Showing papers in "Insect Conservation and Diversity in 2012"

Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk?

Abstract: During the 2009-2010 overwintering season and following a 15-year downward trend, the total area in Mexico occupied by the eastern North American population of overwintering monarch butterflies reached an all-time low. Despite an increase, it remained low in 2010-2011. 2. Although the data set is small, the decline in abundance is statistically signifi- cant using both linear and exponential regression models. 3. Three factors appear to have contributed to reduce monarch abundance: degra- dation of the forest in the overwintering areas; the loss of breeding habitat in the Uni- ted States due to the expansion of GM herbicide-resistant crops, with consequent loss of milkweed host plants, as well as continued land development; and severe weather. 4. This decline calls into question the long-term survival of the monarchs' migra- tory phenomenon. Resumen. 1. Durante la temporada invernal 2009-2010, y siguiendo una tenden- cia a la baja de 15 anos, la superficie total ocupada por mariposas monarca en Mexico, provenientes del este America del Norte, llegoa su punto mas bajo. A pesar de su incremento, dicha superficie siguiosiendo baja en 2010-2011. 2. Aunque que el conjunto de datos disponibles es aun pequeno, esta disminucion de la abundancia de mariposas es estadisticamente significativa, tanto si se usan modelos de regresion lineales como exponenciales. 3. Hay tres factores que parecen haber contribuido con esta tendencia de reduc- ciond el numero de mariposas: la degradacion de bosque en las areas de invernacion en Mexico; la perdida de habitat de reproduccion en los Estados Unidos, debido a la expansiond e cultivos geneticamente modificados resistentes a herbicidas, con la consiguiente perdida de las plantas hospederas de algodoncillo, y por continuos cambios en el uso del suelo no favorables para ellas; y, las recientes condiciones cli- maticas severas. 4. Esta disminucion hace que nos cuestionemos sobre la posibilidad de superviven- cia a largo plazo del fenomeno migratorio de las mariposas monarca.

Habitats Directive species lists: urgent need of revision

Abstract: The European Habitats Directive is the main legislative work regarding Europe's nature conservation policy. It lists the protected habitats and species in the European Union. The species lists include 122 arthropods. 2. The current lists of arthropods (Annexes II and IV) present, possibly among other, five obvious biases: taxonomic, geographic, range, size and aesthetic biases. Species of selected taxa (Lepidoptera, Coleoptera, Odonata and Orthoptera), from Northern or Central Europe, relatively widespread, of a large body size and attrac- tive are favoured over species of other taxa, from southern and Mediterranean Eur- ope, endemic or relatively small or inconspicuous. Such biases are obstacles to the effective protection of the European fauna. 3. Two main strategies should be followed to avoid these problems and therefore increase the effectiveness of conservation policies: (i) the adoption of objective and transparent criteria for the listing of protected species, and (ii) implement regular updates and amendments to the lists based on such criteria.

Effects of grazing, vegetation structure and landscape complexity on grassland leafhoppers (Hemiptera: Auchenorrhyncha) and true bugs (Hemiptera: Heteroptera) in Hungary

Abstract: Agricultural intensification is a major cause of biodiversity loss in European farmlands. Grasslands are particularly important habitats for the conser- vation of rich insect assemblages of Central and Eastern Europe. Although regular grazing or mowing of these grasslands is required to maintain diversity, there is no information about how such management and other factors influence Hemiptera assemblages. 2. We studied leafhopper and true bug assemblages in semi-natural grasslands in three regions of the Great Hungarian Plain. We investigated how local vegetation factors and landscape complexity influence assemblages and whether they interact with management effects. 3. Seven pairs of intensively (>1 cow ⁄ ha) versus extensively (0.5 cow ⁄ ha) grazed pastures were sampled in each region by sweep-netting. 4. Sward height was the most important explanatory factor for leafhoppers (84 species, 27264 individuals), as it increased both species number and abundance, and influenced assemblage composition. The extent of grassland surrounding the sample sites negatively affected leafhoppers, whereas extensive grazing decreased abundance and influenced composition. True bug assemblages (140 species, 6656 individuals) were positively affected only by mean sward height, whereas regional differences determined the community composition of both taxa. 5. We conclude that vegetation structure is the primary factor shaping Hemiptera communities and that the various types of grasslands studied are all important habi- tats for the taxon. Therefore, cattle grazing in its current form is beneficial for the rich Hemiptera fauna in lowland pastures of Hungary. However, in some cases, local and landscape factors and great regional differences may confound the effects of grazing, and this must be considered in conservation planning in the future.

Science into practice – how can fundamental science contribute to better management of grasslands for invertebrates?

Abstract: 1. Grasslands are diverse and extensive but are declining in extent in some parts of the globe. Grassland invertebrates can be numerically abundant and are crucial to ecosystem functioning through their roles in herbivory, nutrient cycling and pollination. Most European grasslands are modified through agricultural practices. Indeed, semi-natural grasslands, which often host the most diverse invertebrate assemblages, have suffered catastrophic losses over the last century. 2. Much research exists on grassland management, mainly from Europe, ranging from identifying optimum management of high-quality grasslands through to assessing measures to enhance low-quality grasslands, though most such projects focus solely on the plant assemblage. Monitoring that has been carried out on invertebrates indicates a varied response with invertebrate assemblages often being limited by such factors as lack of habitat connectivity, inappropriate cutting regime and the particular plant species used in enhancement projects. 3. There is a need to promote grassland management that recognises and addresses these key factors whilst also carrying out research into how best to combine the multiple ecosystem services and human benefits that are associated with grasslands.

