Automated identification of aquatic insects: A case study using deep learning and computer vision techniques

Despite huge attention in other domains, deep learning is only very slowly beginning to be applied in biodiversity research. Mayflies (Ephemeroptera), stoneflies (Plecoptera) and caddisflies (Trichoptera), often abbreviated as EPT, are frequently used for freshwater biomonitoring due to their large numbers and sensitivity to environmental changes. However, the unambiguous morphological identification of EPT species is a challenging, but fundamental task. Morphological identification of these freshwater insects is therefore not only extremely time-consuming and costly, but also often leads to misjudgments or generates datasets with low taxonomic resolution. Here, we investigated the application of deep learning to increase the efficiency and taxonomic resolution of biomonitoring programs. Our database contains 90 EPT taxa (genus or species level), with the number of images per category ranging from 21 to 300 (16,650 in total). Upon completion of training, a CNN (Convolutional Neural Network) model was created, capable of automatically classifying these taxa into their appropriate taxonomic categories with an accuracy of 98.7 %. For the extensive set of 68 tested taxa, our model achieved a perfect classification rate of 100 %. We achieved noteworthy classification accuracy with morphologically closely related taxa within the training data (e.g., species of the genus Baetis, Hydropsyche, Perla). Gradient-weighted Class Activation Mapping (Grad-CAM) visualized the morphological features responsible for the classification of the treated species in the CNN models. In the Ephemeroptera, the head was the most important feature, while the thorax and abdomen were equally important for the classification of Plecoptera taxa. For the order Trichoptera, the head and thorax were almost equally important. Our database is recognized as the most extensive aquatic insect database, notably distinguished by its wealth of included categories (taxa). Our approach can help solve long-standing challenges in biodiversity research and address pressing issues in monitoring programs by saving time in sample and data processing.

Bigger is not necessarily better: empirical tests show that dispersal proxies misrepresent actual dispersal ability

Tests for the role of species' relative dispersal abilities in ecological and biogeographical models rely heavily on dispersal proxies, which are seldom substantiated by empirical measures of actual dispersal. This is exemplified by tests of dispersal-range size relationships and by metacommunity research that often features invertebrates, particularly freshwater insects. Using rare and unique empirical data on dispersal abilities of caddisflies, we tested whether actual dispersal abilities were associated with commonly used dispersal proxies (metrics of wing size and shape; expert opinion). Across 59 species in 12 families, wing morphology was not associated with actual dispersal. Within some families, individual wing metrics captured some dispersal differences among species, although useful metrics varied among families and predictive power was typically low. Dispersal abilities assigned by experts were either no better than random or actually poorer than random. Our results cast considerable doubt on research underpinned by dispersal proxies and scrutiny of previous research results may be warranted. Greater progress may lie in employing innovative survey and experimental design to measure actual dispersal in the field.

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.

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.

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 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.

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.

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.

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.

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 1^st-4^th 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.

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.

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.

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.

Towards Insect-Friendly Road Lighting-A Transdisciplinary Multi-Stakeholder Approach Involving Citizen Scientists

Simple Summary

Road lighting is a service provided at night, mainly to ensure the secure and safe passage of humans. However, lighting at night can have adverse effects on insects or ecosystems, which are not yet considered in planning. Here, we introduce a comprehensive approach for the design and implementation of a novel insect-friendly road luminaire. The lighting design provides an optimized radiation geometry that avoids emissions at the trajectory height of insects, reduces the attraction of insects and the fragmentation of their habitats, and at the same time provides adequate night-time illumination in residential areas. The effects of the new design on insect behavior and night sky brightness will be evaluated two years before and two years after the change of the road luminaires and additionally in a direct comparison, as some luminaires of the old design will remain as controls. Citizen scientists are involved in the identification of insects and the measurement of night sky brightness. A broad public engagement program also highlights discussions about the competing interests of different stakeholders in lighting design, explicitly including the effects of illumination on insect fauna and biodiversity.

