Predicting macroinvertebrate average score per taxon (ASPT) at water quality monitoring sites in Japanese rivers.

Biomonitoring with bioindicators such as river macroinvertebrates is fundamental for assessing the status of freshwater ecosystems. In Japan, water quality and biomonitoring surveys are conducted separately, leading to a lack of nationwide information on their relationships and the biological status of water quality monitoring (WQM) sites. To understand the biological status of WQM sites across Japan, we developed a multiple linear regression model to estimate the average score per taxon (ASPT) using river macroinvertebrate data surveyed at a total of 237 "aligned" sites based on the co-occurrence of biomonitoring and WQM sites. The resulting regression model with eight predictors, such as biological oxygen demand, the proportion of urban areas in the catchment, could predict ASPT with reasonable accuracy (e.g., an error of ±1 for 96% of the aligned data). Using this model, we estimated ASPT values at 2925 WQM sites in rivers nationwide, categorizing them into four levels of river environment quality: "very good" (29% of WQM sites), "good" (50%), "fairly good" (14%), and "not good" (8%). Furthermore, we observed statistically significant correlations (p < 0.05; 0.4 ≤ r ≤ 0.7) between ASPT and all eight macroinvertebrate metrics examined, such as mayfly and stonefly richness, providing ecological implications of changes in ASPT.

How non-target chironomid communities respond to mosquito control: Integrating DNA metabarcoding and joint species distribution modelling.

The conservation and management of riparian ecosystems rely on understanding the ecological consequences of anthropogenic stressors that impact natural communities. In this context, studies investigating the effects of anthropogenic stressors require reliable methods capable of mapping the relationships between taxa occurrence or abundance and environmental predictors within a spatio-temporal framework. Here, we present an integrative approach using DNA metabarcoding and Hierarchical Modelling of Species Communities (HMSC) to unravel the intricate dynamics and resilience of chironomid communities exposed to Bacillus thuringiensis var. israelensis (Bti). Chironomid emergence was sampled from a total of 12 floodplain pond mesocosms, half of which received Bti treatment, during a 16-week period spanning spring and summer of 2020. Subsequently, we determined the community compositions of chironomids and examined their genus-specific responses to the Bti treatment, considering their phylogenetic affiliations and ecological traits of the larvae. Additionally, we investigated the impact of the Bti treatment on the body size distribution of emerging chironomids. Our study revealed consistent responses to Bti among different chironomid genera, indicating that neither phylogenetic affiliations nor larval feeding strategies significantly contributed to the observed patterns. Both taxonomic and genetic diversity were positively correlated with the number of emerged individuals. Furthermore, our findings demonstrated Bti-related effects on chironomid body size distribution, which could have relevant implications for size-selective terrestrial predators. Hence, our study highlights the value of employing a combination of DNA metabarcoding and HMSC to unravel the complex dynamics of Bti-related non-target effects on chironomid communities. The insights gained from this integrated framework contribute to our understanding of the ecological consequences of anthropogenic stressors and provide a foundation for informed decision-making regarding the conservation and management of riparian ecosystems.

Evolutionary history of a cold-adapted limnephilid caddisfly: Effects of climate change and topography on genetic structure.

The distribution of organisms is influenced by complex factors such as the phylogenetic evolutionary histories of species, the physiological and ecological characteristics of organisms, climate, and geographical and geohistorical features. In this study, we focused on a caddisfly, Asynarchus sachalinensis (Trichoptera: Limnephilidae), which has adapted to cold habitats. From phylogeographic analyses based on the mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI) and 16S rRNA regions and the nuclear DNA (nDNA) 18S rRNA, 28S rRNA, carbamoyl-phosphate synthetase (CAD), elongation factor-1 alpha (EF1-α), and RNA polymerase II (POLII) regions, two distinct genetic clades were detected. Clade I was shown to be widely distributed from Sakhalin to Honshu, whereas Clade II was only distributed within Honshu. The distributions of these clades overlapped in Honshu. The habitats were located at relatively lower altitudes for Clade I and higher altitudes for Clade II. The divergence time of these clades was estimated to be during the Pleistocene, indicating that repeated climatic changes facilitated distributional shifts. Haplotype network and demographic analyses based on the mtDNA COI region showed contrasting genetic structures in the two clades. It was indicated that the population sizes of Clade I had expanded rapidly in a recent period, whereas Clade II had maintained stable population sizes. The habitats of Clade II were typically isolated and scattered at high altitudes, resulting in restricted migration and dispersal because of their discontinuous "Sky Island" habitats. The habitats of Clade I were located at relatively low altitudes, and it was assumed that the populations were continuous, which resulted in a higher frequency of migration and dispersal between populations. Thus, differences in the spatial scale of the adapted habitats of each clade may have resulted in different patterns of population connectivity and fragmentation associated with repeated climatic changes during the Pleistocene. Our study provided new insight into the distributional patterns of cold-adapted aquatic insects in the Japanese Archipelago. Furthermore, the distributional shifts predicted by ecological niche modeling under future climatic change conditions were different for each clade. Therefore, different principles are required in the assessment of each clade to predict temporal changes in their distributions.

