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Beetle Abundance (beetle + abundance)
Kinds of Beetle Abundance Selected AbstractsWhen the prairie varies: the importance of site characteristics for strategising insect conservationINSECT CONSERVATION AND DIVERSITY, Issue 4 2009CHRIS LOONEY Abstract., 1.,The bunchgrass prairies of the Palouse region in eastern Washington state and adjacent Idaho have been mostly converted to agriculture in the past century. Prairie habitat currently exists only on small remnants scattered across the landscape. 2.,The invertebrate fauna of these habitat remnants is poorly known, both in terms of species diversity and community composition. 3.,Baited pitfall traps were used to sample carrion-attracted beetles during June and July of 2003 from high-quality prairie remnants of varying size and soil characteristics. 4.,Twenty-three beetle species in five families were found. Species richness and Shannon-Wiener diversity were not significantly correlated with habitat area or perimeter,area ratio. 5.,Beetle abundance and community structure were strongly correlated with soil characteristics. Deeper, loessal soils had greater overall beetle abundance than shallower, rocky soils, although some species were more frequently captured in shallower, rocky soil sites. 6.,Conservation plans emphasising only remnant size and condition do not sufficiently capture variability in insect communities across Palouse prairie remnants. [source] A comparison of litter beetle assemblages (Coleoptera) in mature and recently clearfelled Eucalyptus obliqua forestAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2006Susan C Baker Abstract, This study compares litter-dwelling beetles in mature wet eucalypt forest with those in young forest regenerated following clearfelling. The aims of the study were to determine the extent to which these forest ages support differing litter beetle assemblages, and to identify species characteristic of each age. Beetles were collected with pitfall traps in a spatially replicated study design to avoid confounding forest age and site differences. Three transects of traps were located in each of mature and young forest stands at four study sites. Beetle abundance was greatest in young forest, and young and mature forest supported distinctly different beetle assemblages. Of 37 commonly collected species, an indicator species analysis found 9 species characteristic of young logging regeneration, and 7 species characteristic of mature unlogged forest. These species could be useful in other Tasmanian studies concerning forest management impacts. Only two significant indicator species were carabids, suggesting that focusing only on carabids as indicators of forest management may be undesirable. [source] Landscape composition influences patterns of native and exotic lady beetle abundanceDIVERSITY AND DISTRIBUTIONS, Issue 4 2009M. M. Gardiner Abstract Aim, Coccinellid beetles are important predators that contribute to pest suppression in agricultural landscapes. Since the introduction of the exotic coccinellids Coccinella septempunctata L. and Harmonia axyridis Pallas into the USA, several studies have reported a decline of native Coccinellidae in agroecosystems. We aimed to investigate the influence of landscape composition on native and exotic coccinellid abundance within soybean fields. Location, Iowa, Michigan, Minnesota and Wisconsin. Methods, As part of a 2-year study (2005,06) on the biological control of the soybean aphid, Aphis glycines Matsumura, we examined coccinellid communities in 33 soybean fields using yellow sticky card traps. Landscape heterogeneity and composition were measured at multiple spatial scales ranging 1,3.5 km from focal soybean fields where coccinellid sampling took place. Results, Exotic species made up 90% of the total coccinellid community in Michigan soybean fields followed by Wisconsin (84%), Minnesota (66%) and Iowa (57%). Harmonia axyridis was the dominant exotic coccinellid in all states comprising 45,62% of the total coccinellid community, followed by C. septempunctata (13,30%). Two additional exotic species, Hippodamia variegata (Goeze) and Propylea quatuordecimpunctata (L.) were also found in the region. Overall, the most abundant native coccinellid was Hippodamia convergens Guerin-Meneville; however, its abundance varied across the region, comprising 0% (Michigan) to 28% (Iowa) of the total coccinellid community. Landscape structure significantly influenced the composition of coccinellid communities in soybean agroecosystems. We found that native coccinellids were most abundant in low-diversity landscapes with an abundance of grassland habitat