Thermoregulation in endothermic dung beetles (Coleoptera: Scarabaeidae): effect of body size and ecophysiological constraints in flight

We explore the physiological constraints of body temperature as related to body mass and ambient temperature during flight in endothermic dung beetles showing a mass-related breakpoint where species show strong vs. weak endothermy. We found two different strategies in the dung beetles prior to flight; larger beetles (>1.9 g) elevate and maintain their body temperature (T(b)) at levels well above ambient temperature (T(a)) whereas smaller beetles' (<1.9 g) T(b) tends to conform with T(a). Physiological constraints analysis revealed a constant maximum tolerated temperature (in flight) of 42 degrees C and a minimum temperature for flight of around 25 degrees C. These, with body mass, may play a role in thermal niche partitioning and geographical distribution patterns.     

Global dung webs: high trophic generalism of dung beetles along the latitudinal diversity gradient

At the global scale, species diversity is known to strongly increase towards the equator for most taxa. According to theory, a higher resource specificity of consumers facilitates the coexistence of a larger number of species and has been suggested as an explanation for the latitudinal diversity gradient. However, only few studies support the predicted increase in specialisation or even showed opposite results. Surprisingly, analyses for detritivores are still missing. Therefore, we performed an analysis on the degree of trophic specialisation of dung beetles. We summarised 45 studies, covering the resource preferences of a total of 994503 individuals, to calculate the dung specificity in each study region. Our results highlighted a significant (4.3‐fold) increase in the diversity of beetles attracted to vertebrate dung towards the equator. However, their resource specificity was low, unrelated to diversity and revealed a highly generalistic use of dung resources that remained similar along the latitudinal gradient.     

Not all dung beetles feed on dung: Scarabaeinae (Coleoptera: Scarabaeidae) attracted to different carrion types in contrasting habitats at Brazilian Amazon

By understanding how assemblages segregate according to food types, it is possible to depict and understand species distribution and exploitation of similar food resources. Although it is well known that dung beetles may feed on carrion, but the attractiveness of different carrion types for these beetles is still poorly understood. In this study, we compared the dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity attracted to two carrion types in different habitats in an Amazonian landscape. Dung beetles were captured by using pitfall traps baited with decaying cattle beef and cattle liver in native forest, peach palm plantation, teak plantation and exotic pasture. Overall, we captured 582 dung beetles of 43 species, where Canthidium aff. lentum was classified as a specialist of cattle beef, Deltochilum sp. One was considered specialist of liver carrion, 11 were considered generalists and for the 30 remaining species, it was not possible to determine their carrion preference due to the low number. Abundance, but not species richness, was affected by carrion type, and a higher number of beetles was recorded in beef-baited traps compared to liver-baited traps. According to functional groups, endocoprid beetles were more abundant in traps baited with decaying beef, while paracoprid and telecoprid beetles did not show preference for any carrion type. This study suggests a novel scenario of intra-resource segregation, where species vary their preferences depending to the part of the dead corpse being exploited. The amount of food resource, the maintenance of stable populations and trophic preference mediated by chemical cues are some mechanisms that may explain the segregation of dung beetles among carrion types.     

Community structure of ground beetles (Coleoptera: Carabidae) along an altitudinal gradient on Mt. Sobaeksan,Korea

We conducted this study to determine the diversity patterns, community structures, and seasonality of ground beetle assemblages along an altitudinal gradient (437–1420 m) on Mt. Sobaeksan, Korea. Ground beetles were collected by pitfall traps installed along an altitudinal gradient (437, 757, 1100, and 1420 m). A total of 32 species belonging to seven subfamilies were identified from 3259 collected ground beetles. The diversity pattern of the ground beetle assemblage according to altitude was neither monotonic decreased nor hump-shaped. However, subfamily assemblages and wing form diversity patterns differed according to altitude and may be correlated with altitude or some other environmental variables. The dominant species were Synuchus cycloderus (29.4%) and Eucarabus sternbergi sobaeksanensis (15.4%) and their seasonal activities according to altitude were similar. According to non-metric multidimensional scaling, ground beetles and altitudes could be divided into two distinct groups: a low altitude group (437–757 m) and a high altitude group (1100–1420 m). Some species were particularly abundant at high altitudes, such as Aulonocarabus koreanus kwonileeique and Poecilus nitidicollis, while others were highly abundant at low altitudes, such as Pterostichus audax, Pterostichus ishikawai, and Synuchus species.     