A chromosome-level genome assembly for the smoky rubyspot damselfly (Hetaerina titia).

Smoky rubyspot damselflies (Hetaerina titia Drury, 1773) are one of the most commonly encountered odonates along streams and rivers on both slopes of Central America and the Atlantic drainages in the United States and southern Canada. Owing to their highly variable wing pigmentation, they have become a model system for studying sexual selection and interspecific behavioral interference. Here, we sequence and assemble the genome of a female smoky rubyspot. Of the primary assembly (i.e. the principle pseudohaplotype), 98.8% is made up of 12 chromosomal pseudomolecules (2N = 22A + X). There are 75 scaffolds in total, an N50 of 120 Mb, a contig-N50 of 0.64 Mb, and a high arthropod BUSCO score [C: 97.6% (S: 97.3%, D: 0.3%), F: 0.8%, M: 1.6%]. We then compare our assembly to that of the blue-tailed damselfly genome (Ischnura elegans), the most complete damselfly assembly to date, and a recently published assembly for an American rubyspot damselfly (Hetaerina americana). Collectively, these resources make Hetaerina a genome-enabled genus for further studies of the ecological and evolutionary forces shaping biological diversity.

Aquatic insect accumulation of uranium at spring outflows in the Grand Canyon region as influenced by aqueous and sediment geochemistry and biological factors: implications for monitoring.

Potential adverse ecological effects of expanded uranium (U) mining within the Grand Canyon region motivated studies to better understand U exposure and risk to endemic species. This study documents U exposures and analyzes geochemical and biological factors affecting U bioaccumulation at spring-fed systems within the Grand Canyon region. The principal objective was to determine if aqueous U was broadly indicative of U accumulated by insect larvae, a dominate fauna. Analyses focused on three widely distributed taxa: Argia sp. (a predatory damselfly), Culicidae (suspension feeding mosquitos), and Limnephilus sp. (a detritivorous caddisfly). The study showed that U accumulated by aquatic insects (and periphyton) generally correlated positively with total dissolved U, although correlations were strongest when based on modeled concentrations of the U-dicarbonato complex, UO2(CO3)2-2, and UO2(OH)2. Sediment metal concentration was a redundant indicator of U bioaccumulation. Neither insect size or U in the gut content of Limnephilus sp. substantially affected correlations between aqueous U and whole-body U concentrations. However, in Limnephilus sp., the gut and its content contained large quantities of U. Estimates of the sediment burden in the gut indicated that sediment was a minor source of U mass but contributed substantially to the total insect weight. As a result, whole-body U concentration would tend to vary inversely with the sediment burden of the gut. The correlations between aqueous U and bioaccumulated U provide an initial relational baseline against which newly acquired data could be evaluated for changes in U exposure during and after mining operations.

Eggs in faeces: defensive mechanisms and effects of faecal coating by a water scavenger beetle, Coelostoma stultum (Coleopterea: Hydrophilidae).