Abstract

(1) The project “Tatort Streetlight” implements an insect-friendly road light design in a four year before–after, control–impact (BACI) approach involving citizen scientists. It will broaden the stakeholder interests from solely anthropogenic perspectives to include the welfare of insects and ecosystems. Motivated by the detrimental impacts of road lighting systems on insects, the project aims to find solutions to reduce the insect attraction and habitat fragmentation resulting from roadway illumination. (2) The citizen science approach invites stakeholders to take part and join forces for the development of a sustainable and environmentally friendly road lighting solution. Here, we describe the project strategy, stakeholder participation and motivation, and how the effects of the alternative road luminaire and lighting design can be evaluated. (3) The study compares the changes in (a) insect behavior, (b) night sky brightness, and (c) stakeholder participation and awareness. For this purpose, different experimental areas and stakeholders in four communities in Germany are identified. (4) The project transfers knowledge of adverse effects of improperly managed road illumination and interacts with various stakeholders to develop a new road lighting system that will consider the well-being of street users, local residents, and insects.

The fauna of aquatic invertebrates in the river impacted by wastewaters from the pulp and paper industry (Komi Republic)

BACKGROUND

Invertebrates are important elements of aquatic ecosystems and play a crucial role in the transformation of matter and energy in continental water bodies. Communities of aquatic invertebrates are characterised by high sensitivity to pollution by nutrients and toxic substances and acidification of water bodies; they serve as good bioindicators of the quality of the aquatic environment and impacts on hydroecosystems. All hydrobionts participate in the processes of self-purification of water bodies.The presented dataset provides information on the aquatic invertebrate community of a large northern river. During 2018-2020, we collected data on changes in the quantitative indicators of the development of benthic and planktonic communities, as well as the species diversity of their fauna. The dataset combines information about the occurrence and abundance of benthic and planktonic invertebrates and summarises data of aquatic invertebrate species found in the Vychegda River in the zone of influence from the pulp and paper mill.

NEW INFORMATION

The presented dataset is part of a monitoring programme of the river ecosystems in the production area of Mondi Syktyvkar JSC (the European North-East of Russia, Komi Republic). The dataset describes the structure of benthic invertebrate and plankton communities in the Northern Dvina River Basin. The data on the finding and abundance of large taxa of aquatic invertebrates and species of some groups: Oligochaeta, Cladocera, Copepoda, Rotifera, Ephemeroptera, Plecoptera and Trichoptera are presented. In total, the resource includes 8720 findings of invertebrates, of which 6041 are for zoobenthos organisms and 2679 for zooplankton organisms.

Vertical Migration of Adult Plecoptera and Trichoptera above Forested Headwater Streams

Stream insects are essential components of aquatic and terrestrial ecosystem structure and function. Terrestrial stages are important components of terrestrial food webs, and flight-capable individuals are responsible for long-distance dispersal. Horizontal migrations by flying or crawling adults away from stream channels that link insects to riparian food webs and movements across catchment boundaries are well established through empirical research, but studies examining vertical migration of adult stream insects into forest canopies are generally lacking. This study focused on differences in adult Plecoptera and Trichoptera abundance at ground level versus the riparian canopy and differences in abundances among summer and autumn sampling periods to empirically demonstrate use of canopy ecosystems by stream insects. Malaise traps at ground level and canopy traps placed 8 to 10 m above the stream at four sites in the Mosquito Creek watershed (Pennsylvania) were used to examine vertical migration. Larval assemblages were collected and compared to adult assemblage to investigate patterns of local migration in the catchment. We found significantly more stream insects at ground level than in the forest canopy for Trichoptera, Plecoptera, and all individual plecopteran families, but a meaningful number of individuals were found in the riparian canopy. Canopy abundances were similar to abundances captured in adjacent ground-level habitats in other studies. Comparisons of adult and larval abundances among sites, taxa, and stages indicated site- and taxon-specific patterns for vertical movement into riparian canopies. Demonstrating that adult stream insects utilize riparian forest canopies indicates that riparian forest conservation should be prioritized over reforestation and that several potential research questions exist to inform riparian management.

