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Abstract The two sibling and syntopic odonate species Sympetrum striolatum and Sympetrum vulgatum are common and widespread in Central Europe. While S. striolatum has strong positive population trends, declines of S. vulgatum are observed. The aim of this study was to identify possible drivers of these diverging trends. We presumed that differences in egg development may lead to differences in survival until hatching. First, eggs laid in non-permanent or shrinking waterbodies may suffer of increasing drought periods. Second, differences in developement may cause increased size-mediated intraguild predation, a common cause of reduced survival in odonate larvae. Egg development time and hatching rates were recorded of eleven egg clutches of S. vulgatum and ten clutches of S. striolatum under simulated drought vs. water and direct vs. delayed development treatments. Hatching rates were reduced under drought conditions, and particularly so in S. vulgatum. We did not observe obligate winter diapause in any of the egg clutches. But, S. vulgatum varied widely in development between clutches, while the eggs of S. striolatum developed much faster and hatched highly synchronously. This would provide S. striolatum with a temporal advantage that may lead to a size-advantage over most S. vulgatum. We also found that S. vulgatum grew faster. Faster larval growth would only compensate for those S. vulgatum with fast egg development. The current population trends may be partly attributed to lowered survival of S. vulgatum under drought and by phenological and, thus, size benefits of S. striolatum. Implications for insect conservation Our results show that population dynamics of two closely related dragonfly species can be explained by climatically induced changes in their interactions. Understanding the causes and processes of behavioural changes resulting in differing population trends is fundamental for the protection of species.

The final instar larvae of the two species of the southern African gomphid genus Ceratogomphus, the South African endemic C. triceraticus and the more widespread C. pictus, are compared based on exuviae. Main differences are the shapes of the prementum and of the last abdominal segments, giving C. pictus a more slender and pointed appearance. Ceratogomphus triceraticus is slightly larger and on average significantly so. The habitats of both species are described based on own observations in South Africa.

Insects are reportedly experiencing widespread declines, but we generally have sparse data on their abundance. Correcting this shortfall will take more effort than professional entomologists alone can manage. Volunteer nature enthusiasts can greatly help to monitor the abundance of dragonflies and damselflies (Odonata), iconic freshwater sentinels and one of the few nonpollinator insect groups appreciated by the public and amenable to citizen science. Although counting individual odonates is common in some locations, current data will not enable a global perspective on odonate abundance patterns and trends. Borrowing insight from butterfly monitoring efforts, we outline basic plans for a global volunteer network to count odonates, including organizational structure, advertising and recruiting, and data collection, submission, and synthesis. We hope our proposal serves as a catalyst for richer coordinated efforts to understand population trends of odonates and other insects in the Anthropocene.

We investigated the effects of the presence of bladderwort plants on survival of early instar larvae of one coenagrionid and two libellulids in laboratory experiments. In all three species survival...

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation. ispartof: ECOLOGY LETTERS vol:25 issue:2 pages:255-263 ispartof: location:England status: published

The global population structure and dispersal patterns of Pantala flavescens (Fabricius, 1798) are evaluated using a geographically extensive mitochondrial DNA dataset, a more limited samples of nuclear markers, wing isotopic (δ²H) data and a literature review. No spatial or temporal haplotype structure was recovered between the samples. Isotope data suggest that most samples were immigrants at the collection locations. A literature review of migration events for the species confirms regular inter-and intra-continental migrations occur (the majority reported from Asia, Africa and Australasia), with individuals and swarms dispersing thousands of kilometers over land and oceans. Migrations coincide with prevailing winds and seasonal rains, which points to a mechanism we name the “pantropical Pantala conveyor belt”, suggesting widespread gene flow is possible for an aquatic insect with excellent flying ability linked to rapid larval development. Funding: Ware would like to acknowledge funding from NSF DBI #1564386.

Recent studies suggest insect declines in parts of Europe; however, the generality of these trends across different taxa and regions remains unclear. Standardized data are not available to assess large-scale, long-term changes for most insect groups but opportunistic citizen science data is widespread for some taxa. We compiled over 1 million occurrence records of Odonata (dragonflies and damselflies) from different regional databases across Germany. We used occupancy-detection models to estimate annual distributional changes between 1980 and 2016 for each species. We related species attributes to changes in the species’ distributions and inferred possible drivers of change. Species showing increases were generally warm-adapted species and/or running water species while species showing decreases were cold-adapted species using standing water habitats such as bogs. We developed a novel approach using time-series clustering to identify groups of species with similar patterns of temporal change. Using this method, we defined five typical patterns of change for Odonata – each associated with a specific combination of species attributes. Overall, trends in Odonata provide mixed news – improved water quality, coupled with positive impacts of climate change, could explain the positive trend status of many species. At the same time, declining species point to conservation challenges associated with habitat loss and degradation. Our study demonstrates the great value of citizen science data for assessing large-scale distributional change and conservation decision-making.