Identifying high-quality pond habitats for Odonata in lowland England: implications for agri-environment schemes

Abstract: 1. Agricultural intensification has contributed to severe declines in odonate (dragonfly and damselfly) populations. The objective of our study is to benefit current measures for the conservation of odonates by establishing the conditions favourable to Odonata and focusing on ponds within agricultural land. 2. Our landscape-scale study used exuvial counts and habitat measurements from 29 ponds across a catchment in England, over 3 years, to determine key factors affecting odonate abundance and species richness. 3. Ponds dominated by floating and submerged vegetation were the most transparent, supported the highest abundance and species richness of exuviae, and were always fully or partially surrounded by buffer strips. Ponds lacking vegetation were turbid, yielding no exuviae even if they were buffered. English agri-environment schemes (AES) currently support pond and buffer strip creation and management. 4. Abundance of exuviae was higher in recently created ponds compared to older ponds, whereas ponds that had dried out the previous summer had fewer exuviae. 5. Species richness of exuviae decreased with increasing distance to the nearest viable pond, falling by more than 40% for distances over 100 m. 6. We conclude that odonate conservation would be more effective if AES would consider the spatial scale at which ponds are created and the location, type, and quality of ponds targeted for buffer strips.

A critique of the dragonfly delusion hypothesis: why sampling exuviae does not avoid bias

Abstract: . 1. A recent study comparing adult and exuvial odonate richness concluded that adult surveys overestimate the number of species reproducing successfully. The authors called this phenomenon the “dragonfly delusion” and recommended that only exuviae be used for biomonitoring and habitat quality assessment. However, they drew this conclusion from limited surveys and detection-naive analysis and failed to acknowledge that exuvial richness is typically biased low. 2. Here, we quantify the exuvial bias using two related metrics: (i) species detectability from concurrent adult and exuvial surveys and (ii) estimated exuvial species richness at a site based on imperfect detectability and the regional pool (cumulative total across study sites) of exuvial species observed. 3. Using concurrent adult and exuvial data from lakes in south-west France, we found that detectability was generally lower in 1-h exuvial searches than in 20-min adult searches and that exuvial surveys may lead to strong negative bias in richness estimation. This suggests the alleged delusion of adult surveys was exaggerated. 4. Controlling for species detection probability is crucial in making unbiased inferences on how many odonate species occupy a site and, by extension, comparing adult and exuvial species richness. Exuviae sampling avoids positive bias, not bias in general, and requires either relatively intensive search effort, statistical accounting of false species absences, or acceptance of negatively biased richness.

Saproxylic beetle thrives on the openness in management: a case study on the ecological requirements of Cucujus cinnaberinus from Central Europe

Abstract: . 1. Saproxylic beetles are a key group when assessing forest biodiversity, and biologists have been trying to explore their ecological requirements. 2. We studied Cucujus cinnaberinus in its recent stronghold (i.e. Czech Republic, Central Europe). 3. Our analyses using a generalised linear model (GLZ) revealed that sufficient sun exposure was the most important habitat parameter at the tree level and that the species preferred dead wood with well-peeled bark at an intermediate stage of decay at the microhabitat level. 4. Redundancy analysis (RDA) of species associations showed that the microhabitat of C. cinnaberinus was often prepared by early phloeoxylophages. Silvanids and large carabids were significant associates, and the non-coleopteran taxa associated with C. cinnaberinus were ants (Lasius spp.), mites, springtails, and centipedes. Only one species of bracket fungus Phellinus populicola was significantly associated with C. cinnaberinus. 5. Cucujus cinnaberinus microhabitats were species-rich compared with those from which this species was absent. C. cinnaberinus shares its habitat with several red-listed beetles. The most common functional groups were predators and scavengers. However, we found no difference in the composition of functional groups between sites with and without C. cinnaberinus in our study samples. 6. The results contribute to the debate about the decline in saproxylic species in relation to the decline in open spaces in forest landscapes. The habitat requirements of many saproxylic beetles indicate that modern forest management should pay more attention to open forest stands, rather than hands-off practices that naturally lead to canopy closure.

Pitfall trapping bias and arthropod body mass

Abstract: . 1. Pitfall trapping is one of the most widely used arthropod sampling techniques. However, relative species abundance in pitfall trap catches differs from that found using quadrat samples. This difference, here termed bias, reflects the fact that pitfall trap catch is influenced not only by abundance but also by other factors, including activity, which may be linked to body size. Here, we investigate whether the bias affecting pitfall trap catches of a particular species is related to the typical body mass of individuals of that species. 2. Data were extracted from five studies where pitfall trapping bias was quantified and covered 32 species of spiders and carabid beetles. Bias was expressed as the ratio of biomass captured by pitfall traps to that measured by quadrat counts (four field studies), or as the product of mean speed of movement and probability of capture per trap encounter, at standard density (one laboratory study). 3. Pitfall trapping bias and body mass were strongly related on a log–log scale, with log(body mass) explaining 78% of the variation in log(bias) (P < 0.0001). There was no significant effect of arthropod group (spiders, carabids) or study location (field, laboratory). 4. A method is proposed to correct pitfall catches of each of a group of species, based on the typical body mass of an individual of each species. This approach may remove much of the bias in pitfall trap data and so improve the value of this type of data in studies of arthropod communities.