while exotic coccinellids were associated with the abundance of forested habitats. Main conclusion, We propose that grassland dominated landscapes with low structural diversity and low amounts of forested habitat may be resistant to exotic coccinellid build-up, particularly H. axyridis and therefore represent landscape-scale refuges for native coccinellid biodiversity. [source] Population persistence of the parasitoid fly Zaira cinerea (Fallén) (Diptera: Tachinidae) utilizing multiple host carabid beetles with different seasonality and qualityENTOMOLOGICAL SCIENCE, Issue 3 2010Atsushi OHWAKI Abstract Zaira cinerea (Fallén) is a parasitoid fly (Diptera: Tachinidae) that attacks adult carabid beetles. To better understand mechanisms of population persistence in this species, we examined seasonality of host beetle abundance, the frequency of parasitism, and the timing of fly eclosion. In addition, we evaluated host quality using numbers of larvae or puparia per individual beetle as a measure of quality. The fly parasitized only large carabids (,15 mm body length); the lengths of fly puparia reached 7.4,10.8 mm during development in beetle abdomens, and larger hosts are likely essential. Of the 18 large carabid species collected in this study, we chose two, Carabus maiyasanus Bates and Leptocarabus procerulus (Bates), because they were large and abundant (87% of total catch). The two carabids had different phonologies; C. maiyasanus was abundant from spring to summer, and its abundance dropped sharply in autumn, while L. procerulus was abundant in autumn and rare from spring to summer except July. Parasitism was observed in all the months from May to November except June, and adult flies eclosed more than once a year (in early summer, late summer, and mid-autumn), indicating that the species is multivoltine. Host quality of L. procerulus was higher than that of C. maiyasanus. Carabus maiyasanus was mainly used as a host from spring to summer, and L. procerulus was used in autumn. Thus, adult beetles of one or both species are available over most of spring, summer, and autumn, allowing population persistence of this fly species over time. [source] When the prairie varies: the importance of site characteristics for strategising insect conservationINSECT CONSERVATION AND DIVERSITY, Issue 4 2009CHRIS LOONEY Abstract., 1.,The bunchgrass prairies of the Palouse region in eastern Washington state and adjacent Idaho have been mostly converted to agriculture in the past century. Prairie habitat currently exists only on small remnants scattered across the landscape. 2.,The invertebrate fauna of these habitat remnants is poorly known, both in terms of species diversity and community composition. 3.,Baited pitfall traps were used to sample carrion-attracted beetles during June and July of 2003 from high-quality prairie remnants of varying size and soil characteristics. 4.,Twenty-three beetle species in five families were found. Species richness and Shannon-Wiener diversity were not significantly correlated with habitat area or perimeter,area ratio. 5.,Beetle abundance and community structure were strongly correlated with soil characteristics. Deeper, loessal soils had greater overall beetle abundance than shallower, rocky soils, although some species were more frequently captured in shallower, rocky soil sites. 6.,Conservation plans emphasising only remnant size and condition do not sufficiently capture variability in insect communities across Palouse prairie remnants. [source] Improving the design and management of forest strips in human-dominated tropical landscapes: a field test on Amazonian dung beetlesJOURNAL OF APPLIED ECOLOGY, Issue 4 2010Jos Barlow Summary 1.,The future of tropical forest species depends in part on their ability to survive in human-modified landscapes. Forest strips present a priority area for biodiversity research because they are a common feature of many managed landscapes, are often afforded a high level of legal protection, and can provide a cost-effective and politically acceptable conservation strategy. 2.,Despite the potential conservation benefits that could be provided by forest strips, ecologists currently lack sufficient evidence to inform policy and guide their design and management. 3.,We used a quasi-experimental landscape in the Brazilian Amazon to test the importance of four management-relevant variables (forest type, isolation distance, forest structure, and large mammal activity) on the potential biodiversity conservation value of narrow forest strips for dung beetles. 