The egg stage in insect development is vulnerable to fluctuations in environmental conditions and attacks by natural enemies. Protective devices are effective means of avoiding both abiotic and biotic damage to eggs. Although some insects use their faeces as a protective device, few studies have focused on using faeces for egg protection, and studies that examined the mechanism are lacking. Females of a water scavenger beetle, Coelostoma stultum, typically lay eggs and coat them with cocoons and their faeces. The efficacy of a double defensive device, however, remains uncertain. Here, we conducted field observations and laboratory experiments to assess the protective effects of cocoons with faecal coating on eggs against predation and determine the duration and mechanisms of this defence. Our findings reveal that the faeces on the egg cocoon protected eggs from predation by the pill bugs, Armadillidium vulgare, and marsh slugs, Deroceras laeve. Laboratory experiments showed that the defensive effect of faecal coating was maintained for three days and decreased daily. The double protective traits with faecal coating on the egg cocoons protected the eggs from instense predation pressure in C. stultum. The behavioural patterns of the pill bugs and egg predation rates indicate that the faecal coating behaviour in C. stultum protects eggs with chemical compounds and textural camouflage in mud when the antennae of the pill bugs touch faeces. It is important to note that for this defence to be effective, the chemistry and texture of the faeces should be similar to that of the oviposition sites.

Reference genome for the American rubyspot damselfly, Hetaerina americana.

Damselflies and dragonflies (Order: Odonata) play important roles in both aquatic and terrestrial food webs and can serve as sentinels of ecosystem health and predictors of population trends in other taxa. The habitat requirements and limited dispersal of lotic damselflies make them especially sensitive to habitat loss and fragmentation. As such, landscape genomic studies of these taxa can help focus conservation efforts on watersheds with high levels of genetic diversity, local adaptation, and even cryptic endemism. Here, as part of the California Conservation Genomics Project (CCGP), we report the first reference genome for the American rubyspot damselfly, Hetaerina americana, a species associated with springs, streams and rivers throughout California. Following the CCGP assembly pipeline, we produced two de novo genome assemblies. The primary assembly includes 1,630,044,487 base pairs, with a contig N50 of 5.4 Mb, a scaffold N50 of 86.2 Mb, and a BUSCO completeness score of 97.6%. This is the seventh Odonata genome to be made publicly available and the first for the subfamily Hetaerininae. This reference genome fills an important phylogenetic gap in our understanding of Odonata genome evolution, and provides a genomic resource for a host of interesting ecological, evolutionary, and conservation questions for which the rubyspot damselfly genus Hetaerina is an important model system.

A major flood caused by a typhoon did not affect the population genetic structure of a river mayfly metapopulation.

Floods affect the population structure of organisms that inhabit streams. In recent decades, the scale of floods has become larger due to climate change. Under these circumstances, on 12 October 2019, the largest typhoon in the history of observation in Japan struck the Japanese Archipelago. This typhoon caused heavy rainfall in various places, and the Chikuma-Shinano River System (Japan's largest) suffered great damage. Eight years before the large-scale disturbance in the river system, the population structure of the mayfly Isonychia japonica was studied in detail using quantitative sampling (population numbers and biomass) and by sequencing the mtDNA cytochrome c oxidase subunit I. To understand the impact of the flood on the population and genetic structures, we repeated the same research approximately 1 year after the flood. Direct comparison of sites before and after the flood revealed no significant changes between pre- and post-flood population genetic structure. This indicates high in situ resistance and/or resilience recovery of the populations to the disturbance. We hypothesize that this high resistance/resilience to flood disturbance is a result of strong selection for such traits in the rivers of the Japanese Archipelago, which are short, steep, flow rapidly and violently, and are strongly affected by floods.

Aquatic-Terrestrial Insecticide Fluxes: Midges as Neonicotinoid Vectors.