Structure and function of the mandibles of adult dung beetles (Coleoptera : Scarabaeidae)

The mouthparts of adult dung beetles (Coleoptera : Scarabaeidae) are adapted for manipulation of soft, pasty food—usually the excrement of vertebrates. Nutrients are derived primarily from micro-organisms contained in the food and these must be broken up before ingestion. The mandibles, particularly the molar lobes, are designed to finely grind these particulates; the molae function as a mortar-pestle system, which mills the organic “grist” contained in the food by a combination of squeezing and grinding actions. The ability of the molae to finely grind food particles resides primarily in the structure of the molar surface, which consists of a series of ridges bearing rows of submicroscopic scrapers (“tritors”). The incisor lobes of the mandibles scrape food from the surfaces of the galeae and lacinae, which bring food into the preoral cavity. The structure of the mouthparts of Canthon pilularius (L.), which is described in detail, is basically the same as that of 10 other species examined. Those of Aphodius and Geotrupes are similar in some respects to those of scarabaeines but are obviously less well specialized for microphagy.     

Phylogeography of the Namib Desert dung beetles Scarabaeus (Pachysoma) MacLeay (Coleoptera: Scarabaeidae)

Aim Namib biogeography in many instances remains reliant on advanced and detailed systematic studies. This study attempts to combine molecular phylogenetic data, geology and palaeo‐climatic data to (i) resolve the relationships of the 13 morphological species of Scarabaeus (Pachysoma) and (ii) relate their evolution to past climatic and geological events. Location South Africa and Namibia. Methods Sequencing of a 1197 bp segment of the mitochondrial cytochrome oxidase I (COI) gene of the 13 species within Scarabaeus (Pachysoma) was undertaken. Analyses performed included Parsimony and Maximum Likelihood as well as imposing a molecular clock. Results The molecular phylogeny showed strong support for 11 of the 13 morphological species. The remaining two species, S. (P.) glentoni and S. (P.) hippocrates, formed a complex and could not be assigned specific status on the basis of the COI gene phylogeny. Strong support for the three species formerly classified within the genus Neopachysoma was consistently obtained. The subgenus appears to have arisen c. 2.9 Ma. Species within the subgenus arose at different times, with the common ancestor to Neopachysoma and the hippocrates complex having evolved 2.65 and 2.4 Ma, respectively. Scarabaeus (P.) denticollis, S. (P.) rotundigenus, S. (P.) rodriguesi and S. (P.) schinzi are some of the youngest species, having diverged between 2 million and 600,000 years ago. Main conclusions Scarabaeus (Pachysoma) is a derived monophyletic clade within the Scarabaeini. The subgenus appears to be young in comparison with the age of the Namib Desert, which dates back to the Miocene (c. 15 Ma). The psammophilous taxa are shown to disperse with their substratum and habitat, barchan dunes. Clear south/north evolutionary gradients can be seen within the species of this subgenus, which are consistent with the unidirectional wind regime. Species with a suite of mostly plesiomorphic characters have a southerly distribution while their derived psammophilous relatives have central to northern Namib distributions. Major rivers such as the Orange, Buffels and Holgat appear to be gene barriers to certain species as well as areas of origin of speciation events.     

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.     

Carabidae diversity along an altitudinal gradient in a Peruvian cloud forest (Coleoptera)

Carabid beetles were sampled at five sites, ranging from 1500 m to 3400 m, along a 15 km transect in the cloud forest of Manu National Park, Perú. Seasonal collections during a one year period yielded 77 morphospecies, of which 60% are projected to be undescribed species. There was a significant negative correlation between species richness and altitude, with the number of carabid species declining at the rate of one species for each 100 m increase in altitude. The majority of species (70.1 %) were restricted to only one altitudinal site and no species was found at more than three of the five altitudinal sites. Only one genus, Pelmatellus (Tribe Harpalini), was found at all five sites. Active (hand) collections yielded approximately twice as many species per individuals collected than passive (pitfall trap) collections. This study is the first systematic sampling ofcarabid beetles of a high altitude gradient in the cloud forests of southeastern Perú and supports the need to conserve the zone of extremely high biodiversity present on the eastern slopes of the Peruvian Andes.     