AIM: Land use change, such as urbanization and intensification of agricultural practices, poses major threats for biodiversity. We examined whether the composition of freshwater species differs between landscapes dominated by urban, agricultural or more natural structures in a region with a long history of landscape transformation. We determined the differences and characteristics of the dragonfly fauna in relation to major land use categories. We particularly focused on urban land use, as it generally induces a high level of landscape transformation. LOCATION: Germany. METHODS: We used distribution data of dragonflies derived from a citizen science database, which was compiled for the German distribution atlas. To analyse whether different land use categories are associated with distinct species compositions, we performed the classification method random forest. RESULTS: Based on dragonfly abundance per grid cell, we identified distinct land use‐related assemblages that were separated by two gradients, that is, the level of transformation and a gradient from open land to forest. In particular, urban landscapes possessed a distinct species composition with specific species, all of which were opportunistic and supported by warm climate. They also comprised significantly higher α‐diversity than intensive agricultural landscapes. Similar values of γ‐diversity over all land use categories implied a countrywide homogenized dragonfly fauna, which is probably caused by historic land use. MAIN CONCLUSIONS: Our results indicate that land use is a relevant driver for the composition of freshwater species at the landscape scale. Urban landscapes maintain species diversity better than agricultural landscapes, but they modify the species composition. Additional research on the effects of land use change is required to understand species responses and predict future distributions in a changing world in order to plan sustainable conservation strategies.

Here we build on the manifesto ‘World Scientists’ Warning to Humanity, issued by the Alliance of World Scientists. As a group of conservation biologists deeply concerned about the decline of insect populations, we here review what we know about the drivers of insect extinctions, their consequences, and how extinctions can negatively impact humanity. We are causing insect extinctions by driving habitat loss, degradation, and fragmentation, use of polluting and harmful substances, the spread of invasive species, global climate change, direct overexploitation, and co-extinction of species dependent on other species. With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits, and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends. From pollination and decomposition, to being resources for new medicines, habitat quality indication and many others, insects provide essential and irreplaceable services. We appeal for urgent action to close key knowledge gaps and curb insect extinctions. An investment in research programs that generate local, regional and global strategies that counter this trend is essential. Solutions are available and implementable, but urgent action is needed now to match our intentions.

The fate of humans and insects intertwine, especially through the medium of plants. Global environmental change, including land transformation and contamination, is causing concerning insect diversity loss, articulated in the companion review Scientists' warning to humanity on insect extinctions. Yet, despite a sound philosophical foundation, recognized ethical values, and scientific evidence, globally we are performing poorly at instigating effective insect conservation. As insects are a major component of the tapestry of life, insect conservation would do well to integrate better with overall biodiversity conservation and climate change mitigation. This also involves popularizing insects, especially through use of iconic species, through more media coverage, and more inclusive education. Insect conservationists need to liaise better with decision makers, stakeholders, and land managers, especially at the conceptually familiar scale of the landscape. Enough evidence is now available, and synthesized here, which illustrates that multiple strategies work at local levels towards saving insects. We now need to expand these locally-crafted strategies globally. Tangible actions include ensuring maintenance of biotic complexity, especially through improving temporal and spatial heterogeneity, functional connectivity, and metapopulation dynamics, while maintaining unique habitats, across landscape mosaics, as well as instigating better communication. Key is to have more expansive sustainable agriculture and forestry, improved regulation and prevention of environmental risks, and greater recognition of protected areas alongside agro-ecology in novel landscapes. Future-proofing insect diversity is now critical, with the benefits far reaching, including continued provision of valuable ecosystem services and the conservation of a rich and impressive component of Earth's biodiversity.

We report cases of long-distance dispersal in Odonata, some of which were directly observed by identifying single individuals of riverine species in unsuitable habitat, mostly desert, far distant from reproduction habitats. The shortest possible linear distances of the observation points to reproduction habitats were measured. Furthermore, established populations of riverine species were recorded in artificial lakes in central and southern Namibia far distant from the next regular reproduction sites. Our records demonstrate that single individuals of riverine species were probably covering distances of several hundred kilometres over arid landscape without any intervening possible reproduction habitat. Although it is likely that only small numbers of individuals of the river populations may disperse long distances, relatively recent colonizations of artificial habitats suggest that a few, or even single, dispersing individuals may lead to large-scale-range expansions.

