Dung beetle (Coleoptera: Scarabaeinae) persistence in Amazonian forest fragments and adjacent pastures: biogeographic implications for alpha and beta diversity

The aim of this study is to analyze the effects of habitat loss and forest replacement by cattle pasture on the alpha and beta diversity, abundance, biomass and species composition of dung beetles with different dispersal ability. Dung beetles were captured in 19 forest fragments and neighbouring pastures. Forest fragment area ranged from 3.7 to 4825 ha and in this study were grouped into four categories: small, medium, large and control forest. A total of 35,048 dung beetles representing 101 species were collected. Forest fragments had the highest richness with 81 species, followed by pasture with 58 species. Replacement of forest by pasture reduced species richness; however, due to the proximity and connectivity of these areas with Cerrado patches, pastures also had high species richness, but species composition was independent of adjacent fragments. Small fragments had lower abundance and species richness than our other habitat categories, even pastures. Our results highlight that proximity and connectivity with Cerrado areas influenced the patterns of alpha and beta diversity of dung beetles in fragments and pastures. We highlight that the ability to cross the pasture matrix is a strong adaptive trait for species living in human-modified landscapes. Consequently, species with these abilities are less susceptible to the effects of forest fragmentation and local extinction. Our results reinforce the importance of considering the biogeographic location and distribution pattern of species in forest fragmentation studies.     

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 community (Coleoptera: Scarabaeidae: Scarabaeinae) in a tropical landscape at the Lachua Region,Guatemala

Biological diversity conservation within natural reserves has been prioritized, but conservation efforts outside protected areas (where most human activities take place) have been very little considered. In this scenario, an alternative agricultural practice that may reduce the impacts of fragmentation in outer landscapes is a perforation process, which involves conservation in agricultural fields surrounded by continuous forests. Such practices enhance the positive impact of ecological services on fields. In this study we analyzed the biological diversity state in perforation fields and their surrounding forests. The analysis was done using dung beetles as biological indicators. A nested pattern in dung beetles distribution was found, which ordered the surrounding continuous forest sites as the ones with the highest species richness, followed by the perforation fields, and placed the fragmentation practice fields (continuous agricultural fields surrounding forest patches) with the lowest one. Indicator species for perforation fields and surrounding continuous forests were chosen. In general, perforation practice fields differed in composition, based upon functional groups richness and identity; it also contained a higher species richness than the fragmentation practice. Agricultural practices that enhance biological diversity conservation such as perforation, should be recommended and considered in natural resource management by local communities in order to take advantage of ecological services that otherwise may be gradually lost.     

Attractiveness of Different Food Resources to Dung Beetles (Coleoptera: Scarabaeidae) of a Dry Tropical Area

Excrement scarcity is one of the main historical factors leading dung beetles to adapt to other food resources. In the Caatinga, a seasonally tropical dry forest, harsh environmental conditions seem to restrict the availability of food resources. In this scenario, the aim of our study was to experimentally investigate the attractiveness of different potential food resources to these insects in the Caatinga. Field samplings were performed, and we tested five resources in pitfall baited traps: excrement, carrion, fruits of two species of columnar cacti, and seeds of one species of Euphorbiaceae (Jatropha mollissima (Pohl)). In a controlled setting, we tested dietary preferences of Deltochilum verruciferum Felsche by offering one or two resources simultaneously. In the field experiments, 297 dung beetles (9 species) were recovered from the traps, and D. verruciferum was the most abundant species. Carrion and excrement were the most attractive resources. Controlled dietary preference tests with D. verruciferum evidenced that these beetles used all tested food resources, excrement and carrion most pronouncedly. Our findings support copro-necrophagy as the main feeding habit of D. verruciferum, but also suggest that alternative resources might be utilized if preferred resources are scarce.     

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.     

