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Simple Summary: Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in freshwater and brackish water habitats in northern Sri Lanka and other parts of the world. Dengue vector control in the form of source reduction targets only freshwater habitats. Since biological control is a component of integrated vector control, the present study investigated the predatory efficacy of dragonfly nymphs and damselfly nymphs that develop in both freshwater and brackish water habitats targeting Ae. aegypti larval forms in laboratory conditions. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum were found to be the most effective among six different species tested in both freshwater and brackish water conditions. The findings suggest that these odonate nymphs could serve as biological control agents to target preimaginal forms of dengue vectors under varying salinity conditions. Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in brackish water (BW). However, dengue vector control exclusively targets freshwater (FW) habitats. The present study evaluated the predatory efficacy of nymphal odonates that can develop in both FW and BW. Nymphs of three damselfly and three dragonfly species from FW and BW habitats were identified and acclimatized to FW (<0.5 gL−1 salt) and BW (10 gL−1 salt) mesocosm conditions. The experiment was repeated nine times with nine different individual predators per species under both salinity conditions. One hundred L3 Ae. aegypti from FW and BW laboratory colonies were introduced to determine the predatory rate (PR) and clearance rate (CR) after 24, 48, and 72 h, and one hundred L3 larvae were introduced every 24 h. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum showed the highest PR and CR under both rearing conditions at all times. However, damselfly and dragonfly nymphs significantly (p < 0.05) differed in their CR under both FW and BW conditions. Thus, all six odonate species have predatory potential and this suggests that they could be used as biological control agents to eliminate preimaginal stages of Ae. aegypti developing in both FW and BW habitats. [ABSTRACT FROM AUTHOR]

Simple Summary: Chironomids are probably the most speciose family among aquatic insects, colonizing almost all freshwater habitats. The emphasis of the present research is on: (1) taxonomic composition as the most efficient tool for describing biodiversity in natural habitats; and (2) natural habitat type as the most important factor able to explain different chironomid assemblages. This is because the habitat type summarizes a combination of different biotic and abiotic factors present at each site, determining taxa assemblages. Different spatial scales are often proposed as relevant factors for modeling community composition, but with regard to chironomids, spatial factors act only at a small scale, while environmental factors are the most important determinants for species distribution. Factors responsible for species distribution of benthic macroinvertebrates, including responses at different spatial scales, have been previously investigated. The aim of the present research was to review the most relevant factors explaining chironomid species distribution focusing on factors operating at different spatial scales, such as latitude, longitude, altitude, substrate, salinity, water temperature, current velocity, conductivity, acidity, dissolved oxygen, nutrient content etc. acting at regional levels and at a large or small water basin level. Data including chironomid species abundances from different lentic and lotic waters in Italy and other surrounding countries were analyzed using partial canonical correspondence analysis (pCCA) and multiple discriminant analysis (DISCR). Spatial analyses, including univariate Moran's I correlograms, multivariate Mantel correlograms and Moran's eigenvector maps (MEMs), were thereafter carried out. The results showed that habitat type, including different types of lotic waters (i.e., kryal, crenal, rhithral, potamal) and different lake types (i.e., littoral, sublittoral, profundal zones), is the most significant factor separating chironomid assemblages, while spatial factors act only as indirect influencers. [ABSTRACT FROM AUTHOR]

Simple Summary: This study is a case study on the diversity patterns, population aspects, emergence and ecological drivers of the so-far poorly studied water beetle family Scirtidae. Although they can be very abundant in karstic lotic freshwater habitats, there are still insufficient data on their biology and ecology. The family was studied over a period of 15 years in specific lotic habitats of springs and tufa barriers in the karst freshwater ecosystem of Plitvice Lakes NP, Croatia. Scirtidae showed a longitudinal gradient, as the genus Elodes was recorded only in the spring area, while the genus Hydrocyphon was found only in downstream sites with tufa barriers. Their emergence showed a seasonal character, with males dominating earlier in the season and females appearing later. The type of substrate determined their distribution, with a preference for bryophytes. Their abundance and emergence were primarily determined according to the parameters that showed the greatest fluctuations over the 15-year period: water discharge, water temperature and oxygen saturation. Compared to previous results from similar studies on other insect groups, our results clearly show the high potential of the family Scirtidae as indicators of habitat quality. Due to ongoing changes and a decline in biodiversity, science today should rely on long-term species-based ecological studies. We have conducted a long-term ecological dynamics study on the water beetle family Scirtidae, which, although it is very abundant in benthic communities, is still poorly studied. The main objective of this study was to investigate the population aspects (composition, diversity, sex ratio) and ecological aspects (emergence patterns, seasonal dynamics and preferences for environmental factors) of the family Scirtidae over 15 years in Plitvice Lakes NP, Croatia. The study was conducted at three sites and in five different substrate types. A total of three taxa with different distributions were recorded in the study area: Hydrocyphon novaki and H. deflexicollis on the tufa barriers and the Elodes sp. in the spring area. The sex ratio was in favour of males in spring and early summer, while it shifted in favour of females towards the end of autumn. The abundance and emergence of the family were primarily determined by the environmental parameters which showed the greatest fluctuations over a period of 15 years: water temperature, water discharge and oxygen saturation. Our results clearly show that Scirtidae can be used as indicators of stream zonation and habitat quality. Based on the methodology and the results of this study, we conclude that Scirtidae should be used in future monitoring and protection measures in karst freshwater habitats in southeastern Europe. [ABSTRACT FROM AUTHOR]

