Mining and urbanization affect river chemical water quality and macroinvertebrate communities in the upper Selenga River Basin, Mongolia.

Mongolia is a country with a quickly growing economy mainly based on mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River Basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites: (1) nutrients, (2) saline components (Cl-, Na +, Mg2+, SO42-, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 32 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program.

The genome sequence of the cinnamon sedge caddisfly, Limnephilus marmoratus (Curtis, 1834).

We present a genome assembly from an individual Limnephilus marmoratus (a caddisfly; Arthropoda; Insecta; Trichoptera; Limnephilidae). The genome sequence is 1,630 megabases in span. Most of the assembly (99.93%) is scaffolded into 30 chromosomal pseudomolecules, including the assembled Z sex chromosome. The mitochondrial genome has also been assembled and is 15.4 kilobases in length.

The genome sequence of a caddisfly, Limnephilus lunatus (Curtis, 1834).

We present a genome assembly from an individual Limnephilus lunatus (a caddisfly; Arthropoda; Insecta; Trichoptera; Limnephilidae). The genome sequence is 1,270 megabases in span. Most of the assembly is scaffolded into 13 chromosomal pseudomolecules, including the assembled Z chromosome. The mitochondrial genome has also been assembled and is 15.4 kilobases long.

Land use drives detritivore size structure and decomposition through shifts in resource quality and quantity.

Land use change and nutrient pollution are two pervasive stressors that can modify carbon cycling, as they influence the inputs and the transformation of detritus. Understanding their impact on stream food webs and on diversity is particularly pressing, as streams are largely fuelled by detrital material received from the adjacent riparian environment. Here we assess how a switch from native deciduous forest to Eucalyptus plantations and nutrient enrichment alter the size distribution of stream detritivore communities and decomposition rates of detritus. As expected, more detritus resulted in higher size-independent, or overall, abundance (i.e. higher intercept of size spectra). This change in overall abundance was mainly driven by a change of the relative contribution of large taxa (Amphipoda and Trichoptera), which changed from an average relative abundance of 55.5 to 77.2 % between the sites compared for resource quantity differences in our study. In contrast, detritus quality modified the relative abundance of large vs small individuals (i.e. size spectra slopes), with shallow slopes of size spectra (proportionately more large individuals) associated with sites with nutrient-richer waters and steeper slopes (proportionately fewer large individuals) associated with sites draining Eucalyptus plantations. Decomposition rates of alder leaves due to macroinvertebrates increased from 0.0003 to 0.0142 when relative contribution of large organisms increased (modelled slopes of size spectra: -1.00 and - 0.33, respectively), highlighting the importance of large sized individuals for ecosystem functioning. Our study reveals that land use change and nutrient pollution can greatly impair the transfer of energy through the detrital or 'brown' food web by means of intra- and inter-specific responses to quality and quantity of the detritus. These responses enable linking land use change and nutrient pollution to ecosystem productivity and carbon cycling.

Altitudinal and seasonal distribution of benthic macroinvertebrates in River Tons - a tributary of Yamuna River, Uttarakhand, India.

The main tributary of the Yamuna, the Tons River, exhibits altitudinal changes in its macroinvertebrate community's diversity, abundance, and composition. Between May 2019 and April 2021, the study was conducted in the upper section of the river. A total of 48 numbers of taxa from 34 families and ten orders were recorded during the investigation. At this elevation of 1150 to 1287 m, the two most predominant orders are Ephemeroptera (32.9%) and Trichoptera (29.5%). During the premonsoon season, they had the lowest macroinvertebrate density (250-290 individuals/m2), and the post-monsoon season had the highest density (600-640 individuals/m2). During the post-monsoon season, the maximum larval forms (60%) of various insect orders were predominant. The findings indicated that lower altitudes (1150-1232 m) have higher macroinvertebrate abundance than higher ones. The diversity of dominance is shallow at site-I (0.0738) and strong at the site-IV during the premonsoon season (0.03837). Taxa richness, as measured by the Margalef index (D), peaked in the spring season (January to March) at 6.9 and reached its lowest point (5.74) in the premonsoon season (April to May). Only 16 taxa were discovered in site-I and site-II, but 39 taxa were discovered at low altitudes (site-IV, 1100 m) (1277-1287 m). The Tons River contains a total of 12 and 13 genera, respectively, that belong to the orders Ephemeroptera and Trichoptera, according to qualitative study of the macroinvertebrates. The current study supports the use of macroinvertebrates as bioindicator species for monitoring biodiversity and assessing the health of ecosystems.