4.,Information-theoretic model selection based on AICc revealed strong support for the influence of large mammal activity and forest type on dung beetle abundance; isolation distance on species richness; and forest structure on the relative abundance of matrix-tolerant species. Multi-dimensional scaling showed a strong influence of forest type and isolation on community composition and structure, with riparian and dry-land strips having complementary sets of species. 5.,Synthesis and applications. To enhance the conservation value and ecological integrity of forest strips in human-modified landscapes we recommend that strip design considers both isolation distance and whether or not the strips encompass perennial streams. In addition, we identify the maintenance of forest structure and the protection of large mammal populations as being crucially important for conserving forest dung beetle communities. [source] Understanding the biodiversity consequences of habitat change: the value of secondary and plantation forests for neotropical dung beetlesJOURNAL OF APPLIED ECOLOGY, Issue 3 2008Toby A. Gardner Summary 1Secondary and plantation forests are becoming increasingly widespread in the tropics. A recent meta-analysis on the impacts of land-use change on tropical forest dung beetles concluded that regenerating forests can be effective in helping to offset species loss following deforestation. However, our understanding of the extent to which these results can be generalized to new locations remains very poor. 2We attempted to overcome many of the design limitations that characterize previous studies by collecting spatially independent dung beetle samples from primary, secondary and Eucalyptus plantation forests in north-east Brazilian Amazonia across a large quasi-experimental landscape that minimized confounding edge and fragmentation effects. 3We recorded 9203 dung beetles, comprising 85 species. Species richness was significantly higher in primary forest and the majority of species were more abundant there than elsewhere, whereas secondary and plantation sites harboured an impoverished subset of primary forest species. 4Our data illustrate the low value of tropical secondary and plantation forests for dung beetles in our study area, and our conclusions are more pessimistic than those of earlier studies. 5Because of differences in the order of species rank-abundance and rank-biomass patterns, re-coding community data from abundance to biomass significantly altered the analytical weight of individual species in determining community patterns. Larger bodied beetles were more prone to local extinctions and abundance declines and this effect was consistent both within and between genera. 6Synthesis and applications. Our study demonstrates that secondary and plantation forests in a large neotropical landscape host exceptionally impoverished dung beetle communities. Furthermore, the depletion of beetle abundance combined with a reduction in average body mass in converted forests is likely to have detrimental consequences for the maintenance of dung beetle-mediated ecosystem services in these habitats. Differences in biogeographical and landscape context, and the influence of common limitations in sampling design, may explain why many other studies have painted a more optimistic picture of the conservation value of anthropogenic habitats. In the absence of further evidence we caution strongly against the claim that forest regeneration schemes on degraded land can effectively offset the loss of species following deforestation, and urge that conservation strategies prioritize the protection of remaining areas of primary forest. [source] Refuge habitats modify impact of insecticide disturbance on carabid beetle communitiesJOURNAL OF APPLIED ECOLOGY, Issue 2 2001Jana C. Lee Summary 1Carabid beetles are polyphagous predators that can act as biological control agents of insect pests and weeds. While current agricultural practices often create a harsh environment, habitat management such as the establishment of within-field refuges has been proposed to enhance carabid beetle abundance and impact. We examined the joint effects of refuge habitats and insecticide application on carabid activity density (parameter of population density and relative activity) and species composition in a cornfield. 2Our 2-year study comprised four treatments: (i) ,refuge/,insecticide; (ii) +refuge/,insecticide; (iii) ,refuge/+insecticide; (iv) +refuge/+insecticide. Refuge strips consisted of grasses, legumes and perennial flowering plants. ,,Refuge' strips were planted with corn and not treated with insecticide. 