Simple Summary: Aquatic habitats in urban areas are often important for conservation of local biodiversity. Although Odonata are widely used as ecological indicators of freshwater habitat integrity and health, our understanding and knowledge of their ecological requirements in urban landscapes is not yet complete. Therefore, the taxonomic and functional diversity of Odonata assemblages was analyzed in a semi-natural wetland in the Croatian capital in the summers of 2020 and 2023. The two main habitat types, anthropogenically disturbed and natural oxbow lakes, mostly had comparable assemblage metrics. However, we found significant differences in relation to the time scale, where most metrics were lower in 2023, indicating the negative impact of extreme climate events (including droughts) that occurred in this region after 2020. As even some species of conservation concern were detected, our results indicate that semi-natural urban wetlands, especially natural oxbow lakes, have great potential to function as good habitats for Odonata. As the human population in urban areas is continuously growing, urbanization is one of the greatest threats to biodiversity. To mitigate the negative effects, the inclusion of blue zones (aquatic habitats) in modern urban development practices is strongly recommended, as they could be beneficial for the local biodiversity conservation. Odonata are a flagship group and are widely used in freshwater conservation as ecological indicators of habitat integrity and health. However, our understanding of their ecological requirements in urban landscapes is not yet complete. Therefore, we analyzed the taxonomic and functional diversity of Odonata in a semi-natural wetland in the Croatian capital. This study was conducted in the summers of 2020 and 2023. Most taxonomic and functional assemblage metrics were comparable between the two main habitat types, anthropogenically disturbed and natural oxbow lakes. However, significant differences were found in relation to the time scale, where most metrics were lower in 2023, indicating the negative impact of extreme climate events (including droughts) that occurred in this region after 2020. With 19 species recorded, our results indicate that semi-natural urban wetlands, especially natural oxbow lakes, have great potential to function as good habitats for Odonata, where even some species of conservation concern were detected. When developing landscape management plans in urban areas, it is essential to consider the importance of habitat heterogeneity in terms of good structure of aquatic macrophytes (presence of submerged, emergent and floating vegetation), which would ensure the most suitable habitat conditions for local Odonata species. [ABSTRACT FROM AUTHOR]

Simple Summary: The Chironomidae family stands out as the most widely dispersed and often the most abundant insect group in freshwater habitats. The significance of color patterns is well-recognized, as they fulfill multiple roles such as communication, camouflage, mimicking, and defense. However, the taxonomy of species within this family, relying on color patterns, as well as the shape and distribution of thoracic pigmentation, wing markings, and leg pigmentation, remains controversial and unstable. Here, we conduct a comprehensive review on the taxonomy of a Chiromidae genus, Stictochironomus from China, which is characterized by a combination of distinctive wing and leg markings. Using DNA barcode data and morphological data, two new species to science from China are well supported. Species delimitation analyses performed with distance-based approach and coalescent tree-based approaches also support them as distinct species. Therefore, color patterns should be a good diagnostic characteristic for species delimitation in Stictochironomus. Furthermore, we provided an up-to-date taxonomic key for male adults of Stictochironomus from China. The genus Stictochironomus (Diptera: Chironomidae) has an almost worldwide distribution, with more than 30 species. However, species delimitation and identification based on the markings on the wings and legs are controversial and uncertain. In this study, we focused on color patterns to review the adults of the genus from China, and two new species (S. trifuscipes sp. nov. and S. quadrimaculatus sp. nov.) are described and figured. DNA barcodes can accurately separate the two new species with specific color patterns. However, heterospecific individuals form a monophyletic cluster in the phylogeny tree. For example, S. maculipennis (Meigen) and S. pictulus (Meigen), which have a lower interspecific genetic divergence, form a single clade. Sequences with the same species name but with high intraspecific distance form more than one phylogenetic clade, such as S. sticticus (Fabricius) of three clades, S. pictulus of four clades, S. akizukii (Tokunaga) and S. juncaii Qi, Shi, and Wang of two clades, might have potential cryptic species diversity. Species delimitation analysis using ASAP, PTP, and GMYC clearly delineated them as separate species. Consequently, color patterns are a good diagnostic characteristic for species delimitation in Stictochironomus. The distance-based analysis shows that a threshold of 4.5–7.7% is appropriate for species delimitation in Stictochironomus. Additionally, an updated key including color pattern variation for male adults of known Stictochironomus species from China is provided. [ABSTRACT FROM AUTHOR]