Catalog of the Hydroptilidae (Insecta, Trichoptera).

The microcaddisfly (Trichoptera: Hydroptilidae) fauna is catalogued from a review of more than 1,300 literature citations through the end of 2020 to include 2,665 currently recognized, valid species in six subfamilies and 76 genera. Fourteen subspecies are included in the total as well as 23 fossil species and three fossil genera. The family Ptilocolepidae (Trichoptera), also covered in this catalogue, comprises 19 valid species in two genera; two subspecies and two fossil species are included in the total. The monotypic genus Eutonella, currently considered incertae sedis within Trichoptera, was formerly placed in Hydroptilidae and is also included in this catalogue. Genus-group and species-group synonyms are listed. Information on the type locality, type depository, sex of type, distribution by country, and other relevant taxonomic or biological information is included for each nominal species. Summary information on taxonomy, phylogeny, distribution, immature stages, and biology are provided for each subfamily, tribe, and genus where known. An index to all nominal taxa is provided to facilitate catalog use.

The InBIO barcoding initiative database: DNA barcodes of Iberian Trichoptera, documenting biodiversity for freshwater biomonitoring in a Mediterranean hotspot.

Background: The Trichoptera are an important component of freshwater ecosystems. In the Iberian Peninsula, 380 taxa of caddisflies are known, with nearly 1/3 of the total species being endemic in the region. A reference collection of morphologically identified Trichoptera specimens, representing 142 Iberian taxa, was constructed. The InBIO Barcoding Initiative (IBI) Trichoptera 01 dataset contains records of 438 sequenced specimens. The species of this dataset correspond to about 37% of Iberian Trichoptera species diversity. Specimens were collected between 1975 and 2018 and are deposited in the IBI collection at the CIBIO (Research Center in Biodiversity and Genetic Resources, Portugal) or in the collection Marcos A. González at the University of Santiago de Compostela (Spain). New information: Twenty-nine species, from nine different families, were new additions to the Barcode of Life Data System (BOLD). A success identification rate of over 80% was achieved when comparing morphological identifications and DNA barcodes for the species analysed. This encouraging step advances incorporation of informed Environmental DNA tools in biomonitoring schemes, given the shortcomings of morphological identifications of larvae and adult Caddisflies in such studies. DNA barcoding was not successful in identifying species in six Trichoptera genera: Hydropsyche (Hydropsychidae), Athripsodes (Leptoceridae), Wormaldia (Philopotamidae), Polycentropus (Polycentropodidae) Rhyacophila (Rhyacophilidae) and Sericostoma (Sericostomatidae). The high levels of intraspecific genetic variability found, combined with a lack of a barcode gap and a challenging morphological identification, rendered these species as needing additional studies to resolve their taxonomy.

Case design and flow resistance in high-alpine caddisfly larvae (Insecta, Trichoptera).

For evaluating hydraulic stress reduction strategies of caddisfly larvae, our study has three goals. First, creating a database on Reynolds numbers (Re) and drag coefficients valid for Limnephilidae larvae with cylindrical mineral cases. Second, evaluating the effects of submerged weight and biometry in cases with comparable length/width ratios. And third, collecting field data in an alpine environment for gaining insights into the hydraulic niches occupied by thirteen Drusinae species. Biometric data were subsequently combined with published Reynolds numbers and mean flow velocity data measured immediately upstream of Limnephilidae larvae at the moment of dislodgement. This provides drag coefficients for the range of Reynolds numbers obtained in the field. Data reveal that heavy cases strongly benefit from compensating drag by submerged weight, thereby enabling species to utilize high velocity spots, an important benefit for filtering species. Supplementary Information: The online version contains supplementary material available at 10.1007/s10750-022-04981-y.

Using the multi-omics approach to reveal the silk composition in Plectrocnemia conspersa.