3Before planting and insecticide application, carabid activity density in the crop areas was similar across all treatments. Insecticide application immediately reduced carabid activity density and altered community composition in the crop area. 4Refuge strips had significantly higher activity density of beetles than ,refuge strips before planting and during the summer. 5During summer, as new carabids emerged and insecticide toxicity declined, the presence of refuge strips influenced carabids in the adjacent crop area. Carabid activity density within crop areas previously treated with insecticide was significantly higher when adjacent to refuge strips. Also, carabid communities within insecticide-treated crop areas were affected by the presence or absence of a refuge strip. 6The presence of refuge strips did not consistently augment carabid numbers in crop areas where insecticide was not applied. One explanation may be that insecticides decreased the quality of crop habitat to carabids by depletion of prey and direct mortality. However, subsequent rebounds in prey density and the absence of competing predators may make these areas relatively more attractive than unperturbed crop habitats to carabid colonization from refuges. 7This study demonstrates that refuges may buffer the negative consequences of insecticide application on carabids in adjacent fields. Diversifying agro-ecosystems with refuge habitats may be a viable strategy for maintaining carabid populations in disturbed agricultural landscapes to keep pests below outbreak levels. [source] Factors influencing duiker dung decay in north-east Gabon: are dung beetles hiding duikers?AFRICAN JOURNAL OF ECOLOGY, Issue 1 2009Nathalie Van Vliet Abstract We analysed seasonality of dung decay time and the influence of rainfall, leaf fall, beetle attack and moisture on dung decay. Our study was carried out at the Ipassa Reserve, north-east Gabon. We compared the seasonality of dung decay with the seasonality of dung beetle abundance and guild structure. Dung beetle activity was the main factor influencing dung decay in our study site. Decay time was the highest during the main dry season (3.4 days) and the lowest during the short rainy season (0.7 days). Dung decay time was closely related to dung beetle abundance, especially to the abundance of nocturnal beetles. We discuss the implications of such results for duiker survey methods based on dung pellet counts in areas where decay time is extremely short or unknown. Résumé Nous avons analysé le caractère saisonnier de la durée de décomposition des crottes et l'influence des chutes de pluie, des chutes de feuilles, des attaques de coléoptères et de l'humidité sur la décomposition des crottes. Notre étude s'est déroulée dans la Réserve d'Ipassa, au nord-est du Gabon. Nous avons comparé le caractère saisonnier de la décomposition des crottes avec celui de l'abondance des coléoptères et la structure des guildes. L'activité des bousiers était le principal facteur influençant la décomposition des crottes sur notre site d'étude. La durée de la décomposition était plus longue pendant la grande saison sèche (3,4 jours) et plus courte pendant la petite saison des pluies (0,7 jour). La durée de la décomposition était étroitement liée à l'abondance des bousiers, spécialement celle des coléoptères nocturnes. Nous discutons les implications de ces résultats pour les méthodes de recensement des céphalophes qui se basent sur le comptage des crottes, dans des régions où le temps de décomposition est extrêmement court, ou inconnu. [source] Dung Beetle Assemblages and Seasonality in Primary Forest and Forest Fragments on Agricultural Landscapes in Budongo, UgandaBIOTROPICA, Issue 4 2009Philip Nyeko ABSTRACT Very little is known about the diversity of arthropods in the fast-disappearing fragments of natural forests in sub-Saharan Africa. This study investigated: (1) the influence of forest fragment characteristics on dung beetle species richness, composition, abundance, and diversity; and (2) the relationship between dung beetle assemblages and rainfall pattern. Beetles were sampled through 12 mo using dung baited pitfall traps. A total of 18,073 dung beetles belonging to three subfamilies and 45 species were captured. The subfamily Scarabaeinae was the most abundant (99%) and species rich (89%). Fast-burying tunnellers (paracoprids) were the most dominant functional group. Catharsius sesostris, Copris nepos, and Heliocopris punctiventris were the three most abundant species, and had the highest contributions to dissimilarities between forests. With few exceptions, dung beetle abundance, species richness, and diversity were generally higher in larger forest fragments (100,150 ha) than in smaller ones (10,50 ha) and the nature reserve (1042 ha). Forest fragment size had a highly significant positive relationship with