Simple Summary: Chironomids or non-biting midges, which are a diverse group of insects, can be found in various freshwater habitats. Plitvice Lakes National Park in Croatia, known for its rich freshwater environment, is an ideal location for studying these insects in the long term. Our study aimed to uncover the types of chironomids present, understand their seasonal patterns, and identify factors influencing their emergence in Plitvice Lakes. For 14 years, we set up traps at a tufa barrier within the National Park to collect chironomids on a monthly basis. During this time, we discovered more than 80 chironomid species. Interestingly, we found that water temperature and organic matter were the key factors affecting chironomid emergence in this area. Toward the end of our study, we noticed that the time these insects spent in flight seemed to increase. Although we have not yet found statistical significance, this could be related to the higher water temperatures in winter. In summary, our research sheds light on the fascinating world of chironomids in Plitvice Lakes, highlighting their diversity, seasonal patterns and the environmental factors influencing their behavior. Chironomids are found in all types of freshwater habitats; they are a ubiquitous and highly diverse group of aquatic insects. Plitvice Lakes National Park is the oldest and largest national park in Croatia and consists of numerous and diverse freshwater habitats, making the area an ideal location for long-term research into the chironomid emergence patterns and phenology. The main objectives of this study were to identify the composition of the chironomid community, determine the phenology of the identified species, and assess the main factors influencing their emergence in Plitvice Lakes. During 14 years of research, more than 13,000 chironomids belonging to more than 80 species were recorded. The most abundant species was found to be Parametriocnemus stylatus. The highest abundance of chironomids was recorded in lotic habitats with faster water current over substrates of moss and algae and pebbles. Water temperature and the availability of organic matter were found to be the main factors that drive chironomid emergence at the tufa barrier studied. In the last years of this study, a prolonged flight period was observed. Although this is not statistically significant (at this stage of the study), it could be due to a higher water temperature in winter. [ABSTRACT FROM AUTHOR]

Simple Summary: True bugs (Hemiptera: Heteroptera) of the infraorder Gerromorpha are known as semiaquatic bugs due to their ability to walk on the surface of water. Veliidae is the most diverse family of semiaquatic bugs, including six subfamilies, 61 genera, and more than 960 described species. The genus Paravelia Breddin, 1898 (Veliidae: Veliinae), or broad-shouldered water-striders, occurs in a wide variety of lentic and lotic freshwater habitats, and is represented in Brazil by 38 species. Although the diversity of Paravelia in the country is relatively well known, eight states remain with no records of the genus. Aiming to fill these gaps, several expeditions were carried out between 2018 and 2021. As a result, a new species is described from Pernambuco State, three species are recorded for the first time in Ceará, Pernambuco and Piauí states, and an updated key to the Brazilian species of the genus is provided. The broad-shouldered water-strider genus Paravelia Breddin, 1898 (Hemiptera: Heteroptera: Veliidae: Veliinae) is currently represented in Brazil by 38 species. Although the diversity of the genus in the country is relatively well known, eight states remain with no records of any species: Acre, Alagoas, Ceará (CE), Paraíba, Paraná, Pernambuco (PE), Piauí (PI), and Tocantins. Aiming to fill these gaps, several expeditions were carried out at conservation areas of the Caatinga biome between 2018 and 2021: Aiuaba Ecological Station (CE), Catimbau National Park (PE), and Serra das Confusões National Park (PI). Paravelia luisi sp. nov., a new species from PE, is described and illustrated. In addition, new records of P. bilobata Rodrigues, Moreira, Nieser, Chen & Melo, 2014, P. digitata Rodrigues & Moreira, 2016, and P. nieseri Moreira & Barbosa, 2012, and an updated key to the Brazilian species of Paravelia are provided. This study increases the number of species of Paravelia known in Brazil to 39 and provides the first records of the genus from three states: PE, with two species, and CE and PI, with one species each. [ABSTRACT FROM AUTHOR]

