Search Results (98)

Annual killifishes of the genus Nothobranchius live in seasonal water bodies in Eastern Africa. Adults die at the end of the rainy season when seasonal pools desiccate but diapaused embryos persist in the sediments and hatch in subsequent rainy seasons. Embryos use environmental cues to determine optimal hatching conditions to begin a new generation. We simulated a predation event by crushing Nothobranchius embryos and tested if embryos of N. eggersi and N. foerschi adjust time of hatching in response to these chemical cues. We placed individual diapause III embryos in cups of dechlorinated water dosed with either (1) blank water, (2) odor of crushed chironomids, or (3) odor of crushed Nothobranchius embryos. Although N. eggersi Red embryos hatched at a significantly faster rate than embryos from N. eggersi Solid blue or N. foerschi, the effect of the cue was consistent for all three types of Nothobranchius embryos used in this study. The odor of crushed Nothobranchius embryos caused a significant delay in time to hatch relative to the two control treatments. These data suggest that Nothobranchius embryos attend to chemical alarm cues derived from crushed conspecific embryos and delay hatching as a bet-hedging strategy to avoid hatching when they detect risk of predation. Full article

The region of South-East Europe, located in geologically and climatically diverse areas, hosts a wide range of freshwater habitats. However, comprehensive studies of macroinvertebrate communities are limited, and research on Chironomidae (Diptera) is particularly scarce. We present data on the diversity and structure of chironomid assemblages in hilly and mountainous streams across three ecoregions: the Pannonian Lowland (Ecoregion 11), the Dinaric Western Balkans (Ecoregion 5), and the Eastern Balkans (Ecoregion 7) and provide a comparative overview of their community patterns based on 130 samples. According to the CCA results and Monte Carlo permutation tests, water temperature, dissolved oxygen, conductivity, pH, and altitude were identified as statistically significant parameters influencing Chironomidae assemblages across the ecoregions, collectively explaining 72.20% of the variation. The higher diversity indices were recorded in each season in the Pannonian Lowland and the highest within-ecoregion similarity. Dissimilarity was highest between ER11 and ER7 and lowest between ER5 and ER7. These results demonstrate that the ecoregion was the strongest influence of the studied environmental variables on Chironomidae assemblages, with community patterns closely reflecting their spatial distribution across distinct ecoregional settings. Full article

Yellow eels were sampled by electrofishing in 1979, 1980, and 1981 in Vester Vedsted Stream, Denmark, which has as its outlet to the North Sea. Yellow eels were aged by burning the otoliths. The gender of the eels was not specified, and they varied from 6.5 to 48.5 cm in length. The ages varied from 0+ to 10+ years. The annual growth rate Δ varied from 3.4 cm for the youngest eels to 2.2 cm for eels over 10 years old, with a mean of 3.1 cm. Body mass wet weight was correlated to energy content (kcal), with an annual mean growth rate Δ of 5.33 kcal. In contrast to body length, the annual growth rate Δ of energy content (kcal) increased with age. Von Bertalanffy growth trajectory (cm) of length-at-age was calculated, and L∞ = 118.4 cm. Annual natural mortality M was calculated, and M was significantly dependent on body mass, i.e., high M at low body mass vs. low M at high body mass. The biological production was calculated to be 13.5 g wet weight m⁻² per year. A total of 780 eel stomachs were analyzed, 287 (37%) of which were empty. Mass (wet weight, g) of food content increased more than proportionally with eel body mass. Chironomid larvae, Ephemeroptera nymphs, Simulium larvae, and Gammarus pulex were the dominant food taxa, followed by Trichoptera larvae. The size of Chironomid larvae, Ephemeroptera nymphs, and Simulium larvae prey was independent of the length of the eel, whereas the size of Gammarus pulex increased with increased eel length. Full article

Chironomid subfossils were analysed at the Čepkeliai palaeolake in southern Lithuania in order to reconstruct the environmental history of the site during the Early Holocene, paying particular attention to climate change. Mean July air temperatures were inferred using two different chironomid–climate calibration data sets. As currently no chironomid-based climate calibration set is available from Lithuania, calibration data sets from Fennoscandia, Finland, and Poland were used instead. Our reconstructions suggest that mean July temperatures varied between 13.2 °C and 18.5 °C during the Early Holocene, similar to present-day temperatures. Both reconstructions show a series of climatic events that occurred during the Early Holocene, including the Preboreal oscillation and the “10.2”, “9.2”, and “8.2” oscillations. The reconstruction results correlate well with those carried out simultaneously in neighbouring countries, providing valuable information for this period, as such studies are still rare in the Eastern Baltic region. Full article