Inferring species decline from collection records: roller dung beetles in Italy (Coleoptera, Scarabaeidae)

The decline of roller dung beetles (Coleoptera, Scarabaeidae) in Italy, at national and regional level, was described using a database of both literature and unpublished data, since the late of 19th century. The probability of finding roller species was assessed for each decade of the 20th century in order to detect changes in their distribution and status. An analysis of decline was performed using a complementary approach of different extinction indexes, according to IUCN criteria. During the 20th century, both the absolute number of records and the UTM cells where roller beetles were found increased clearly as a consequence of the escalation of entomological surveys. Nevertheless, comparing R species (rollers) with all the scarab dung beetles from the first to the last quarter of the 20th century, the relative frequency of roller records decreased by 31%, while the relative number of occupied UTM cells dropped by 23%. Six roller species showed a significant decline in Italy from the first to the second part of the 20th century, and nine in the last 30years. Other two species disappeared from the majority of the northern regions. Finally, the values of all the extinction indexes were strongly correlated and detected a high risk of extinction in Italy for six species. A gradual change in land use during the last three decades, consisting of a reduced extension of grasslands in favour of either intensive agriculture or reforestation after abandonment of livestock raising, was likely the main factor inducing decline and local extinction of roller species.     

Life history traits and resource utilisation in an assemblage of north temperate Aphodius dung beetles (Coleoptera: Scarabaeidae)

To help understand and interpret the structure and function of Aphodius dung beetle assemblages, life history traits and resource utilisation were studied for the ten species comprising the local assemblage of intensively grazed pastures in southern Ireland Most species were univoltine but one species ( A fimetarius ) was at least partly bivoltine However, temporal overlap m adult flight periods does not necessarily imply overlap in resource use Three different strategies of ovarian development were distinguished and were related to the preferred oviposition site and successional occurrence of the various species Evidence suggested that absence of mature eggs in a female's ovaries did not necessarily imply that a female was in a non-reproductive state Two species ( A prodromus and A sphacelatus ) did not breed in dung, in the laboratory larvae were reared in decaying vegetation One species ( A errattcus ) developed m brood masses beneath the dung pat Larvae of all the other species developed within the dung pat There were consistent Interspecific differences in the larval development rates, with two species ( A rufipes and A rufus ) overwintering mainly as prepupae and the other species mainly as adults Previous studies have considered Aphodius assemblages as single guilds but the detailed natural histories of these species may affect guild designation     

Discontinuous gas-exchange cycles in Scarabaeus dung beetles (Coleoptera: Scarabaeidae): mass-scaling and temperature dependence.

Although discontinuous gas exchange cycles (DGC) are known from many insects, the effects of body size and temperature on DGC have not been widely examined. Here, these effects are investigated in five Scarabaeus dung beetle species from mesic and xeric habitats. The investigation tests two hypotheses: that previous estimates of the scaling exponents for the DGC and its characteristics are more broadly applicable to insects, and that, in response to temperature, both DGC frequency and the quantity of CO2 emitted during the open (O) phase (O-phase emission volume) are modulated. Like previous workers, we find that V&d2;co2 scaled as mass0.968 and that O-phase emission volume scaled as mass0.833. However, temperature-associated increases in .Vco2 (Q10's of 2.19-2.65) were modulated mostly by increases in DGC frequency since O-phase volumes remained constant across temperature. Flutter (F)-phase and O-phase durations were closely coupled to DGC duration, although the relationship between closed (C)-phase duration and DGC duration was less pronounced. We show that ventilation phase coefficients, previously considered a measure of the proportional duration of each phase of the DGC, calculated from the slopes of these relationships are a measure of change in phase duration with change in DGC duration and not a measure of the way in which total DGC duration is apportioned among phases. We suggest that proportions be used to estimate the contribution of each of the phases to the total duration of the DGC.     

Edge and land use effects on dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in Brazilian cerrado vegetation

The Edge Influence is one of the most pervasive effects of habitat fragmentation, as many forest remnants in anthropogenic landscapes are within 100 m of edges. Forest remnants may also affect the surrounding anthropogenic matrix, possibly resulting in a matrix–edge–remnant diversity gradient for some species groups. We sampled dung beetles in 15 agricultural landscapes using pitfall traps placed along transects in matrix–edge–remnant gradients. The remnants were a native savanna-like vegetation, the cerrado, and the matrix was composed of three human-dominated environments (sugarcane, eucalyptus, pasture). More species were observed in cerrado remnants than in adjacent land uses. Dung beetles were also more abundant in the cerrado than in the landscape matrix of sugarcane and eucalypt, but not of pasture. Dung beetles were severely affected by anthropogenic land uses, and notwithstanding their high abundance in some land uses such as pasture, the species richness in these areas tended to be smaller than in the cerrado remnants. We also found that the influence of the edge was evident only for abundance, particularly in landscapes with a pasture matrix. However, this land use disrupts the species composition of communities, indicating that communities located in cerrado and pasture have a distinct species composition, and that both communities are affected by edge distance. Thus, anthropogenic land uses may severely affect dung beetles, and this impact can extend to communities located in cerrado remnants as well as to those in matrices, with possible consequences for ecological processes such as decomposition and nutrient cycling.     