Exposure of freshwater ecosystems to insecticides can negatively impact the development of emerging aquatic insects. These insects serve as an important nutritional subsidy for terrestrial insectivores. Changes in insect emergence phenology (i.e., emergence success and temporal pattern) or fluxes of insecticides retained by the emerging adults have the potential to negatively impact terrestrial food webs. These processes are influenced by contaminant toxicity, lipohilicity, or metabolic processes. The interplay between emergence phenology, contaminant retention through metamorphosis, and associated contaminant flux is not yet understood for current-use insecticides. In a microcosm study, we evaluated the impacts of a 24-h pulse exposure of one of three current-use insecticides, namely pirimicarb, indoxacarb, and thiacloprid, at two environmentally realistic concentration levels on the larval development and emergence of the nonbiting midge Chironomus riparius. In addition, we measured insecticide concentrations in the larvae and adults using ultrahigh performance liquid chromatography coupled to tandem mass spectrometry by electrospray ionization. Exposure to pirimicarb delayed larval development and emergence, and exposure to indoxacarb reduced emergence success. The neonicotinoid thiacloprid had the greatest impact by reducing larval survival and emergence success. At the same time, thiacloprid was the only insecticide measured in the adults with average concentrations of 10.3 and 37.3 ng/g after exposure at 0.1 and 4 µg/L, respectively. In addition, an approximate 30% higher survival to emergence after exposure to 0.1 µg/L relative to a 4-µg/L exposure resulted in a relatively higher flux of thiacloprid, from the aquatic to the terrestrial environment, at the lower exposure. Our experimental results help to explain the impacts of current-use insecticides on aquatic-terrestrial subsidy coupling and indicate the potential for widespread dietary exposure of terrestrial insectivores preying on emerging aquatic insects to the neonicotinoid thiacloprid. Environ Toxicol Chem 2023;42:60-70. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

New species of Claudiotendipes Andersen, Mendes & Pinho and Tapajos Trivinho-Strixino, Silva & Oliveira from Brazil (Diptera, Chironomidae, Chironominae)

ABSTRACT Two recently revealed genera, Claudiotendipes, consisting of three distinct species, and the monotypic Tapajos, have new species described. We describe and figure Claudiotendipes gilbertoi sp. n., based on male adult specimens collected in the southern Atlantic Forest of Rio Grande do Sul State. Additionally, we describe and figure Tapajos froehlichi sp. n., from male adults collected in the Amazon Forest from Amazonas and Rondônia States. In order to place the newly described T. froehlichi sp. n., minor emendations have been made to the diagnosis and description of Tapajos.

An updated distribution list of Leptophlebiidae Banks, 1900 (Ephemeroptera: Insecta) for Piauí state / Uma lista de distribuição atualizada de Leptophlebiidae Banks, 1900 (Ephemeroptera: Insecta) para o estado do Piauí

Abstract Leptophlebiidae is the second most diverse family within Ephemeroptera, with species distributed across various States in Brazil, but with gaps in distribution records in others. Currently, nine species of Leptophlebiidae are recorded for the state of Piauí. Based on this information gap, the objective of this study was to present an updated species list of the family Leptophlebiidae new occurrence records and distributional sites for the state of Piauí, Brazil. By analyzing 447 specimens, we have significantly expanded our knowledge about the distribution of Leptophlebiidae species in the state of Piauí, increasing the recorded species from nine to 17. We have also added new occurrence records for six species and, for the first time, documented the presence of four genera. It is important to highlight that there is still an extensive area within the Cerrado and Brazilian semiarid regions where the occurrence of Ephemeroptera is unknown, confirming that the diversity in this area is underestimated and that knowledge of Ephemeroptera species and their distributions can expand with increased sampling efforts in the coming years, reducing the Linnean and Wallacean shortfall regarding this group. Our results also demonstrate the urgent need for inventories in the southern part of the state of Piauí, particularly in the sub-basins of the middle and upper Parnaíba river, which are considered suitable for monoculture expansion in Brazil.

Resumo Leptophlebiidae é a segunda família mais diversa de Ephemeroptera, com espécies distribuídas em vários estados do Brasil, mas com lacunas no registro de distribuição em outros. Por exemplo, no estado do Piauí tem registrado apenas nove espécies de Leptophlebiidae. Baseada nessa lacuna de informação, o objetivo deste estudo foi apresentar uma lista atualizada de espécies da família Leptophlebiidae, novos registros de ocorrência e sítios de distribuição para o estado do Piauí, Brasil. Ao analisar 447 exemplares, ampliamos significativamente nosso conhecimento sobre a distribuição das espécies de Leptophlebiidae no estado do Piauí, aumentando o número de espécies registradas de nove para 17. Também adicionamos novos registros de ocorrência para seis espécies e, pela primeira vez, documentamos a presença de quatro gêneros. Destacamos que ainda existe uma extensa área do Cerrado e semiárido brasileiro que se desconhece a ocorrência de Ephemeroptera, confirmando que a diversidade nessa área é subestimada e que o conhecimento sobre as espécies de Ephemeroptera e suas distribuições podem se expandir com o aumento do esforço amostral nos próximos anos, diminuindo as lacunas Lineana e Wallaceana sobre esse grupo. Nossos resultados também demonstram a necessidade emergencial de inventários no sul do Estado do Piauí, principalmente nas sub-bacias do médio e alto rio Parnaíba que é considerado adequado para a expansão da monocultura no Brasil.