Similar to Lepidoptera, the larvae of Trichoptera are also capable of producing silk. Plectrocnemia conspersa, a predatory species belonging to the suborder Annulipalpia, builds massive silken retreats with preycapturing nets. In this study, we describe the silk glands of P. conspersa and use the multi-omics methods to obtain a complete picture of the fiber composition. A combination of silk gland-specific transcriptome and proteomic analyses of the spun-out fibers yielded 27 significant candidates whose full-length sequences and gene structures were retrieved from the publicly available genome database. About one-third of the candidates were completely novel proteins for which there are no described homologs, including a group of five pseudofibroins, proteins with a composition similar to fibroin heavy chain. The rest were homologs of lepidopteran silk proteins, although some had a larger number of paralogs. On the other hand, P. conspersa fibers lacked some proteins that are regular components in moth silk. In summary, the multi-omics approach provides an opportunity to compare the overall composition of silk with other insect species. A sufficient number of such studies will make it possible to distinguish between the basic components of all silks and the proteins that represent the adaptation of the fibers for specific purposes or environments.

Conservation of Three-Dimensional Structure of Lepidoptera and Trichoptera L-Fibroins for 290 Million Years.

The divergence of sister orders Trichoptera (caddisflies) and Lepidoptera (moths and butterflies) from a silk-spinning ancestor occurred around 290 million years ago. Trichoptera larvae are mainly aquatic, and Lepidoptera larvae are almost entirely terrestrial-distinct habitats that required molecular adaptation of their silk for deployment in water and air, respectively. The major protein components of their silks are heavy chain and light chain fibroins. In an effort to identify molecular changes in L-fibroins that may have contributed to the divergent use of silk in water and air, we used the ColabFold implementation of AlphaFold2 to predict three-dimensional structures of L-fibroins from both orders. A comparison of the structures revealed that despite the ancient divergence, profoundly different habitats, and low sequence conservation, a novel 10-helix core structure was strongly conserved in L-fibroins from both orders. Previously known intra- and intermolecular disulfide linkages were accurately predicted. Structural variations outside of the core may represent molecular changes that contributed to the evolution of insect silks adapted to water or air. The distributions of electrostatic potential, for example, were not conserved and present distinct order-specific surfaces for potential interactions with or modulation by external factors. Additionally, the interactions of L-fibroins with the H-fibroin C-termini are different for these orders; lepidopteran L-fibroins have N-terminal insertions that are not present in trichopteran L-fibroins, which form an unstructured ribbon in isolation but become part of an intermolecular ß-sheet when folded with their corresponding H-fibroin C-termini. The results are an example of protein structure prediction from deep sequence data of understudied proteins made possible by AlphaFold2.

Species-specific traits predict whole-assemblage detritus processing by pond invertebrates.

Functional trait diversity determines if ecosystem processes are sensitive to shifts in species abundances or composition. For example, trait variation suggests detritivores process detritus at different rates and make different contributions to whole-assemblage processing, which could be sensitive to compositional shifts. Here, we used a series of microcosm experiments to quantify species-specific coarse and fine particulate organic matter (CPOM and FPOM) processing for ten larval caddisfly species and three non-caddisfly species in high-elevation wetlands. We then compared trait-based models including life history, dietary, and extrinsic traits to determine which traits explained interspecific variation in detritus processing. Finally, we compared processing by mixed caddisfly assemblages in microcosms and natural ponds to additive predictions based on species-specific processing to determine if single-species effects are additive in multi-species assemblages. We found considerable interspecific variation in biomass-specific CPOM (13-fold differences) and FPOM (8-fold differences) processing. Furthermore, on a mass-specific basis, amphipods, chironomids, and caddisflies processed similar amounts of detritus, suggesting non-shredder taxa could process more than previously recognized. Trait models including dietary percent detritus, development rate, body size, and wetland hydroperiod explained 81 and 57% of interspecific variation in CPOM and FPOM processing, respectively. Finally, species-specific additive predictions were strikingly similar to mixed-assemblage processing in microcosms and natural ponds, with the largest difference being a 15% overestimate. Thus, additivity of species-specific processing suggests single-species rates may be useful for understanding functional consequences of shifting assemblages, and a trait-based approach to predicting species-specific processing could support generating additive predictions of whole-assemblage processing.

Early evolution of wing scales prior to the rise of moths and butterflies.

Although scales are a defining and conspicuous feature of moths and butterflies (Lepidoptera),1-3 their earliest evolution predates the group but is shrouded by a dearth of fossil evidence. Herein, we report two new species in mid-Cretaceous Kachin amber, representing lineages closely related to Lepidoptera: one represents the extinct Tarachoptera, with dense scales on the fore- and hindwings, while the other is an early lineage of caddisflies, with a hindwing covered by a single layer of angustifoliate scales. A novel phylogenetic analysis of 174 morphological characters and 73 extant and fossil representatives of Mecopterida demonstrates a monophyletic origin of scales in the common ancestor of Tarachoptera, Trichoptera, and Lepidoptera; that Tarachoptera are monophyletic but their scale morphology is plesiomorphic for the whole group; and that scales were lost early in caddisfly evolution before reappearing multiple times within the clade. Collectively, these fossils provide clarity into the origin and early evolution of scales before their diversification among the moths and butterflies.

A new pattern of parasitism in water mites (Hydrachnidia)? An insight into their relationships with pupae of caddisflies (Trichoptera).

To date, relatively few data have been available regarding the parasitism of water mite larvae on caddisflies; most available information relates to the adult stadia, fewer to caddisfly larvae, with just single references to pupae. The present paper examines the occurrence (phoresy and parasitism) of Piona stjordalensis larvae (119 individuals) on the larvae and pupae of Mystacides longicornis. It is possible that water mite larvae exhibit a new type of parasitism on caddisflies, with two consecutive parasitic larval stadia: one on the pupa, the other on the imago.

The curious case of methylparaben: Anthropogenic contaminant or natural origin?

The widespread use of methylparaben as a preservative has caused increased exposure to natural aquatic systems in recent decades. However, current studies have suggested that exposure to this compound can result in endocrine disrupting effects, raising much concern regarding its environmental impact. In contast, methylparaben has also been found to be part of the metabolome of some organisms, prompting the question as to whether this compound may be more natural than previously assumed. Through a combination of field studies investigating the natural presence of methylparaben across different taxa, and a 54-day microcosm experiment examining the bioaccumulation and movement of methylparaben across different life stages of aquatic insects (order Trichoptera), our results offer evidence suggesting the natural origin of methylparaben in aquatic and terrestrial biota. This study improves our understanding of the role and impact this compound has on biota and challenges the current paradigm that methylparaben is exclusively a harmful anthropogenic contaminant. Our findings highlight the need for further research on this topic to fully understand the origin and role of parabens in the environment which will allow for a comprehensive understanding of the extent of environmental contamination and result in a representative assessment of the environmental risk that may pose.

Genome size evolution in the diverse insect order Trichoptera.

BACKGROUND: Genome size is implicated in the form, function, and ecological success of a species. Two principally different mechanisms are proposed as major drivers of eukaryotic genome evolution and diversity: polyploidy (i.e., whole-genome duplication) or smaller duplication events and bursts in the activity of repetitive elements. Here, we generated de novo genome assemblies of 17 caddisflies covering all major lineages of Trichoptera. Using these and previously sequenced genomes, we use caddisflies as a model for understanding genome size evolution in diverse insect lineages. RESULTS: We detect a ∼14-fold variation in genome size across the order Trichoptera. We find strong evidence that repetitive element expansions, particularly those of transposable elements (TEs), are important drivers of large caddisfly genome sizes. Using an innovative method to examine TEs associated with universal single-copy orthologs (i.e., BUSCO genes), we find that TE expansions have a major impact on protein-coding gene regions, with TE-gene associations showing a linear relationship with increasing genome size. Intriguingly, we find that expanded genomes preferentially evolved in caddisfly clades with a higher ecological diversity (i.e., various feeding modes, diversification in variable, less stable environments). CONCLUSION: Our findings provide a platform to test hypotheses about the potential evolutionary roles of TE activity and TE-gene associations, particularly in groups with high species, ecological, and functional diversities.

Checklist of the caddisflies (Insecta, Trichoptera) of the Upper Midwest region of the United States.

Five hundred and fifty-two caddisfly species are reported from the Upper Midwest region of the United States, an area that includes 13 states and ~ 2 million km2. Of these, 62 species are reported for the first time from the state of Iowa, 25 from Wisconsin, 18 from South Dakota, 12 from Illinois, five from Indiana, four from North Dakota, four from Minnesota, and one from Nebraska. The Upper Midwest fauna contains nearly 40% of all species known from the United States and Canada, as well as 22 species endemic to the region. Overall species richness was highest in Michigan (319 species), Kentucky (296), Minnesota (292), and Wisconsin (284). Differences in state species assemblages within the region largely followed a geographic pattern, with species richness declining in the western prairie states. There are almost certainly further species remaining to be found in this large region.