Pastoral Practices to Reverse Shrub Encroachment of Sub-Alpine Grasslands: Dung Beetles (Coleoptera,Scarabaeoidea) Respond More Quickly Than Vegetation

In recent decades, pastoral abandonment has produced profound ecological changes in the Alps. In particular, the reduction in grazing has led to extensive shrub encroachment of semi-natural grasslands, which may represent a threat to open habitat biodiversity. To reverse shrub encroachment, we assessed short-term effects of two different pastoral practices on vegetation and dung beetles (Coleoptera, Scarabaeoidea). Strategic placement of mineral mix supplements (MMS) and arrangement of temporary night camp areas (TNCA) for cattle were carried out during summer 2011 in the Val Troncea Natural Park, north-western Italian Alps. In 2012, one year after treatment, a reduction in shrub cover and an increase in bare ground cover around MMS sites was detected. A more intense effect was detected within TNCA through increases in forage pastoral value, and in the cover and height of the herbaceous layer. Immediately after treatment, changes in dung beetle diversity (total abundance, species richness, Shannon diversity, taxonomic and functional diversity) showed a limited disturbance effect caused by high cattle density. In contrast, dung beetle diversity significantly increased one year later both at MMS and TNCA sites, with a stronger effect within TNCA. Multivariate Regression Trees and associated Indicator Value analyses showed that some ecologically relevant dung beetle species preferred areas deprived of shrub vegetation. Our main conclusions are: i) TNCA are more effective than MMS in terms of changes to vegetation and dung beetles, ii) dung beetles respond more quickly than vegetation to pastoral practices, and iii) the main driver of the rapid response by dung beetles is the removal of shrubs. The resulting increase in dung beetle abundance and diversity, which are largely responsible for grassland ecosystem functioning, may have a positive effect on meso-eutrophic grassland restoration. Shrub encroachment in the Alps may therefore be reversed, and restoration of grassland enhanced, by using appropriate pastoral practices.     

Pitfall Trapping for Ants (Hymenoptera, Formicidae) in Mesic Australia: What is the Best Trapping Period?

Increasing trapping periods from 48 h through 5 days and 7 days to 14 days increased species richness of ants captured. However, a high proportion of genera (15/20) and morphospecies (22/33) were taken in the initial 48 h period, and 7 day periods yielded all species later accumulated by 14 days trap use. The shorter periods provide samples that may be adequate for appraising representativeness or typicalness of local ant assemblages, as the data most commonly needed for site evaluation or comparisons, but more extensive sampling is necessary to accumulate all rarer species, including those that may have individual conservation significance.     

A revision of Dichotomius (Homocanthonides) Luederwaldt, 1929 (Coleoptera: Scarabaeidae: Scarabaeinae)

The monospecific subgenus Dichotomius (Homocanthonides) is revised and its single species, Dichotomius (H.) smaragdinus (Perty, 1830) is redescribed and distinguished from other Dichotomius species. Dichotomius (H.) smaragdinus is a polymorphic species and its distribution comprises the Brazilian Cerrado. For the first time, morphological variation and male genital organ are described and illustrated. We believe that this species might be endangered due to extensive deforestation of Brazilian Cerrado by agricultural and pasture expansion. Thus, we highlight the importance of preserving this very unusual Dichotomius species.     

Dung burial strategies in some South African coprine and onitine dung beetles (Scarabaeidae: Scarabaeinae)

ABSTRACT.