Nutritional Compositions of Aquatic Insects Living in Rice Fields, with a Particular Focus on Odonate Larvae.

Although the human consumption of aquatic insects is prevalent in many regions, the nutritional composition of the insects has not been comprehensively determined. The proximate composition of Pantala sp. was shown to be a good source of protein (49.45 ± 0.32 g/100 g DW), as well as of minerals such as sodium, calcium, potassium, phosphorus, zinc, and iron. All nine essential amino acids are present in this species, with valine being the most abundant. The major fatty acids are palmitic acid (1.19 ± 0.02 g/100 g DW), oleic acid (0.63 ± 0.02 g/100 g DW), and linoleic acid (0.55 ± 0.01 g/100 g DW). Lead (Pb), arsenic (As), and cadmium (Cd) showed a value of 0.18 ± 0.01 mg·kg-1, 3.51 ± 0.12 mg·kg-1, and 0.17 ± 0.00 mg·kg-1, respectively. Furthermore, microplastic (MP) contamination in odonate larvae (419 individuals belonging to three identified families) was found in varying shapes, e.g., fibers, fragments, and rods. FTIR analysis revealed the following MP polymers, polyethylene terephthalate, polyvinyl acetate, bis(2-ethylhexyl), polybutadiene, poly(methyl methacrylate-co-methacrylic acid); P(MMA-co-MA), poly(ethylene glycol) tetrahydrofurfuryl ether, poly(acrylonitrile-co-butadiene), and polypropylene glycol. The results of this work could be a nutritional reference for food security and the risk of eating insects.

Catchment scale deforestation increases the uniqueness of subtropical stream communities.

Local communities and individual species jointly contribute to the overall beta diversity in metacommunities. However, it is mostly unknown whether the local contribution (LCBD) and the species contribution (SCBD) to beta diversity can be predicted by local and regional environmental characteristics and by species traits and taxonomic relatedness, respectively. We investigated the LCBD and SCBD of stream benthic diatoms and insects along a gradient of land use intensification, ranging from streams in pristine forests to agricultural catchments in southeast subtropical Brazil. We expected that the LCBD would be negatively related to forest cover and positively related to the most unique streams in terms of environmental characteristics and land use (hereafter environmental and land use uniqueness, respectively). We also expected that species with a high SCBD would occur at sites with reduced forest cover. We found that the LCBD of diatoms and insects was negatively related to forest cover. The LCBD of insects was also positively related to environmental and land use uniqueness. As forest cover was negatively related to uniqueness in land use, biologically unique streams were those that deviated from the typical regional land cover. We also found that diatom traits, insect traits, and taxonomic relatedness partly explained SCBD. Furthermore, the SCBD of diatoms was positively correlated with forest cover, but the inverse was found for insects. We showed that deforestation creates novel and unique communities in subtropical streams and that species that contribute the most to beta diversity can occur at opposite ends of a land use gradient.

Analysis of Differential Gene Expression of the Aquatic Insect Protohermes costalis (Walker) (Megaloptera: Corydalidae) in Response to Cadmium Exposure.

Heavy metal pollution in freshwater ecosystems is a serious threat to aquatic organisms. Species of Megaloptera are important predators of aquatic invertebrates and have been widely used as bioindicators in assessing the quality of freshwater ecosystems. In this study, we determined the differential gene expression profile of Protohermes costalis (Walker) (Megaloptera: Corydalidae) in response to cadmium (Cd) exposure by using transcriptome analysis. A total of 60,627 unigenes were obtained in the transcriptomes of 150 mg/liter (PL), 1,000 mg/liter (PH) CdCl2 treatment, and the no Cd control (PC). Differential expression gene (DEG) analysis by pairwise comparison identified 2,794 DEGs after filtering the noninsect genes and repetitive counts. 606 DEGs were shared in comparisons of PL versus PC and PH versus PC, with 165 DEGs consistently up-regulated and 441 down-regulated by both PL and PH. Six heat shock proteins (HSPs) in the HSP70 family were identified in P. costalis and PcosHSP68 was up-regulated by both PL and PH. Real-time quantitative polymerase chain reaction (RT-qPCR) confirmed that the expression levels of PcosHSP68 in PL and PH were higher than that of PC by 31 and 197%, respectively. These results showed that exposure to Cd altered the gene expression profiles of P. costalis and the transcriptome data presented in this study provide insight into future studying on molecular mechanisms of Cd toxicity to these insects.