Are migratory monarchs really declining in eastern North America? Examining evidence from two fall census programs

Abstract: . 1. The status of the eastern North American monarch butterfly population is a highly sensitive issue, given that winter and breeding habitats are being lost at an alarming rate each year, and because of this, most believe the population to be declining, although there has been little empirical data to support this idea. In a recent forum article of this journal, Brower et al. (2011) report a statistically significant decline in winter colony size over a 17-year period and suggest that this is the first sign of impending collapse. 2. I conducted an analysis of numbers of migrating monarchs from two fall monitoring stations in the United States (Cape May, NJ and Peninsula Point, MI), which span 15 and 19 years, respectively, and at both locations there was no significant linear trend in average monarch numbers counted over time, which is in marked contrast to the conclusion drawn by Brower et al. (2011). 3. Although I identify several possible reasons for the discrepancy between the fall census counts and size of the overwintering areas, these differing patterns argue for a more balanced perspective regarding the status of this population, and certainly for considering more than one phase of the life cycle. Even though it is difficult to imagine how monarchs will fare in the future with so many threats to their population, the data presented here suggest that the population remains stable for now, probably because of the high fecundity of the species and its ability to rebound from small winter numbers.

Effect of deadwood position on saproxylic beetles in temperate forests and conservation interest of oak snags

Abstract: . 1. Intensive forestry has drastically reduced the volume of standing deadwood, even more than total deadwood volume. It has been demonstrated in boreal forests that snags have a high conservation value for many saproxylic species and that the lying or standing aspect of the deadwood makes a difference. The conservation of saproxylic beetles in the changing deadwood landscape of temperate managed forests depends on a deeper understanding of the ecological value of forest stand legacies. 2. Our study questioned whether the retention of oak snags is an important conservation concern in European temperate forests. We analysed the differences in saproxylic beetle fauna between oak snags and logs and explored the diameter effect on log–snag differences. We compared the species composition and richness of saproxylic beetle assemblages in a temperate deciduous forest. Emergence traps were set in a balanced sampling design of 22 ground-lying logs and 22 oak snags with a range of intermediate decay stages and 2 diameter classes. 3. Oak snags yielded more individuals per volume unit and supported more species than logs, and exhibited significantly dissimilar assemblages from logs and hosted original species. Snags, especially large snags, were more interesting for rare beetle species conservation than logs. The feeding guild structure slightly differed between snags and logs. Overall, log–snag differences depended on the diameter class. 4. We confirm that saproxylic biodiversity would significantly benefit from forestry measures favouring oak snag retention (especially large snags), even though further multi-scale studies are necessary to develop quantitative retention guidelines.

Evaluating the impacts and conservation value of exotic and native tree afforestation in Cerrado grasslands using dung beetles

Abstract: . 1. Although plantation forests are being established at an increasing rate, their effects on biodiversity are still debated. 2. Native candeias [Eremanthus erythropappus (DC.) Mac Leish] and exotic eucalyptus (Eucalyptus spp.) have recently been planted on Cerrado grasslands. The Cerrado is the second largest biome of Brazil and one of the most threatened savanna ecosystems. 3. Here, we use dung beetles (Scarabaeinae) to investigate the effects of the land-use changes associated to afforestation on Cerrado insect biodiversity. We sampled dung beetles in candeia (4- and 6-year-old) and eucalyptus plantations (1- and 4-year-old), natural candeia formations (candeiais), native grasslands and natural forests. 4. Dung beetle diversity in plantations was lower than in grasslands and forests, but was not different from diversity in natural candeiais. Candeia and 1-year-old eucalyptus plantations, grasslands and natural candeiais all had similar community composition, distinct from natural forests. Four-year-old eucalyptus plantations were intermediate between those two groups. Overall, afforestation was detrimental for dung beetles. 5. Differences between exotic and native plantations were only apparent in older plantations, and seemed to be due to differences associated to canopy openness rather than to the origin of the planted species. Candeia plantations were of better conservation value for open-area species (62% species shared between grasslands and candeia plantation) whereas eucalyptus plantations were so for forest species (26% species shared between forests and eucalyptus plantations). We recommend considering this result before deciding where to plant which species.

Improving occurrence‐based rarity metrics in conservation studies by including multiple rarity cut‐off points

Abstract: . 1. This study aims to develop a new method for assigning rarity weights to species in evaluations of the relative rarity of arthropod assemblages in conservation/monitoring studies. 2. A flexible characteristic was included in the rarity weighting method by introducing the possibility of fitting the method to a rarity cut-off point defined as the threshold of occurrence below which species are considered as being rare. This allows calculation of a rarity metric (index of relative rarity IRR) with multiple rarity cut-off points. 3. The proposed weighting method was used and compared with three previously proposed methods in a theoretical analysis. IRR values were then calculated for spider assemblages of a National Nature Reserve in France. Two methods of rankings were proposed: a local ranking between sites of the Nature Reserve, and a regional ranking in comparison to a reference database. 4. The proposed weighting method consistently weighted species according to the chosen rarity cut-offs. Species weights were less biased toward common species and rare species weights were less dispersed than with previous methods. Assemblages were consistently ranked according to the rarity of spiders in each assemblage. The index showed different patterns of rarity in assemblages which could not be detected by previous rarity metrics. 5. This method provides an improved understanding of assemblage rarity patterns relative to previous methods and can be consistently applied to other arthropod taxa in other geographic area and/or spatial scales.