• 1 The dung colonization and dung burial behaviour of twelve crepuscular/nocturnal tunnelling (paracoprid) species of beetles were examined in order to identify mechanisms which might facilitate resource (dung) partitioning. The species were selected from a diverse assemblage of dung beetles, the members of which coexist in the sandy-soil regions of Natal, South Africa.
• 2 The pattern of dung colonization in relation to dung age was examined in the field using baited pitfall traps. Some species, e.g. Onitis deceptor Peringuey, Catharsius tricornutus De Geer and Copris elphenor Klug, showed a marked preference for fresh dung (1–2 days old) whereas other species, e.g. O. viridulus Boheman and Copris fallaciosus Gillet, preferred older dung (3–7 days old).
• 3 Two distinct patterns of dung burial were recognized. In the Coprini, dung burial was complete within 24–48h of pad colonization, and the level of dung burial was similar in the laboratory and in the field. In the Onitini, dung burial occurred progressively over a 12-day period, although the timing of initiation of dung burial varied between species: in O. deceptor nearly all individuals had begun burial within 2 days of pad colonization, whereas only 20% of O. viridulus had commenced dung burial by that time. However, nearly all O. viridulus had buried substantial quantities of dung by day 12.
• 4 The mass of dung buried per pair by the larger coprine beetles (100–300 g) and onitine beetles (400–1000 g) suggests that there is potential for inter- and intraspecific competition, even in pads colonized by relatively few beetles. The colonization and use of dung of different ages are discussed as means of resource partitioning in relation to the relative abilities of species to compete for dung.

     

Revision of the southern African genus Macroderes Westwood (Coleoptera: Scarabaeidae: Scarabaeinae)

The southern African genus Macroderes Westwood is revised. Six new species, M. amplior n. sp., M. minutus n. sp., M. endroedyi n. sp., M. namakwanus n. sp., M. foveatus n. sp., and M. cornutus n. sp., are described.The neotype of M. bias (Olivier) is designated.Two new synonymies are established: M. pilula Sharp is a junior synonym of M. bias (Olivier), and M. westwoodi Preudhomme de Borre is a junior synonym of M. undulatus Preudhomme de Borre. A key to species and notes on biology and distribution are given.     

Identification of the Cues Used in the Host Finding Behavior During the Phoretic Association Ceroptera rufitarsis (Diptera: Sphaeroceridae) and Dung Beetles (Coleoptera: Scarabaeidae)

Ceroptera rufitarsis (Meigen) (Diptera: Sphaeroceridae) is a tiny fly phoretic on several roller dung beetles of the genus Scarabaeus L. (Coleoptera: Scarabaeidae). We investigated the attractiveness of Scarabaeus sacer L. and S. cicatricosus Lucas both under field and laboratory conditions. Several cues potentially responsible for the host finding behavior were tested in order to determine the basis of attraction of Ceroptera rufitarsis to Scarabaeus beetles. Visual cues, especially host movements, constituted the main factor responsible for host finding behavior and host choice while chemical cues did not play any role in host discrimination.     

Thermoregulatory strategies in two closely related sympatric Scarabaeus species (Coleoptera: Scarabaeinae)

Abstract. The thermoregulation strategies of Scarabaeus sacer L. and Scarabaeus cicatricosus Lucas were studied in the Doñana National Park, Spain. In this area, both species coexist, showing the same habitat and food preferences. However, S. cicatricosus is active during warmer parts of the day compared to S. sacer. Both species thermoregulate their thoracic temperature but, whereas the abdomen of S. sacer is a passive thermal window, S. cicatricosus actively thermoregulates abdominal temperature by increasing heat transfer from the thorax to the abdomen at high T_a values. In the case of S. sacer, their endothermy indicates an adaptive capacity to thorax heat retention, as occurs mainly in winter‐flying insects. This mechanism, possibly related to the aerodynamic flight posture in Scarabaeinae, could be an effective barrier to retard the rate of abdominal heat loss during flight. This endothermic strategy makes flight difficult at higher temperatures, although it allows flight during cooler periods of the day. On the other hand, S. cicatricosus showed a different adaptive behaviour to S. sacer. In this case, a significant decrease in abdominal heat loss at higher ambient temperatures would indicate a decrease in heat transfer from the thorax to the abdomen, as occurs in some desert and semiarid insects. This ‘heat exchanger’ mechanism observed in S. cicatricosus could be due to the irregular posture adopted during flight, with the posterior legs clearly extended and separate from the body. This behaviour increases turbulence and convective cooling, favouring exposure of the soft abdominal tergal cuticle and, subsequently, water loss. Thus, for S. cicatricosus, the well‐adapted ‘heat exchanger’ permits flight during periods of the day when temperatures would possibly be lethal for those species with high endothermy. From an adaptive viewpoint, these mechanisms of thermoregulation may explain how both closely‐related sympatric species respond in different ways to environmental temperature, favouring their coexistence.     

Evolutionary patterns of hind wing morphology in dung beetles (Coleoptera: Scarabaeinae)

The shape of wings can be a good predictor of adaptations to different selective pressures and the value of wing features in taxonomy and phylogeny has long been recognized. In our investigation of the hind wing evolution of dung beetles (Scarabaeinae) we use geometric morphometrics combined with a cladistic approach. The variations of entire hind wings and of three specific regions of 80 dung beetle species were investigated using 19 landmarks and outline data. Extensive evidence indicates that the wing as a whole and the three separate regions were under different selective pressures. The detailed evolutionary patterns of the three regions and the reconstruction of the ancestral forms were computed by mapping the geometric morphometrics data onto a tree based on a cladistic character analysis.     

Susceptibility of Sap Beetles (Coleoptera: Nitidulidae) to Entomopathogenic Nematodes

Nitidulid beetles (Coleoptera) are considered to be serious pests of date palms throughout the world. They attack ripe fruit, causing it to rot, and damage is reflected in both reduced yield and lower fruit quality. The present study was aimed at an evaluation of the susceptibility to different sap beetles to entomopathogenic nematodes. We further tested nematode efficacy in pots filled with soil infested by third instar larvae of the two beetle species. In Petri dish assay, mortality levels of Carpophilus humeralis and C. hemipterus exposed to Heterorhabditis sp. IS-5 strain indicated that the latter is less susceptible to nematode infection. Exposure of both sap beetle species to different nematode strains gave moderate levels of mortality (35-65%) with the heterorhabditid strains HP88, IS-5 and IS-25. The IS-12 strain of Heterorhabditis sp. showed poor virulence (<35% mortality) against larvae of C. humeralis as well as larvae and pupae of C. humipterus. The nematode species S. riobrave showed moderate virulence (35-65%) mortality to larvae and pupae of S. humeralis as well as to larvae of C. hemipterus . Exposure of C. hemeralis to different concentrations of Heterorhabditis sp. IS-5 in pots containing soil resulted in high mortality (>65%). In contrast, the lower concentrations (500 and 1000 nematodes/pot) caused low mortality (35%) of C. hemipterus . Other heterorhabditid strains caused 95-100% mortality of C. humeralis in pot assay. The HP88 strain of H. bacteriophora and the Tx strain of Steinernema riobrave showed poor effectiveness. Incubation of different nematode strains with the C. humeralis larvae at high temperature (32 C) resulted in an increase in insect mortality with the IS-12 and IS-21 strains. Reduced mortality was recorded with the HP88 strain treatment at the higher temperature. The IS-5 and IS-12 strains were equally effective in all three soil types tested, whereas the IS-19 strain was more effective in the Almog type soil than in the others.     

Diurnal Tiger Beetles (Coleoptera: Cicindelidae) Capture Prey Without Sight

Although much research has examined the process of prey capture by tiger beetles, an underlying assumption in this work is that tiger beetles are principally, or even exclusively, visual predators. Because this assumption is untested, we performed a series of experiments on four diurnally active tiger beetles in the Genus Cicindela. Individual beetles were placed in chambers in complete darkness and allowed to forage on apterous Drosophila for 6 h. Contrary to expectations, adults of all tested species captured more than 90% of prey items. These results show that other modalities can be used by tiger beetles during prey capture. Beyond potentially providing an explanation for observed night activity in tiger beetle species, the significance of these findings lies in the need to test underlying assumptions of even well-studied organisms.