Based on a distribution database brought together for the recently published Atlas of the European dragonflies and damselflies, we describe the patterns of diversity and endemism of these insect groups. Highest species richness, as well as richness of predominantly lentic species, occurs in central and western-central Europe. Strictly lotic species have their centre of diversity in southwest France and parts of the Iberian Peninsula. The highest number of endemic species is found in southwest France, the Iberian Peninsula and the Balkan Peninsula. A comparison of the diversity patterns of Odonata species listed in the EU Habitats Directive with those listed in the European Red List highlights a strong mismatch between species threatened in Europe, which are mainly found in the Mediterranean, and species legally protected by the European Union, which are concentrated in central and western Europe. This mismatch has a historical origin, as the species listed in the Habitats Directive were mostly selected in the 1970s and 1980s when water quality in western and central Europe was poor. Since the 1990s, water and habitat quality has improved in these parts of Europe while in the same period the pressure on aquatic habitats in the Mediterranean has increased greatly.

We review the knowledge about the thermal reaction norms of larval growth in Odonata with a focus on the temperature response function. We re-analyze literature data and present our own results on growth rates of larvae of 14 species of Libellulidae reared at different temperatures. Temperature response curves (TRC) were fitted in order to estimate two relevant components of the thermal reaction, namely the optimum temperature for growth (Topt) and the increase of growth rate with temperature (Q10). We also examined what is known about the thermal minimum (Tmin) and the thermal maximum (Tmax) for growth to delimit the thermal ranges of odonates. All information indicates that larval growth is generally warm adapted, with species-specific variation of Topt of 21–31°C, Tmin of 8–12°C, and Tmax of up to 44°C (the latter being the upper lethal limit, the true Tmax for growth remains unknown). The values of Q10 distinguish some more specialized species, mostly with high Topt and of tropical origin, and others ...

African freshwater ecosystems are increasingly being impacted by humans, requiring an effective tool to assess these impacts for future conservation action. Such a tool, the Dragonfly Biotic Index (DBI), was earlier developed to assess the quality of South Africa’s freshwater ecosystems and is based on combining the scores of three sub-indices (geographical distribution, threat status, and habitat sensitivity) for each South African dragonfly species. The sum of the DBI scores for all the species recorded at assessed sites indicates the relative quality of these sites. The International Union for the Conservation of Nature/Species Survival Commission (IUCN/SSC) has assessed the threat status of certain aquatic taxa in Africa, including dragonflies. These assessments, coupled with the latest information on the geographical distribution of each species, makes it possible here to geographically expand the South African DBI into a continental-scale assessment index (the African Dragonfly Biotic Index (ADBI)) by adapting the South African DBI sub-indices. We develop this continental index here. However, there are challenges when undertaking an assessment at the continental scale compared to a national scale. In particular, the habitat sensitivity sub-index of the South African DBI is a relative, quantitative measure based on numbers of individual dragonflies recorded from natural versus human-modified or artificial freshwater systems. While the data for the two sub-indices, species’ geographical distribution and Red List threat statuses, are available across the continent, this is not the case for the habitat sensitivity sub-index at this large spatial scale. This meant that an alternative sub-index measure was required. We overcame this challenge by exploring an alternative sub-index, i.e. the ‘species vulnerability sub-index’, based on knowledge of the vulnerabilities of the species to certain types of landscape transformation. Then, the species vulnerability sub-index scores were calculated and combined with the geographical distribution and Red List threat status sub-index scores to develop ADBI scores for a core of 604 dragonfly species with adequate data across the African continent. These ADBI scores provide a workable framework and baseline for determining freshwater quality, both lotic and lentic, relative to human disturbance at a continental spatial scale. The ADBI enables the monitoring of quality changes, for better or worse, over the continent in years to come. Overall, the ADBI also has the potential to help identify threats to, and sensitivities of, African freshwater ecosystems, leading to conservation action.

This study investigates whether cities have the potential of hosting high species diversity of dragonflies (Odonata), a target group in freshwater conservation. We reviewed the dragonfly fauna of 30 cities in Central Europe and analysed their species richness compared to the regional species pools in the hinterlands, i.e. estimated the amount of regional diversity represented in cities. In particular, we examined the occurrence of species of conservation concern at the European scale. Results revealed that 92.6% of all 81 Central European dragonfly species occurred in cities, as well as 85.7% of 14 species of conservation concern. As expected, assemblages of city species were subsets of the regional species pool and city species richness increased with regional species numbers. Some cities hosted the complete regional species pool. Ten species of conservation concern established autochthonous populations and six of them, such as Aeshna viridis and Ophiogomphus cecilia, were abundant at least in single cities. We conclude that there is good potential for cities to host high dragonfly diversity and even to promote species of conservation concern. To exploit this potential we recommend city planners to focus on the needs of regionally characteristic species.