beetle abundance, but only when the nature reserve is excluded in the analysis. Dung beetle abundance and species richness showed direct weak relationships with litter depth (positive) and groundcover (negative) but not tree density, tree species richness, and fragment isolation distance. Dung beetle abundance and species richness were strongly correlated with monthly changes in rainfall. Results of this study indicate that forest fragments on agricultural lands in the Budongo landscape, especially medium-sized (100,150 ha) ones, represent important conservation areas for dung beetles. [source] Seasonality of a Diverse Beetle Assemblage Inhabiting Lowland Tropical Rain Forest in AustraliaBIOTROPICA, Issue 3 2009Peter S. Grimbacher ABSTRACT One of the least understood aspects of insect diversity in tropical rain forests is the temporal structuring, or seasonality, of communities. We collected 29,986 beetles of 1473 species over a 4-yr period (45 monthly samples), with the aim to document the temporal dynamics of a trophically diverse beetle assemblage from lowland tropical rain forest at Cape Tribulation, Australia. Malaise and flight interception traps were used to sample adult beetles at five locations at both ground and canopy levels. Beetles were caught throughout the year, but individual species were patchy in their temporal distribution, with the 124 more abundant species on average being present only 56 percent of the time. Climatic variables (precipitation, temperature, and solar radiation) were poorly correlated with adult beetle abundance, possibly because: (1) seasonality of total beetle abundance was slight; (2) the peak activity period (September,November) did not correspond to any climatic maxima or minima; or (3) responses were nonlinear owing to the existence of thresholds or developmental time-lags. Our results do not concur with the majority of tropical insect seasonality studies suggesting a wet season peak of insect activity, perhaps because there is no uniform pattern of insect seasonally for the humid tropics. Herbivores showed low seasonality and individual species' peaks were less temporally aggregated compared to nonherbivores. Canopy-caught and larger beetles (> 5 mm) showed greater seasonality and peaked later in the year compared to smaller or ground-caught beetles. Thus seasonality of adult beetles varied according to the traits of feeding ecology, body size, and habitat strata. [source] Effects of landscape composition and substrate availability on saproxylic beetles in boreal forests: a study using experimental logs for monitoring assemblagesECOGRAPHY, Issue 2 2006Heloise Gibb Intensive forestry practises in the Swedish landscape have led to the loss and fragmentation of stable old-growth habitats. We investigated relationships between landscape composition at multiple scales and the composition of saproxylic beetle assemblages in nine clear-cut, mature managed and old-growth spruce-dominated forest stands in the central boreal zone of Sweden. We set out fresh spruce and birch logs and created spruce snags in 2001,2002 to experimentally test the effects of coarse woody debris (CWD) type and forest management on the composition of early and late successional, and red-listed saproxylic beetle assemblages. We examined effects of CWD availability at 100 m, and landscape composition at 1 and 10 km on saproxylic beetle abundances. Additionally, we tested whether assemblage similarity decreased with increasing distance between sites. We collected beetles from the experimental logs using eclector and window traps in four periods during 2003. CWD was measured and landscape composition data was obtained from maps of remotely sensed data. The composition of saproxylic beetles differed among different CWD substrates and between clear-cuts and the older stand types, however differences between mature managed and old-growth forests were significant only for red-listed species. Assemblage similarities for red-listed species on clear-cuts were more different at greater distances apart, indicating that they have more localised distributions. CWD availability within 100 m of the study sites was rarely important in determining the abundance of species, suggesting that early successional saproxylic beetles can disperse further than this distance. At a larger scale, a large area of suitable stand types within both 1 and 10 km resulted in greater abundances in the study sites for several common and habitat-specific species. The availability of suitable habitat at scales of 1,10 km is thus likely to be important in the survival of many saproxylic species in forestry-fragmented areas. [source] | ||||||||||||||||||||||