Influences of environmental parameters and phytoplankton productivity on benthic invertebrates in a tropical oligotrophic lake, northern Malaysia

Studies that associate environmental parameters with aquatic organisms in man-made lakes remain limited by accessibility and interest particularly in many Asian countries. With missed opportunities to monitor environmental transitions at Lake Kenyir, our knowledge of lake transition is restricted to the non-mixing shallow waters only. Triplicate monthly benthic invertebrate samples were collected concurrently with various environmental parameters at three locations (zones A-C) of Kenyir Lake, Malaysia. Our results affirmed that the northeast part of Lake Kenyir is oligotrophic. Abundance of phytoplankton, total suspended solids, phosphate, nitrite and nitrate drive the abundance of various groups of benthic invertebrates. All of these extrinsic variables (except phosphate) negatively influenced the density of Trichoptera and positively influenced (P<0.05) the densities of Polychaeta, Oligochaeta, Bivalvia, Gastropod, Isopoda and Copepod in all zones. Phosphate negatively influenced the density of Trichoptera and positively influenced (P<0.05) the densities of Oligochaeta, Bivalvia and Copepod. Its influences on the Polychaeta, Gastropod and Isopoda densities were zone-specific. Overall, seasons equally influenced the relationships between extrinsic and response variables in all zones. The results of this study are useful to evaluate the lake's environmental quality, in conservation and in similar projects involving environmental handling, monitoring and recovery.

Holo- and hemimetabolism of aquatic insects: Implications for a differential cross-ecosystem flux of metals

Increased metal concentrations in aquatic habitats come as a result of both anthropogenic and natural sources. Emerging aquatic insects that play an indispensable role in these environments, transferring resources and energy to higher trophic levels in both aquatic and terrestrial habitats, may inadvertently also act as biovectors for metals and other contaminants. This study measured levels of 22 different metals detected in biofilm, aquatic and terrestrial life stages of Trichoptera and Odonata, as well as riparian spiders, to examine the uptake and transfer from freshwater to terrestrial ecosystems. We show that emerging insects transfer metals from aquatic to terrestrial ecosystems, however with large losses observed on the boundary of these two environments. Significantly lower concentrations of most metals in adult insects were observed in both hemimetabolous (Odonata) and holometabolous insect orders (Trichoptera). In holometabolous Trichoptera, however, this difference was greater between aquatic life stages (larvae to pupae) compared to that between pupae and adults. Trophic transfer may have also played a role in decreasing metal concentrations, as metal concentrations generally adhered to the following pattern: biofilm > aquatic insects > terrestrial invertebrates. Exceptions to this observation were detected with a handful of essential (Cu, Zn, Se) and non-essential metals (Cd, Ag), which measured higher concentrations in adult aquatic insects compared to their larval counterparts, as well as in aquatic and terrestrial predators compared to their prey. Overall, all metals were found to be bioavailable and biotransferred from contaminated waters to terrestrial invertebrates to some degree, suggesting that risks associated with metal-contaminated freshwaters could extend to terrestrial systems through the emergence of these potential invertebrate biovectors.

Phylogeography of the northernmost distributed Anisocentropus caddisflies and their comparative genetic structures based on habitat preferences