Summary 1. Increasing temperature and invading species may interact in their effects on communities. In this study, we investigated how rising temperatures alter larval interactions between a naturally range-expanding dragonfly, Crocothemis erythraea, and a native northern European species, Leucorrhinia dubia. Initial studies revealed that C. erythraea grow up to 3.5 times faster than L. dubia at temperatures above 16 °C. As a result, we hypothesised that divergent temperature responses would lead to rapid size differences between coexisting larvae and, consequently, to asymmetric intraguild predation at higher ambient temperatures. 2. Mortality and growth rates were measured in interaction treatments (with both species present) and non-interaction controls (one species present) at four different temperature regimes: at an ambient temperature representative of central Germany, where both species overlap in distribution, and at temperatures increased by 2, 4 and 6 °C. 3. The mortality of C. erythraea did not differ between treatment and control. In contrast, mortality of L. dubia remained similar over all temperatures in the controls, but increased with temperature in the presence of the other species and was significantly higher there than in the controls. We concluded that L. dubia suffered asymmetric intraguild predation, particularly at increased temperature. Reduced growth rate of L. dubia in the interaction treatment at higher temperatures also suggested asymmetric competition for prey in the first phase of the experiment. 4. The results imply that the range expansion of C. erythraea may cause reduction in population size of syntopic L. dubia when temperature rises by more than 2 °C. The consequences for future range patterns, as well as other factors that may influence the interaction in nature, are discussed.

International audience; Indicators on the state of global biodiversity illustrate continued decline, while pressure on biodiversity keeps rising. This necessitates revisiting site prioritization and species protection for conservation. Patterns of richness and threat of four well-studied aquatic taxa, the fishes, crabs, molluscs and dragonflies largely coincide at the continental scale, at least in Africa. For this study, we focus on dragonflies, for which there is a point locality database, as a surrogate taxon, modeling the species at the fine-scale, using species distribution modeling. With this approach, we built a protected areas network using spatial planning software. Priority areas for dragonfly conservation largely coincided with analyses of global biodiversity hotspots. The Zambian swamps and woodlands, as well as the rainforests of the Lower Guinea and Congo Basin are emphasized as hotspots of dragonfly diversity. Among globally threatened species, 72% were recorded at least once in a protected area. Although the current reserve network covers 10.7% of the landscape, the proportional representation of species geographic distributions in reserves is only 1.2%. The reserve network is therefore inefficient concerning freshwater species, and many areas of conservation priority that are not formally protected remain. The advantage of operating at the fine scale, while covering a large geographic area is that it shifts the focus from the large-scale hotspots to smaller priority areas within and beyond hotspots. Also, by operating at the fine-scale for a large geographical area, the potential exists for local conservation managers to consider campaigning for the inclusion of the priority areas that are not formally protected, while adjacent to the existing reserve networks. Where this is not possible, we recommend monitoring these areas to detect future threats to the habitats that these might face.

In this paper, we present an approach for describing the environmentally induced temporal pattern of structured populations by partial integro-differential equations. Populations are structured according to size or stage. Growth, energy allocation and stage transitions are affected by environmental conditions of which temperature, photoperiod, water depth and food supply were taken into account. The resulting modelling framework was applied to describe, analyse and predict alterations in populations with continuous development, populations with distinct state structures and interacting populations. Our exemplary applications consider populations of freshwater Amphipoda, Isopoda and Odonata. The model was capable of simulating life cycle alterations in dependence on temperature in interaction with other environmental factors: (1) population dynamics, (2) seasonal regulation, (3) water depth-dependent dispersal, (4) intraguild predation and (5) consumer-resource dynamics.

Agriocnemis bumhilli sp. n., a new damselfly from the Kwando River in northeastern Namibia is described. The new species is similar to Agriocnemis angolensis but characterized by unique male appendages, swollen abdominal segments 9 and 10, the complete absence of antehumeral stripes, and smaller size. The species is illustrated and a photograph is provided. For comparison, an illustrated key to the other members of Agriocnemis within south-central Africa is provided.