Positive cascade effects of forest fragmentation on acorn weevils mediated by seed size enlargement

Abstract: . 1. Today, forest fragmentation is one of the major threats to biodiversity worldwide. In this context, fragmented populations of specialised forest organisms face an increasing risk of extinction because of factors such as local food scarcity. Nonetheless, the role of food availability may differ depending on organism size, which is expected to determine the energy requirements and mobility between fragments. 2. A field study was carried out on Curculio elephas, a forest beetle with low dispersal potential, whose larval development takes place in oak Quercus spp. acorns. 3. For a similar seed crop per tree, acorn size was larger in isolated oaks than in trees located in forest patches. Thus, fragmentation increased local food availability for C. elephas. Larger acorns enabled larval size to increase, a key fitness proxy associated with individual survival, adult size, and potential female fecundity. Indeed, the number of both adults and larvae was higher in isolated trees than in forest patches. 4. In the current scenario of increasing forest fragmentation, the survival likelihood of specialist insects may strongly depend on their ability to adapt to altered environmental conditions. To the best of our knowledge, this is the first study to report on how some forest insects may take advantage of fragmentation-mediated changes to survive in isolated trees. 5. From a conservation perspective, management policies should preserve isolated trees as a source of seeds and fauna for the natural regeneration of forest ecosystems after unproductive farmlands have been abandoned.

Predicting the distributions of under‐recorded Odonata using species distribution models

Abstract: . 1. Absences in distributional data may result either from the true absence of a species or from a false absence due to lack of recording effort. I use general linear models (GLMs) and species distribution models (SDMs) to investigate this problem in North American Odonata and present a potential solution. 2. I use multi-model selection methods based on Akaike’s information criterion to evaluate the ability of water–energy variables, human population density, and recording effort to explain patterns of odonate diversity in the USA and Canada using GLMs. Water–energy variables explain a large proportion of the variance in odonate diversity, but the residuals of these models are significantly related to recorder effort. 3. I then create SDMs for 176 species that are found solely in the USA and Canada using model averaging of eight different methods. These give predictions of hypothetical true distributions of each of the 176 species based on climate variables, which I compare with observed distributions to identify areas where potential under-recording may occur. 4. Under-recording appears to be highest in northern Canada, Alaska, and Quebec, as well as the interior of the USA. The proportion of predicted species that have been observed is related to recorder effort and population density. Maps for individual species have been made available online (http://www.odonatacentral.org/) to facilitate recording in the future. 5. This analysis has illustrated a problem with current odonate recording in the form of unbalanced recorder effort. However, the SDM approach also provides the solution, targeting recorder effort in such a way as to maximise returns from limited resources.

Management pressure drives leafhopper communities in vineyards in Southern Switzerland

Abstract: The effects of the current changes in traditional agricultural practices in the Alps on the biodiversity affecting ecosystem functions and services are little known. Vineyards are among the oldest anthropogenic environments of high cultural and natural value that shape the landscape of large areas in Central and Southern Europe. In several mountain regions of the Alps, vineyards are a valid alternative to the landscape homogenisation that has followed post-cultural land abandonment and agriculture intensification. Key unanswered questions remain regarding the rela- tive contribution of several factors that influence biodiversity, and the level in man- agement pressure with regard to taxonomic and functional diversity enhancement. 2. To answer these questions, we sampled leafhoppers (Auchenorrhyncha) as a model taxon using different standard techniques along 24 vine transects within 8 vineyard complexes in Southern Switzerland. Each transect included one vine row, vine canopy, its interrow and the adjacent slope; the latter two were permanently grass-covered. Data were analysed using a four-step approach. 3. Environment (five variables) and Management (four variables) accounted for most of the variance in the leafhopper assemblage. Pesticide use (insecticide and her- bicide) and slope mowing are the most important management predictors of leafhop- per species composition. 4. With increasing management pressure (i.e. pesticide and mowing), the number of indicator species and particularly the specialists (i.e. stenotopic and oligotopic spe- cies) decreases dramatically. 5. To promote taxonomic and functional complexity of communities in vineyard systems, we suggest low management pressure with moderate use of pesticide and a low intensity regime of slope mowing.

Bias of reduced‐effort community surveys for adult Odonata of lentic waters

Abstract: . 1. Repeat surveys are needed to capture a representative spectrum of adult odonate richness at a site, but specifics on frequency and duration of surveys and associated inferential biases are poorly understood. 2. Weekly 1 h surveys of mature male dragonflies and damselflies were repeated at least 15 times at 19 ponds, lakes and wetlands scattered throughout North America. For each site, we tallied the data remaining when the weekly frequency was reduced to 75% (every 1.5 weeks), 50% (biweekly), 33% (triweekly), and 25% (monthly) and the 1 h survey to 50, 40, 30, 20 and 10 min subsets. 3. Reducing the original effort by half (i.e. to 30 min biweekly) retained about 80% of the species on average. The smallest effort (10 min monthly) retained about 49% of species. The greatest rate of information loss occurred between 20 and 10 min. 4. Across-site analysis found that data subsets correlated to the original data set (r > 0.81) despite up to 50% species loss. Strong correlations (r ≥ 0.98) remained with 10–15% species loss. 5. Biweekly surveys lasting 20–40 min each may provide a representative and cost-effective sample of adult odonate richness in lentic study sites. Losing a handful of species should not greatly undermine richness and compositional comparisons among sites.

