat in the nocturnal species and highly curved in the diurnal species. The role of the canthus—a cuticular structure that partially or completely divides the dung beetle eye into dorsal and ventral parts—remains a mystery, but the large number of species investigated in this study nevertheless allowed us to reject any correlation between its presence and the nesting behavior or time of activity of the beetles.     

Seasonal distribution and prevalence of dung beetles (Coleoptera: Scarabaeidae) in Kurukshetra,Northern India

A total of 8306 individuals as 29 species from 3 subfamilies (Hybosorinae, Aphodiinae, Scarabaeinae) were trapped by pitfall bait trapping. The maximum number of species of Scarabaeinae (68.97%) and number of individuals of Aphodiinae (56.84%) take part in the formation of a community. The number of species, number of individuals, diversity and dominance changes throughout the season. Seasonal prevalence of 82.76% of species and 50.81% of individuals was found in June. Aphodius campestris was found to be more attracted to the pitfall bait traps. The beetle community found in May shows the maximum Shannon's Diversity Index (2.46) but Margalef's Diversity Index was highest in August (3.06). Environmental factors play an important role in the occurrence and abundance of dung beetles. In the present study non-significant but positive correlations between temperature and species richness, abundance and diversity were found. Percent relative humidity showed a positive correlation with abundance only, and negative correlations with species richness and diversity.     

Unexpectedly diverse forest dung beetle communities in degraded rain forest landscapes in Madagascar

Tropical forests, which harbor high levels of biodiversity, are being lost at an alarming speed. Madagascar, a biodiversity hotspot, has lost more than half of its original forest cover. Most of the remaining forests are small fragments of primary and secondary forest with differing degrees of human impact. These forests, as well as coffee and fruit plantations, may be important in supporting the forest-dependent biodiversity in Madagascar but this has been little studied. In Madagascar, dung beetles, which offer important ecosystem services, are largely restricted to forests. We examined the ability of fragmented and degraded forests to support dung beetle diversity, compared to the large areas of primary forest in eastern Madagascar. We found a general trend of a reduction of species with a loss of forest connectivity. In contrast, a higher level of forest disturbance was associated with higher species diversity. In several sites of low-quality forest as many or more species were found as in less disturbed and primary forests. The average size of dung beetles was smaller in the lower quality localities than in the primary forests. These findings suggest that many forest dung beetles in Madagascar are better adapted to forest disturbance than earlier expected, although they require some level of connectivity to surrounding forest.     

中国四种蜣螂幼虫形态记述(鞘翅目:金龟科:金龟亚科)

基于3龄幼虫首次描述了中国4种蜣螂幼虫的形态特征,分别是：捷氏凯蜣螂Caccobius jessoensis Harold、短亮凯蜣螂C．brevis Waterhouse、双顶嗡蜣螂Onthophagus bivertex Heyden和小驼嗡蜣螂0．gibbulus（Pallas）。文中列出了中国凯蜣螂和嗡蜣螂属幼虫分种检索表。标本保存在沈阳农业大学昆虫博物馆。     

Dung beetle assemblages in primary forest and disturbed habitats in a tropical dry forest landscape in western Mexico

Dung beetles (Scarabaeinae) are conspicuous components in most terrestrial ecosystems, performing important ecological functions and services. Being sensitive to several types of disturbance, they have been successfully used as indicators of habitat change. Dung beetle communities in tropical rainforests have been well studied, but considerably less information is available for tropical dry forests. In this study I sampled dung beetles in two undisturbed habitats, deciduous forest and semideciduous forest, and two disturbed habitats, secondary forest and open area habitat, in the Chamela-Cuixmala region of western Mexico. Dung beetle species with high indicator value for each habitat were identified. Beetle abundance, observed species richness and estimated species richness were similar in the three forest habitats, but significantly lower in the open area habitat. A more detailed analysis of species-specific abundances in the three forest habitats revealed some differences. Transects of one of the undisturbed habitats, the deciduous forest, were more similar to the non-adjacent transects of disturbed secondary forest, than to the adjacent undisturbed semideciduous forest transects. Unlike studies in other tropical sites that have found a decrease in equitability in Scarabaeinae assemblages between undisturbed forest and disturbed habitat (particularly open habitats), in the Chamela-Cuixmala region all four habitats showed similar low equitability in community structure, with two or three very dominant species.     

Subtle Land‐Use Change and Tropical Biodiversity: Dung Beetle Communities in Cerrado Grasslands and Exotic Pastures

Although many tropical savannas are highly influenced by humans, the patterns of biodiversity loss in these systems remain poorly understood. In particular, the biodiversity consequences of replacing native grasslands with exotic pastures have not been studied. Here we examine how the conversion of the native savanna grasslands affects dung beetle communities. Our study was conducted in 14 native (grassland: campo limpo), and 21 exotic (Urochloa spp. monoculture) pastures in Carrancas, Minas Gerais, Brazil. We collected 4996 dung beetle individuals from 66 species: 3139 individuals from 50 species in native pastures and 1857 individuals from 55 species in the exotic pastures. Exotic pastures had lower dung beetle richness, abundance and biomass than native pastures. Species composition between the two pasture types was significantly different and exotic pastures were dominated by few abundant species. Indicator species analysis detected 16 species indicators of native pastures and three of exotic pastures, according to relative abundance and frequency in each pasture system. Our results show that the conversion of native pastures to exotic pastures leads to a predictable loss of local species richness, increasing dominance and changes in species composition. These results highlight the importance of maintaining native pastures in the Cerrado agro‐pastoral landscape. Abstract in Portuguese is available at http://www.blackwell‐synergy.com/loi/btp .     

Les modalités du percher dans un assemblage de Scarabaeinae de la forêt de Guyane française

Le percher est un comportement répandu chez les espèces d’un assemblage de Scarabaeinae d’une forêt non perturbée de Guyane française. Quarante-trois espèces de percheurs ont été répertoriées sur 7 ans d’échantillonnage. Les fouisseurs diurnes de petite taille (moyenne 7,0 mm) dominaient sur les feuilles isolées et autour des défécations de Singes hurleurs ou des fèces humaines, avec une hauteur moyenne de percher de 62,8 cm. Les hauteurs étaient positivement corrélées aux tailles des insectes excepté pour cinq grandes espèces dont trois possédaient une défense chimique contre les prédateurs. Deux complexes mimétiques ont été identifiés. L’agrégation en dehors de la présence de ressource a été montrée. Les défécations de singes provoquaient une concentration d’insectes dont des Canthon (Glaphyrocanthon) arboricoles qui formaient leurs pilules sur les feuilles. D’autres espèces perchaient en attente de rencontrer au sol un partenaire ou de se livrer au kleptoparasitisme. Les signaux olfactifs pourraient jouer un rôle dans diverses modalités du percher. Compétition et prédation semblent être les principales contraintes auxquelles le percher répond.