3 This is the first continent-wide overview of insect diversity and status sufficiently fine-scaled to be used in con- servation planning. We analyze patterns of richness and the conservation status of African dragonflies and dam- selflies (Insecta: Odonata), commonly referred to as dragonflies, to determine threats to species and freshwater habitats, location of diversity hotspots, necessary conservation actions, and research gaps. Major centers of drag- onfly diversity in Africa are tropical forest areas that include highlands. Most threatened species - as classified by the International Union for Conservation of Nature global Red List - are concentrated in highlands from Kenya to South Africa (together with the Cape Floristic Region), western Africa (including mountains on the Cameroon-Nigeria border), and Ethiopia. Currently available knowledge can be applied throughout Africa's freshwater systems to help minimize or mitigate the impact of future development actions, allowing dragonflies to act as "guardians of the watershed". The private sector can be advised to safeguard sensitive habitats and species when selecting sites for development. Key sites and species for monitoring can be identified by checking the distribution of threatened species at www.iucnredlist.org.

1. Rising environmental temperature will likely affect life cycle and range of species. To forecast such effects in an odonate, we simulated the continent-wide life cycle distribution pattern and range of a dragonfly applying a dynamic population model. 2. The model was used to investigate how much of the current voltinism patterns and distribution range of the species are correctly predicted by using temperature and day length as the only environmental factors. We forecasted the range and voltinism changes on a European extent for the year 2050 using one GCM (CSIRO) driven by one greenhouse gas emission scenario (b2a) according to the IPCC. 3. The model run lead to 80% correctly predicted distribution range, with a sensitivity of 94% and a specificity of 55%, the latter because of high error in predicting absence in southern Europe. 4. The projected voltinism ranged from 1 to 2 years per generation in southern latitudes to 5 years in the north. A comparison with field data indicated correct predictions in 50% of all cases, while the other 50% were slight over- or underestimates by half a year per generation. 5. We conclude that the model led to sufficient predictions of range as well as of life cycle pattern in central and northern Europe. Wrong predictions of presence for southern Europe may be caused by factors not recognised in the model, likely competition by con generics, while incorrect voltinism was possibly because of habitat effects. 6. Simulations with increased temperature scenarios implied a future northward shift of the fundamental niche and a decreased development duration towards the northern range.

A new species of Crenigomphus is described and illustrated from a type series of eight males and eight females, all collected along the Okavango River in Namibia during December 2004, three non-type adult specimens and several exuviae (holotype ♂ Namibia, N'Kwazi Lodge, 19 xii 2004, deposited at NMNW). Both sexes lack foliations at S8-9 as occur in some Crenigomphus, but the male is peculiar in having exceptionally long cerci. The latter character is normally present in the genus Paragomphus. Other characters typical of Crenigomphus include all wings having a bright yellow costal border, S10 longer than S9 in males, colouration mostly ochreous with few darker markings, and the strong blackish serration at the posterior end of the cerci. The larval characters based on exuviae, one associated with an emerged male, do not allow clear separation from Paragomphus.

1. Freshwater communities are often structured by predation. In permanent lentic freshwater habitats dragonfly larvae are major predators which, in return, suffer predation by fish. Antipredator traits vary between the dragonfly species, and the dragonfly communities are therefore shaped by the presence of fish. But fish communities vary, and as different fish species affect dragonflies in different ways, the species composition of the fish community may affect the composition of the dragonfly community. 2. We sampled dragonfly larvae in 24 lakes with a known fish stock in south-western Sweden, and explored the impact of fish as well as vegetation structure on dragonfly communities by means of multivariate analyses. 3. We found that the presence of four fish species affected the community structure of dragonflies. The impact strength depended mainly on the abundance of Perca fluviatilis, with which most dragonfly species were negatively correlated. Many dragonfly species were also positively correlated with the occurrence of at least one fish species, which may reflect similar habitat requirements or imply indirect positive effects of these fish species. 4. Of the 24 recorded dragonfly species, four did not occur in lakes dominated by P. fluviatilis, whereas only one species was lacking in lakes dominated by Rutilus rutilus. The dragonfly species diversity was higher in R. rutilus lakes than in P. fluviatilis lakes. 5. Our results suggest that the fish species composition is a major determinant of the dragonfly community, which in turn will influence the lower trophic levels.

1. For modelling the future ecological responses to climate change, data on individual species and on variation within and between populations from different latitudes are required. 2. We examined ...

1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well-studied example is the development of longer abdominal spin ...

With a total of 75 species the odonate diversity in the Namibian desert is surprisingly high. Based on their distribution characteristics, invasion patterns, and breeding success, there are six well-defined categories of Odonata: widespread species - (1) permanently living in the desert, and desert biased, (2) permanently living in the desert, but not desert-biased; (3) entering the desert seasonally; (4) entering from neighbouring tropical or temperate regions, whose populations may breed in the desert sometimes or locally. Category (5) consists of species with highly localised breeding populations in the desert, which are widely isolated from potential source populations. The last category (6) consists of species restricted to allochthonous perennial rivers. We discuss these patterns from a geographical and a temporal perspective. On the one hand, there have been different spatial directions from where species have entered deserts. On the other hand, Odonate distribution patterns in the deserts...

