Long‐distance dispersal of non‐native pine bark beetles from host resources

1. Dispersal and host detection are behaviours promoting the spread of invading populations in a landscape matrix. In fragmented landscapes, the spatial arrangement of habitat structure affects the dispersal success of organisms. 2. The aim of the present study was to determine the long distance dispersal capabilities of two non‐native pine bark beetles (Hylurgus ligniperda and Hylastes ater) in a modified and fragmented landscape with non‐native pine trees. The role of pine density in relation to the abundance of dispersing beetles was also investigated. 3. This study took place in the Southern Alps, New Zealand. A network of insect panel traps was installed in remote valleys at known distances from pine resources (plantations or windbreaks). Beetle abundance was compared with spatially weighted estimates of nearby pine plantations and pine windbreaks. 4. Both beetles were found ≥25 km from the nearest host patch, indicating strong dispersal and host detection capabilities. Small pine patches appear to serve as stepping stones, promoting spread through the landscape. Hylurgus ligniperda (F.) abundance had a strong inverse association with pine plantations and windbreaks, whereas H. ater abundance was not correlated with distance to pine plantations but positively correlated with distance to pine windbreaks, probably reflecting differences in biology and niche preferences. Host availability and dispersed beetle abundance are the proposed limiting factors impeding the spread of these beetles. 5. These mechanistic insights into the spread and persistence of H. ater and H. ligniperda in a fragmented landscape provide ecologists and land managers with a better understanding of factors leading to successful invasion events, particularly in relation to the importance of long‐distance dispersal ability and the distribution and size of host patches.     

Positive effects of wheat variety mixtures on aboveground arthropods are weak and variable

Although modern agriculture generally relies on homogeneous varieties that are usually grown in pure stands, crop variety mixtures have been used for a long time, notably to improve resistance to fungal diseases. A growing number of studies suggest that intraspecific plant diversity may also enhance the abundance and diversity of wild species and thereby some ecosystem services such as biological control by natural predators. However, positive effects of the genetic diversity of plant species on the diversity of associated communities have mostly been documented in natural systems, with only a handful of studies targeting crop species in agroecosystems. Here, we investigated the ecological effects of the number of winter wheat varieties (Triticum aestivum) on aboveground arthropods and particularly predatory species. We manipulated the number of wheat varieties (1, 2, 4 or 8) in 120 plots (80 m² each) to examine how wheat diversity and stand characteristics impact communities of three dominant aboveground arthropod groups that include many predatory species: ground beetles, rove beetles and spiders. The number of wheat varieties had a weak, but positive effect on predator abundance, notably spider abundance. In contrast, wheat functional diversity, as assessed by the number of wheat functional groups, was only negatively related to the diversity of spiders. Among wheat stand characteristics, the variance in plant height, wheat biomass and the Green Area Index were weakly correlated with ground beetle, rove beetle and predatory diversity, respectively. The Green Area Index was also weakly correlated with ground beetle abundance. Our study suggests that wheat variety mixtures have variable and limited effects on aboveground arthropods and probably low effectiveness to enhance biological control, but these results should be further tested under low-input agriculture in real fields.     

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.     

Increasing representation of localized dung beetles across a chronosequence of regenerating vegetation and natural dune forest in South Africa