Effects of Trace Metals and Municipal Wastewater on the Ephemeroptera, Plecoptera, and Trichoptera of a Stream Community.

Abundances of EPT larvae sampled in a Central European locality affected by mining and smelting, as well as by the continual inflow of treated communal wastewaters (WWs), were recorded. High concentrations of trace metals in water (maximum 1200 µg·L-1 for zinc) and sediments (maximum 140,000 mg·kg-1 in dry weight for lead) were found at the most contaminated sites. The highest loads of pesticides, pharmaceuticals, and illegal drugs were found under the WW effluent. Other associated factors such as the physicochemical parameters of the water and alterations to microhabitats were also evaluated and taken into account. Although EPT richness was lower at affected sites, abundances did not fall. Stoneflies were dominant at unaffected sites, while caddisflies dominated at affected sites. Only baetid mayflies were detected at the sites contaminated by trace metals and WWs; ephemerellid, heptageniid, and leptophlebiid mayflies were absent from these sites. The site contaminated by trace metals was also inhabited by numerous limnephilid caddisflies, in which limb malformations were detected in up to 11.8% of all specimens of a single taxon. Downstream from the entrance of the WWs, the locality was dominated by hydropsychid caddisflies. The increasing prevalence of predator or passive filter-feeding strategies in these EPT communities was significantly related to increasing water conductivity and acute ecosystemic exposure to 'poorly treated' WWs.

Direct and indirect effects of amphidromous shrimps on nutrient mineralization in streams in Japan.

Animals affect element cycling in ecosystems by consumption and excretion. Amphidromous shrimps frequently dominate low-mid altitude streams, where downstream connectivity to oceans is sustained. Although shrimps' direct influence on benthic communities has been studied, little is known about their influences on nutrient cycling. Here, we hypothesized that the dominance of shrimps alters nutrient mineralization by benthic macroinvertebrates in streams due to the difference in the quality and quantity of excretion between shrimps and aquatic insects. We tested this hypothesis through a field manipulative experiment, excretion measurements of animals, and field surveys. In the field manipulative experiment, the presence of shrimps slightly decreased the biomass of aquatic insects but tripled total benthic macroinvertebrate biomass directly through their own biomass. The mass-specific NH4+ excretion rate by shrimps was similar to aquatic insects, and the areal NH4+ excretion by benthic macroinvertebrates was increased by 2.5 times in the presence of shrimps. In contrast, shrimps excreted significantly less soluble reactive phosphorus (SRP) than aquatic insects, and the presence of shrimps did not affect areal SRP excretion by benthic macroinvertebrates. The field survey showed a positive correlation of NO3- concentration with the shrimp density, inferring the excess NH4+ was nitrified. Although the nutrient concentration of stream water is frequently attributed to watershed conditions, the results of this study indicate that downstream connectivity to oceans may also influence nutrient dynamics of the stream through the density of amphidromous shrimps.

Species- and element-specific patterns of metal flux from contaminated wetlands versus metals shed with exuviae in emerging dragonflies.