Simple Summary: Mayflies are among the most susceptible insect groups in mountain freshwater bodies, where they are facing different environmental threats, resulting in loss of species assemblage and diversity. In this study, we described the structure of the community of mayflies in three different streams in the dry-hot valley of Baima Snow Mountain, China, and assessed the potential effect of environmental variation over this specific group of insects. The results showed clear shifts in the community structure of mayflies between the streams. From the study area, 18 taxa were identified, with Baetis sp. and Baetiella marginata being the most prevalent. Overall, the Yeri stream hosted suitable habitats for several taxa of mayflies than the other two streams, as demonstrated by the highest species richness and diversity. Moreover, there was high environmental heterogeneity between the streams, in turn influencing the species of mayflies, particularly in the Sharong stream. As expected, the results also showed that some of the environmental factors such as altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Mountain freshwater ecosystems are threatened all over the world by a range of human-induced stresses, ensuing in a rapid loss of habitats and species diversity. Many macroinvertebrates are reactive to habitat disturbance, and mayflies (Ephemeroptera) are amongst the most sensitive groups. Despite they are susceptible to environmental deviation, knowledge concerning their species richness and diversity is still unknown in remote areas. The objectives of this study were to (1) investigate the mayfly species assemblage and community composition along different mountain streams and assess potential differences, and (2) identify the environmental variation and its influence on the structure of mayfly communities within such freshwater systems. We collected biological and environmental data from 35 sites situated along elevation gradients in the Baima Snow Mountain, northwest Yunnan, China. Multivariate analyses were performed on the environmental variables and the mayfly species composition, as well as on richness and diversity indices. We found that the community composition of mayflies was different across all three watercourses. Among the 18 Ephemeroptera taxa identified, Baetis sp. and Baetiella marginata were highly dominant, accounting for over 50% of the dissimilarity of each stream. In terms of species assemblages, almost all sites in the Yeri stream hosted good-quality habitats for several mayfly species, as reflected by the highest species richness. The Benzilan stream followed, whereas the Sharong stream showed relatively low mayfly assemblage. This variation was explained by the high environmental heterogeneity between the three watercourses. In particular, the RDA model revealed that among the different environmental factors analyzed, altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Moreover, the altitude alone explained 17.74% of the variation, and in-depth analysis confirmed its significant effect on diversity indices. Further research should focus on evaluating the scale of threats to this important group of insects in the mountain freshwater ecosystem, particularly the impact of human-induced disturbances such as land use/landcover alterations. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, we aimed to evaluate the relationship between human transformations of land use/land cover and adult dragonfly diversity. Based on previous studies, we assumed that with increasing rates of environmental degradation and declining levels of naturalness, the representation of species with high conservation value would significantly decrease, which, however, would not affect the regional alpha diversity. Our results have shown that species richness did not correspond to habitat naturalness, but the occurrence of endangered species was significantly positively correlated with increasing naturalness; thus, habitat degradation and/or the level of naturalness significantly affected species composition, while species richness remained unchanged. Based on our analyses, it is evident that most natural areas, and therefore the least affected areas, provide suitable conditions for the largest number of endangered species. This research extends our knowledge about the impact of human activities, especially the conversion and degradation of habitats, on the composition of odonates and freshwater animals at the regional scale. Understanding the impact of the changing proportion of land-use patterns on species diversity is a critical issue in conservation biology, and odonates are good bioindicators of these environmental changes. Some freshwater ecosystems that have been modified due to human activities can serve as important secondary habitats for odonate assemblages; however, the majority of studies addressing the value of secondary habitats in industrial and urban areas for adult dragonfly diversity have been limited to the local scale, and the value of such habitats for gamma diversity is still unclear. The aim of this study was to determine the relationship between human transformations of land use/land cover and dragonfly diversity. We interpolated the information based on dragonfly occurrence per grid cell and land cover data, indicating naturalness and degradation in 677 grid cells in the Czech Republic. Species richness did not correspond to habitat naturalness, but the occurrence of endangered species was significantly positively correlated with increasing naturalness; thus, habitat degradation and/or the level of naturalness significantly affected species composition, while species richness remained unchanged. Threatened species that occur predominantly in natural areas and threatened species with a dominant occurrence in degraded squares were also separated, which indicated that the conservation of the latter should be prioritised. [ABSTRACT FROM AUTHOR]