Differences in genetic variability between two ecotypes of the endangered myrmecophilous butterfly Phengaris (=Maculinea) alcon– the setting of conservation priorities

Abstract: . 1. The endangered butterfly Phengaris alcon exists in two ecotypes (P. ‘alcon’ and P. ‘rebeli’), which inhabit contrasting biotopes (wet and warm/dry grasslands respectively) and use different larval food plants. The initially flower-bud-feeding caterpillars complete their development as social parasites of Myrmica ants, and the specificity of these relationships shows geographical variation. 2. We studied the genetic structure of 16 populations (365 individuals) of both ecotypes in eastern Europe, sampling P. ‘rebeli’ in two disjunct areas in Lithuania and southern Poland, and P. ‘alcon’ on Polish localities between them. We analysed the cytochrome c oxidase subunit I (COI) mitochondrial gene, the EF1-α nuclear gene and five polymorphic microsatellite loci. 3. All individuals shared an identical COI haplotype, which we hypothesise may be linked to a selective sweep associated with the presence of the Wolbachia B strain in all populations. 4. For nuclear markers, we did not find a clear pattern reflecting division into two putative ecotypes. However, ecotypes differed significantly in their genetic variability, i.e., the P. ‘rebeli’ ecotype was less polymorphic, and its populations were much more differentiated (FST: 0.632 for EF1-α and 0.504 for microsatellites) than the P. ‘alcon’ ecotype (0.177 and 0.082, respectively). 5. Our microsatellite data suggest that all populations of P. ‘alcon’ form a single clade but that P ‘rebeli’ can be split into either six or two clades. The former model would indicate many independent origins, especially in the mountainous areas of southern Poland. The latter, not mutually exclusive, grouping clearly reflects the use of different host ants.

Current protected sites do not allow the representation of endangered invertebrates: the Spanish case

Abstract: Using a recently created database representing the joint effort of around 100 invertebrate taxonomists, this study uses the information on 52 arthro- poda and 27 mollusca species that are endangered and critically endangered to exam- ine to what extent invertebrate species are represented in existing Spanish protected areas. 2. As distribution information is available at a 100 km 2 resolution, we consider different area thresholds to judge cells as being protected. 3. Approximately 19% of the area represented by the grid cells with observed occurrences rates as extant protected reserves, and 36% is included within the Natu- ra 2000 network. 4. If having 50% of the cell area as a Natura 2000 reserve is considered as suffi- cient to have effective protection, almost 68% of species and 32% of probable popu- lations (contiguous cell groups) would be represented. 5. However, 77% of species and 94% of probable populations are not represented in the current protected reserves if we establish that at least 95% of each cell area should belong to a reserve to provide effective protection. 6. Thus, existing conservation strategies, which are based primarily on the protec- tion of certain areas and vertebrate species, may be insufficient to ensure the conser- vation of invertebrate species.

Range expansion and enemy recruitment by eight alien gall wasp species in Britain

Abstract: Biological invasions involving continuous range expansion differ from discontinuous introductions in that invaded and native ranges remain connected, potentially allowing pursuit of range expanding species by their natural enemies. The establishment in Britain of eight alien herbivorous gall wasps (Hymenoptera: Cynipi- nae) provides a rare opportunity to study continuous range expansion and natural enemy recruitment in a guild of related and ecologically similar species. 2. Four aliens (Andricus kollari, A. quercuscalicis, A. lignicolus ,a ndA. corruptrix) reached the UK before 1990, while four more recent invaders (A. aries, A. grossula- riae, A. lucidus ,a ndAphelonyx cerricola) reached Britain by 2000. We provide the first parasitoid records for the recent invaders, update community development for the earlier set, and use dates of first record to estimate rates of spread for all eight species. 3. While the recent invaders are restricted to southern and eastern England, three of the early invaders have reached northern Scotland. From their origins in southern England, invading gall wasps have expanded their distributions across the UK at mean rates ranging from 1.4 km ⁄ year to >20 km ⁄ year. Variation in range expan- sion rate was not related to life history differences, including voltinism or host oak association. 4. All species have recruited native parasitoid enemies since their arrival, and we found no evidence of pursuit by non-native natural enemies from continental Eur- ope. Our results suggest that over timescales predicted for rapid climate change, her- bivore ⁄ parasitoid communities are unlikely to expand their range as sets of interacting species. Rather, we expect host range expansions to trigger local reassem- bly of communities.