Dragonfly adults and their aquatic immature stages are important parts of food webs and provide a link between aquatic and terrestrial components. During emergence, contaminants can be exported into terrestrial food webs as immature adults fly away or be shed with their exuviae and remain in the wetland. Our previous work established metals accumulating in dragonfly nymphs throughout a contaminated constructed wetland designed to regulate pH and sequester trace metals from an industrial effluent line. Here, we evaluated the concentration and mass of metals leaving the wetland in flying emergents versus remaining in the wetland with the shed exuviae in 10 species of dragonflies belonging to 8 genera. Nine elements (Cu, Zn, Cd, Mn, V, Mg, Fe, Al, Pb) were evaluated that include essential and nonessential elements as well as trace and major metals. Metal concentrations in the emergent body and exuviae can differ by orders of magnitude. Aluminum, Fe, Mn, and Pb were largely shed in the exuviae. Vanadium and Cd were more variable among species but also tended to be shed with the exuviae. In contrast, Cu, Zn, and Mg showed a higher tendency to leave the wetland with an emerging dragonfly. Metals shed in dragonfly exuviae can moderate the transport of metals from contaminated wetlands. Taxonomic- and metal-specific variability in daily metal flux from the wetland depended upon concentration accumulated, individual body mass, and number of individuals emerging, with each factor's relative importance often differing among species. This illustrates the importance of evaluating the mass of metals in an individual and not only concentrations. Furthermore, differences in numbers of each species emerging will magnify differences in individual metal flux when calculating community metal flux. A better understanding of the variability of metal accumulation in nymphs/larvae and metal shedding during metamorphosis among both metals and species is needed.

The return to land: association between hairworm infection and aquatic insect development.

Host manipulation by parasites can shape host behaviour, community structure, and the flow of energy through food webs. A well-known example of host manipulation comes from hairworms (phylum Nematomorpha), which somehow cause their terrestrial insect definitive hosts to enter water, a phenomenon that has received lots of attention in recent years. However, little focus has been directed towards the interactions between hairworms and their aquatic insect hosts and the return of dormant hairworms from water to land. Here, we ask whether hairworm cyst infections impact, either directly or indirectly, the life history of their aquatic transport hosts. By observing the development of last-instar Olinga jeanae (Trichoptera: Conoesucidae) caddisfly larvae naturally infected with Gordius-type hairworm cysts under controlled conditions, we found that higher numbers of cysts per infected caddisfly correlated with a decrease in time to pupation. These new observations suggest that, apart from the striking host manipulation that brings the parasite from land to water, the presence of dormant hairworms is associated with changes in the development of their aquatic hosts, either through direct or indirect mechanisms, which may accelerate their transition from water to land.

Simulium maiaherzogae sp. nov., a new species of black fly (Diptera, Simuliidae) from rock fields of southeastern Brazil.

A new species of black fly from rock fields of southeaster Brazil, Simulium maiaherzogae sp. nov., is described based on morphological features of larval, pupal and adult specimens. Morphological features of this new species were compared with members of Simulium (Trichodagmia) Enderlein 1934, showing a high similarity with S. scutistriatum Lutz 1909 and S. itajara Nascimento, et al. 2020. However, features of the male and female scutum and genitalia, pupal tubercles disposition, pupal gills, larval cephalic appendages, larval gill histoblast, numbers of posterior proleg hooks and rectal papillae lobules, allow to differentiate S. maiaherzogae sp. nov. Moreover, a more detailed analysis using Scanning Electron Microscopy (SEM) showed significant differences and numerical variations in meristic data between the new species and S. scutistriatum. The known distribution of this new species is restricted to the Rio do Salto sub-basin, headland of the Middle Paraíba do Sul River, near the Ibitipoca State Park, a region recognised for its biodiversity richness, but with rare simuliids records.

Gas exchange and dive behaviour in the diving beetle Platynectes decempunctatus (Coleoptera: Dytiscidae).

Many aquatic insects use bubbles on the body surface to store and supply O2 for their dives. There are two types of bubbles: air stores, which store O2 gained from air at the surface, and gas gills that allow passive extraction of O2 from water. Many insects using air stores and gas gills return to the surface to replenish their bubbles and, therefore, their requirement for O2 influences dive behaviour. In this study, we investigate gas exchange and dive behaviour in the diving beetle Platynectes decempunctatus that uses a sub-elytral air store and a small compressible gas gill. We measure the PO2 within the air store during tethered dives, as well as the amount of O2 exchanged during surfacing events. Buoyancy experiments monitor the volume of gas in the gas gill and how it changes during dives. We also directly link O2-consumption rate at three temperatures (10, 15 and 20 °C) with dive duration, surfacing frequency and movement activity. These data are incorporated in a gas exchange model, which shows that the small gas gill of P. decempunctatus contributes less than 10% of the total O2 used during the dive, while up to 10% is supplied by cutaneous uptake.