The status and trends of global biodiversity are often measured with a bias towards datasets limited to terrestrial vertebrates. The first global assessment of an insect order (Odonata) provides new context to the ongoing discussion of current biodiversity loss. A randomly selected sample of 1500 (26.4%) of the 5680 described dragonflies and damselflies was assessed using IUCN’s Red List criteria. Distribution maps for each species were created and species were assigned to habitat types. These data were analysed in respect to threat level for regions and habitat types. We have found that one in 10 species of dragonflies and damselflies is threatened with extinction. This threat level is among the lowest of groups that have been assessed to date, suggesting that previous estimates of extinction risk for insects might be misleading. However, Odonata only comprise a small invertebrate order, with above-average dispersal ability and relatively wide distribution ranges. For conservation science and policy to be truly representative of global biodiversity a representative cross-section of invertebrates needs to be included. Fil: Clausnitzer, Viola. Philipps-University of Marburg; Alemania Fil: Kalkman, Vincent J.. National Museum of Natural History; Países Bajos Fil: Ram, Mala. Zoological Society of London. Institute of Zoology; Reino Unido Fil: Collen, Ben. The Zoological Society Of London; Reino Unido Fil: Baillie, Jonathan E.M.. The Zoological Society Of London; Reino Unido Fil: Bedjanič, Matjaž. No especifica; Fil: Darwall, William R.T.. Unión Internacional para la Conservación de la Naturaleza; Reino Unido Fil: Dijkstra, Klaas-Douwe B.. National Museum of Natural History; Países Bajos Fil: Dow, Rory. No especifica; Fil: Hawking, John. Latrobe University; Australia Fil: Karube, Haruki. Kanagawa Prefectural Museum of Natural ; Japón Fil: Malikova, Elena. Blagoveshchensk State Pedagogical University; Rusia Fil: Paulson, Dennis. University of Puget Sound; Estados Unidos Fil: Schütte, Kai. Universitat Hamburg; Alemania Fil: Suhling, Frank. Universität Braunschweig; Alemania Fil: Villanueva, Reagan J.. Ateneo de Davao University,; Filipinas Fil: Von Ellenrieder, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Wilson, Keith. No especifica

It has been shown that life history, behavioural as well as morphological traits vary with the habitats occupied by odonate larvae. Here we ask the following questions: (1) Are the morphological tr ...

Summary 1. Precise models for the phenology of different species are essential for predicting the potential effects of any temporal mismatch of life cycles with environmental parameters under different climate change scenarios. Here we investigated the effects of ambient water temperature on the onset and synchrony of emergence for a widespread European riverine dragonfly, Gomphus vulgatissimus. 2. Long-term field data on the annual emergence from two rivers in northern Germany, and additional data from a laboratory experiment with different temperature regimes, were used to develop a model that predicted the onset of emergence by using mainly the temperature sum (degree days) as a parameter. 3. Model predictions of the onset of emergence fitted the observations well and could be transferred between localities. This was particularly so when weighting early winter temperature data by using a day length and a temperature-response function, implying potential additional control mechanisms for the onset of emergence. 4. We simulated effects of different winter temperature regimes on the emergence curves in order to predict the effects of climate change. These indicated an acceleration of emergence by 6–7 days per 1 °C temperature increase, which is corroborated by the laboratory data and is in the upper range of data published for other dragonflies.

Potential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonfly Gomphus vulgatissimus (L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium-sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology of G. vulgatissimus, leading to an extension of the flight season in certain regions along the gradient.

We classified 542 records of voltinism for 275 species and subspecies of Odonata according to three variables: geographical latitude, systematic position and habitat type. We sorted records according to voltinism—categories being three or more generations per year, two generations per year, one generation per year, one generation in two years and one generation in three or more years. We sought to correlate the voltinism of each record with latitude of the study site, thus demonstrating an overall negative correlation between voltinism and latitude. After allowing for phylogenetic similarity a negative correlation remains, although it decreases in strength after removal of taxonomic correlates, mainly between family and genus levels. A negative correlation exists at the species level within most families, with the exception of Lestidae. In genera for which we lacked data for latitudes 0-31°N/S no significant correlation between latitude and voltinism exists. In temporary waters most species compl...

Dragonflies have been proposed as indicators for the ecosystem health of freshwater wetlands. For their useful functioning as indicators it is, however, necessary to identify species compositions in specific habitats and species-habitat associations, particularly in the tropics, where such knowledge is still weak. We examined the dragonfly species composition of 133 localities in the arid environment of western Namibia. An analysis of nestedness indicated that distinct, and predictable patterns of species associations can be expected. Discriminant analyses revealed that most of the nine habitat types separated by structural and hydrological parameters are well discriminated by their dragonfly assemblages. Spring brooks in particular host a specific assemblage, which is threatened due to the habitat restriction of several species, as well as by recent habitat loss and degradation. Using a hierarchical method of several criteria we demonstrated the selection of a set of potential indicator species from the species set, most of these being useful indicators for spring brook assemblages. The conservation status of certain habitats and species is discussed. We propose that dragonflies will have a high indicator potential for threatened freshwater wetlands in such areas and may also serve as an indication of the sustainable use of water resources including evaluating measures to rehabilitate environments.

SUMMARY 1. Behavioural differences among prey species may result from evolutionary adaptations that facilitate coexistence with different predators and influence vulnerability to predators. It has been hypothesised that prey species modify their behaviour in relation to the risk posed by particular predators. 2. We examined the relationship between anti-predator behaviour and predation risk in five species of larval odonates in combination with three predatory fish species (perch, gudgeon and rudd) that differ in foraging behaviour. The odonates, Platycnemis pennipes, Coenagrion puella, Lestes sponsa, Sympetrum striolatum and Libellula depressa, differ with regard to their life cycle and habitat, including water depth, occurrence in temporary ponds and co-existence with fish. 3. The odonate species differed in their response to fish: (i) Two species showed a flexible response. Larval C. puella reduced activity in the presence of fish, regardless of species, whereas L. depressa altered their activity only in the presence of gudgeon. (ii) Independent of fish species, all odonates except L. depressa exhibited spatial avoidance of fish. This was interpreted as a more general anti-predator response. (iii) In some cases the odonates showed no response to predators and their behaviour was thus independent of predation risk. 4. Our results confirm that all odonates responded to the presence of at least some predatory fish, and that some odonate species discriminated between fish species. However, we found no significant correlation between behavioural modifications and predation risk, indicating that anti-predator responses and predation risk depend on the particular predator and the species being preyed on.

and aggressive animals, which are among the most charismatic African dragonflies (e.g. Clausnitzer 2001, Silsby 2001). The genus traditionally includes one Madagascar species (O. lachesis Ris, 1912) and three species confined to continental tropical Africa: O. fraseri Pinhey, 1956, O. fuelleborni Grunberg, 1902 (with subspecies occidentis Ris, 1912) and O. lugubris Karsch, 1895. Zygonoides Fraser, 1957 was originally introduced as a genus for all species of Olpogastra except O. lugubris, but it was subsequently made a subgenus of Olpogastra by Pinhey (1961). The revision of Zygonoides was made necessary by the discovery of O. fraseri – previously known only from the Ugandan type series – in western Africa, which made the status of O. fuelleborni occidentis unclear, and by discovery of larvae of all four mainland taxa. In this paper we (1) reassess the status of Zygonoides, (2) revise and diagnose its species, (3) describe larval characters of all continental Zygonoides taxa, and (4) compare it with related genera.

Descriptions and illustrations of the final stadium larvae of Gomphidia bredoi, G. gamblesi and G. quarrei are presented, based on exuviae collected in Ivory Coast, Cameroon, Kenya and Namibia. The three species can be separated by the presence/ absence and shape of an abdominal dorsal spine on segment 9, by the numbers of abdominal lateral spines and by several characteristic processes on the head.

Information on larval biology of Macromia splendens was compiled and supplemented by hitherto unpublished data. Larvae inhabit mainly calm river stretches, sometimes artificial impoundments, and lentic margins of lotic sections. From the majority of records it is concluded that the larvae mainly dwell in sandy substrates in shallow water, which sometimes contains little leaf litter. Larvae occur in smaller numbers on substrates dominated by coarse detritus or on bedrock in deeper water. Larvae of M. splendens are able to burrow in sand, but such burrowing takes a long time, and sometimes parts of their body remain uncovered. Therefore, they are considered shallow burrowers. Based on head-width frequency distributions recorded at the Gardon de Mialet, southern France, the species is believed to require two years per generation.