Knowledge of the factors that determine the distribution ranges of organisms is necessary to understand their evolutionary and ecological significance and contribution to biodiversity. A very effective mean of studying such factors is to compare the distribution characteristics and genetic structures of closely related species with differing habitat preferences. Freshwater aquatic insects are relatively easy to observe and the basis of their corresponding niche differentiation easier to identify. Freshwater habitats are categorized lotic or lentic water according to flow regime. In Japanese Islands, the genus Anisocentropus of the calamoceratid caddisfly, the target group in this study, was morphologically reconfirmed that three species, that is, Anisocentropus kawamurai, A. pallidus, and A. magnificus. Among these, A. kawamurai prefers lotic environments and A. pallidus is adapted to lentic water habitats. The distribution range of these sister species overlaps within the Japanese Islands. We estimated the phylogeny and the evolutionary history of Anisocentropus caddisflies worldwide. We estimated divergence periods by two methods, a single locus with various specimens and multiple loci with reduced numbers of the specimens. As a result, we elucidated the phylogenetic position of Japanese species within the cosmopolitan genus Anisocentropus, and also revealed their dual origin. In addition, we demonstrated that the contrasting genetic structures between the sister species distributed in widely overlapping areas were due to differentiation in their respective adapted environmental preferences. Although, in general, it is known that species adapted to lentic water have greater dispersal potential and so are associated with wider distribution areas by means of examining their comparative genetic structures, we revealed a new pattern of genetic locality existing in the genetic structures of the species adapted to lentic water. We then present evidence that suggests the ecological preferences of a species are an important factor in understanding the evolutionary history of that species.

Mitochondrial genome of Macrostemum floridum (Trichoptera)

Trichoptera are a group of the benthic organism, almost all of which live in water during their life cycle. Trichoptera usually develop through egg, larva, pupa, and moth stages. In its larval stage, Trichoptera usually live in water and are often called the caddisfly. In this study, the mitochondrial genome of Macrostemum floridum was analyzed. The total length of the mitochondrial genome is 15,424 bp and consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and one control region. The genome has a typical mitochondrial gene sequence of Trichoptera. Phylogenetic analysis of the mitochondrial genomes of 23 species of Trichoptera and Lepidoptera showed that M. floridum forms a monophyletic group with other species of Lepidoptera.

Draft Genome Assemblies and Annotations of Agrypnia vestita Walker, and Hesperophylax magnus Banks Reveal Substantial Repetitive Element Expansion in Tube Case-Making Caddisflies (Insecta: Trichoptera)

Trichoptera (caddisflies) play an essential role in freshwater ecosystems; for instance, larvae process organic material from the water and are food for a variety of predators. Knowledge on the genomic diversity of caddisflies can facilitate comparative and phylogenetic studies thereby allowing scientists to better understand the evolutionary history of caddisflies. Although Trichoptera are the most diverse aquatic insect order, they remain poorly represented in terms of genomic resources. To date, all long-read based genomes have been sequenced from individuals in the retreat-making suborder, Annulipalpia, leaving ∼275 Ma of evolution without high-quality genomic resources. Here, we report the first long-read based de novo genome assemblies of two tube case-making Trichoptera from the suborder Integripalpia, Agrypnia vestita Walker and Hesperophylax magnus Banks. We find that these tube case-making caddisflies have genome sizes that are at least 3-fold larger than those of currently sequenced annulipalpian genomes and that this pattern is at least partly driven by major expansion of repetitive elements. In H. magnus, long interspersed nuclear elements alone exceed the entire genome size of some annulipalpian counterparts suggesting that caddisflies have high potential as a model for understanding genome size evolution in diverse insect lineages.

Elevation alters outcome of competition between resident and range-shifting species

Species' geographic range shifts toward higher latitudes and elevations are among the most frequently reported consequences of climate change. However, the role of species interactions in setting range margins remains poorly understood. We used cage experiments in ponds to test competing hypotheses about the role of abiotic and biotic mechanisms for structuring range boundaries of an upslope range-shifting caddisfly Limnephilus picturatus. We found that competition with a ubiquitous species Limnephilus externus significantly decreased L. picturatus survival and emergence at subalpine elevations supporting the notion that species interactions play a critical role in determining upslope range limits. However, without competitors, L. picturatus survival was greater at high-elevation than low-elevation sites. This was contrary to decreases in body mass (a proxy for fecundity) with elevation regardless of the presence of competitors. We ultimately show that species interactions can be important for setting upslope range margins. Yet, our results also highlight the complications in defining what may be abiotically stressful for this species and the importance of considering multiple demographic variables. Understanding how species ranges will respond in a changing climate will require quantifying species interactions and how they are influenced by the abiotic context in which they play out.