Abandonment of grazing in a mediterranean grassland area: consequences for ant assemblages

Abstract: . 1. Abandonment of traditional activities in the rural areas is widespread in the developed world, and in the case of grazing, it is known to have negative consequences on the diversity of plant communities. Few studies have examined the impact of grazing abandonment on fauna, which in the case of ants is of considerable interest, given their usefulness as an indicator for monitoring environmental change. 2. Here, we present the results of a study conducted in Mediterranean grasslands of central Spain. Using pitfall traps, ants were sampled from 10 40 m× 20 m plots; five of them located in grazed systems and five in abandoned grazing systems. Descriptors used for the ant assemblage were ant species composition, ant species richness, ant functional groups, and subguilds of granivores. We used a seed bait test to discriminate between granivorous and non-granivorous ant species. 3. Our results show that abandoned grazing systems have more ant species and more heterogeneous ant assemblages. Changes in ant species composition and ant functional groups are more pronounced in habitats where woody encroachment progresses more rapidly (i.e. dry sectors and tree islands). Specialised granivores have reduced importance in the same habitat types. Conversely, facultative granivores increase their presence in abandoned grazing systems. 4. The increased functional and species ant diversity observed with grazing abandonment can be explained by the generation of a more heterogeneous environment at the smaller scales, in spite of being more homogenous at the larger scales, because the latter are less significant for the organisms studied.

Species richness and turnover patterns in European tenebrionid beetles

Abstract: We used a hyperdiverse invertebrate group, tenebrionid beetles, to test competing hypotheses about the factors correlated with the spatial variation in spe- cies richness and composition across Europe. 2. We considered the following hypotheses for explaining variation in species rich- ness, (i) spatial heterogeneity, (ii) environmental energy, and (iii) dispersal limitation and post-glacial recolonisation, and the following hypotheses for variation in species composition, (i) current climate, (ii) Pleistocene glaciations, and (iii) neutral dynam- ics. 3. We used inventories of 36 European territories, built from a database contain- ing the distributions of 1010 species or subspecies. Area, spatial position, and topo- graphical and climatic variables were used as predictors in regression (richness) and constrained analysis of principal coordinates (composition) analyses. 4. The latitudinal richness gradient found in European tenebrionids was mostly explained by the joint effect of environmental and spatial variables, supporting the climate and incomplete recolonisation hypotheses. 5. A parabolic relationship of endemism with longitude points to the presence of centres of endemism in the Iberian Peninsula and the Balkans. Current climatic con- ditions alone were not sufficient to explain spatial turnover patterns of European tenebrionids, which are largely influenced by spatial factors. 6. Both the Pleistocene glaciations and neutral hypotheses were supported, but the fact that turnover is not uniform across Europe suggests that the historical effects of Pleistocene glaciations had a deeper impact on tenebrionid assemblages than neutral dynamics. Thus, variation in species richness seems more directly controlled by cli- matic factors, whereas geographical constraints related to dispersal limitation or sto- chastic colonisation events influenced species composition.

Impact of wild ungulate grazing on Orthoptera abundance and diversity in subalpine grasslands

Abstract: . 1. Grasslands cover approximately 40% of the Earth’s terrestrial landscape, supporting large communities of vertebrate and invertebrate herbivores. Orthoptera play an important role, consuming relatively large amounts of biomass. Their occurrence can be strongly affected by habitat diversity and structure, which can be shaped by large herbivores. Several studies have focused on the impact of livestock on Orthoptera communities, but little is known about how wild ungulates influence the abundance and diversity of these insects in grassland ecosystems. 2. We studied Orthoptera abundance and diversity in subalpine grasslands in the Swiss Alps, where grazing by red deer and chamois has created a mosaic of short- and tall-grass patches. Data on vegetation structure, habitat diversity and plant nitrogen (N) content allowed us to consider how these parameters affected the occurrence of Orthoptera at our study sites. 3. We found a total of nine Orthoptera species with an average density of 2.6 individuals m−2. Neither Orthoptera abundance nor diversity differed between short- and tall-grass patches created by large ungulates. Both Orthoptera abundance and diversity were, however, positively influenced by increasing vegetation height, but negatively by increasing habitat diversity within patches. Increasing plant N content promoted a more even spread of species within the insect assemblage on short- but not on tall-grass patches. 4. Large-scale habitat alteration by wild ungulates had no direct effect on the abundance and diversity of Orthoptera. However, we observed that they indirectly affected Orthoptera abundance and diversity by altering plant N content and the structure of the habitat at small scales.

Trait-specific effects of habitat isolation on carabid species richness and community composition in managed grasslands

Abstract: . 1. Isolation of natural and semi-natural habitats, a consequence of increasing management intensification, has been identified as a major threat to the diversity of many taxa in agricultural landscapes. Yet, it is increasingly apparent that the effects of habitat isolation vary not only among distantly but also closely related taxa, depending on their respective ecological traits. 2. We studied the effects of habitat isolation on carabid beetles with different dispersal potential in common perennial grasslands. The grasslands belonged to three isolation classes: (i) situated in a continuous belt of grasslands, (ii) in an arable matrix but connected to the continuous belt via corridors or (iii) completely isolated in the arable matrix. 3. Neither total carabid species richness nor richness of carabids with high dispersal potential was affected by habitat isolation. In contrast, richness of carabid species with low dispersal potential was more than two times lower in isolated than in continuous grasslands. Communities of isolated sites were characterised by species with high dispersal potential whereas species with low dispersal potential were associated with continuous or well connected grasslands. 4. Our results revealed trait-specific responses of carabids to habitat isolation and highlight the need for considering these differences when predicting effects of landscape structure on carabid diversity. Grassy corridors seemed to assist the dispersal of carabids with low dispersal potential, thereby allowing these species to persist also in non-continuous but connected habitats. Thus, corridors represent a suitable measure to maintain the diversity of carabids in spatially structured grasslands in agricultural landscapes.

Down in the flood? How moth communities are shaped in temperate floodplain forests

Abstract: . 1. We investigated moth communities in relation to flood regime across three riparian regions in lowland eastern Austria. Moths sampled with light traps were segregated into resident and stray species. Resident moths were further partitioned into arboreal and ground-layer species based on their larval habitat. 2. Regional differences in species diversity and species composition were far stronger than local differences related to flood regime. 3. Stray species (17% of all species and 6% of all individuals sampled) as well as uniques had only negligible influence on diversity and species composition patterns. The single most abundant species turned out to be more problematic for diversity comparisons across regions and habitats than the many rare species and strays. 4. Overall moth diversity and ground-layer moth diversity were generally not reduced in flooded habitats relative to non-flooded habitats, and diversity of arboreal moths did not show significant differences between flood regimes. 5. Differences between habitats in their ground-layer vegetation appear to be more important for floodplain forest moth diversity than variation in woody vegetation with its associated arboreal moth fauna. 6. Patterns in species composition were largely governed by ubiquitous forest species and not by floodplain or wetland habitat specialists. Eighteen of the 44 commonest species were more abundant in flooded habitats, and only 10 of them were more frequent in non-flooded habitats. 7. Our results revealed no general negative impact of flooding on the diversity and species composition of one rich group of terrestrial herbivorous insects.

Importance of marginal habitats for grassland diversity: fallows and overgrown tall-grass steppe as key habitats of endangered ground-beetle Carabus hungaricus

Abstract: To facilitate effective conservation management of dry-grassland diver- sity we studied the habitat selection of Carabus hungaricus, the globally declining, highly endangered, dry-grassland specialist beetle listed in the EU Habitats Directive, and several co-occurring beetles at a pannonian dry-grassland fragment, the Pouzdr- any steppe, SE Czech Republic. The beetles were sampled using 186 pitfall traps from March to November 2006. Number of C. hungaricus captures in each trap was related to vegetation and abiotic habitat characteristics; captures of all sampled bee- tles in each trap were related to each other. 2. We found that C. hungaricus prefers relatively humid patches of tall-grass steppe within the xeric grassland and tall-grass ruderal vegetation nearby. During the breed- ing period, females preferred drier and warmer sites than males. 3. Its potential competitors, i.e., Carabus spp., Calosoma spp. (Coleoptera: Carabi- dae), and other species of conservation interest, including Meloe spp. (Coleoptera: Meloidae), Dorcadion spp. (Coleoptera: Cerambycidae), were associated with vegeta- tion avoided by C. hungaricus, such as short-grass and bare-soil patches and woody plants. 4. Vegetation structure within 2.5 m affected C. hungaricus captures more than on smaller and larger scales. Carabus hungaricus enters unfavoured non-forest habitats such as arable land, which allows it to spread into suitable habitats within agricul- tural landscapes. It strictly avoids closed forest; even narrow strips of forest thus likely act as migration barriers. 5. The preference of C. hungaricus for overgrown steppe and fallow land highlights that habitats often considered of low conservation value are important to sustain grassland biodiversity.

Genetic and phenotypic differentiation in endemic Scaptotrigona hellwegeri (Apidae: Meliponini): implications for the conservation of stingless bee populations in contrasting environments

Abstract: The western forests of Mexico are rich in species of stingless bee, possi- bly a consequence of the diverse habitats found across different altitudes of the Trans-Mexican Volcanic Belt (TMVB) and the Pacific coast (PAC). 2. Scaptotrigona hellwegeri is an example of a stingless bee species found across the TMVB and PAC. It is currently considered a single species. Its TMVB popula- tions have become rare and rapidly impacted by human-modified habitats. Translo- cation of S. hellwegeri colonies from the PAC tropical lowlands to TMVB subtropical highlands has been considered, as colonies at PAC are more abundant and even used in stingless beekeeping. 3. Morphometric analyses of meristic characters plus genetic analysis at microsat- ellite loci and sequencing of the cox1 region of mtDNA were used to evaluate pheno- typic and genetic differentiation in S. hellwegeri from TMVB and PAC. 4. Significant morphometric differences were detected between S. hellwegeri from TMVB and PAC. Corrected nuclear multilocus F¢ST was 0.592 (P < 0.01), support- ing the view that TMVB and PAC populations are markedly genetically differenti- ated. A 573 bp sequence of the cox1 region of mtDNA showed six sites of divergence, with sequence divergence between PAC and TMVB populations of 1.1%. 5. Our morphometric and genetic results make evident that S. hellwegeri from TMVB and PAC are significantly differentiated and represent two genetic lineages. An immediate recommendation is to restrict the movement of colonies from the low- land PAC regions to TMVB, where colonies are currently scarce.

Grazing impacts on Auchenorrhyncha diversity and abundance on a Scottish upland estate

Abstract: . 1. Livestock grazing impacts on insect populations in a variety of ways. For phytophagous insects the impact is primarily a result of altering the structure and species assemblage of vegetation. However not all species react in similar ways and even within an order there may be winners and losers from different grazing regimes. 2. A long-term, replicated, controlled experiment, comprising four grazing treatments, was established within an upland acid grassland area in Scotland. Auchenorrhyncha were sampled by suction sampling and sweep-netting in the fifth year following the start of the treatments. 3. A significant treatment effect was apparent in the suction samples with Auchenorrhyncha abundance being three to four times higher in the ungrazed plots compared to the other treatments. Abundance was also highest from the ungrazed plots in the sweep net samples, but this effect was not statistically significant. Redundancy analysis (RDA) showed that a suite of species which are typical of shaded positions responded with increased abundance in the ungrazed plots. 4. The findings demonstrate that the assemblages found in ungrazed areas can be vastly different to those found in even lightly grazed areas and therefore, underline the benefits of varied grazing regimes in maximising diversity. Furthermore, the work underlines the benefit of employing multiple sampling methods.

Chironomid (Diptera) distribution and diversity in Tibetan streams with different glacial influence

Abstract: . 1. We collected chironomid larvae and measured basic environmental variables in eight high mountain streams with different degrees of glacial influence in southern Tibet. 2. In total, 32 chironomid taxa were collected. The Orthocladiinae subfamily dominated both in taxon number and in abundance. 3. Both average taxon number and abundance were lower in glacier-fed streams compared with those of non-glacial origin. The total taxon number collected (γ diversity) was similar regardless of glacial influence. However, spot diversity (α diversity) was higher in non-glacial streams, while glacier-fed streams supported higher species turnover (β diversity). 4. Detrended correspondence analysis scattered the study sites along the first ordination axis, representing a combination of distance from glacier and channel stability. Two-way indicator analysis distinguished three groups of sites. Group 1 represented the sites closest to the glacier and were characterised by unstable channel conditions and low temperature with characteristic taxa Diamesa sp. 1, Orthocladius (Eud.) sp. and Rheocricotopus sp. Group 2 was made up of glacier-fed streams situated further from glaciers, with unstable channels and characterised by Orthocladius (Euo.) sp. Group 3 contained non-glacial streams as well as a glacier-fed stream further from the glacier margin. For these sites, stable channels and high conductivity were characteristic and Cricotopus (C.) sp., Pseudosmittia sp, Polypedilum sp., Eukiefferiella gracei group and Pagastia sp. 1 were the dominating taxa. 5. We propose a general distribution pattern of chironomids in the streams of glacial and non-glacial influence in Tibet, which is in accordance with the model proposed by Milner et al. (2001a) Freshwater Biology, 46, 1833–1847.

Water beetle biodiversity in Mediterranean standing waters: assemblage composition, environmental drivers and nestedness patterns

Abstract: . 1. Nowadays, it is widely accepted that increasing human activity is highly related to the current biodiversity loss, this fact being especially worrying in aquatic ecosystems, mainly in semi-arid areas. To date, studies on the biodiversity of small standing waters are focused on Central and Northern Europe, Mediterranean regions being poorly documented. 2. Here, data for aquatic Coleoptera in SE Iberia have been used to: (i) explore the relative contribution of standing waters to regional aquatic biodiversity, (ii) identify the environmental drivers structuring beetle assemblages, (iii) determine the degree to which standing water assemblages are nested subsets, and (iv) make recommendations for the conservation and management of the habitats studied. 3. Water beetles are a hyperdiverse group of aquatic insects which represent good surrogates of aquatic biodiversity. A total of 95 sites across eight habitat types were sampled, 174 species being recorded (11% were Iberian endemics). 4. Habitat types generally had distinct aquatic beetle faunas; a combination of conductivity, anthropogenic impact and altitude best explaining differences in assemblages across sites. Beetle faunas were significantly nested, this being the case across all sites, and for both fresh and saline systems independently. Disturbance was identified as a key driver of nestedness across sites overall, and particularly in freshwaters, whereas conductivity was more important in saline waters. 5. Our study identifies the biodiversity importance of lentic inland waters in the Iberian southeast, and points to the influence that human activities already exert on the invertebrate faunas of western Mediterranean wetlands.

High mobility reduces beta-diversity among orthopteran communities – implications for conservation

Abstract: . 1. The analysis of β-diversity, i.e. species turnover, across space is central to a wide array of ecological and evolutionary topics, also providing critical information to conservation planning. Although dispersal limitation has been demonstrated to play an important role in determining insect community structure, very little research has been done to test whether mobility might affect the diversity distribution of species across multiple spatial scales. 2. We considered orthopterans (Ensifera and Caelifera) inhabiting hay meadows to test whether species mobility modifies β-diversity patterns across three nested spatial scales (1-m2 plots within meadow, 1000-m2 meadows within landscape, and 19.6-km2 landscapes within a region) and along a gradient of management intensity. 3. Orthopteran community composition varied most significantly over broader spatial scales. Larger proportion of regional γ-diversity was mainly composed of β-diversity at the landscape scale, whereas this proportion was smaller at the plot and meadow scale. 4. Mobility, but not management, strongly modified β-diversity patterns. Sedentary species contributed to a greater proportion of β-diversity across all the investigated scales compared with mobile species. 5. Measures currently included in most agri-environment schemes have only focused on the extensive management at the field scale. Our results imply that orthopteran diversity would benefit from maintaining extensively managed meadows scattered throughout the whole region, as the loss of species-rich isolated grassland patches due to abandonment or eutrophication might cause severe reductions of the regional species pool. Increasing connectivity might be also considered as a complementary measure to increase species occupancy and population persistence, particularly for sedentary species.