Simple Summary: Freshwater biodiversity is facing a severe crisis due to many different human-caused impacts, such as climate change, pollution, habitat alterations, etc. Aquatic insects are one of the most important bioindicators used in freshwater ecological quality assessment systems, yet knowledge on diversity dynamics of their communities is incomplete. In the current study, we compare and evaluate performance of different diversity measures, i.e., commonly used simple diversity indices vs. novel complex measures incorporating ecological information of species (feeding behavior and stream zonation preferences). As a target group, we chose caddisflies, a species-rich, aquatic insect order, in different habitats of an anthropogenically unimpacted, connected karst barrage lake/riverine system. In line with our hypothesis, the complex diversity measures were more efficient in ranking and distinguishing different habitats, particularly the ones with similar communities. We also constructed a novel measure to rank the habitats by sensitivity to climate change, based on diversity of caddisfly communities and vulnerability of species inhabiting them. As expected, the springs were ranked as most vulnerable habitats. Our study further underlines the importance of integrating ecological information into biodiversity and vulnerability assessment of freshwater communities. Freshwater biodiversity is facing a severe crisis due to many human impacts, yet the diversity dynamics of freshwater communities and possibilities of assessing these are vastly unexplored. We aimed at emphasizing different aspects of portraying diversity of a species-rich, aquatic insect group (caddisflies; Trichoptera) across four different habitats in an anthropogenically unimpacted, connected karst barrage lake/riverine system. To define diversity, we used common indices with pre-set sensitivity to species abundance/dominance; i.e., sensitivity parameter (species richness, Shannon, Simpson, Berger-Parker) and diversity profiles based on continuous gradients of this sensitivity parameter: the naïve and non-naïve diversity profiles developed by Leinster and Cobbold. The non-naïve diversity profiles show diversity profiles with regard to the similarity among species in terms of ecological traits and preferences, whereas the naïve diversity profile is called mathematically "naïve" as it assumes absolute dissimilarity between species that is almost never true. The commonly used indices and the naïve diversity profile both ranked the springs as least diverse and tufa barriers as most diverse. The non-naïve diversity profiles based on similarity matrices (using feeding behavior and stream zonation preferences of species), showed even greater differences between these habitats, while ranking stream habitats close together, regardless of their longitudinal position. We constructed the Climate Score index (CSI) in order to assess how diversity and species' vulnerability project the community's resistance and/or resilience to climate change. The CSI ranked the springs as most vulnerable, followed by all habitats longitudinally placed below them. We highlight the importance of integrating ecological information into biodiversity and vulnerability assessment of freshwater communities. [ABSTRACT FROM AUTHOR]

Simple Summary: The expansion of urban areas in combination with climate change places great pressure on species found in freshwater habitats. Dragonflies are iconic freshwater organisms due to their large body sizes and striking coloration. They have been widely used to indicate the impacts of natural and human-mediated activities on freshwater communities, while also indicating the mitigation measures required to ensure their conservation. Here, we review the major threats to dragonflies in southern Africa, specifically those in urban areas. We also provide information on effective mitigation measures to protect dragonflies and other aquatic insects in urban spaces. Using three densely populated areas as case studies, we highlight some of the greatest challenges for dragonflies in South Africa. More importantly, we give a summary of current mitigation measures which have maintained dragonflies in urban spaces. In addition to these mitigation measures, public involvement and raising awareness contribute greatly to the common cause of protecting dragonflies around us. Urban settlements range from small villages in rural areas to large metropoles with densely packed infrastructures. Urbanization presents many challenges to the maintenance of freshwater quality and conservation of freshwater biota, especially in Africa. There are many opportunities as well, particularly by fostering contributions from citizen scientists. We review the relationships between dragonflies and urbanization in southern Africa. Shifts in dragonfly assemblages indicate environmental change, as different species are variously sensitive to abiotic and biotic water and bank conditions. They are also conservation umbrellas for many other co-occurring species. Major threats to southern African dragonflies include increasing infrastructure densification, frequent droughts, habitat loss, pollution, and invasive alien vegetation. Mitigation measures include implementation of conservation corridors, maintenance of healthy permanent ponds, pollution reduction, and removal of invasive alien trees. Citizen science is now an important approach for supplementing and supporting professional scientific research. [ABSTRACT FROM AUTHOR]