Aim Species assemblages with high proportions of localized taxa occur in regional islands with a history of strong eco‐climatic separation from adjacent systems. Current disturbance in such islands of relictualism or endemism disrupts the distinctive local character in favour of regionally distributed taxa with a wider range of tolerances. However, rehabilitation of the system should restore the localized biota. Thus, we used biogeographical composition to assess progress towards restoration of the dung beetle fauna associated with such an island of endemism following dredge‐mining. Location The study was conducted in natural coastal dune forest and a 23‐year chronosequence of regenerating dune vegetation in the Maputaland centre of endemism, KwaZulu‐Natal, South Africa. Methods Dung beetles were trapped in eight stands of regenerating vegetation of different ages (< 1 year to ~21 years) and in four stands of natural dune forest with differing ecological characteristics defined by measurements of vegetative physiognomy and microclimate. Species groups defined from multivariate analysis of biogeographical distribution patterns and vegetation associations were used to demonstrate quantitative compositional changes in the dung beetle assemblages across the chronosequence to natural forest. Results Three biogeographical groups were defined. One group comprised species widespread in southern Africa or both southern and east Africa. The other two groups were endemic, one to the east coast and the other to Maputaland. There was a general trend from dominance by regionally distributed dung beetle taxa to dominance by locally distributed taxa across the chronosequence of regenerating vegetation from grassland, to open Acacia karroo thicket, to dense A. karroo‐dominated woodland. However, this trend was linked closely to the relative physiognomic and microclimatic similarity between the regenerating vegetation and natural forest. Thus, proportions of locally distributed taxa were lower in older chronosequence woodland (~18–~21 years) with its low canopy cover and open understorey than in dense early chronosequence woodland (~9–~12 years), which is physiognomically and microclimatically closer to species‐diverse natural forest with its dense canopy and understorey. Overall, the present dung beetle community comprises five species groups. Single widespread (21 spp.) and endemic groups (14 spp.) showed similar patterns of association with early chronosequence grassland and open thicket stands. A single widespread (3 spp.) and two endemic shade‐associated groups (3 and 11 spp.) showed differing patterns of association centred, respectively, in late chronosequence woodland, natural forest, or all shaded stands. Main conclusions At 23 years, vegetative regeneration is still at an early stage, but abundant activity of most, although not all species recorded in natural forest, is recovered with the closure of the woodland canopy at ~9 years. Compositional differences with respect to natural forest vary closely with vegetative physiognomy and its effect on the microclimate. Therefore, full compositional recovery is dependent on the re‐establishment of natural forest physiognomy and microclimate.     

Primary Seed Dispersal by Red Howler Monkeys and the Effect of Defecation Patterns on the Fate of Dispersed Seeds1

The effectiveness of a seed disperser depends on the quantity and quality of dispersal. The quality of dispersal depends in large part on factors that affect the post–dispersal fate of seeds, and yet this aspect of dispersal quality is rarely assessed. In the particular case of seed dispersal through endozoochory, the defecation pattern produced has the potential of affecting the fate of dispersed seeds and consequently, dispersal quality and effectiveness. In this study, I assessed the effects of dung presence and dung/seed densities on seed predation by rodents and secondary dispersal by dung beetles. In particular, I compared seed fates in clumped defecation patterns, as those produced by howler monkeys, with seed fates in scattered defecation patterns, as those produced by other frugivores. I also determined the prevalence of red howler monkeys (Alouatta seniculus) as seed dispersers at the plant community level in Central Amazonia by determining the number of species they dispersed in a 25–month period. I found that dung presence and amount affected rodent and dung beetle behavior. Seed predation rates were higher when dung was present, and when it was in higher densities. The same number of seeds was buried by dung beedes, in dumped versus scattered defecation patterns, but more seeds were buried when they were inside large dung–piles versus small piles. Seed density had no effect on rodent or dung beetle behavior. Results indicate that caution should be taken when categorizing an animal as a high or low quality seed disperser before carefully examining the factors that affect the fate of dispersed seeds. Red howler monkeys dispersed the seeds of 137 species during the study period, which is the highest yet reported number for an Alouatta species, and should thus be considered highly prevalent seed dispersers at the plant community level in Central Amazonian terra firme rain forests.     

Spatial distribution, resource utilisation and intraspecific competition in the dung beetle Aphodius ater

Competitive interactions in northern temperate dung beetles are poorly understood. This investigation therefore comprises a series of field and experimental work on a dung beetle species common in northern Europe, Aphodius ater, with special focus on intraspecific competitive interactions. The between-pat distribution of adult A. ater in relation to the age of sheep dung pats was studied in the field. The distribution of both sexes was contagious in the fresh pats but became more regular with increasing pat age. The successional occurrence of males and females did not differ, but immature females tended to occur in fresh pats while mature females were mainly found in older pats. With increasing age of pats, the egg load of females also increased. Egg-laying behaviour of the beetles was studied in laboratory experiments. The mean number of eggs laid per female per dung pat decreased with increasing beetle density. Thus, density-dependent processes seem to regulate resource utilisation with regard to breeding behaviour, resulting in equal exploitation of the available pats. Survival and weight of recently hatched beetles decreased with increasing initial density of eggs. Hence, in A. ater, competition between larvae for food within pats does occur. Received: 4 February 1998 / Accepted: 20 April 1998     

Taxonomic review of Agraphydrus from Japan (Coleoptera: Hydrophilidae: Acidocerinae)

The Japanese species of the genus Agraphydrus are revised. Five species are recognized, including Agraphydrus ogatai sp. nov. from Honshu, Shikoku and Kyushu. The new species can be distinguished by the coarse ground punctures on the pronotum and elytra, and by the shape of parameres. All species except A. luteilateralis are redescribed. All species are diagnosed, relevant morphological characters are illustrated, distributional records are summarized and an updated key is provided.     

Attractiveness of baits to dung beetles in Brazilian savanna and exotic pasturelands

The Brazilian savanna is the second largest ecosystem in Brazil. It is also one of the most endangered, with only 20% of its habitat remaining unchanged. Agriculture and livestock have been indicated as the main agents of destruction of the Brazilian savanna. Brazilian livestock, for example, is the main reason for cultivation of exotic grasses such as Urochloa spp. (from Africa). Dung beetles are widely used in ecological assessment, mainly because they are recognized as bioindicators of environmental changes. Therefore, efficient sampling is required for any research involving the biodiversity of this group. In order to mitigate the lack of information on efficiency of the attractiveness of baits in the endangered Brazilian savanna and in exotic pasturelands, we sampled dung beetles in four native patches of the Brazilian savanna and in four areas of pastures with Urochloa spp. Dung beetles were captured with pitfall traps baited with carcass, cattle dung, human feces and pig dung, with a total sampling effort of 384 traps. We sampled 7544 individuals belonging to 43 species and 18 genera of dung beetles. Thirty‐eight species were collected in the Brazilian savanna and 24 species in exotic pastureland. In both ecosystems traps baited with human feces sampled greater abundance and species richness of dung beetles when compared with the other three baits used. Our results showed that human feces is a reliable, easy and inexpensive bait to sample greater abundance and species richness of generalist dung beetles in both native and exotic habitats, with clear structural differences.     

Ground beetle communities on reclaimed mine spoil: Effects of organic matter application and revegetation

On a study site in the Lusatian lignite mining region (Germany), sandy mine spoil was ameliorated with either sewage sludge, compost or mineral fertilizer. Plots were sown with the grass Secale multicaule and planted with pine seedlings except for a control that was not meliorated and not revegetated. Pitfall catches of ground beetles in 1996/97 yielded high numbers of species and individuals directly after revegetation. The dominant beetles were xerophilic species, known to prefer open sandy sites. Catches in different plots were positively correlated with the amount of vegetation cover and declined as follows: amelioration with sewage sludge > compost > mineral fertilizer > untreated control. Even beetles characteristic of open sandy sites showed a distinct preference for plots with high vegetation cover treated with organic waste. For the dominant species, an attraction to shelter and a more balanced, humid microclimate is assumed. A year-to-year comparison showed an increase in beetles typical of dry grasslands and ruderal sites in the second year, while characteristic species of open sandy sites decreased. Application of organic waste combined with revegetation led to an immediate increase in beetle numbers. In the long term, revegetation would be expected to reduce suitable habitats for endangered ground beetles which prefer open sites with poor sandy soils. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.