Complex and nonlinear climate-driven changes in freshwater insect communities over 42 years

The ongoing biodiversity crisis becomes evident in the widely observed decline in abundance and diversity of species, profound changes in community structure, and shifts in species' phenology. Insects are among the most affected groups, with documented decreases in abundance up to 76% in the last 25-30 years in some terrestrial ecosystems. Identifying the underlying drivers is a major obstacle as most ecosystems are affected by multiple stressors simultaneously and in situ measurements of environmental variables are often missing. In our study, we investigated a headwater stream belonging to the most common stream type in Germany located in a nature reserve with no major anthropogenic impacts except climate change. We used the most comprehensive quantitative long-term data set on aquatic insects available, which includes weekly measurements of species-level insect abundance, daily water temperature and stream discharge as well as measurements of additional physicochemical variables for a 42-year period (1969-2010). Overall, water temperature increased by 1.88 °C and discharge patterns changed significantly. These changes were accompanied by an 81.6% decline in insect abundance, but an increase in richness (+8.5%), Shannon diversity (+22.7%), evenness (+22.4%), and interannual turnover (+34%). Moreover, the community's trophic structure and phenology changed: the duration of emergence increased by 15.2 days, whereas the peak of emergence moved 13.4 days earlier. Additionally, we observed short-term fluctuations (<5 years) in almost all metrics as well as complex and nonlinear responses of the community toward climate change that would have been missed by simply using snapshot data or shorter time series. Our results indicate that climate change has already altered biotic communities severely even in protected areas, where no other interacting stressors (pollution, habitat fragmentation, etc.) are present. This is a striking example of the scientific value of comprehensive long-term data in capturing the complex responses of communities toward climate change.

The ionotropic receptor gene family in Lepidoptera and Trichoptera: Annotation, evolutionary and functional perspectives

Lepidoptera (moths and butterflies) and Trichoptera (caddisflies), belonging to the superorder Amphiesmenoptera, are the most diverse insect orders as representatives of the terrestrial and aquatic insects, respectively. The insects of the two orders possess different biological and behavioral characteristics, especially their larvae, presumably resulting in the differences of the ionotropic receptor (IR) genes in numbers, sequence characteristics or gene structure. Here, we employed genomics, transcriptomics, bioinformatics, phylogenetics and molecular biology strategies to characterize the IR gene repertoire in Lepidoptera and Trichoptera. Genome and transcriptome analyses with exhaustive homology-based searches and manual efforts, in 32 lepidopterans and five trichopterans, led to the identification of 1449 genes encoding IRs with 1170 full-length sequences, representing the most comprehensive set of chemoreceptor superfamilies across the Amphiesmenoptera. Analysis of gene gains and losses in orthologous groups implied that some IRs were lost in related species, and multiple gene copies occurred mainly in divergent IRs (D-IRs) by gene duplications. Phylogenetic analysis of 2442 IR proteins from 67 species revealed that Lepidoptera and Trichoptera IRs could be classified into three subfamilies, i.e., 14 antennal IRs (A-IRs), five Lepidoptera-specific IRs (LS-IRs) and four D-IRs. Of the three subfamilies, A-IRs and LS-IRs members within orthologous groups exhibited high conservation of gene structure, but D-IRs shared extremely low amino acid identities (below 30%). Expression profiles revealed functional diversities of IRs from Bombyx mori and Papilio xuthus involving smell, taste or reproduction, in which some genes displayed sex-biased expression in antennae associated with specific chemosensory behaviors of female or male adults. Our current study has provided insights into the evolution, conservation and divergence of IRs between/within Lepidoptera and Trichoptera, and allows for further experiments to investigate IR functions.

Aquatic Insects Are Dramatically Underrepresented in Genomic Research

Aquatic insects comprise 10% of all insect diversity, can be found on every continent except Antarctica, and are key components of freshwater ecosystems. However, aquatic insect genome biology lags dramatically behind that of terrestrial insects. If genomic effort was spread evenly, one aquatic insect genome would be sequenced for every ~9 terrestrial insect genomes. