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Abstract
This chapter introduces the insect order Odonata. It provides the most recent phylogeny and up-to-date systematics as well as genera and species numbers of the various families in the biogeographic regions. We also present an overview about the general biology, ecology and behavior of Odonata. This includes details on morphology and ultrastructures. We also attempt an updated categorization of odonate life cycle types. The subchapters on ecology and behavior focus on various aspects of habitat selection and microhabitat occupancy, including effects of biotic interactions and antipredation behavior. Finally, we summarize collection and sampling methods for adult and larval Odonata.
... These semivoltine taxa reside in cold to cool environments (see Table 1) where larvae may reach the final (F-0) instar stage by the end of summer but do not emerge as adults until the following year (Suhling, Sahlén, et al., 2015). For these taxa, larval diapause provides a mechanism to ensure overwinter survival, followed by spring metamorphosis and emergence. ...
... The strongest negative associations between PHOTO and DOY were exhibited by genera with semivoltine life cycles and cool to cold thermal preferences (Calopteryx sp., Hetaerina sp.), while positive associations were exhibited by univoltine genera with warm to hot preferences (Argia sp., Sympetrum sp., Plathemis sp.; see Table 1; Figure 4). This functional distinction is intuitive because photoperiod is a key predictor of diapause and as mentioned above, diapause is common to many odonate life cycles (Suhling, Sahlén, et al., 2015). For odonates with Type 1 life cycles, longer days (increasing photoperiod) may allow larvae to reach a mid to late instar stage prior to winter diapause, with rapid development and emergence the following spring (Corbett, 2003). ...
... We propose that aquatic habitat stability may provide a useful lens for understanding phenological responses to precipitation. Because odonates at temperate latitudes are rarely multivoltine (Suhling, Sahlén, et al., 2015), they will be vulnerable to any hydrologic disturbance that disrupts egg or larval development. Relevant disturbances would include intermittent drying in low precipitation regions or flooding in high precipitation regions. ...
Global change may cause widespread phenological shifts. But knowledge of the extent and generality of these shifts is limited by the availability of phenological records with sufficiently large spatiotemporal extents. Using North American odonates (damselflies and dragonflies) as a model system, we show how a combination of natural history museum and community science collections, beginning in 1901 and extending through 2020, can be leveraged to better understand phenology. We begin with an analysis of odonate functional traits. Principal coordinate analysis is used to place odonate genera within a three‐dimensional trait ordination. From this, we identify seven distinct functional groups and select a single odonate genus to represent each group. Next, we pair the odonate records with a list of environmental covariates, including air temperature and degree days, photoperiod, precipitation, latitude, and elevation. An iterative subsampling process is then used to mitigate spatiotemporal sampling bias within the odonate dataset. Finally, we use path analysis to quantify the direct effects of degree days, photoperiod, and precipitation on odonate emergence timing, while accounting for indirect effects of latitude, elevation, and year. Path models showed that degree days, photoperiod, and precipitation each have a significant influence on odonate emergence timing, but degree days have the largest overall effect. Notably, the effect that each covariate has on emergence timing varied among functional groups, with positive relationships observed for some group representatives and negative relationships observed for others. For instance, Calopteryx sp. emerged earlier as degree days increased, while Sympetrum sp. emerged later. Previous studies have linked odonate emergence timing to temperature, photoperiod, or precipitation. By using natural history museum and community science data to simultaneously examine all three influences, we show that systems‐level understanding of odonate phenology may now be possible.
... Worldwide there exist about 6000 species (Stork 2018: 5899; another 1000 to 1500 species are expected to exist per Pessaq et al. 2018) of Odonata which comprise the three suborders Zygoptera (damselflies), Anisoptera (dragonflies), and Anisozygoptera (damsel dragons) (Suhling et al. 2015;Morse 2017;St. Quentin and Beier 1968). ...
... In addition predators of Odonata larvae, their prey, and their various defense mechanisms against opponents are well known in spite of the fact that there was not realized any chemical defense mechanism in larvae or adults of this insect order (Corbet 1999;Suhling et al. 2015). The risk of fish predation is reduced by various behavioral and morphological features of the odonate larvae. ...
... As was shown by Crespo (2011), larvae of Odonata can sense infochemicals from various predators and even learn to associate them with predator presence. Invertebrate predators include other Odonata larvae including conspecifics (cannibalism), dytiscid beetles (larvae and adults), crayfish, belostomatid bugs, and several water birds (see Suhling et al. 2015). Other larvae exhibit nocturnal circadian rhythms in order to reduce predation pressure (Pierce 1988). ...
This chapter compiles active and passive defensive mechanisms of aquatic and semiaquatic developmental stages of all insect orders against various predators. Mainly escape reactions, mechanical defense, defensive stridulation, and especially chemical defenses are described, illustrated, and tabulated. Apart from the large aquatic groups of ephemeropteran, Odonata or Trichoptera larvae especially aquatic bugs and water beetles are considered by even including small groups from Collembola up to Mecoptera. Differences between defensive mechanisms and strategies in aquatic and terrestrial insects are described. Aquatic insects especially rely on escape, mechanical defenses, defensive stridulation, and chemical defenses. Exocrine glands are mainly restricted to large taxa with both terrestrial and aquatic representatives (adephagan beetles, Heteroptera) and not invented in aquatic groups. Chemically aquatic insects especially evolved biosynthesis of aromatic and few aliphatic compounds against microorganisms. In contrast mainly steroids are targeted against cold-blooded vertebrates such as fishes and amphibians. As compared with terrestrial insects, aquatic representatives lack many mechanisms of defense such as reflex bleeding, incorporation of toxic compounds from plants, freshwater animals, or microorganisms. Exocrine secretions of water insects are usually externalized by secretion grooming in order to receive a clean body surface, to achieve an optimal breathing, and to modify the wettability of the body surface. Generally there exists a considerable lack of knowledge concerning bionomy and especially defenses of aquatic insects.
... However, in some cases, their identification may be complicated (e.g. females of Coenagrionidae), and their presence close to water is only temporary as they disperse to terrestrial surroundings until sexually mature (Wildermuth, 2010;Suhling et al., 2015). Nevertheless, based on our data, we may conclude that the primary question is not what to sample but the purpose of that sampling. ...
... Although odonate exuviae and juveniles are evidence for species indigeneity, drawing conclusions based on their sampling may lead to considerable bias. In most cases, the mature adult life span exceeds the emergence period as well as the length of the juvenile period (Suhling et al., 2015). Therefore, in a long-term study with visits realised only several times per season, the probability of species' detection would be highest when focusing on adults. ...
• Most ecological studies involving insects are based on medium‐ and short‐term observations; however, the extent to which such data captures reality remains unclear.
• We investigated the long‐term dynamics of two Odonata communities (disturbed and undisturbed sites) over 18 years and analysed the differences in the short‐ and long‐term results. We also focused on the sampling methodology to enhance the efficacy and objectivity of long‐term monitoring involving Odonata.
• During one year, we captured only 53% of the overall species richness; during three consecutive sampling years, it was 65%. To capture 95%, we needed 16 years. Changes in quantitative similarity (Renkonen index, P) were more pronounced within sites over time than between sites. Species constancy significantly increased with the maximum abundance class but decreased with increasing fluctuation ratio and specialisation (Dragonfly Biotic Index). Based on exuviae, we detected half of the species compared to adults, but the species accumulation curves peaked after a few sampling years.
• Long‐ and short‐term monitoring yield different results, both qualitatively (species richness, specialisation) and quantitatively (abundance, dominance). Ideal sampling should be sequential, lasting at least 10 years (capturing >80% of species). Intermittent sampling (one‐year interspersed with pauses), allowing the inclusion of multiple sites in monitoring programme, may also provide satisfactory results when performed over a longer period.
• Over the long term, sampling adults semi‐quantitatively and exuviae qualitatively provided sufficient information, while being feasible in terms of both personnel and costs, thereby overcoming the main pitfalls of long‐term monitoring programmes.
... Odonates occur in streams in their immature stages, and they are important representatives of the trophic structure in these ecosystems due to their predatory feeding mode (Corbet, 2004). Immature stages of odonates have a diverse range of life habits and ecological requirements, thus the assemblage structure of immature odonates is influenced by several habitat characteristics, such as water current, water abiotic conditions and microhabitat type (Hofmann & Mason, 2005;Suhling et al., 2015). The sensitiveness of the immature stages of Odonata foi testada através de diagramas de ordenação e análise de redundância. ...
... The differential occupation of stream habitats by odonates is generally associated with their relationships with the aquatic vegetation and water flow regime (Corbet, 2004). The immature stages of odonate species that usually prefer either stronger or depositional areas in streams show large differences in the morphology and life habits associated with the adaptation to water current variation (Corbet, 2004;Suhling et al., 2015). In this study, Argia, Heteragrion and Calopterygidae showed preference by riffles. ...
Aim
Describe the diversity of immature stages of Odonata (Insecta) in streams from a subtropical island in southern Brazil and investigate the influence of environmental variables on the composition of their assemblages.
Methods
Eleven low-order streams (1st to 3rd order) were sampled in two conservation units located in the island of Santa Catarina (southern Brazil) between 2010 and 2012. Immature specimens of Odonata were collected using a Surber sampler. The influence of water abiotic parameters and habitat structure (mesohabitats: riffle vs. pool areas, microhabitats: litter vs. stone substrates) on the composition of Odonata was tested through the seasons using ordination diagrams and redundancy analysis.
Results
Nine odonate genera from seven families were recorded in the study region. The genera Desmogomphus, Epigomphus (Gomphidae), Heteragrion (Heteragrionidae) and Perilestes (Perilestidae) have their first records described for the state of Santa Catarina. Additionally, biological notes are provided for other odonate genera concerning substrate use. The composition of Odonata communities changed over the seasons and they were influenced by water temperature and velocity. Additionally, odonate composition differed significantly between microhabitats (substrate type) and mesohabitats (riffle vs. pool areas) in the streams studied.
Conclusions
The lower genera richness of Odonata recorded in the island of Santa Catarina in relation to other Brazilian subtropical streams is probably associated with the insular condition of the study region. This study also demonstrated that substrate (organic and inorganic) and mesohabitat (riffle and pool) types were important drivers of the composition of the fauna of immature odonates, evidencing the role of climate and habitat structure in influencing subtropical stream insect communities.
... The order Odonata is regarded as a monophyletic group; it comprises three suborders: Zygoptera or damselflies, Anisoptera or true dragonflies and a small suborder Anisozygoptera with four species (Suhling et al. 2015). Odonata has a tropical origin (Corbet 1999), and today the highest diversity is found near the equatorial areas (Paulson 2006 and a larger pterothorax where the wings are inserted. ...
... Water extraction is a primary threat to desert springs, but invasions by non-native species also pose serious threats . These threats are the main factors of the decline of odonate populations (Suhling et al. 2015) and therefore the main threats to the species that occur in the CCB. ...
In this chapter we review some of the main characteristics of the Cuatro Ciénegas Basin, touching upon the physical setting, its geologic history, and animal diversity. We go through all the chapters of the volume summarizing the different interpretations of the authors regarding the origin and structuring of the particular communities. We present a list of animal taxa that have been recorded from the area, noting the number of species and supraspecific taxa that are endemic to the CCB: a total of 885 species are reported for the CCB in this volume, of which 38 (4.3%) are endemic. A brief discussion on the future challenges that the CCB faces is presented.
... The order Odonata is regarded as a monophyletic group; it comprises three suborders: Zygoptera or damselflies, Anisoptera or true dragonflies and a small suborder Anisozygoptera with four species (Suhling et al. 2015). Odonata has a tropical origin (Corbet 1999), and today the highest diversity is found near the equatorial areas (Paulson 2006). ...
... Water extraction is a primary threat to desert springs, but invasions by non-native species also pose serious threats (Hendrickson et al. 2008). These threats are the main factors of the decline of odonate populations (Suhling et al. 2015) and therefore the main threats to the species that occur in the CCB. ...
A summary of the present knowledge on the diversity of Odonata occurring in the Cuatro Ciénegas Basin (CCB) is presented. The work is based on published records, and the results from samplings are carried out between the years 2009 and 2013 in 23 sites. A list of the 67 Odonata species from the CCB is provided including 19 new state records. Finally, the biogeographic affinities, conservation status, and major threats are discussed.
... The order Odonata is regarded as a monophyletic group; it comprises three suborders: Zygoptera or damselflies, Anisoptera or true dragonflies and a small suborder Anisozygoptera with four species (Suhling et al. 2015). Odonata has a tropical origin (Corbet 1999), and today the highest diversity is found near the equatorial areas (Paulson 2006 and a larger pterothorax where the wings are inserted. ...
... Water extraction is a primary threat to desert springs, but invasions by non-native species also pose serious threats . These threats are the main factors of the decline of odonate populations (Suhling et al. 2015) and therefore the main threats to the species that occur in the CCB. ...
Soil is one of the less studied resources of terrestrial ecosystems, both in terms of its biodiversity and internal processes. In particular, microarthropods of desert ecosystems have been poorly studied worldwide, and probably less than 10% of the total soil species have been described. Nevertheless, microarthropods are responsible for one of the most important environmental functions: the decomposition of organic matter. In this chapter, we present the results of the first survey of soil microarthropod communities from the CCB. The study was conducted in 2015–2016 to identify the microarthropods’ diversity in its components of richness and abundance. We collected 6721 organisms of 6 classes, 26 orders, and 60 families. Acari was the most abundant and diverse group and is dominated by Prostigmata (20 families) and Oribatida (16 families). Hexapoda is represented by Collembola, Coleoptera, Hemiptera, Hymenoptera, and Psocoptera. Differences in mite assemblages are attributable to the type of vegetation in the different sites of the CCB. The site’s taxonomic diversity is associated with habitat heterogeneity. The high productivity micro-habitats could produce high levels of biomass and not necessarily more diverse communities. We observed broad similarities in microarthropod composition at familial level among arid-semiarid ecosystems elsewhere in the world. Knowledge of soil microarthropod community will be helpful to understand the network of interactions and the flow of nutrients and energy within this desert ecosystem; all these are crucial elements to assess the health of the soil and to establish appropriate strategies for it use, management, and conservation.
... Therefore, the simple ratio of Zygoptera/Anisoptera may be too robust to detect more subtle differences within individual taxa. Specifically, the two largest families Coenagrionidae (Zygoptera) and Libellulidae (Anisoptera) include species with the greatest migratory capacity which dominate in open, unshaded habitats Suhling et al., 2015), suggesting their affinity with highly disturbed sites. ...
... Although the proportion of forest specialists may correlate with the proportion of Zygoptera (Dolný et al., 2012), the largest cosmopolitan family of Zygoptera, Coenagrionidae, is known to contain most of the most widespread or ubiquitous odonate species. The same applies to Libellulidae Suhling et al., 2015). Considering that these two groups comprised a large portion of our dataset (41% and 79%, respectively), it is clear that the family-level approach is more accurate and thus, may serve a fast assessment of forest degradation level better. ...
Odonata have proven to be good indicators of freshwater as well as terrestrial habitat conditions. Several studies have shown changes in odonate species richness and/or community composition in response to deforestation, suggesting their potential as bioassessment tools in the tropics. However, former approaches using Odonata as an indicator group required comparative samples from differently disturbed sites and/or knowledge of the focal species environmental specificity. Here, we tested a robust, adult-based bioassessment method assuming that the level of tropical forest degradation reflects the proportional representation of the taxa above species. Based on Web of Science, ScienceDirect, and Scopus databases, we used data from previously published studies linking odonate assemblages to human-mediated disturbances in tropical forests. We hypothesized that along a disturbance gradient (from primary forest to non-forest), (i)the proportion of the suborder Zygoptera (mostly habitat specialists sensitive to deforestation)will decrease in favor of the suborder Anisoptera (high proportion of generalists); and (ii)the proportions of largely generalist families Coenagrionidae and Libellulidae will increase at the expense of other Zygoptera and Anisoptera, respectively. Our results revealed that a ratio of Zygoptera/Anisoptera is a poor indicator of tropical forest conditions, probably because of ecological diversity within these groups. However, the proportions of Coenagrionidae/other Zygoptera and Libellulidae/other Anisoptera significantly increased along a disturbance gradient, suggesting their potential to be a good indicator of well-preserved, altered, and heavily degraded forest habitats. Therefore, our results are in line with studies presenting the usefulness of adult Odonata as versatile indicators for assessing human-mediated changes in tropical forest environments, supporting the practical use of this group in biological monitoring.
... These are more prolific due to their requirements in terms of temperature, oxygen concentration in water, etc., that are less restrictive. Many of these taxa, particularly Odonata that inhabit seasonal streams, use to show a preference for slow flowing waters typical of many Mediterranean seasonal streams of mid to low order, or at least of some microhabitats found in them, such as pools in the shores (Suhling et al. 2015). Perlodidae are also frequent in permanent streams, where they can coexist with Perlidae which, under these conditions, probably act as top predator relegating Perlodidae to a lower trophic level. ...
... When considering both prey and non-animal matter, the five studied taxa show a relatively high niche breadth, supporting their previously mentioned generalist habits (Stewart & Stark 2002, Askew 2004. Broadly, Odonata nymphs feed on all kinds of prey they can overcome (even from their same species under certain conditions, van Buskirk 1989), and the type of prey depends more on the habitat of the nymph (Suhling et al. 2015). In our study, this generalist behaviour is also found when including non-animal matter. ...
– In the present article, we show the results of a study carried out in a seasonal stream where several taxa of Plecoptera and Odonata coexist. We analyzed the diet of selected top predators within these macroinvertebrate groups during a whole hydrological year and we studied the possible variations of diet with size. Moreover, we quantified their niche breadth and diet overlap. The results show that only in two taxa, one stonefly and one dragonfly, ontogenetic shifts in diet occur. The stonefly (isoperla morenica) reduces its intake of animal matter with size and the dragonfly (onychogomphus forcipatus) increases it. From a trophic niche point of view, all the studied taxa show a relatively narrow niche considering only prey (discarding non-animal resources), and a high niche overlap. This could lead to competition among them, but the fact that they are coexisting in this relatively adverse environment suggests that this is not the case and that prey are not limiting. © 2018 Universite de Paris VI (Pierre et Marie Curie). All rights reserved.
... Odonates are wellknown as indicators of good environmental conditions and species diversity, and they are being used in many ecological studies around the world (e.g., Samways and Steytler 1995;Sahlén and Ekestubbe 2001;Koch et al. 2014;Renner et al. 2016a). Another reason to use odonates as model organisms is related to the life stages of the group, as they have aquatic larvae and terrestrial adults, both stages being selective in terms of habitat choice (Suhling et al. 2015). ...
... We also see this pattern when considering the land cover variables. It is well known that terrestrial factors are very important to adult odonates, while the aquatic factors are more crucial to larvae (Suhling et al. 2015). Terrestrial factors may limit the dispersal of certain species and prevent their egg laying, while at the same time favouring other species (e.g., Stoks and Cordoba-Aguilar 2012). ...
The biogeographical region known as the Pampa biome in southern Brazil, was originally mainly covered with open fields or grassland, with areas of riparian forest surrounding the water bodies. Today this landscape appears highly fragmented due to agricultural activities such as rice cultivation, extensive cattle farming, and forest plantations. Studies have shown that the Pampa biome has high levels of biodiversity and endemism, but with regard to invertebrates, this biome is still one of the least known in Brazil. We therefore designed a study comparing the dragonfly (Odonata) communities to environmental and landscape features in this area, measuring diversity by species richness, relative abundance and Shannon index. Our results showed that the Pampa is a biome very rich in odonates, and that the species communities are highly dependent on the environmental conditions of the area. Habitats such as Rivers/Streams, bordered by native grasslands and riparian forests, were shown to harbour communities that were ecologically more complex and sensitive than other habitat types. Man-made lakes and agricultural areas displayed lower levels of biodiversity and odonate communities dominated by generalist species. By combining data on the communities of Odonata and other taxa, our analyses may be instrumental in determining priority areas for future conservation measures within the area.
... This Dispersal routes to the Indo-Australian Archipelago 3 capability, however, is largely restricted to species which breed in standing waters. Species of running water, especially in the tropics, usually have low dispersal capacities (Suhling et al., 2015). With around 6000 described species, Odonata constitute almost 5% of all recorded animal diversity in freshwater habitats (Balian, Segers, Lévèque, & Martens, 2008). ...
... With around 6000 described species, Odonata constitute almost 5% of all recorded animal diversity in freshwater habitats (Balian, Segers, Lévèque, & Martens, 2008). The highest species and family diversity is found in the tropics, especially those of America and Asia (Suhling et al., 2015). Due to their size and coloration Odonata receive much attention and therefore their taxonomy and distribution are relatively well known. ...
Information on the origin of distribution patterns shown by freshwater invertebrates in the Indo-Australian Archipelago is poor. Here we present a molecular based hypothesis of the phylogenetic relationships of Argiolestidae, a family of damselflies found throughout the tropical parts of the Eastern Hemisphere. We use this to address the following questions: (1) did Argiolestidae colonize Wallacea and the Philippines from the Eurasian or from the Australian continent? (2) Is the presence of Argiolestidae in New Guinea the result of a single colonization event, i.e. are the Argiolestidae found in New Guinea monophyletic? The results show that clades occurring in the Philippines, Wallacea and New Guinea all originate from Australian ancestors. Representatives in Sundaland are most closely related to African genera and failed to reach the Philippines and Wallacea. The presence of Argiolestidae north of Australia is the result of at least three colonization events from Australia to areas that presently compose New Guinea and probably a fourth from Australia to Sulawesi. The two most diverse lineages found north of Australia show different distribution patterns. One reaching north as far as Luzon, presumably facilitated by Late Oligocene to Miocene islands arcs (Melanesian Arc System). The other clade shows a diversification of two genera and numerous species in the eastern tail of New Guinea, an area largely corresponding with the East Papuan Composite Terrane (EPCT) followed by the expansion of one genus into the rest of New Guinea. The EPCT's importance as source area for the New Guinean fauna has been suggested on the basis of distribution patterns, but we present the first evidence based on phylogeny reconstruction of strong diversification on this formerly isolated landmass.
... In amphibious insects the emergence from larva to adult or subimago (Corbet, 1964) leads to a change of habitat -the way of living -and therefore to various adjustment mechanisms (Bellmann, 2002;Dettner & Peters, 2003;Suhling et al. 2015). In odonates, leaving the water body and developing flight capability necessitates a transformation of respiratory organs (Sternberg & Buchwald, 1999;Suhling et al. 2015). ...
... In amphibious insects the emergence from larva to adult or subimago (Corbet, 1964) leads to a change of habitat -the way of living -and therefore to various adjustment mechanisms (Bellmann, 2002;Dettner & Peters, 2003;Suhling et al. 2015). In odonates, leaving the water body and developing flight capability necessitates a transformation of respiratory organs (Sternberg & Buchwald, 1999;Suhling et al. 2015). After searching for an appropriate emergence support (Miller, 1964;Prinzhorn, 2013;Ubukata, 1973) and climbing the selected substrate, the larva clings with its claws to the substrate and tests its position by swinging its abdomen and legs (Bellmann, 1993;Corbet, 1999;Sternberg & Buchwald, 1999). ...
The transition between larval and adult stage in amphibious insects is called emergence. During emergence
abdominal contractions and excretion of liquid drops can be observed in several insect orders.
Since the function of these processes is not yet known in odonates, this study examines the probable function
of abdominal contractions and excretion of liquid drops in Zygoptera and Anisoptera. By subdividing
the emergence into 12 successive stages and counting abdominal contractions as well as the excreted liquid
drops during these stages we set up a systematic data collection. In all investigated individuals, both
processes began in the middle of the entire emergence. We found that abdominal contractions occurred
more frequently at the beginning of the latter half of emergence. The number of excreted liquid drops,
however, was higher in the end, shortly before the maiden flight. Concerning the number of excreted liquid
drops, we found a significant difference between Zygoptera and Anisoptera. Our findings suggest that
there might be a relationship between the two processes, probably explainable by the hemolymph circulation
as seen in Lepidoptera. However, abdominal contractions and liquid drops seemed to be crucial for
the emergence of Zygoptera and Anisoptera.
... The order Odonata (dragonflies and damselflies) contains more than 6300 described species (Schorr & Paulson, 2021). The estimated number of extant species varies from 7000 to 7500, suggesting that about 10%-20% of species diversity is still unknown (Suhling et al., 2015). Odonates can be good bioindicators of environmental quality disturbance. ...
The use of mitochondrial markers for taxonomic identification and biodiversity monitoring is not without risks or limitations. Most importantly, the natural transfer of DNA from the mitochondria to the nucleus generates nonfunctional nuclear copies of mitochondrial DNA (NUMTs). Their abundance and size vary significantly among taxa, and NUMTs have been reported to complicate molecular studies based on mitochondrial markers in several insect orders, most prominently in Orthoptera. The significance of this phenomenon in Odonata has not yet been properly addressed. Here, we present a complete mitochondrial genome and a draft nuclear genome of Leucorrhinia albifrons (Odonata: Libellulidae), as well as NUMT and cox1 sequences from the related species Leucorrhinia dubia. We document the presence of NUMTs in the L. albifrons nuclear genome and in nuclear genomes of two other Odonata species available in public databases. Our results show that NUMTs can have a serious impact on barcoding, phylogenetic, population and phylogeographic studies of Odonata, especially when the barcode is located in the cox1 gene, the most frequently used molecular marker for Odonata. We suggest that nad1 should be used alone or in combination with cox1 to minimize unintended confusion with NUMTs. Finally, we present a mitophylogenomic analysis of Odonata and document several cases of misidentified mitochondrial genomes belonging to species different from those indicated in public databases. In conclusion, our findings represent an important step for future metabarcoding studies of Odonata based on mitochondrial DNA markers.
... Odonates are insects with aquatic nymphal development and terrestrial (aerial) adults [36]. While some rare dispersal events have been reported at the nymphal stage, the vast majority of the movements are performed by flying adults [37]. ...
Anthropogenic activities cause loss and fragmentation of natural habitats and have strong effects on population maintenance by increasing their isolation. Pond ecosystems are scattered waterbodies that can interact as a network connected by dispersal events of freshwater organisms. Identifying local genetic differentiations and understanding how gene flow occurs across these networks is essential to prevent risks associated with environmental perturbations. This study aimed to investigate genetic diversity and structure of Anax imperator Leach, 1815 populations at both regional and European scales using seven microsatellites markers. Seven populations of A. imperator were sampled in northwestern France and four populations were sampled in Italy (Sicily), Czech Republic, Switzerland and United Kingdom (U.K.). French populations presented a low genetic differentiation indicating a high gene flow and confirming dispersal events of this species between ponds at regional scale. No pattern of isolation by distance was found at the European scale. The populations presented a low genetic differentiation and no pattern of isolation by distance, suggesting historical or current movements of individuals. Only the U.K. population presented a significant genetic differentiation from other European populations, suggesting that the English Channel might act as a barrier to gene flow for A. imperator. However, Bayesian analysis showed that some dispersal events could occur between the U.K. and France (Normandy), probably facilitated by prevailing winds.
... The Dinaric Western Balkans area is characterized by an extremely complex hydrological network [41] and extraordinary diversity of biota [42], yet it is still greatly understudied. Although Odonata are considered to be among the well-studied aquatic insect orders [43], their ecological requirements in karst rivers and streams are very poorly known [22,44], especially in intermittent habitats. Therefore, the main objectives of this study were (i) to compare Odonata assemblages (species richness, diversity, and abundance) in two focal habitat types: macrophyte rich and macrophyte poor, in the Mediterranean intermittent karst rivers; (ii) to examine the functional diversity of Odonata assemblages and detect changes in functional traits; and (iii) to determine the main environmental drivers that shape these assemblages. ...
Assemblages of adult Odonata were studied in four intermittent karst rivers encompassing macrophyte-rich (MRH) and macrophyte-poor habitats (MPH) in southern Europe, where temporary lotic habitats are the predominant freshwater type but are still understudied. With a total of 25 recorded species, the studied habitats support species-rich Odonata assemblages, as already shown for intermittent rivers in the Mediterranean. Aquatic macrophyte abundance, conductivity, and water velocity are the most significant determinants of Odonata assemblages in the studied IRES. MRH promote higher Odonata abundance and the taxonomic and functional diversity of their assemblages compared to the MPH. Odonata assemblages in MRH are characterized by higher values of body size and a higher share of species preferring lentic and temporary hydrological conditions. Moreover, their assemblages are characterized by various patterns of nymphal development and drought resilience strategies. In contrast, MPH are preferred by lotic species, with nymphal development all year round and with no specific drought-resisting strategies. Our results contribute to the knowledge of diversity and ecological requirements of dragonflies and damselflies in IRES habitats, which could provide scientific background for future conservation activities and bioassessment protocols of such habitats and their biota.
... The differences in life habit and behavior usually lead to specific association and preference by substrate types among larval odonate taxa (Corbet, 2004). In view of the low mobility of the larval stage, most odonate taxa tend to avoid microhabitats with stronger flow in lotic environments (Corbet, 2004;Suhling et al., 2015). Stream flow is generally higher in microhabitats characterized by coarser particles such as stone and gravel, while litter substrates are characterized by areas accumulation and deposition of organic material, with reduced water flow (Lampert & Sommer, 2007;McCabe, 2011). ...
Aim
We assessed the influence of substrate type and categories of riparian vegetation widths on the community structure of Odonata (Insecta) in southern Brazilian streams.
Methods
Sampling took place in twelve stream reaches differing in their riparian vegetation widths (from more than 40 m up to less than 5 m). Larval odonates were collected in inorganic (stone and gravel) and organic (leaf litter) substrates at each stream reach. Differences in Odonata composition among substrates and categories of riparian vegetation width were tested using PERMANOVA and visualized with ordination diagrams. In addition, we assessed the influence of riparian vegetation width taking into account two levels of resolutions: fine (four categories: > 40 m, 30-15 m, 15-5 m and < 5 m) and coarse (narrower and broader than 15 m).
Results
Odonata composition differed more strongly according to substrate type regardless of the level of resolution. Organic substrate (litter) had different composition and higher richness than inorganic ones. Odonata composition significantly differed between riparian vegetation widths at the coarser level of resolution (narrower and broader than 15 m); at the coarser level, the interaction between substrate and riparian widths was significant, with the composition from litter substrate in broader widths differing from stone and gravel in narrower widths.
Conclusions
The composition of odonate larvae responded to the major reductions in riparian widths (above > 15 m), indicating that reductions above this level are enough to affect the community structure of Odonata. Additionally, the different composition of Odonata in organic substrates in broader riparian vegetation widths compared to inorganic substrates in narrower widths indicate a complex relationship between riparian vegetation and substrate in the assembly of insect communities in southern Brazilian forest streams. The interaction between riparian vegetation widths and substrate suggests that the effects of reductions in riparian widths on Odonata composition are not similar across substrate types.
... The choice of which group to use would depend on the specific question asked, and other considerations such as the amount of resources and personnel available, the time of year, time constraints, and level of taxonomic experience. Adult male Odonata are colourful, conspicuous and easy to locate at their riverside territories (Suhling et al., 2015;Moore and Martin, 2018). They are quick to sample, requiring only a net, and are easy to identify to species level with the use a field guide . ...
Biological surrogates in conservation biology are valuable for rapid biodiversity and environmental surveys, and as an early warning of potential threats. However, these surrogates need to be simple and inexpensive to apply. The umbrella index was applied here to quantify the selection of surrogate species for biodiversity assessments, but requires interrogation for application in areas rich in threatened endemic species. Aquatic larvae of Ephemeroptera, Plecoptera and Trichoptera (EPT), as well as the adult Odonata, are all highly responsive to changes in freshwater condition. Using the umbrella index, we evaluated the performance of the surrogate species approach for aquatic insect conservation in a region (Greater Cape Floristic Region) with an exceptional level of rare and endemic species, across multiple rivers with different disturbance levels. Due to a lack of species level information, EPT taxa were calculated using morphospecies within families, and Odonata were identified to species level. The umbrella index identified eight EPT species and seven Odonata species as potential sur-rogates. Both these groups co-occurred with high percentages of their own overall groups (EPT surrogates for overall EPT, and Odonata surrogates for overall Odonata), as well as for the other group (EPT surrogates for overall Odonata, and Odonata surrogates for overall EPT). The index was surprisingly flexible, and performed well in an area with so many species of conservation concern, as well as across spatial scales greater than a single river, with varying degrees of disturbance. Both EPT and Odonata showed promise as potential biodiversity surrogates, and for future conservation planning. Ideally, conservationists should aim to use taxa that are easy to identify to species level, with known sensitivities to human disturbance. However, when this is not a possibility, the umbrella index is still applicable and accurate for morphospecies (family level sensitivities).
... Damselflies and dragonflies (Order Odonata, hereafter dragonflies or odonates) are considered one of the oldest insect groups and occur in most regions of the world, especially in the tropics (Corbet & Brooks 2008). Almost all odonate larvae live in freshwater habitats, wheras the adults are terrestrial, often spending much time on the wing (Suhling et al. 2015). In both life stages they require specific physical and chemical conditions to survive and tend to react quickly to any alteration of their natural environment . ...
Compared to other archipelagos of the Pacific, the New Caledonian Odonata fauna is rich and diverse with 56 valid species or subspecies (23 endemics, 41%) from eight families (four Zygoptera: Argiolestidae, Coenagrionidae, Isostictidae, Lestidae, and four Anisoptera: Aeshnidae, Corduliidae, Synthemistidae, Libellulidae) and 31 genera (including four endemics, 13%). In Zygoptera, we record 19 species including 12 endemics (63%), and among Anisoptera, we record 37 species or subspecies, including 11 endemics (30%). We removed five species from the list that had been erroneously recorded as occurring in New Caledonia: Tramea carolina (Linnaeus, 1763), Austroargiolestes icteromelas (Selys-Longchamps, 1862), Ischnura torresiana Tillyard, 1913, Xiphiagrion cyanomelas Selys-Longchamps, 1876 and Hemicordulia oceanica Selys-Longchamps, 1871. The occurrence of Tramea limbata (Desjardins, 1835) appears also doubtful, but we were unable to clarify to which taxon this record referred hence we excluded it from our update. From a biogeographic perspective, the New Caledonian fauna has mostly Australian affinities with some connections with southeast Asia and the Pacific region. We provide for each species, whenever information was available, a distribution map with a brief review of its known ecology, behaviour and phenology. We also evaluated each species’ conservation status, in light of known threats (range restriction, scarcity and human activity including altered water flow). We consider seventeen species (30%) endangered. The most immediate threats concern water pollution including alteration to the flow of water courses caused by mining, deforestation and fires. Invasive species, such as alien fish, may be predators of concern for odonata larva, although this has not yet been proven in New Caledonia.
... Damselflies and dragonflies (Order Odonata, hereafter dragonflies or odonates) are considered one of the oldest insect groups and occur in most regions of the world, especially in the tropics (Corbet & Brooks 2008). Almost all odonate larvae live in freshwater habitats, wheras the adults are terrestrial, often spending much time on the wing (Suhling et al. 2015). In both life stages they require specific physical and chemical conditions to survive and tend to react quickly to any alteration of their natural environment . ...
Compared to other archipelagos of the Pacific, the New Caledonian Odonata fauna is rich and diverse with 56 valid species or subspecies (23 endemics, 41%) from eight families (four Zygoptera: Argiolestidae, Coenagrionidae, Isostictidae, Lestidae, and four Anisoptera: Aeshnidae, Corduliidae, Synthemistidae, Libellulidae) and 31 genera (including four endemics, 13%). In Zygoptera, we record 19 species including 12 endemics (63%), and among Anisoptera, we record 37 species or subspecies, including 11 endemics (30%). We removed five species from the list that had been erroneously recorded as occurring in New Caledonia: Tramea carolina (Linnaeus, 1763), Austroargiolestes icteromelas (Selys-Longchamps, 1862), Ischnura torresiana Tillyard, 1913, Xiphiagrion cyanomelas Selys-Longchamps, 1876 and Hemicordulia oceanica Selys-Longchamps, 1871. The occurrence of Tramea limbata (Desjardins, 1835) appears also doubtful, but we were unable to clarify to which taxon this record referred hence we excluded it from our update. From a biogeographic perspective, the New Caledonian fauna has mostly Australian affinities with some connections with southeast Asia and the Pacific region.
We provide for each species, whenever information was available, a distribution map with a brief review of its known ecology, behaviour and phenology. We also evaluated each species’ conservation status, in light of known threats (range restriction, scarcity and human activity including altered water flow). We consider seventeen species (30%) endangered.
The most immediate threats concern water pollution including alteration to the flow of water courses caused by mining, deforestation and fires. Invasive species, such as alien fish, may be predators of concern for odonata larva, although this has not yet been proven in New Caledonia.
... Extant dragonflies are widely used to study insect ecology, behaviour and biogeography (van Tol and Müller, 2003; van Tol et al., 2009;S anchez-Herrera and Ware, 2012;Suhling et al., 2015). The larvae (nymphs) mostly live in an aquatic environment, helping to reconstruct the past ecology (Zhang, 1999;Huang and Lin, 2001) and ancient behaviour can be recovered deduced from body structures (Zheng et al., 2017a). ...
... It can be assumed, however, that a species also will utilize the resources of surrounding habitats if these resources are limited in the natal habitat. In odonates, adults must be able to locate various resources that are crucial to their survival and reproduction, including especially habitat for foraging, roosting and reproductive activities, within terrestrial environments (Kirkton & Schultz 2001;Suhling et al. 2015). Moreover, sites providing these resources often may not coincide in space (Eason & Switzer 2006). ...
Although it is well recognized that insects’ habitat use and requirements may change during the season,
very little attention has been devoted to diel habitat changes in most insects. In this study, we compared
habitat utilization patterns of Sympetrum depressiusculum (Selys, 1841) adult dragonflies between daytime
activities and nocturnal roosting. During daytime, we captured and marked adult individuals with fluorescent
paint in different habitats. At night, we searched, using UV light, for marked individuals that remained
on the habitats. We found that habitat selection for daytime activities and that for nocturnal roosting differed
significantly. Adults clearly avoided ponds and their immediate surroundings for nocturnal roosting,
whereas this habitat type was frequently utilized for daytime activities. We suggest that nocturnal avoidance
of the riparian area is associated with lower temperatures, which adversely affect thermoregulation,
and that selection of specific habitats for nocturnal roosting is closely associated with vegetation structure
providing stability during windy nights and serving as a suitable shelter. Such habitat properties are found
especially on fallow land, a habitat type whose representation in agricultural areas has been gradually
decreasing in recent decades.
... Platystictidae (shadowdamsels) currently consist of about 250 extant species in eight genera and four tropical subfamilies (Wilson 1997;Van Tol 2005;Van Tol et al. 2009;Dow & Orr 2012;Dijkstra et al. 2014;Haber & Wagner 2014;Schorr & Paulson 2015;Suhling et al. 2015;Dow et al. 2016;Phan & Kompier 2016;Bedjani c et al. 2016), and two fossil species of the genus Mesosticta Huang, Azar,Cai & Nel, 2015from mid-Cretaceous Burmese amber (Huang et al. 2015;Zheng et al. 2016a). The subfamily Palaemnematinae (Palaemnema Selys, 1860) is confined to central and north-western South America, while Sinostictinae (Sinosticta Wilson, 1997), Platystictinae (Platysticta Selys, 1860, Ceylonosticta Fraser, 1931) and Protostictinae (Protosticta Selys, 1885, Drepanosticta Laidlaw, 1917, Telosticta Dow & Orr, 2012and Sulcosticta van Tol, 2005) are restricted to South-East Asia. ...
Odonatans are quite rare in the fossil record compared with the other insects, especially in Cretaceous amber inclusions. The extant family Platystictidae is one of the most diverse Zygoptera, but short of fossil records. In this paper, a new species, Mesosticta davidattenboroughi sp. nov., is described from mid-Cretaceous Burmese amber, representing the third-known fossil species of Platystictidae. Mesosticta davidattenboroughi sp. nov. has a long IR1 beginning one cell distal of the base of RP2, confirming the previous attribution of Mesosticta Huang, Azar, Cai & Nel, 2015 to Platystictidae. It differs from other species of Mesosticta in having a long IR1 and a basally crossed subdiscoidal cell. The fossil genus Mesosticta shares the diagnostic characters of the modern platystictid genera, viz. a basally recessed ‘CuP’ (shared by all species), a very long IR1 (only in Mesosticta davidattenboroughi sp. nov.), and a specialized subdiscoidal area mostly rhomboidal in shape (only in Mesosticta electronica Zheng, Zhang, Chang & Wang, 2016). Based on the platystictid damselflies from Burmese amber, a new subfamily Mesostictinae subfam. nov. is established. Mesostictinae subfam. nov. represents the first fossil group of modern platystictid damselflies, documenting the appearance of Platystictidae as early as mid-Cretaceous. It differs from modern Platystictidae by the presence of fewer postnodal and postsubnodal crossveins, a short MP, the base of RP2 being nearer to the subnodus and the nodus lying more distally.
http://zoobank.org/urn:lsid:zoobank.org:pub:6669DBCD-F2EF-4C84-9623-BD33142AD36B
... Dragonflies are insects whose activity is highly dependent on insolation. They have a complex life cycle, with an obligate aquatic larval period and elaborate adult behaviour (for a recent review, see Suhling et al., 2015). Even if sunny habitats harbour high odonate species richness, some groups have specialised in living in forests, where both insolation and heat are limited (Cordero-Rivera, 2006). ...
Damselflies adapted to forest habitats are expected to be negatively affected by the disturbance of riparian forests, due to the change in insolation when trees are cleared. In this paper, we compare survivorship and behaviour of two populations of Heteragrion cooki by means of mark-recapture methods and focal observations of adults. We found similar densities of males (but not of females) in both streams, and similar recapture rates, higher for males (50%) than for females (20%). Body size was also significantly different between populations, with smaller individuals in the shadiest stream. The analysis of daily survival rates indicated that in the shaded stream, males survived better than females, whereas in the sunnier stream survival was similar between sexes, but varied over time. Furthermore, in the sunny stream, body size was negatively correlated with survival. Males arrived earlier than females to the stream, with a maximum activity between 13 and 16 hours. They defended small patches of the stream, exhibiting high site fidelity and aggressive behaviour against conspecific males. Copulation, which was very rarely seen in the stream, lasted about six minutes. Pairs in tandem remained for an average of 45 minutes laying eggs on roots and lianas. We found that H. cooki was not drastically affected by the loss of riparian vegetation, maintaining similar densities of males in both streams, probably because small remnants of native forests were still found near to the stream.
... Since 2000 to date, description of new species slowed down and rendered approximately 16 species, i.e., approximately one species per year (Gonz alez-Soriano & Novelo-Guti errez, 2014). Three hundred and fifty-six species are considered a relatively high biodiversity estimate as it accounts for 5.9% of the odonate species known worldwide (>5950 species plus an additional 1000-1500 awaiting description; Suhling et al., 2015). However, whether the slowdown in odonate species description implies that we are close to knowing all Mexican species is unclear, especially given that collecting activities have not been homogeneous through the whole country. ...
With the aim of protecting Mexican diversity, one current governmental task is to complete national biological inventories. In the case of odonate insects, several researchers have hypothesized that species richness is complete (205 dragonflies and 151 damselflies), but there has not been any formal exercise to test this. Thus, we have investigated whether odonate species richness (for Mexican endemics, dragonflies (suborder Anisoptera), damselflies (suborder Zygoptera) and total species) is complete using sample-based and coverage-based rarefaction curves. Along with this, we also showed how good distribution data are in the country. The rarefaction curves have indicated 100% completeness for all groups suggesting that the inventory is complete. However, species' distribution data is highly patchy regarding areas either well (e.g. central Mexico) or badly (e.g. coast of Guerrero and Oaxaca) collected. We encourage researchers to continue odonate sampling in order to support at least three conservation actions: (i) conservation assessment of endangered species; (ii) knowledge of range shifts given rising global temperatures; and (iii) increase public interest and awareness in protected, touristic areas.
1. Climate change has the potential to modify habitat characteristics and, consequently, induce species responses to ongoing environmental changes. Functional traits determine both if a species can persist and maintain stable population sizes in particular ecological conditions, and its capacity to disperse to more favourable habitats.
2. Given that functional traits evolve over time, one could expect closely related species to show similar responses to climate change, which should identify vulnerable lineages. Alternatively, species-specific functional traits may anticipate species responses to climate change, and therefore, trait composition should be a strong predictor.
3. We compiled a comprehensive dataset of functional traits of 84 Iberian and Moroccan odonate species and built a phylogenetic tree to determine if dissimilarity of traits and phylogenetic relatedness are relevant to better discriminate species range-shift responses to climate change.
4. Modelling results for 66 species showed clear impacts of the increase in temperature and drought events on their potential distribution. The traits that best discriminated species that expanded their ranges were multivoltinism, short-life cycles and preference for temporary habitats, whereas species with a reduced and displaced potential distribution were mostly semivoltine, with a short flying season, oviposition on gravel and restricted to permanent streams, small rivers or oligotrophic lakes. Trait conservatism was rejected and phylogenetic relatedness
was a poor predictor of range shifts.
5. Considering odonates as model organisms, traits such as voltinism, beginning and prolongation of flight period and preference of temporal habitats should be examined to anticipate range-shift responses of freshwater insects to climate change.
The present study aimed to determine the wing asymmetry and sexual asymmetry of Pantala flavescens (Fabricius 1798) collected from a paddy field. P. flavescens is known as the longest migratory insect species and the morphological architecture of their hindwing aids in long-distance gliding. In our study, we collected F1 generation of male and female P. flavescens and used for geometric morphometric study to investigate wing asymmetry. We observed no difference in wing size between sexes from the study, but there are significant (p < 0.05) shape differences. The female population was more asymmetric than male population, with a high shape-related fluctuation asymmetry (FA). Discriminant function analysis was used to validate wing asymmetry (right-left) and sexual asymmetry of P. flavescens. Canonical variant analysis discriminated the forewings and hindwings of P. flavescens both sexes in a distinct morphospace. The PC’s warp shape analysis proved that, when compared to forewings, the highest amount of shape variations was observed in hindwings, especially in anal lobe regions. Based on the results, pesticide and fertilizer used in the paddy fields are the primary reason for the high level of FA, and the morphological variations observed in the hindwings may influence the migratory behaviour of P. flavescens.
Members of the insect order Odonata are known as good ecological indicators. Many are sensitive to habitat modifications and are easily monitored for use in environmental assessment studies. Rapid assessments rely on efficient sampling techniques. However, there is limited information available on sampling techniques for adult odonates, and protocols require evaluation. To do this, we standardized counting methods during sampling of odonates from August to November 2016 at the Mula River, Pune, India. We used four counting techniques; full-width belt transect (FWBT), full-circle point count (FCPC), half-width belt transect (HWBT), and half-circle point count (HCPC). For HWBT and HCPC areas facing the river were sampled, and for each technique we took multiple temporal replicates. We compared species detected per unit time, species detected per unit area, new species detected per unit time, and new species detected per unit area. Additionally, we compared species estimates. With HCPC we detected the maximum number of species and new species per unit area, whereas FWBT returned maximum coverage of recorded species. We recommend our proposed techniques be considered in the future across various habitats to decide the most suitable sampling strategy for the different habitats or situations.
This research-level text documents the latest advances in odonate biology and relates these to a broader ecological and evolutionary research agenda. Despite being one of the smallest insect orders, dragonflies offer a number of advantages for both laboratory and field studies. In fact, they continue to make a crucial contribution to the advancement of our broader understanding of insect ecology and evolution. This new edition provides a critical summary of the major advances in these fields. Contributions from many of the leading researchers in dragonfly biology offer new perspectives and paradigms as well as additional unpublished data. The editors have carefully assembled a mix of theoretical and applied chapters (including those addressing conservation and monitoring) as well as a balance of emerging (e.g. molecular evolution) and established research topics, providing suggestions for future study in each case. This accessible text is not about dragonflies per se, but rather an essential source of knowledge that describes how different sets of evolutionary and ecological principles/ideas have been tested on a particular taxon. This second edition of Dragonflies and Damselflies is suitable for graduate students and researchers in entomology, evolutionary biology, population and behavioral ecology, community ecology, and conservation biology. It will be of particular interest and use to those working on insects and an indispensable reference text for odonate biologists.
Human activities affect the structure, dynamics, and energy flow of aquatic ecosystems. River damming, a common anthropic impact in Brazil, changes solar incidence, water flow, and temperature of waterbodies, thereby affecting their fauna. Due to their high sensitivity to environmental changes, the Odonata may be indicators of these impacts. We sampled two ecologically distinct sites, (1) a quasi‐pristine forested area; and (2) a nearby human‐impacted reservoir landscape, to evaluate the effects of damming on odonate community structure. The species composition of quasi‐pristine communities was more heterogeneous and differed almost completely (indicating high turnover) from that of the reservoir‐area communities. The capacity of the reservoir to maintain local fauna was almost nil. The communities in the changed landscape had the highest local diversity, which is related to the high occurrence of widespread generalist South American species. We also tested two recently proposed bioindication ratio tools based on the richness or abundance of high‐level taxonomic categories; both effectively reflected the extent of the impacts of damming. The best performing ratios were Coenagrionidae/other Zygoptera richness ratio, Zygoptera/Anisoptera abundance ratio, and Libellulidae/other Anisoptera richness ratio. The reservoir landscape promotes biotic homogenization. However, the water supply system entails the preservation of part of the native habitat in its surrounding areas, consequently maintaining forest‐dependent biodiversity in quasi‐pristine environments.
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.
Macroinvertebrates and small fishes can both be important predators of zooplankton in littoral zones of shallow lakes. The aim of this study is to analyze how these predators may interact to affect zooplankton, algal biomass, and water turbidity. We performed a 15-day mesocosms experiment in 12 tanks (1300 l) simulating a littoral zone. A 2 × 2 factorial experiment was designed as follows: (1) Control without predators, (2) 7 nymphs of Anisoptera, (3) 2 visual zooplanktivorous fish and (4) 7 Anisoptera and 2 fishes. Results showed significant effects of fish on the abundance of Cladocera and its concentration among the macrophyte zone. On the other hand, we found no effects of Anisoptera on zooplankton abundance or distribution. No significant interaction between the predator effects was found on most response variables. Water turbidity increased only in the treatments with fish. Macrophytes offer a refuge for zooplankton to fish predation, but antagonist interactions appear when both predators were present, and the shelter effect of vegetated patches to the main herbivores against fish predation was less important when Anisoptera was present. The macroinvertebrate fauna of the littoral zone should be carefully considered in the restoration plans of shallow eutrophic lakes.
Ponds are lentic waterbodies with a high conservation value for biodiversity that have long been overlooked by management policies. Recent initiatives aimed to promote the conservation of these ecosystems by restoring or creating new ponds throughout Europe. Therefore, studying responses of aquatic invertebrates to local pond characteristics and connectivity between them is determinant to understand community dynamics and colonization processes of these scattered ecosystems. We studied larval communities of odonates in 20 created or restored ponds to assess their colonization during the first 2 or 3 years. Community dynamics in relation to pond vegetation, landscape context and connectivity with other ponds were also investigated. No difference in species richness was found between restored and created ponds. Most species colonized the ponds during the first year, but a different pattern in colonization was observed between Anisoptera and Zygoptera. Community composition was related to the landscape context of ponds and the time since pond creation or restoration. Abundances were positively related to pond connectivity, especially in the suborder Zygoptera. No relationship was found between vegetation and Anisopteran larvae, while Zygoptera seem more sensible to the vegetation structure due to their endophytic oviposition. This work confirms the high colonization capacity of odonates and shows that creation of new ponds could be as efficient as pond restoration to enhance the conservation of freshwater species. It also highlights that landscape characteristics and connectivity between ponds are determinant to support higher abundances and a posteriori increase population viability at the landscape scale.
Farming expansion has negative impacts on freshwater biodiversity. However, the effects of agricultural land use are not similar across taxa and depend on local context. For instance, the impacts of agricultural expansion are understudied in the Neotropics (one of the leading regions in cropland expansion). Knowledge of the effects of agricultural land use on aquatic insects from South American subtropical grasslands (Pampa) is even more incipient. We tested whether landscape modification related to increased agricultural land use was associated with taxonomic homogenization in odonate communities in waterbodies in the Brazilian Pampa. Odonates were collected in waterbodies differing in the main land-use class in their surroundings (cropland or grassland). Cropland and grassland sites differed with respect to their abiotic conditions (water chemistry) and species composition of Odonata. Additionally, we found higher variation in the composition of Odonata (and suborders Anisoptera and Zygoptera separately) in grassland than cropland sites. We found an interplay between agricultural and grassland land uses and the variation in the composition of odonate communities in the Brazilian Pampa. Specifically, landscape modification by agriculture modified the abiotic conditions in the waterbodies, which may have favored species able to establish as larvae under harsher environmental conditions.
Implications for insect conservation
We suggest that the maintenance of mixed-grassland and cropland land uses in the fields adjacent to waterbodies can limit the negative effects of agricultural encroachment on Odonata communities with respect to biotic homogenization in the Brazilian Pampa.
Interspecific interactions, such as competition, are among the key factors that determine the distribution, abundance and diversity of organisms in natural communities of aquatic ecosystems. However, a marked reduction in the environmental integrity of streams may lead to modifications of the natural dynamics of these communities, including co-occurrence patterns and body size. In the Amazon, the replacement of forests by production systems is one of the leading causes of alterations to riverine ecosystem. The insects of the order Odonata (dragonflies and damselflies) are predators known to compete for environmental resources but are also sensitive to environmental changes such as those caused by shifts in land use. In this scenario, the present study evaluated species co-occurrence and body size patterns in adult odonates found at preserved and altered Amazonian streams, to determine whether there are morphological differences among the species that enable their coexistence. During the study, 98 streams in the eastern Amazon region were sampled, and a habitat integrity index (HII) was used to evaluate the integrity of each stream (based on variables such as the condition of the riparian vegetation and channel, and land use). Ten male individuals were selected from each species, and nine morphometric measurements were taken from each individual. A total of 3588 specimens were collected and distributed in nine families, 49 genera and 134 species. We found a non-random pattern of co-occurrence in the species of the odonate suborder Zygoptera and a random pattern in the suborder Anisoptera, in both preserved and altered streams. We found morphological divergence between pairs of zygopteran species, in the whole sample and both categories of stream integrity separately. No such morphological divergence was found in the pairs of anisopteran species. The distribution patterns of odonate species are limited by specific environmental processes, especially in preserved environments and in specialists, such as most zygopterans. Zygopteran species have more specific microhabitat requirements, which could explain this pattern, whereas anisopterans prefer open environments, which usually have a greater supply of resources, although there tends to be less microhabitat heterogeneity, which leads to reduced competition. Given this, future studies should use limiting similarity (e.g. morphological attributes) in addition to environmental and spatial factors to better understand the factors structuring these communities. Among these mechanisms, the effects of common ancestry (phylogenetic inertia) and biogeography are important factors that should also be considered in future studies.
Understanding species responses to urbanization is important to realize their specific conservation needs. Odonates (dragonflies and damselflies) are freshwater insects perceived as good ecological indicators. To investigate responses of tropical odonates to an urbanization gradient, we sampled adult odonates along an urbanization gradient at six sites along the Mula River across Pune City, Maharashtra, India. For species–habitat analysis, we first performed a variable reduction using principal component analysis. we analyzed species–habitat data using redundancy analysis and canonical correspondence analysis. We documented 15 odonates across 6 sites. Our statistical analyses on patterns of odonate assemblages across sites and environmental variables did not return significant results. However, we detected site-exclusivity in a few species based on occurrence data and identified urban sensitive, urban tolerant and generalist species. We found that the odonate diversity was highest at a moderately urbanized site. We believe that increase in diversity due to moderate amounts of disturbance can be explained by the intermediate disturbance hypothesis. Based on our data, we suggest that for the conservation of odonates in the urban context, anthropogenic disturbance needs to be regulated. Here, we demonstrate that understanding species–habitat associations is the first step towards understanding their ecological and conservation requirements. To conserve odonates and rivers in metropolitan cities like Pune, restoring original river-side habitat and reducing the disturbance at highly urbanized sites to at least intermediate levels needs to be done on an urgent basis.
Three media (sediment, surface water, and dragonfly larvae tissue) were collected from wetlands surrounding an industrial effluent treatment facility prior to closure. Samples were analyzed for metals, total mercury, and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) concentrations. Sediment and surface water concentrations were compared to provincial and federal guidelines, as well as reference wetland concentrations. Exceedances of arsenic, cadmium, chromium, copper, zinc, and PCDD/PCDF guidelines were found in deeper areas of wetlands historically contaminated from effluent, as well as wetlands exposed to current effluent inputs. Composite Libellulidae samples were collected from wetlands, and comparisons were made to reference tissue concentrations +20%. Elevated As, Cu and Pb tissue concentrations were measured at two site wetlands, but total mercury (THg) and PCDD/PCDF reference tissue concentrations were higher than wetlands near the effluent treatment facility. Spearman rho tests identified a significant correlation between sediment and tissue Pb concentrations and between surface water and sediment THg concentrations. Results suggest relatively low ecological risk to macroinvertebrates within wetlands near the effluent treatment facility from current effluent inputs.
All natural populations show fluctuations in space or time. This is fundamental for the maintenance of biodiversity, as it allows species to coexist. Long-term ecological studies are rare, mainly due to logistics, but studies like the one presented below recognize the dimensionality of temporal change and the ecological processes that lead to shifts in community composition over time. Here, we used three sampling occasions from a dataset spanning 20 years where dragonflies in central Sweden were monitored. Our aim was to investigate how the prevalence of ecological and biological species traits varied over time measured as Community-level Weighted Means of trait values (CWM). Most CWM values varied significantly between years. Most of the traits changed between the second and the last sampling occasion, but not between the two first ones. These changes could be linked to major changes in species abundance. Our work indicates that fundamental shifts in community structure can occur over a short time, providing environmental drivers act on species turnover. In our case, Climate change and pH levels in lakes are most likely the most important factors.
The department of Ñeembucú, in southwestern Paraguay, is home to the virtually unexplored Ñeem-bucú Wetlands, the second largest wetland system in the country, representing a major gap in biodiversity knowledge. As organisms ubiquitous with wetlands, the Odonata, or dragonflies (Anisoptera) and dam-selflies (Zygoptera), have the potential to be effective indicators of wetland habitats in the face of increasing anthropogenic impacts in the region. We therefore comprehensively surveyed the Odonata in central Ñeembucú over a period of two years using a listing method. Here, we present an annotated checklist and identification key to the species present in central Ñeembucú with details on their habitat preferences, phenology and behaviour. We found 60 species but estimate a total of between 62 and 90 species. Eleven (18%) are new records for Paraguay. Species composition is similar to the Argentine Humid Chaco, with four bioregional endemics, whilst representatives from the Andean-Patagonian subre-gion are present in open areas. Such partitioning of species from different bioregions into different habitats is typical of ecotonal regions. Two further species are endemic to the Paraná-Paraguay basin and three are highly localised, indicating the high conservation value of the Ñeembucú Wetlands. Eleven species have the potential to be effective indicators of the Paraguay River, large permanent wetlands, grassy temporary wetlands and wooded temporary wetlands, providing an effective tool to identify critical wetland ecosystems in the face of the growing threats from human activities. We also provide recommendations for the protection and management of wetlands in the region.
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Odonatans are rare as amber inclusions, but quite diverse in Cretaceous Burmese amber. In the past two years, over 20 new species have been found by the present authors after studying over 250 odonatans from 300,000 amber inclusions. Most of them have now been published, and here we provide a brief review. Three suborders of crown Odonata have been recorded, including the damselfly families or superfamilies Platycnemididae, Platystictidae, Perilestidae, Hemiphlebiidae, Coenagrionoidea, Pseudostigmatoidea, Mesomegaloprepidae and Dysagrionidae, plus the dragonfly families Lindeniidae, Gomphaeschnidae and Burmaeshnidae, and the damsel-dragonfly family Burmaphlebiidae.
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 was reduced compared to treatments with a non-carnivorous submerged plant, with effective mortality that could be related to bladderwort being 19–45% dependent on the prey species. Individuals of all species were found in capture bladders. We also recorded the microhabitat use of the early instar larvae and found that the species with highest use of vegetation had highest mortality due to bladderwort. We conclude that bladderwort may have effects on odonate larvae that translate into natural conditions and we discuss factors that may affect predation by bladderwort on odonates in the field.
Central Iran has been faced with deterioration of water quality and quantity, but yet the biodiversity of freshwater-associated insects in this area remains uncertain and without this information the development of conservation strategies is not possible. Here we explore Odonata diversity patterns and species assemblages in three terrestrial ecoregions of Central Iran. We used the first three Hill numbers and phylogenetic generalizations of these indices to compare the species diversity between the ecoregions. To compare Odonata species composition a PERMANOVA analysis was performed. Alpha-diversity of each water body was estimated by Hill numbers, taxonomic diversity, taxonomic distinctness and average taxonomic distinctness. The effects of habitat and environmental factors on Odonata diversity indices were modelled using a linear mixed model. About 42% of all Odonata that have been reported in Iran were found during this study. Species richness in the Desert and Steppe ecoregions were almost equal, the same pattern was observed for phylogenetic diversity indices. The Steppe ecoregion also had significantly different Odonata assemblage. Results of the linear mixed model showed that environmental factors have different effects on different diversity indices. Additionally different diversity indices resulted in different outcomes when comparing ecoregions, demonstrating that single measure cannot precisely assess the properties of an assemblage’s diversity. The high diversity of Odonata observed in such an arid environment shows the importance of man-made water bodies, as well as the necessity of preparing a conservation plan for these ecosystems.
Insect extraordinary evolutionary success is due to different reasons among which their ability to receive and respond to a great variety of sensory cues thanks to their developed sense organs encompassing a high number of diversified sensilla, mainly located on their antennae. The successful invasion of lotic and lentic freshwaters by terrestrial insect required physiological constraints also regarding sensory systems. This chapter reviews the present knowledge about antennal sensory equipment in adult and aquatic stages of Ephemeroptera, Odonata, Plecoptera and Trichoptera. These insect orders have aquatic larval stages well adapted to this environment, while they move to the terrestrial habitat as adults. To be able to receive sensory cues in two very different biotopes during the young and the adult stage is a fundamental prerequisite for these insects. The data reported are mainly based on morphological investigations under scanning and transmission electron microscope (SEM, TEM), and behavioural and electrophysiological investigations (the latter available only for Odonata and Plecoptera). The chapter considers separately the main sensory capacities located on the antennae in the above-reported aquatic insect orders, in particular mechanoreception, chemoreception, thermo-hygroreception and their modifications from the aquatic to the adult stage.
Habitat loss and fragmentation induce a decline and endangerment of freshwater organisms such as Aeshna viridis, an endangered dragonfly species characterised by a specific insect–plant association to the macrophyte Stratiotes aloides. In order to implement conservation measures, a good level of knowledge about the occurrence, habitat requirements and quality, as well as patch size of the species is important. We analysed the influence of several habitat parameters on the presence/absence and abundance of A. viridis exuviae using habitat models (generalised linear mixed-effect models). The ditches populated by A. viridis were classified as moderately polluted and meso- to eutrophic with a high cover of emerged S. aloides stands. The main factor contributing to the presence of A. viridis was the coverage of emerged S. aloides combined with the ditch width. The 90% probability of the presence of A. viridis was achieved at a cover of 14% (8.4 m²) and/or 77% (46.2 m²) of emerged S. aloides. The number of A. viridis exuviae was positively affected by the cover of emerged S. aloides and negatively affected by the sediment thickness, water maintenance and water temperature in March and August. The habitat parameters – water temperature and sediment thickness – are associated with S. aloides in the beginning of siltation of ditch succession. If ditch cleaning takes place during larvae development, eggs and larvae are removed by these procedures. In an optimal situation, the S. aloides populations occur in a mosaic of different states of siltation, which is managed by adapted water maintenance.
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.
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.
High mountain habitats of Bosnia and Herzegovina are often isolated and difficult to access. That is
why to this day, the dragonfly fauna of the mountain region in BiH remained almost entirely unexplored.
The aim of this study was to present the first overview of the dragonfly fauna of Zelengora
Mt. and the National Park Sutjeska, the area which includes some of the most important habitats of
these insects in the country. This paper is a result of the authors’ research combined with the analysis
of existing data. The dragonfly (Odonata) fauna of Zelengora Mt. and NP Sutjeska consists of a total
of 35 species, representing 55% of the fauna of this insect order in BiH. Together with data obtained
with the studies in 2015 and 2016, this paper also includes unpublished data collected by the authors
between 2009 and 2014, literature data and the data from the collections of the National Museum
of Bosnia and Herzegovina. A total of 457 records from 53 sites were collected and over 76% of these
represent new data. According to the number of sites inhabited by a single species, the most numerous
are: Cordulegaster bidentata Selys, 1843 (recorded at 26 sites), Cordulia aenea (Linnaeus, 1758)
(23 sites), Aeshna grandis (Linnaeus, 1758) (15 sites), Libellula quadrimaculata Linnaeus, 1758 (15
sites) and Enallagma cyathigerum (Charpentier, 1840) (14 sites). The following localities were inhabited
by the highest number of species: Orlovačko Lake (22 species), Gornje Bare Lake (20 species) and
Donje Bare Lake (19 species), where also the highest number of threatened and endangered species
was recorded. The most important recorded species were: Coenagrion scitulum (Rambur, 1842), Coenagrion
hastulatum (Charpentier, 1825), A. grandis, Aeshna juncea (Linnaeus, 1758), Somatochlora
metallica (Vander Linden, 1825), Cordulegaster heros Theischinger, 1979, C. bidentata and Sympetrum
flaveolum (Linnaeus, 1758). For relict species C. hastulatum and S. metallica, mountain lakes of Zelengora
Mt. are the only known habitat in Bosnia and Herzegovina so far. Additionally, these lakes were
determined as the most important habitats in the country for A. grandis and A. juncea. Among the
registered species, 30 species are included in the Red list of protected species in Republic of Srpska.
Additionally, we have recorded all three dragonfly species listed on the Red list of the Federation of
Bosnia and Herzegovina. Moreover, C. heros is listed in Annexes II and IV of the Habitats Directive of
the European Union and as vulnerable (VU) species on the Mediterranean Red list.
The role of hydroperiod as an environmental filter in structuring wetland assemblages is usually associated with trait selection in invertebrates. However, the effects of changes in the hydroperiod of non-permanent wetlands on invertebrate assemblages are still unclear, and few studies have assessed the functional structure of insect assemblages along the hydroperiod gradient. In this study, we investigated the effects of different hydroperiod lengths on the functional structure of Odonata assemblages in non-permanent wetlands (posteriorly classified as ‘short-’, ‘medium-’ and ‘long-hydroperiod’) in southern Brazil in 2013 and 2014. Biological traits related to life-history strategies in temporary waters were assessed according to seasonal patterns of occurrence of nymphal and adult stages of odonates. Following the rationale of an environmental filter produced by hydroperiod, we expected to find (1) higher functional diversity in longer hydroperiods and (2) trait-convergence patterns in odonate assemblages in shorter hydroperiods. Patterns of functional diversity were detected along the hydroperiod gradient. More specifically, higher functional dispersion was found in long-hydroperiod wetlands and trait-convergence patterns occurred in wetlands with shorter hydroperiods, supporting our general hypothesis. Odonate taxa with life-history traits associated with shorter life cycles predominated in medium- and short-hydroperiod wetlands. Our results thus suggest that more pronounced reductions in wetland hydroperiod length should produce odonate assemblages functionally more similar, and these results gain special importance as climate change scenarios indicate that the hydrology of wetlands will be affected by variation in rainfall regimes.
Since most aquatic insects remain below the surface of the water, they are rarely seen, so the high diversity of insects that inhabit freshwater ecosystems for at least part of their lives is poorly known by most people. Along with other small invertebrates, aquatic insects are an indispensable part of the food web and of nutrient cycling in freshwater ecosystems, and are an essential component of the diets of fish, amphibians, and many birds and mammals. This chapter focuses on the mayflies (Ephemeroptera), dragonflies and damselflies (Odonata), stoneflies (Plecoptera), bugs (Hemiptera-Heteroptera), hellgrammites (Megaloptera), spongillaflies (Neuroptera-Sisyridae, Nevrorthidae), and caddisflies (Trichoptera). A high diversity of aquatic insect species is of value to people for a variety of other reasons, but four are particularly important, including the role of insects in food webs, in biomonitoring, in fishing, and in control of n.
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.
Reflex immobilization in dragonfly larvae (Odonata)-Larv ae of 18 European Anisoptera species, mainly final instar, were studied with respect to reflex immobilization (RI). In Brachytron pratense, Somatochlora flavomaculata. S. meridionalis and S. metallica RI revealed an obligatory reaction to disturbance in the water. An additional 4 species exhibited facultative RI. All the other species reacted by rapid escape or became immobile for some time but only when they were brought on land. RI was released exclusively by tactile stimulation, especially by a firm grip on the thorax or abdomen, but not on the legs or antennae. In 3 Somatochlora spp. RI lasted 83, 87 and 154 s (median values) and varied between 5 and 679 s. The posture during RI, depicted in 10 line drawings, differed according to the species. In Somatochlora up to 3 postures were recorded: larvae either extended their legs laterally or folded them closely against the body or held them obliquely upwards. In individuals that were successively stimulated, the duration of RI tended to decrease, but not in all cases. Larvae of 2 Somatochlora alpestris. S. arctica and S. flavomaculata exhibited RI already in the first free-living larval instar. The adaptive value of RI which is assumed to be an antipredation strategy, is discussed with respect to the species, microhabitats and potential predators.
Filed guide and introduction to ecology and distribution of all Odonata recorded in Namibia up to 2007.
Understanding the ecology and evolution of morphological defences in animals and plants may help us to understand and protect biodiversity. Several species of dragonfly larvae express lateral and dorsal abdominal spines. In some species these spines seem to be fixed, and in others they are induced by the presence of predatory fish. Larger spines are adaptations to reduce predation risk by fish, but incur a cost because large spines are associated with a higher predation risk by invertebrate predators. The difference in vulnerability to different predators has the potential to affect temporal and spatial variation in the morphology of dragonfly larvae, and may ultimately result in speciation. Future focus on the joint evolution of correlated defensive traits such as morphology and behaviour and their plasticity might be fruitful for a better understanding of the development of animal diversity.
In this paper the trends of dragonfly expansions during the last decades in Germany and Europe are summarized. It is shown, that there is a general expansion of many species to the north: Mediterranean species expanded to Central and Northern Europe, whereas some African species expanded to Southern Europe, some are even new to the continent. In general this means an increase of biodiversity, but looking at the ecological effects, in the medium term a decrease can be expected for mooreland and alpine species. Dragonflies can be regarded as a good indicator group for climatic change. Already now in some areas or regions negative effects on waters bodies and their dragonfly communities can be observed and more will occur if e.g. temperature rises or precipitation decreases. The consequences for nature conservation strategies – such as the NATURA 2000 network – are outlined and the general need for monitoring programmes is emphasised.
For nine dragonfly species (five aeshnids and four libellulids) all previous and verifiable data are related to the vertical climate zones and nature regions of the western Peruvian Andes and the Peruvian Pacific coast. Climate changes due to the El Niño and La Niña phenomena, as well as the global climate change have an influence on the different natural regions and also restrict aquatic biotopes. These changes influence the dispersal and behavior of some dragonflies and concern also loss of habitats as well as alterations of biotic and abiotic factors at and in water.
However new waters and habitats also are formed in most nature regions. Specialists like Rhionaeschna peralta, a species of high mountain regions and the Puna, are not able to react to habitat losses by adaptation, while other species such as R. maita and R. marchali do colonize new habitats also in higher altitudes. While the here represented aeshnids change their distribution ranges within the vertical nature regions of the west Andes, this is suspected for three of the four libellulids (Orthemis ferruginea, O. discolor and Pantala flavescens) as latitudinally respectively longitudinally immigrations and expansions of their areals.
For all species discussed, a seasonally earlier flight beginning is detectable, but for no species an extension of their flight time.
Altogether, the above named three libellulid do react more flexibly and faster to the alterations by climate changes than the majority of the five aeshnid species.
The influence of increased UV-B and UV-A radiation possibly affects also the site occurrence of some species in high altitudes of the Andes.