Many researchers have used the species composition, relative abundance and distribution pattern of profundal benthic macroinvertebrate communities in particular, especially chironomid fauna, as indicators of the trophic state and pollution of lakes. In addition, compared with previous benthic macroinvertebrate data, it is expected that the process of eutrophication/oligotrophication of lakes can also be traced. Benthic macroinvertebrate distribution was studied in Lake Kawaguchi, Japan (maximum depth 16.1 m; mean depth 9.3 m), on 7 March 2025. The benthic animals identified were aquatic oligochaetes, chironomid larvae, shellfish and others. Differences among environmental factors and zoobenthos densities and rank correlation were analyzed using a non-parametric test. The mean density of oligochaetes, which was the dominant group, was 2457 ± 1247 individuals/m², followed by chironomid larvae at 816 ± 391 individuals/m². The larvae of Propsilocerus akamusi were the most abundant species at 669 ± 358 individuals/m², followed by Chironomus plumosus at 109 ± 114 individuals/m². Other chironomids (38 ± 75 individuals/m²) were also captured. Benthic communities were collected at all sites, but each taxa had its own characteristics. Oligochaetes and C. plumosus were widely distributed throughout the lake, whereas the distribution of P. akamusi was skewed toward the western part of the lake. In comparison with previous studies, P. akamusi larvae were now found to be the most abundant chironomid species in this lake, accounting for an increased percentage of the chironomid community, while C. plumosus larvae had decreased in recent years. In addition, the higher levels of organic matter in the upper sediment layer of the lake suggest ongoing eutrophication. Previous studies classified Lake Kawaguchi as mesotrophic–eutrophic, but reconsideration of this classification is warranted given the above findings. We suggest that this lake be ranked as a eutrophic lake (chlorophyll-a concentration; ca. 0.05 mg/L) based on a long-term investigation of the changes in chironomid fauna. Full article

To prepare for a boosted sterile insect technique (SIT) field trial in Saint-Joseph, Reunion island, we compared the attractiveness of two adult mosquito traps for Aedes albopictus and Aedes aegypti. In addition, we explored the co-occurrence of these species in their usual larval habitats. Two traps were compared with two conditions each using a Latin square design: BG Sentinel trap baited with carbon dioxide (CO₂) with/without addition of BG Lure and ovi-sticky trap with/without hay. The ovi-sticky traps proved ineffective. For both Aedes species, CO₂-baited traps were equally effective at catching females when baited with the lure or not. In contrast, they were more attractive to males than for females with the lure. Aedes aegypti larvae were found in four of six vacoas (Pandanus utilis), and one of four anthropogenic breeding sites. In vacoas, the densities of Aedes albopictus and Aedes aegypti larvae were negatively correlated, whereas the correlation was positive between chironomids and Aedes aegypti. The abundance of adults and larvae varied according to weather conditions. Finally, CO₂-baited traps were used without lure for the entomological monitoring to assess the effectiveness of the area-wide boosted SIT intervention to reduce costs and logistics. Full article

Eutrophication has intensified in lacustrine systems across the American continent, which has been primarily driven by human activities such as intensive agriculture, wastewater discharge, and land-use change. This phenomenon adversely affects water quality, biodiversity, and ecosystem functioning. However, studies addressing the historical evolution of trophic states in lakes and reservoirs remain limited—particularly in tropical and subtropical regions. In this context, sedimentary records serve as invaluable archives for reconstructing the environmental history of water bodies. Paleolimnological approaches enable the development of robust chronologies to further analyze physical, geochemical, and biological proxies to infer long-term changes in primary productivity and trophic status. This review synthesizes the main methodologies used in paleolimnological research focused on trophic state reconstruction with particular attention to the utility of proxies such as fossil pigments, diatoms, chironomids, and elemental geochemistry. It further underscores the need to broaden spatial research coverage, fostering interdisciplinary integration and the use of emerging tools such as sedimentary DNA among others. High-resolution temporal records are critical for disentangling natural variability from anthropogenically induced changes, providing essential evidence to inform science-based lake management and restoration strategies under anthropogenic and climate pressures. Full article

There are very few data linking recent climatic changes to changes in biological communities in the Russian Arctic, and no palaeoecological data are available from the Novaya Zemlya archipelago (NZ). We studied chironomid, cladoceran, and diatom communities from a 165-year-old sediment core from a lake on Southern Island, NZ. Sixteen diatom and four cladoceran species new to NZ were found in the lake. Significant changes occurred in biological communities; species turnover was highest for diatoms (2.533 SD), followed by chironomids (1.781 SD) and cladocerans (0.614 SD). Biological communities showed a correlation with meteorologically recorded climate parameters. For chironomids, the strongest relationships were found for T_June, T_July, and T_ann. Both planktonic proxies, diatoms, and cladocerans showed a relationship with summer and annual air temperature and precipitation. The largest shifts in communities can be linked to recent climatic events, including the onset of steady warming following the variable conditions at the end of the LIA (ca. 1905), the cooling associated with the highest precipitation on record between 1950 and 1970, and, probably, the anthropogenic influence specific to Novaya Zemlya at this time. The new data provide a valuable basis for future ecological studies in one of the least explored and remote Arctic regions. Full article

(1) Background: Aquatic organisms are more sensitive to pollutants than terrestrial ones, making them ideal for ecotoxicology studies. Chironomids, a key bioindicator species, have been widely used in environmental pollution research. With the continuous deepening of research on water environmental pollution and the continuous development of molecular biology, it is therefore very important to understand the current research progress of the toxicology of chironomids. (2) Methods: This study used bibliometrics to analyze 1465 publications on chironomid toxicology from the Web of Science and PubMed databases, aiming to reveal research trends, hotspots, and future directions. The data analysis involved Microsoft Excel, VOS viewer, CiteSpace, and ChatGLM. (3) Results: Heavy metals, pesticides, and microplastics were the main pollutants studied, with Chironomus riparius being the most researched species. The analysis indicated a growing research trend since 1998, reflecting an increasing global concern over aquatic pollution. This study concludes that more molecular-level research is needed to uncover toxic mechanisms and improve environmental risk assessments. (4) Conclusions: This work will aid scientists and policymakers in developing better pollution control strategies and conservation efforts for aquatic ecosystems, ultimately contributing to environmental protection and public health. Full article

The dipteran family Chironomidae is the most widely distributed and, frequently, the most abundant group of insects in freshwater environments. Ecologically, the group plays an important role in trophic cycles and detritus processing in aquatic ecosystems and can be the most productive group of secondary producers in running waters. The annual secondary production of Chironomidae was estimated using emergence trap data from riffles and pools from two stations on the middle reaches of the Shinano River: Tokida Bridge Area (slope 1/180) and Iwano Bridge Area (1/1000). Emergence traps were set up for 24 h on the river’s water surface at three points each in the riffles and pools monthly from April 2015 to March 2019. Five subfamilies of Chironomidae were recorded during the investigation period: Chironominae, Orthocladiinae, Tanypodinae, Diamesinae, and Prodiamesinae. In the Shinano River (Tokida + Iwano area), Orthocladiinae and Diamesinae were the dominant subfamilies in terms of both density (63.2% and 19.0%, respectively) and biomass (62.2% and 25.2%, respectively). Each year’s annual secondary production measured as ash free dry weight (AFDW) was 11.33–55.04 g/m²/year in Tokida and 5.83–38.43 g/m²/year in Iwano. The average annual secondary production of detritus feeder Chironomidae (all except for Tanypodinae) was 24.46 ± 20.38 (ranging from 11.13 in 2015 to 54.67 in 2018) in the Tokida area and 19.61 ± 16.38 (ranging from 5.41 in 2016 to 37.53 in 2017) in the Iwano area. On the other hand, that of carnivorous Chironomidae (Tanypodinae) was 0.22 ± 0.10 (ranging from 0.13 in 2016 to 0.37 in 2018) in the Tokida area and 0.66 ± 0.24 (ranging from 0.42 in 2016 to 0.90 in 2017) in the Iwano area, and overall secondary production averaged 22.48 g/m²/year in the middle reaches of the Shinano River. These values were higher than in previous reports. Full article

In some estuaries, low inflow and/or isolation from the ocean can result in evapoconcentration and hypersalinity (≥40 ppt). This can create osmoregulatory and energetic challenges for the faunal community, leading to reductions in diversity as more species pass their thresholds. As climate change is increasing the magnitude and duration of hypersaline conditions, we used benthic macroinvertebrate data from 12 estuaries across a Mediterranean climatic region (southwestern Australia) to assess the influence of salinity (0–122 ppt) on the invertebrate fauna. Taxa richness and diversity were highest in salinities between 0 and 39 ppt, peaking at salinities closest to seawater, while total density peaked at 40–49 ppt. Beyond 50 ppt, these measures declined significantly. Community composition changed markedly along the salinity gradient. In lower salinities, communities were diverse, comprising polychaetes, malacostracans, hexapods, ostracods, bivalves, and gastropods. However, in salinities ≥50 ppt, many taxa declined, leading to communities dominated by polychaetes (mainly Capitella spp.) and hexapods (mostly larval chironomids). At 90 ppt, only polychaetes and hexapods remained, and at ≥110 ppt, only the latter taxon persisted. This faunal shift towards insect dominance in hypersaline conditions mirrors observations in other Mediterranean and arid/semi-arid regions, with the resulting communities resembling saline wetlands or salt lakes. This loss of invertebrates can substantially impact ecosystem functioning and trophic pathways, and the findings of this study provide a basis for predicting how these communities will respond to increasing hypersalinity driven by climate change. Full article

