Variations in the Odonata Assemblages: How Do the Dry Season and Water Bodies Influence Them?

Diverse abiotic and biotic factors drive the ecological variation of communities across spatial and temporal dimensions. Within the Amazonian landscape, various freshwater environments exhibit distinct physicochemical characteristics. Thus, our study delved into the fluctuations of Odonata assemblages amidst distinct water bodies within Amazonia, encompassing two distinct climatic seasons. Comparative analysis was conducted on Odonata species diversity and assemblage composition across a blackwater pond, a lake, and a stream, spanning the initiation and culmination of the dry season in the southwestern Amazon region in Peru. Our methodology involved capturing adult Odonata using entomological nets on three separate occasions between 11:00 and 14:00 h for each water body in May (beginning of the dry season) and October (end of the dry season) of 2018. We also evaluated the influence of temperature, precipitation, and percent cloud cover on the abundance and richness of adult Odonata. Species richness and composition differed among the three water bodies in both periods of the dry season. No effect of the dry season periods on species richness and abundance was observed. However, except in the oxbow lake, the more abundant species were substituted to the end of the dry season. Our study highlights the influence of water body types on Odonata species diversity and composition. The effects of the sampling period during the dry season may not be immediately apparent in conventional diversity metrics, such as species richness and abundance. Instead, its effects manifest predominantly in the relative abundance of the species that compose these assemblages.

Amazonian Odonata Trait Bank.

Discussion regarding the gaps of knowledge on Odonata is common in the literature. Such gaps are even greater when dealing with basic biological data for biodiverse environments like the Amazon Rainforest. Therefore, studies that address, classify, and standardize functional traits allow the elaboration of a wide range of ecological and evolutionary hypotheses. Moreover, such endeavors aid conservation and management planning by providing a better understanding of which functional traits are filtered or favored under environmental changes. Here, our main goal was to produce a database with 68 functional traits of 218 Odonata species that occur in the Brazilian Amazon. We extracted data on behavior, habit/habitat (larvae and adults), thermoregulation, and geographic distribution from 419 literature sources classified into different research areas. Moreover, we measured 22 morphological traits of approximately 2500 adults and categorized species distributions based on approximately 40,000 geographic records for the Americas. As a result, we provided a functional matrix and identified different functional patterns for the Odonata suborders, as well as a strong relationship between the different trait categories. For this reason, we recommend the selection of key traits that represent a set of functional variables, reducing the sampling effort. In conclusion, we detect and discuss gaps in the literature and suggest research to be developed with the present Amazonian Odonata Trait Bank (AMO-TB).

Checklist of Damselflies and Dragonflies (Odonata) from Acre state, and the first record of Drepanoneura loutoni von Ellenrieder & Garrison, 2008 for Brazil / Checklist das Libélulas (Odonata) do estado do Acre, e o primeiro registro de Drepanoneura loutoni von Ellenrieder & Garrison, 2008 para o Brasil

Abstract: Here we present the first Odonata (Insecta) species list for the state of Acre, Northern Brazil, adding ecological aspects and notes on its taxonomy and conservation status. Regarding Odonata samplings, Acre is one of the least explored states in the northern region of Brazil and an area of geographic importance, as it is a transition between the Andean and Amazon regions. Collections were carried out in 35 streams, distributed in nine municipalities. We also supplemented our database from the review of secondary literature and data from biological collections. We recorded 140 species, distributed in 55 genera, of which 16 species are new records for the state, making Acre state the second in the number of recorded species in northern Brazil. Of the recorded species, 113 are classified within some threat category of the IUCN red list and 110 in the ICMBio national list. Analyzing the taxonomic information on each recorded species, knowledge of females and larvae is still very limited and, most of the time, only available to adult males. For the first time, the occurrence of Drepanoneura loutonivon Ellenrieder & Garrison (2008) is reported for Brazil, and we also present photos of its main morphological characters, with comments on its biology. Our study shows the importance of conducting biodiversity research in poorly studied areas; such as the state of Acre, and serves as a basis for future expeditions in the region.

Resumo: Apresentamos a primeira lista de espécies de Odonata (Insecta) para o estado do Acre no Brasil, adicionando aspectos ecológicos e notas sobre o seu estado de conservação. O Acre é um dos estados com o menor esforço de coleta da região Norte do Brasil e uma área de importância geográfica, pois é uma transição entre os Andes e a Amazônia. Foram realizadas coletas em 35 riachos, distribuídos em nove municípios e também complementados com informações de dados secundários de revisão na literatura e bases de dados de coleções biológicas. Registramos 140 espécies, distribuídas em 55 gêneros, das quais 16 espécies são novos registros para o estado, tornando-o o segundo em número de espécies na região Norte do Brasil. Das espécies registradas, 113 estão classificadas dentro de alguma categoria de ameaça da lista vermelha da IUCN e 110 na lista nacional do ICMBio. Analisando as informações do conhecimento das espécies, o conhecimento das fêmeas e larvas ainda muito limitado e na maioria das vezes disponíveis apenas para os machos adultos. Pela primeira vez é registrada a ocorrência da Drepanoneura loutoni von Ellenrieder & Garrison (2008) no Brasil, também apresentamos fotos das principais estruturas, com comentários sobre sua biologia. Nosso trabalho mostra a importância da realização de estudos de biodiversidade em áreas ainda pouco estudadas como a do estado do Acre e serve como base para futuras expedições na região.

A new Epipleoneura Williamson, 1915 (Zygoptera, Coenagrionidae) from northern Brazil and notes on E. venezuelensis Rácenis, 1955.

Epipleoneura lencionii sp. nov. is erected based on specimens from Acre State (holotype: 10º7'38.5″S; 67º38'6.7″W, 12.ix.2017, Miguel, T.B. leg). Additional material collected in Minas Gerais was also studied, but subsequently was lost in a fire at the National Museum of Rio de Janeiro. We compared the new species with E. venezuelensis Rácenis, 1955. Epipleoneura lencionii differs from E. venezuelensis by the orientation of the lateral lobes on the male epiproct and by the shape of the posterior lobe of the prothorax of the female. The distribution of the species is analyzed and notes on the reproductive behavior of the genus are provided.

Response of aquatic insects to an environmental gradient in Amazonian streams.

The increasing land use in the Amazon region has resulted in the widespread substitution of forest areas with pasture and bauxite mining. These land uses reduce the forest cover of streams and modify their characteristics, reducing the diversity of aquatic insect assemblages. In the present study, we aimed to identify the threshold of the assemblages of the larvae of insects of the orders Ephemeroptera, Plecoptera, and Trichoptera (collectively known as EPT), and adults of the order Odonata, along an environmental gradient of land use and land cover (LULC). We sampled 30 streams along an environmental gradient determined by the proportion of forest, pasture, and bauxite mining observed within the catchment of each stream. We identified 12 taxa associated with forest (nine positively and three negatively) and four negatively associated with pasture. However, no taxa were associated explicitly with the bauxite mining gradient. As forest is converted to pasture, the abundance and frequency of occurrence of the taxa sensitive to pasture are reduced, reflecting their environmental sensitivity and their potential as sentinels of preserved streams. The identification of the thresholds of the EPT and odonates taxa allowed us to determine which of these organisms are positively or negatively associated with the environmental gradient of LULC in Amazonian streams. We hope that the results of the present study can be applied in future biomonitoring programs, particularly for monitoring the response of aquatic insects to the degradation of streams.

Aquatic insects and their environmental predictors: a scientometric study focused on environmental monitoring in lotic environmental.

Since early studies about aquatic ecology, it has been found that changes in environmental conditions alter aquatic insect communities. Based on this, the combined study of environmental conditions and aquatic insect communities has become an important tool to monitor and manage freshwater systems. However, there is no consensus about which environmental predictors and facets of diversity are more useful for environmental monitoring. The objective of this work was to conduct a scientometric analysis to identify the main environmental predictors and biological groups used to monitor and manage lotic freshwater systems. We conducted a scientometric study on the Web of Science platform using the following words: stream, river, aquatic insect, Ephemeroptera, Plecoptera, Trichoptera, Odonata, Heteroptera, Chironomidae, bioindicator, environmental change, anthropic, and land use. Although most of the environmental predictors employed are local, intrinsic of freshwater systems using local environmental and associated landscape variables is a better strategy to predict aquatic insect communities. The facets of diversity most used are composition and richness of species and genera, which are not efficient at measuring the loss of ecosystem services and extinction of phylogenetic lineages. Although very important, these functional and phylogenetic facets are poorly explored for this purpose. Even though tropical regions are the most diverse globally and are experiencing major losses of native vegetation, these ecosystems are the least studied, a knowledge gap that needs addressing to better understand the effect of anthropogenic activities on the diversity of aquatic insects.