Identifying and examining traits that influence the distribution of species is crucial to the understanding of community structure. Theory predicts that traits should differ between species that live in temporary and permanent waters because of differing major environmental variables; viz drying out and predator presence, respectively. Species, however, will also be influenced by their evolutionary history, i.e. by the traits of their common ancestors. We studied differences in life history and behaviour traits in a series of laboratory experiments using pairs of dragonfly species out of three genera of Namibian Libellulidae (Odonata) with one species from each type of habitat. As predicted, growth rates were significantly higher in the temporary water species compared to the permanent water species. Activity and foraging, in contrast, differed between the genera, but did not differ between the habitat types. Hence, our study implies that the behavioural traits are influenced by phylogenetic inertia rather than by the habitat variables, while growth rate is adapted to the habitat. We argue that in all three genera one species has diverged recently from a sister species that lives in the original habitat of the genus, which may be temporary waters in Crocothemis Brauer and in Orthetrum Newman, and permanent waters in Trithemis Brauer. The behavioural traits may therefore be less well adapted. Rapid growth may be the more relevant trait because it is crucial to survival in temporary waters.

We studied how egg size, larval size and egg development time are related to oviposition site selection and mate guarding in a dragonfly assemblage of the Namib desert. Species that oviposited mainly in tandem flight (Pantala flavescens and Sympetrum fonscolombii) spread their eggs over several ponds, which we interpreted as spatial risk spreading. Other species (Orthetrum chrysostigma, Trithemis kirbyi, T. annulata and Crocothemis erythraea) performed noncontact guarding and localized their eggs, usually in a single pond, which we interpreted as distinct habitat selection. Because long oviposition durations increase the risk of disruption by rival males, we predicted that in species that localize their eggs to a distinct oviposition habitat the first-laid eggs of a clutch should be the largest, indicating high quality. Species that perform risk spreading should distribute large eggs randomly over all oviposition sites. We tested our hypothesis at artificial ponds using experimental manipulations of oviposition. In O. chrysostigma and T. kirbyi, egg size and larval size decreased significantly with order of laying, and the time to hatch was randomly distributed. As predicted, within the clutches of P. flavescens and S. fonscolombii, egg size was randomly distributed over a clutch and we found no trend of decrease in larval size or increase in the time to hatch in relation to order of laying.

The status of the odonate fauna of Europe is fairly well known, but the current IUCN Red List presents only six species out of ca 130, two of which are actually out of danger today. In this paper we propose a tentative list of 22 possibly declining or threatened species in the region. For the majority, reliable data of population size and possible decline is still lacking. Also 17 endemic species are listed, most occurring in the two centres of endemism in the area: the south-eastern (mountains and islands) and the western Mediterranean. These species should receive extra attention in future updates of the world Red List due to their limited distribution. The extreme variation in biomes and the human exploitation of habitats make conservation planning complicated in Europe. Within the EU, the FFH directive is a working tool aiding conservation. However, the species included do not fully correspond to those on the current Red List, nor to those discussed in this paper. We believe that future conse...

In this report we review the conservation status of Odonata of southwestern Africa, viz Angola, Botswana, Namibia, Zambia and Zimbabwe. In total, 287 species have been recorded of which three have been previously listed by IUCN. We consider 60 species mainly because of their endemism in the region. The majority of the species have to be categorised as ‘data deficient’ according to IUCN regulations. The most important freshwater habitats in the region are the extensive swamps in the Kalahari basin, such as the Okavango Delta, the Caprivi swamps and the swamps along the courses of the middle Zambezi system, which host a unique odonate community. The most important threats for species in the region include overuse of water, construction of dams in the large rivers and deforestation. We strongly recommend extensive research on the Angolan and Zambian odonate faunas, which appear to be the richest in the regions, although they are poorly investigated.

1. Freshwaters form a gradient from small temporary waters to large permanent waters. Identifying and examining traits that restrict the distribution of species along this gradient are crucial to the understanding of community structure in these habitats. 2. Using dragonfly larvae species, differences in traits important for growth and survival were studied. 3. The traits were studied in a series of laboratory experiments using two pairs of dragonfly species that coexist in the Namibian semi-desert. One species pair was from the most temporary part of the water permanence gradient and the other species pair from an intermediate part of the gradient. 4. As predicted, activity, capture rate, and growth rate were significantly greater in the two temporary water species. Contrary to the prediction made in the work reported here, species differences in microhabitat selection were not related to the species' habitat origin. Cannibalism did not differ between species. 5. The results lend support to the hypothesis that selection has favoured certain combinations of trait values and that these traits are important for a successful life in temporary and permanent waters.

In this article we report underwater oviposition and epilithic oviposition in Anisoptera. We observed Notoaeschna sagittata totally submerged ovipositing on bare rock in the fast current of a rapid. Dendroaeschna conspersa oviposited also underwater, but into wood submerged in very clear water.

A written description and illustrations of the final stadium larva of Nesciothemis farinosa are presented, based on larvae and exuviae collected in Namibia. The larvae were reared in the laboratory until emergence. Additionally, information on larval microhabitat, behaviour and development is provided.