Chironomidae are characterised by cosmopolitan distribution, high abundance and diversity in different aquatic environments, which makes them ideal for studying changes in freshwater ecosystems. To understand the environmental factors influencing chironomid communities, we analysed how altitude and waterbody type (hydromorphological features) affect their composition at 75 study sites from 49 watercourses. A total of 110 chironomid taxa from five subfamilies were identified, with Prodiamesa olivacea, Rheocricotopus fuscipes and Cricotopus bicinctus being the most frequent species. The lowest values of all alpha diversity components were recorded in communities collected from watercourses at altitudes up to 500 m a.s.l., while the highest values were observed in small mountainous rivers and streams. Beta diversity showed that taxa turnover was the dominant component in all situations analysed. Communities in large rivers with fine substrate were characterised by the lowest taxa turnover and the highest levels of nestedness, indicating the existence of an ecological gradient that reduces the number of taxa from one site to another. We identified indicator taxa for different altitudes, as well as groups of taxa that are typical for different waterbody types. Furthermore, the combination of four water parameters (oxygen saturation, conductivity, concentration of ammonium and nitrates) had the strongest influence on the chironomid community composition in the studied watercourses. Full article

Psectrocladius, a genus within the species-rich subfamily Orthocladiinae (Diptera: Chironomidae), remains poorly resolved in molecular phylogenetics due to limited available molecular data. Here, we sequenced and analyzed the complete mitogenomes of five Psectrocladius species, using two Rheocricotopus species as outgroups. Our results reveal that the mitogenomes of Psectrocladius are structurally conserved and retain a presumed ancestral gene order. The nucleotide composition of these newly generated mitogenomes exhibits a pronounced A + T bias, which is characteristic of typical insect mitogenomes. The substitution rates, estimated using Ka/Ks ratios, indicate that all protein-coding genes are under purifying selection. The strongest purifying selection pressure was observed in the CO1 gene, while the weakest was in the ND5 gene. Both the maximum likelihood and Bayesian inference trees consistently show the following topology: ((((P. schlienzi + P. bisetus) + P. barbimanus) + P. oligosetus) + P. aquatronus). This study provides key insights into chironomid mitogenomes and their gene properties, offering valuable reference data for future research. Full article

The interaction between freshwater biota and microplastics (MPs) has recently been described, mostly focusing on indoor experiments using fish, crustaceans, and chironomids. Among aquatic invertebrates, although having an important ecological role, aquatic butterfly larvae have not yet been investigated concerning plastics. We examined the interaction between aquatic larvae of the moth Cataclysta lemnata (Linnaeus, 1758) and MPs. We verified if (i) larvae could use MPs to build their protective cases, (ii) they could chew PVC, and (iii) there were effects on the pupae emergence to adult moths after larvae exposure to PVC. By performing two indoor experiments, (i) we exposed larvae to different MPs polymers, aquatic plant Lemna minuta, and a mix of MPs with L. minuta, and (ii) exposed larvae to a PVC layer. For the first time, we observed that C. lemnata larvae use MPs to build their cases and chewed the PVC layer. About half of the larvae (48.0%) pupated of which 43.7% emerged as adults. Our findings suggest that MPs are used by C. lemnata larvae, potentially affecting their life cycle. Future studies should explore whether MPs are transported by adult moths, linking aquatic and terrestrial ecosystems. Full article

Tanypodinae, a highly diverse subfamily within Chironomidae (Diptera), has been poorly represented in mitochondrial genome (mitogenome) databases, with only a limited number of complete or partial sequences available. To address this gap, we present the first complete mitogenome sequences of 16 Tanypodinae species and 1 Podonominae species. By integrating these novel data with previously published chironomid mitogenomes, we conducted a comprehensive comparative mitogenomic analysis of 21 Tanypodinae species. Our results reveal that Tanypodinae mitogenomes maintain a conserved structural organization, preserving the ancestral insect gene arrangement. The nucleotide composition exhibits significant bias, with the control region demonstrating the highest A + T content among all genomic regions. Evolutionary analysis indicates that all protein-coding genes (PCGs) are subject to purifying selection, with ATP8 exhibiting the most rapid evolutionary rate. Phylogenetic reconstruction based on PCG amino acid sequences delineates seven well-supported clades within Tanypodinae, corresponding to the tribes Pentaneurini, Natarsiini, Procladiini, Tanypodini, Clinotanypodini, Macropelopiini, and Anatopyniini. These findings significantly advance our understanding of mitogenomic architecture and provide critical insights into the phylogenetic relationships within Tanypodinae. Full article