Several of Anisoptera maintain their body temperature more constant than ambient temperature. Species that spend most of their active period on perches (perchers) and make only short flights thermoregulate heliothermically, primarily by means of postural adjustments. Some of the species that fly continuously (fliers) are endothermic regulators during flight. They control body temperature by: (1) controlling metabolic heat production by alternately using gliding or powered flight; (2) controlling heat loss by altering circulation between thorax and abdomen. Small fliers are unable to regulate well because they are subject to high rates of convective heat loss. Cooling constants, as defined by Newton's law of cooling, are related to thoracic weight by a negative power function over a wide size range. Cooling constants are higher in live dragonflies than in dead ones, a difference that is accentuated at high ambient temperatures. High cooling constants at high temperatures probably result from increased rates of circulation. Most fliers, and some large perchers, are able to elevate their body temperature by @'wing-whirring.@' In some species the rate of heat production apparently varies in response to ambient temperature. The body temperature at which flight begins after warm-up is positively correlated with body weight, probably because wing loading increases with increasing body size. The maximum voluntarily tolerated temperature and the threshold of heat torpor of several species were determined. Both parameters are correlated with habitat. The minimum temperature at which flight is possible is positively correlated with body weight and is slightly higher in tropical dragonflies than in temperate zone species. Body temperature is probably more variable relative to air temperature in tropical than in temperate zone species. The ability of dragonflies to maintain a relatively constant body temperature is determined primarily by climate, body size, and behavior.
Many populations are heterogeneous collections of different sizes or stages of conspecifics. Existing overlap indices do not account for the size-/stage-structured nature of these populations. In this paper I present new overlap indices that use information about the sizes of individuals that co-occur in time and space to predict the potential for interactions in size-structured guilds. An index of the opportunity for competition (IOC) calculates the frequency with which similar size classes of two species encounter each other, whereas an index of the opportunity for intraguild predation (IOP) calculates the frequency of encounters among disparate size classes of the same two species. To illustrate that these indices are more appropriate for size-structured populations than conventional indices, I calculated overlap, IOP, and IOC for all species pairs in a diverse assemblage of dragonfly larvae. The new indices revealed size-specific patterns of overlap that were not detected by the conventional index, including that (1) some species with high overlap values should interact mainly as competitors, others mainly as intraguild predators, and many as both competitors and predators, (2) subtle differences in phenology and/or size-specific shifts in habitat distribution can lead to the potential for asymmetric interspecific interactions, (3) some species with low pairwise IOP and IOC values are nonetheless vulnerable to the effects of diffuse competition or intraguild predation, (4) seasonal segregation reduces competitive overlap but at the same time increases the opportunity for intraguild predation. The indices are general in form and should be useful for analyzing distributional data for any size-structured assemblage in which the type and intensity of interaction varies as a function of relative size.
Pericnemis triangularis Laidlaw (Coenagrionidae), Indaeschna grubaueri (Foerster) (Aeshnidae) and Lyriothemis cleis Brauer (Libellulidae) are reported breeding in phytotelmata in the understorey of lowland mixed dipterocarp rainforest in Borneo. The pattern of utilization by the 3 spp. of phytotelmata of varying sizes is surveyed and observations are made in field and laboratory on larval behaviour, especially territoriality and intra- and interspecific predation, and developmental rates. Possible adaptations to special conditions found in phytotlmata, including low oxygen tensions, limited food and close proximity to other larvae are discussed. Descriptions are provided for the larvae of P. triangularis and I. grubaueri.
An updated classification and numbers of described genera and species (until 2010) are provided up to family level. We argue for conserving the family-group names Chlorocyphidae, Euphaeidae and Dicteriadidae, as well as retaining Epiophlebiidae in the suborder Anisozygoptera. Pseudostigmatidae and New World Protoneuridae are sunk in Coenagrionidae and Old World Protoneuridae in Platycnemididae. The families Amphipterygidae and Megapodagrionidae as traditionally recognized are not monophyletic, as may be the superfamily Calopterygoidea. The proposal to separate Chlorogomphidae, Cordulegastridae and Neopetaliidae from Libelluloidea in their own superfamily Cordulegastroidea is adopted. Macromiidae, Libellulidae and Synthemistidae and a restricted Corduliidae are accepted as families, but many genera of Libelluloidea are retained as incertae sedis at present. 5952 extant species in 652 genera have been described up to 2010. These are placed here in 30 families; recent proposals to separate additional families from Amphipterygidae and Megapodagrionidae have not yet been incorporated.
Although Europe is the cradle of dragonfly systematics and despite great progress in the last 2 decades, many issues in naming its species and understanding their evolutionary history remain unresolved. Given the public interest, conservation importance and scientific relevance of Odonata, it is time that remaining questions on the species’ status, names and affinities are settled. We review the extensive but fragmentary literature on the phylogeny, classification and taxonomy of European Odonata, providing summary phylogenies for well-studied groups and an ecological, biogeographic and evolutionary context where possible. Priorities for further taxonomic, phylogenetic and biogeographic research are listed and discussed. We predict that within a decade the phylogeny of all European species will be known.
Currently, many rare and endangered species occur in fragmented habitats. Habitat patch size is often used as an easily measured surrogate of habitat quality and local population size. We investigated whether habitat patch size affects the presence and density of larvae of the endangered dragonfly Aeshna viridis, which for a large part of their life history depend on the macrophyte Stratiotes aloides rosette. The study was performed in four populations, two from Finland and two from Latvia. Our main result was that density of A. viridis and patch occupation increased with area of S. aloides patch. The results may be due to larvae actively avoiding enemies (higher survival) and/or to the possibility that females laid higher number of eggs in the large S. aloides patches. Our results indicate that local abundance and persistence of A. viridis population may depend on the few, large S. aloides patches rather than several small patches of equal total area.
Recent studies show a remarkable scarcity of faunal exchange events between Australia and New Guinea in the Pleistocene despite the presence of a broad land connection for long periods. This is attributed to unfavourable conditions in the connecting area associated with the long established northern Australian Monsoon Climate. This would be expected to have impacted strongly on freshwater faunas with the following results: (1) limited overlap in species, (2) most higher taxonomic groups present in both areas sharing no species or even genera and (3) shared species dominated by lentic species with high dispersal capacity. Testing these predictions for dragonflies showed the turnover in the family, genus and species composition between Australia and New Guinea to be higher than anywhere in the world with only 50% of families and subfamilies, 33% of the genera and 8% of the species being shared. Only one of the 53 shared species favors lotic waters compared with 64% of the 652 combined Australian–New Guinean species. These results agree with our predictions and indicate that the dragonfly fauna of Australia and New Guinea have effectively been separated during the Pleistocene probably due to the prolonged unfavourable climatic conditions in the intervening areas.
Compared to other insect groups, libellulids have a rather high mean number of ovarioles. In addition, the mean ovariole diameter differs greatly between and within species. In general, 2 different types of ovariole arrangement exist: (1) all developing oocytes mature and equal in size; in some species without, and in others with, surrounding connective tissue and (2) oocytes displaying gradual maturation, with only the outermost ovarioles mature. These differences have ecological consequences: the first arrangement occurs in spp. that have stepwise egg production. These spp. will lay one or more clutches, after which an interclutch interval of ovariole regrowth follows. Spp. with the second arrangement have continuous egg production and are able to lay at least some eggs all the time, reducing the length of interclutch intervals. However, no direct connection between mate-guarding strategies and ovariole arrangements can be seen. Nevertheless, it is believed that the process of ovariole maturation differs between these groups. It is concluded that ovary morphology in libellulids may exhibit evolutionary fixed traits, although the whole picture still remains complex. The ovariole arrangement may have a crucial impact on the reproductive ecology of the species.
1. Larvae of Macromia illinoiensis Walsh are often colonised by the zebra mussel, Dreissena polymorpha Pallas, a recent invader to North America. To determine how mussel attachment affects an individual's foraging behaviour, we quantified capture of Hexagenia limbata Hexes mayfly prey and the distance moved by newly-molted final instars before and after an individual's colonisation with zebra mussels.
2. In night trials, larvae sprawled above the sand, and caught more mayflies than individuals in daytime trials, but the estimated distance travelled did not differ. When resting under a layer of sand with only its eyes exposed during the day, an individual could capture a mayfly prey using a sit-and-wait ambush strategy. When sprawled above the sand, some larvae caught prey that rested on their legs.
3. When mussel-free, individuals captured more prey than they did when carrying zebra mussels, although mussel attachment per se did not affect the estimated distance that a larva moved.
4. During day trials, but not night ones, the increasing mussel load of colonised individuals decreased prey capture and the distance moved in an apparent step-wise function. Although the number of mussels carried did not differ, night foragers carried a heavier load. Independent of time of the day, the distance an individual travelled when mussel-free was predictive of the number of prey it caught when colonised, suggesting that the greater general activity of some individuals helped mitigate negative effects that mussel attachment had on prey capture.
5. Our results add to a growing number of negative effects of zebra mussel colonisation on sprawling and hiding dragonfly larvae. Although the impact of these costs on dragonfly populations remains to be determined, a decrease in this guild of predators whose life cycle spans aquatic and terrestrial habitats might have cascading effects across ecosystems.
The oxygen tolerance of aquatic insect larvae with tracheal gills or comparable respiratory mechanisms can be used for bioindication of limiting minimal contents of dissolved oxygen. An analysis of the community permits the retrospective evaluation of critical values. Specific lethal oxygen concentrations and their temperature dependence are given for 22 species. Above a critical temperature, Tc, and specific LC sub(50) increases exponentially. Tc is considerably lower with cold-adapted than with warm-adapted species. The values of oxygen tolerance determined demonstrate that restriction of a species to running water is not determined by oxygen level, temperature and water flow only.
Literature and personal information on the distribution of I. hastata and other odon. spp. in the Azores is reported. I. hastata and I. pumilio are recorded for the first time from the islands of Corvo and Sao Jorge, respectively. I. hastata appears the most common and abundant sp. and its population is formed by only ♀♀ (no ♂♂ were ever recorded). The asexual reproduction of these populations was demonstrated by means of laboratory rearing during several generations. The dispersal ability of this sp. and the possible origin of parthenogenesis after its colonisation of the Azores are briefly discussed. The possible causes of threat are identified and the need for conservation measures is outlined.
Mortality during emergence in two species of dragonfly, Onychogomphus uncatus and Orthetrum coerulescens, was studied at a Mediterranean irrigation canal in France. Overall mortality was 5.2% (n =1901) and 5.7% (n =611), respectively. Predation was low in both species. The prime cause of mortality was incomplete ecdysis resulting from different factors among which heavy wind was the most important in O. coerulescens and lack of suitable emergence supports in O. uncatus. Besides data on mortality the emergence curves of both species are provided.
In order to describe the assemblages of adult Odonata of running waters in the Upper Guinean forest, 36 sites in Liberia and Ghana were analysed using Non-metric Multidimensional Scaling. Five groups were identified, which correspond with different assemblages in the sequence of habitats from small streams to large rivers. Taxonomically related species demonstrate distinct ecological segregation within this gradient, occupying different sections of running waters, or different microhabitats therein. The balance of sun and shade, resulting from a varying degree of habitat openness, is thought to be an important factor in habitat selection, but it is difficult to distinguish from other factors associated with stream size. Anthropogenic opening of stream habitat (e.g. by deforestation or damming) can downscale the present fauna, i.e. result in the invasion of species of downstream habitats (more open) and the disappearance of upstream (dense forest) species.
A brief account is presented of mass dragonfly migrations observed previously in Russia and West Siberia in particular. A mass migration in Libellula quadrimaculata is described in detail. It occurred on 1 July 1981 in the south-western part of the West Siberian Plain in the valley of the Ishym River. From 1968 to 2008 we studied population dynamics, spatial distribution and displacement in dragonflies in the West Siberian forest-steppe. Detailed research was conducted at the biological station of the Russian Academy of Sciences near the Chany Lake. Mass migrations in L. quadrimaculata and some Leucorrhinia spp. followed situations with an extremely high population density and local mass aggregations and occurred with a period of c.10 years, correlated with fluctuation of water level in the region, mainly in the south. It is suggested that dragonfly migration not only optimizes their population size but increases the rate of transport of chemical elements and organic matter to dry land from eutrophic water bodies, which increases the importance of dragonflies to ecosystems at large.
Lestes macrostigma is a stenotopic dragonfly species of Western Palaearctic distribution that has high conservation status almost throughout its range. It inhabits mainly brackish water with a typical plant species, sea club-rush Bolboschoenus maritimus. Due to the absence of special investigations, the nature of this insect–plant association is not clearly understood, but it was supposed that L. macrostigma prefers egg laying in B. maritimus. In this paper we describe the ovipositor morphology and the egg laying behaviour of L. macrostigma in detail. The cutting ovipositor reveals several morphological peculiarities recorded previously in other lestids. The internal surface of the valves reveals rich microsculpture. Numerous single and clustered sensilla of different shape are found on the valves and styli and are probably involved in oviposition–plant recognition by females and/or in production of an egg clutch. Oviposition is carried out in stems of B. maritimus and Juncus maritimus. An egg clutch consists of a row of single eggs deposited in line along the long axis of a plant. Results are discussed in the light of possible morphological and behavioural adaptation to oviposition into specific plant substrates.