Odonata of the state of Maranhão, Brazil: Wallacean shortfall and priority areas for faunistic inventories / Odonata do estado do Maranhão, Brasil: Déficit wallaceano e áreas prioritárias para inventários faunísticos

Abstract: Environmental changes are worrying in a scenario with large knowledge gaps on species diversity and distribution. Many species may become extinct before they are known to science. Considering this scenario, the present study aims to evaluate the known distribution of the species recorded for Maranhão state in Brazilian northeast region and discuss knowledge gaps about Odonata indicating the priority areas for faunistic inventories. Using primary and secondary data together, we present convex minimum polygons of the distribution of all the species registered for the state. In addition, we created maps with the richness of species and number of records of Odonata in the Maranhão state. In primary data sample 269 specimens, represented by 17 genera and 30 species were collected. Of the 30 species collected, 17 are new records for the state of Maranhão; of these, 35.29% are geographically widespread species, occurring in practically all regions of Brazil. Considering the records in the literature, there was a 68% increase in the number of Odonata species known for Maranhão. The most unexplored region is the Cerrado of the state of Maranhão. Furthermore, the transition regions between Cerrado and Amazônia and between Cerrado and Caatinga are also unknown. All these areas are a priority for faunistic inventories.

Resumo: As mudanças ambientais são preocupantes em um cenário com muitas lacunas de conhecimento sobre a distribuição das espécies. Várias espécies podem ser extintas antes mesmo de serem conhecidas pela ciência. Considerando este cenário, o presente estudo tem como objetivo avaliar a distribuição conhecida das espécies de Odonata registradas para o Maranhão, na região nordeste do Brasil e discutir sobre as lacunas de conhecimento sobre Odonata, indicando áreas prioritárias para inventários faunísticos. Usando os dados primários e secundários juntos, nós apresentamos polígonos mínimos convexos da distribuição de todas as espécies registradas para o estado neste estudo. Além disso, criamos mapas com a riqueza de espécies e número de registros de Odonata no Maranhão. Para os dados primários foram coletados 269 indivíduos, representando 17 gêneros e 30 espécies. Das 30 espécies amostradas, 17 são novos registros para o Maranhão; dessas, 35,29% são espécies com ampla distribuição geográfica, ocorrendo em praticamente todas as regiões do Brasil. Considerando os registros na literatura, houve um aumento de 68% no número de espécies conhecidas para o Maranhão. A região mais desconhecida é o Cerrado do Maranhão. Outrossim, a região de transição Cerrado e Amazônia, e a transição entre Cerrado e Caatinga são também desconhecidas. Todas essas áreas são prioritárias para inventários faunísticos.

Effect of oil palm on the Plecoptera and Trichoptera (Insecta) assemblages in streams of eastern Amazon.

The production of oil palm is expected to increase in the Amazon region. However, expansion of oil palm plantation leads to significant changes in the physical structure of aquatic ecosystems, mainly through the reduction of riparian vegetation that is essential for aquatic biodiversity. Here, we evaluated the effects of oil palm on the physical habitat structure of Amazonian stream environments and assemblages of Plecoptera and Trichoptera (PT), ​both found in these streams. We compared streams sampled in oil palm plantations (n = 13) with natural forest areas ("reference" streams, n = 8), located in the eastern Amazon, Brazil. Our results showed that oil palm streams were more likely to be in close proximity to roads, had higher pH values, and higher amounts of fine substrate deposited in the channel than reference streams. Further, these environmental changes had important effects on the aquatic invertebrate assemblages, reducing the abundance and richness of PT. Nevertheless, the genera composition of the assemblages did not differ between reference and oil palm (PERMANOVA, pseudo-F (1,19) = 1.891; p = 0.111). We conclude that oil palm production has clear negative impacts on aquatic environments and PT assemblages in Amazonian streams. We recommend that oil palm producers invest more in planning of road networks to avoid the construction of roads near to the riparian vegetation. This planning can minimize impacts of oil palm production on aquatic systems in the Amazon.

Little effects of reduced-impact logging on insect communities in eastern Amazonia.

Selective logging has become a major source of threats to tropical forest, bringing challenges for both ecologists and managers to develop low-impact forestry. Reduced-impact logging (RIL) is a prominent activity accounting for such forestry practices to prevent strong forest disturbances. Our aims were to evaluate the effects of RIL on insect communities of forested streams from Eastern Amazon and to test the hypothesis of negative effects of RIL on species richness, abundance, and functional feeding groups of aquatic insect assemblages. Neither of the evaluated metrics of the studied assemblages were negatively affected by RIL. Environmental metrics, such as substrate heterogeneity, woody canopy cover, and hill slope height, varied more among RIL streams than in reference streams, indicating a gradient according to logging impacts, and are suitable candidates to monitor RIL impacts in Amazonian streams. In addition, the PHI index also varied among REF and RIL, according to age class and year of logging, which could reflect trends to recover the forest structure after logging in a time frame of only 10 years. We conclude that RIL impacts have not had detrimental impacts on insect communities, but have changed little of the environmental conditions, especially of the riparian vegetation around streams.