Reproductive properties of two sympatric dung beetles,Aphodius haroldianus andA. Elegans (Coleoptera: Scarabaeidae)

1. Reproductive properties of two sympatric dung beetles, Aphodius haroldianus and A. elegans, were studied at a pasture in the central Japan.
2. Overwintered adults of A. haroldianus came flying to dung pats from May to early August and bred from June to July. A. elegans overwintered as larvae, new adults came to dung pats from mid May to mid June. After aestivation, they reproduced from October to November.
3. A. haroldianus was a species with low fecundity and large food reserve for larvae. Female of this species had short duration of residence and laid fewer number of eggs in one dung pat. On the other hand, A. elegans was a species with high fecundity and small food reserve for larvae. Female of this species had long duration of residence and laid larger number of eggs in one dung pat.
4. The daily egg production in A. haroldianus reached a peak (0.40 eggs/female/day) at middle of oviposition period, but, that in A. elegans reached a peak (6.49 eggs/female/ day) at the beginning of oviposition period. The mortality of A. haroldianus female occurred after the daily egg production reached a peak and then rapidly increased, whereas that of A. elegans began soon after the beginning of oviposition and then gradually increased.

     

Interactions between dung beetles (Coleoptera: Scarabaeidae) and the arbovirus vector Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae)

Abstract  The potential for dung beetles to reduce populations of the biting midge and arbovirus vector Culicoides brevitarsis in bovine dung was studied in the Hunter Valley, New South Wales (NSW) between 1999 and 2003 using natural populations of insects. Preliminary work to develop experimental procedures showed that: a few C. brevitarsis could survive in buried dung; dung beetles and C. brevitarsis coming to dung were unaffected by a background of shade-cloth used experimentally to prevent dung burial; the most abundant dung beetle, Onthophagus gazella L. and C. brevitarsis oviposition occurred concurrently in the first 2 d after dung deposition, and the potential for interaction between dung beetles and C. brevitarsis was greatest in open pasture adjacent to trees where cattle congregate at night. Laboratory experiments on dung burial showed that C. brevitarsis numbers decreased as numbers of dung beetles increased or as the dry weight of dung decreased due to burial. This was seldom reflected in the field where, although significant burial occurred experimentally in 9 of 20 trials over 3 years, a significant decline in C. brevitarsis numbers attributable to burial only occurred once. C. brevitarsis numbers in the field were lower in unburied dung in 70% of trials. Differences were significant twice and were considered the result of dung disturbance. In the laboratory, decreasing numbers of C. brevitarsis were related to three characteristics of disturbance: the flattening, spreading and reduction in wet weight of the dung. Evidence of C. brevitarsis activity throughout coastal NSW suggests that, while C. brevitarsis numbers may be modified by dung beetles, the interaction is insufficient to prevent their increase, spread and ability to transmit viruses to livestock.     

Low genetic differentiation among populations ofArabis serrata (Brassicaceae) along an altitudinal gradient

We investigated the extent of genetic differentiation among populations of fujihatazao,Arabis serrata along an altitudinal gradient at Mt. Fuji in Shizuoka Prefecture. This species is a perennial plant, widely distributed in Japan forming small isolated populations. However, at Mt. Fuji, this species constitutes a large population distributed from 1440 to 2400 m altitude. A total of 411 individuals were sampled from ten subpopulations. Eighteen loci were detected on eleven enzyme systems. Eleven loci were monomorphic and seven loci were polymorphic with a mean of 2.11 alleles per loci. Nei's genetic distance (mean 0.01) and genetic identity (mean 0.968) were very similar among populations indicating a low genetic differentiation. The total genetic diversity (H _T ) estimated for the polymorphic loci was, in average, 0.396. The mean gene differentiation (G_ST=0.091) was very low. Gene frequency of seven polymorphic loci was analyzed by spatial autocorrelation methods based on Moran's indexes. Only Pgi-3 exhibited a significant negative autocorrelation (−0.160;P<0.05); other loci values ranged from −0.134 to 0.027. Gene flow estimated by indirect methods varied between genes but most of the values were high (meanNm=20.8) suggesting that subpopulations at different altitudes are probably connected. Despite plants at different altitudes present different ecological traits (e.g., differences in phenology, growth and reproductive traits), subpopulations ofA. serrata are still low differentiated, at least for the loci studied. This may be explained by the recent origin of some habitats (e.g., second crater and surrounded areas) in this locality.     

Species turnover, community boundaries and biogeographical composition of dung beetle assemblages across an altitudinal gradient in South Africa

Aim To identify biogeographical boundaries which are obscured by faunal overlap and habitat modification. Location KwaZulu-Natal in south-east, South Africa beyond the southern tip of the Moçambique Coastal Plain. Methods Species abundance data for dung beetles (Scarabaeidae: Scarabaeinae) were collected at six levels from the coastal escarpment (30°16′S – 500 m) to the top of the nearby Drakensberg (29°35′S – 2850 m). Cross-altitudinal boundaries were identified using clustering techniques, beta-diversity indices, and range edge analysis. Biogeographical data for the species were drawn from an extensive reference collection and used to classify the biogeographical affinities of the assemblages. Results Three discrete communities are defined (<10% similarity) from species abundance distributions. These communities occur in coastal forest (500 m), coastal to highveld grassland (500–1500 m), and montane grassland (1900–2850 m). Two of these communities are biogeographically homogeneous comprising >89% east coast endemics (coastal forest) or >84% South African montane endemics (montane grassland) in terms of abundance. The third community in coastal to highveld grassland is biogeographically more heterogeneous. Predominant biota of this community comprise both South African highveld endemics and elements with distributions extending into the tropics. At highveld levels (1500 m), there are proportionately more highveld endemics whereas at lowland levels (500 m), there are proportionately more tropical elements. At 1000 m, there was a change in the balance between these two groups across an anthropogenic gradient due to a decline in the proportion of endemics in favour of temperate/tropical generalists. This gradient from a natural grassland fragment to improved pastures of Kikuyu grass also parallels a decline in species richness and abundance. Species turnover analyses showed three different cross-altitudinal patterns. Range-edge analysis showed a trimodal pattern of species turnover (peaks in forest and the Drakensberg foothills as in the community analysis but also at 1000 m). Five beta-diversity indices showed either a bimodal pattern of turnover (forest/grassland and foothills/middle Drakensberg slopes) or a trimodal turnover pattern (forest/grassland, highveld/Drakensberg foothills, Drakensberg peaks). Main conclusions Clear altitudinal zonation is revealed by community and biogeographical analysis but one natural biogeographical boundary may be obscured by the process of habitat modification. This boundary at 1000 m is revealed by range-edge analysis and is supported by findings for plant communities. Beta-diversity, species turnover patterns diverged slightly from those suggested by the community and range-edge analyses.     

Guild structure in solitary spider-hunting wasps (Hymenoptera: Pompilidae) compared with null model predictions

Abstract.

• 1 Three aspects of prey utilization are documented in a guild of spider-hunting pompilid wasps at a Breckland heath site: female phenology, size, and microhabitat utilization.
• 2 Twenty-four species were present at the site, 59% of the British fauna. Ten species individually represented more than 1% of the guild.
• 3 Pompilid abundance peaked in early July and mid-late August. Anoplius viaticus had a different life-history from other common guild members, making its inclusion in the guild questionable.
• 4 Most species represented by large samples occurred in all microhabitats and time intervals, and all species overlapped in size with all other species except A. viaticus. Arachnospila anceps was numerically dominant in all microhabitats and most time intervals.
• 5 Mean pair-wise overlaps in phenology and microhabitat utilization were significantly lower than predicted by null models, consistent with the idea that interspecific competition has been important in determining guild structure.
• 6 Female size is highly correlated with prey size, but the distribution of mean female sizes did not generally differ from null expectations.
• 7 Interpretation of comparisons with null models is problematic, particularly because it is difficult to quantify evolutionary ‘favourability’ of different resource states. Null models are currently of limited use because the patterns expected to result from key processes such as competition are uncertain in multi-dimensional systems.