In the tropical Indian Ocean, the Maldive Islands lack surface freshwater, so are unsuitable for dragonfly reproduction. Nevertheless, millions of dragonflies (Insecta, Odonata; mostly globe skimmer, Pantala flavescens) appear suddenly every year starting in October. Arrival dates in the Maldives and India demonstrate that the dragonflies travel from southern India, a distance of some 5001000 km. Dates of arrival and occurrence coincide with the southward passage of the Inter-tropical Convergence Zone (ITCZ). Circumstantial evidence suggests that the dragonflies fly with north-easterly tail winds, within and behind the ITCZ, at altitudes over 1000 m. It is proposed that this massive movement of dragonflies is part of an annual migration across the western Indian Ocean from India to East Africa. Arrival dates in the Seychelles support this hypothesis. Dragonflies also appear (in smaller numbers) in the Maldives in May, with the onset of the southwest monsoon, suggesting a possible return migration from Africa. These proposed migrations of dragonflies, regularly crossing 3500 km or more of open ocean, were previously unknown. It is known that these dragonflies exploit ephemeral rain pools for reproduction; the monsoons and ITCZ bring not only alternating, seasonal rains to India and Africa, but also appropriate winds for dragonflies to follow those rains. Several bird species migrate from India across the western Indian Ocean to wintering grounds in Africa. They do so at the same time as the dragonflies, presumably taking advantage of the same seasonal tail winds. Many of these birds also eat dragonflies; the possible significance of this was not previously appreciated.
This is the first continent-wide overview of insect diversity and status sufficiently fine-scaled to be used in conservation planning. We analyze patterns of richness and the conservation status of African dragonflies and damselflies (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 dragonfly 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.
Nymphs of the dragonfly, Erythrodiplax berenice, are common on rocky mangrove flats in the lower Florida Keys at salinities of 36-48 ppt. Erythrodiplax berenice appears to be the only truly marine odonate, and the nymphs are able to tolerate wide variations in salinity. Hemolymph osmotic pressures for nymphs freshly captured in seawater or held in artificial seawater were 358-412 mOsm. There was little further variation at salinities between freshwater and 260% seawater (2,612 mOsm). In 300% seawater, hemolymph osmotic pressure rapidly increases to about 1,000 mOsm, and death ensues. The transition point between hyper- and hypoosmotic regulation occurred at approximately 350 mOsm seawater. Freshwater- and seawater-acclimated nymphs differ little in body water content (about 80%), but Na content is elevated from 50 to 89 Mmol/g wet wt, respectively. In 35 ppt seawater, Na influx and efflux were approximately balanced near 400 μmol/100g·h. In freshwater (1 mM Na), these fluxes decline to about 10 μmol/100g·h. The time for complete turnover of body Na increases from 0.9 day in seawater to 21 days in freshwater. On rapid transfer from water of 470 mM Na to water of 1 mM Na, the Na efflux in 1 mM was only slightly higher than expected for freshwater-acclimated nymphs. At a water Na level of 0.25 mM, Na efflux increases greatly, and there is a large net loss of Na. Water influxes of nymphs in distilled water or 35 ppt seawater were similar (33 and 40 μ1/g·h, respectively); complete turnover of body water occurs in about 0.8 day. Nymphs of E. berenice rival the better-known dipterans in osmoregulatory abilities and should be studied further to compare mechanisms of hypoosmotic regulation that have presumably evolved independently in these two orders.
Water mites are ubiquitous parasites in freshwater ecosystems. The interaction between water mites and aquatic insects has been scarcely studied from an evolutionary ecology viewpoint. Host finding is an important feature of the water mite's life cycle. The host finding success is suggested to depend upon host behaviour and quality. Water mite parasitism lowers host fitness via different routes: by draining nutrients hosts can suffer from decreased fecundity, increased mortality etc. Host sexes and closely related species are affected differently. Recent studies on host fitness, whilst taking the parasite behaviour into account, revealed results contrasting older studies where knowledge of the parasites' life cycle was absent. The potential for coevolution is discussed. For exploring evolutionary trends a water mite phylogeny is needed. Water mite-aquatic insect interactions can be assumed to provide excellent conditions to conduct experimental studies on direct and indirect effects of multiple natural enemies in freshwater ecosystems.
In the absence of weeds, Notonecta exhibited a Type 2 functional response, but this changed to a Type 3 response as weed density increased. -from Author
Enallagma hageni, Lestes disjunctus, Sympetrum costiferum, Sympetrum danae, Sympetrum internum, and Sympetrum obtrusum were observed emerging from brackish pools with an overall salinity range of 6.0-17.3 ppt in three saltmarshes in Gaspé, Quebec. Lestes congener, Libellula quadrimaculata, and species of Sympetrum were prominent among the larvae in these pools.
By analysis of slow-motion films of dragonflies and damselflies in free flight, released in front of a backdrop or startled during flight, the following flight parameters have been quantified for symmetrical manoeuvres: wingbeat frequency, relative durations of up-and downstroke, phase relationships of the beats of fore-and hindwings, stroke amplitude, mean stroke velocity, flight velocity, nondimensional flight velocity, advance ratio, acceleration, angle of attack and stroke plane.
The wingbeat frequencies are higher in the smaller species and in those with relatively large wing loading. As a rule, Zygoptera have a wingbeat frequency only half that of Anisoptera. The stroke amplitude is almost always much larger in Zygoptera than in Anisoptera, which have a greater range of variation in this respect. Stroke velocity is higher in Anisoptera than in Zygoptera; it is also higher in the more elaborate flight manoeuvres than in others. The calculated stroke velocities resemble those actually measured.
Anisoptera fly more rapidly than Zygoptera. With respect to the nondimensional flight velocities, it is notable that although the values for Anisoptera are higher than those for Zygoptera, they are exceeded by the Calopterygidae; the latter can fold their wings back during rapid forward flight and shoot away, as in the ‘ballistic’ flight of small songbirds. However, the advance ratio is higher in Anisoptera than in Calopterygidae.
Anisoptera also perform better than Zygoptera with respect to acceleration. Three categories of phase relationships between the beats of the fore-and hindwings are established: counterstroking, phase-shifted stroking and parallel stroking. Counterstroking produces uniform flight, whereas the flight produced by phase-shifted and, in particular, parallel stroking is irregular. The angles of attack of the wings are shown to be associated with particular flight manoeuvres, as are the stroke planes. Flight manoeuvres are discussed without drawing detailed aerodynamic conclusions. The flight of Anisoptera is compared with that of Zygoptera.
Cannibalism is a likely mechanism of population regulation in dragonflies that inhabit fish-free temporary ponds. I tested for density-dependent effects of cannibalism on survival and size structure of larvae of the dragonfly Tramea carolina in two short-term experiments in replicated artificial ponds. I was able to distinguish mortality due to cannabalism from other sources of mortality by preventing some populations from engaging in cannibalism. The first experiment included two density levels and the presence or absence of cannabilism in a factorial design. The no-cannibalism treatment was achieved by removing the labial palps from all individuals to prevent them from grasping large prey. T. carolina survived significantly better in the no-cannibalism populations at both densities, and this difference was greater at high density than low density, indicating that the proportion cannibalized was density dependent. A second experiment explored the form of the density-dependent cannibalism curve over a broad range of density. The results were adequately fitby a predator-prey model incorporating size structure, so that not all members of the population were vulnerable to cannibalism. In both experiments the survival of only the smaller instars was reduced, suggesting that cannibalism may reduce variation in the size distributions of dragonfly populations and contribute to emergence synchrony. The results demonstrated that cannibalism was strongly density dependent and may contribute to population regulation of dragonflies in temporary ponds.
The foraging behaviours and vulnerabilities to predation of larvae of four odonate species were studied in the laboratory. Predation by large Aeshna juncea larvae was compared in the presence and absence of zooplankton, and with odonate species presented individually and together. The large larvae of A. juncea showed high foraging activity irrespective of odonate prey treatment. Predation by A. juncea was lowest on Coenagrion hastulatum larvae, which had a "sit and wait" foraging mode, and highest on actively foraging Leucorrhinia dubia larvae. However, both activity and predation on L. dubia were lower in the presence of zooplankton and large A. juncea, perhaps reflecting avoidance of predation risk when foraging. Small larvae of A. juncea showed about the same foraging activity and vulnerability to predation as did L. dubia. Cordulia aenea larvae had intermediate foraging activity levels which were lower in the presence of zooplankton, but suffered high predation, indicating a low odonate predator escape ability. When all four odonate prey larvae were presented together, C. hastulatum and C. aenea experienced the lowest and highest predation, respectively, whereas predation on A. juncea and L. dubia was intermediate. About 25% of the large A. juncea larvae from field populations had preyed on L. dubia and C. hastulatum. The low abundances of A. juncea and C. aenea in the study ponds may explain why these species were not found in the fecal pellets of large A. juncea larvae. The results show that large A. juncea larvae frequently prey on odonate larvae. The intensity of this predation depends on the foraging behaviour of prey odonate larvae. However, the presence of alternative prey (zooplankton) and escape ability of the odonate larvae may also be important.
(1) Larval dragonfly populations were manipulated in large littoral zone enclosures to determine the importance of inter-odonate interactions and the effects of dragonflies on their prey. (2) Initial densities of early emerging odonate cohorts were about six times greater in one group of pens than in others. When initial densities were low, survivorship was higher and growth appeared to be faster than when initial densities were high. Highly significant differences of early species densities were maintained between treatment pens during the 6-month experimental period. (3) Early emerging odonates had a highly significant influence on the abundance of the smaller, late emerging odonates, indicating a strong interaction between odonate species. The interaction appeared to be due to predation by large odonates on small odonates. This is interpreted as an extreme form of interference competition which plays an important role in odonate population regulation. (4) Although there was a large treatment bias in prey species abundance, the results indicate that abundance of early emerging odonates plays some role in prey (especially Tanypodinae) abundance. (5) It is suggested that the primary determinant of community structure and production is an interaction between refuge level and predation rate. It is necessary for prey to be turning over at an unusually high rate and it is possible that odonates function in stimulating the rate of prey production.
We undertook a comprehensive morphological and molecular phylogenetic analysis of dragonfly phylogeny, examining both extant and fossil lineages in simultaneous analyses. The legitimacy of higher-level family groups and the phylogenetic relationship between families were tested. Thirteen families were supported as monophyletic (Aeshnidae, Calopterygidae, Chlorocyphidae, Euphaeidae, Gomphidae, Isostictidae, Lestidae, Libellulidae, Petaluridae, Platystictidae, Polythoridae, Pseudostigmatidae and Synthemistidae) and eight as non-monophyletic (Amphipterygidae, Coenagrionidae, Corduliidae, Megapodagrionidae, Protoneuridae and Synlestidae), although Perilestidae and Platycnemididae were recovered as monophyletic under Bayesian analyses. Nine families were represented by one species, thus monophyly was not tested (Epiophlebiidae, Austropetaliidae, Chlorogomphidae, Cordulegastridae, Macromiidae, Chorismagrionidae, Diphlebiidae, Lestoideidae and Pseudolestidae). Epiprocta and Zygoptera were recovered as monophyletic. Ditaxinerua is supported as the sister lineage to Odonata, Epiophlebiidae and the lestid-like damselflies are sister to the Epiprocta and Zygoptera, respectively. Austropetaliidae + Aeshnidae is the sister lineage to the remaining Anisoptera. Tarsophlebia's placement as sister to Epiprocta or as sister to Epiprocta + Zygoptera was not resolved. Refinements are made to the current classification. Fossil taxa did not seem to provide signals crucial to recovering a robust phylogeny, but were critical to understanding the evolution of key morphological features associated with flight. Characters associated with wing structure were optimized revealing two wing character complexes: the pterostigma–nodal brace complex and the costal wing base & costal–ScP junction complex. In turn, these two complexes appear to be associated; the pterostigma–nodal brace complex allowing for further modification of the wing characters comprised within the costal wing base & costal–ScP junction complex leading the modern odonate wing.
© The Willi Hennig Society 2008.