A new species of Silvatares (Trichoptera, Pisuliidae) from the Democratic Republic of the Congo.

A new species of caddisfly in the family Pisuliidae from the Democratic Republic of the Congo is described and illustrated herein, Silvataresholzenthali sp. nov. Based on the presence of a pair of spines on the endotheca, this species belongs to the thrymmifer group. Additionally, Silvatareslaetae is recorded for the first time from the D.R. Congo.

Comparison of caddisfly (Insecta, Trichoptera) assemblages from lake and river habitats of the Huron Mountains of Michigan (USA).

The caddisfly assemblages of six lakes and 12 1st-4th order streams of the Huron Mountains of northern Upper Michigan (USA) were sampled monthly with ultraviolet lights during June-September 2019. A total of 169 species representing 63 genera and 19 families was collected, including five species not found elsewhere in Michigan and two species endemic to the state. Species assemblages between lotic and lentic habitats were distinct from each other, with 11 species indicating lakes and 23 indicating rivers. Despite the taxonomic differences, biomass of functional feeding groups (FFGs) was similar between lakes and rivers, except for higher biomass of predators in the former and higher biomass of filtering collectors in the latter. The FFG biomass of both habitat types was dominated (50-70%) by shredders. Considering the undisturbed condition of the habitats, the caddisfly assemblages and FFG biomass of the Huron Mountains can serve as regional biological monitoring reference conditions.

De Novo Genome Assembly and Annotation of an Andean Caddisfly, Atopsyche davidsoni Sykora, 1991, a Model for Genome Research of High-Elevation Adaptations.

We sequence, assemble, and annotate the genome of Atopsyche davidsoni Sykora, 1991, the first whole-genome assembly for the caddisfly family Hydrobiosidae. This free-living and predatory caddisfly inhabits streams in the high-elevation Andes and is separated by more than 200 Myr of evolutionary history from the most closely related caddisfly species with genome assemblies available. We demonstrate the promise of PacBio HiFi reads by assembling the most contiguous caddisfly genome assembly to date with a contig N50 of 14 Mb, which is more than 6× more contiguous than the current most contiguous assembly for a caddisfly (Hydropsyche tenuis). We recover 98.8% of insect BUSCO genes indicating a high level of gene completeness. We also provide a genome annotation of 12,232 annotated proteins. This new genome assembly provides an important new resource for studying genomic adaptation of aquatic insects to harsh, high-altitude environments.

Predators balance consequences of climate-change-induced habitat shifts for range-shifting and resident species.

While many species distributions are shifting poleward or up in elevation in response to a changing climate, others are shifting their habitats along localized gradients in environmental conditions as abiotic conditions become more stressful. Whether species are moving across regional or local environmental gradients in response to climate change, range-shifting species become embedded in established communities of competitors and predators. The consequences of these shifts for both resident and shifting species are often unknown, as it can be difficult to isolate the effects of multiple species interactions. Using a model system of insects in high-elevation ponds in the Rocky Mountains of Colorado, we sought to disentangle the effects of predation and intraguild interactions on the survival and development of a semi-permanent pond resident caddisfly Limnephilus externus and the habitat-shifting caddis Asynarchus nigriculus that is being forced into semi-permanent ponds as temporary ponds dry too quickly to complete development. We conducted a manipulative in-situ pond cage experiment in which L. externus and A. nigriculus caddisfly larvae in single-species treatments and together were exposed to the presence/absence of predatory Dytiscus diving beetle larvae. This approach allowed us to isolate the effects of intraguild interactions and predation on the survival and development of both the resident and habitat-shifting species. We found that intraguild interactions had strong negative effects on the resident and habitat-shifting species. Intraguild interactions reduced the survival of the resident L. externus and increased the variation in survival of the shifting A. nigriculus. However, Dytiscus predators reduced these negative effects, stabilizing the community by increasing L. externus survival and reducing variation in A. nigriculus survival. We also found that intraguild interactions reduced L. externus biomass but resulted in increased A. nigriculus development. A. nigriculus development was also increased by predation. Our results show that strong intraguild interactions between resident and shifting species are likely to have negative consequences for both species. However, the presence of predators reduces these negative consequences of the habitat shift on both the resident and the shifting.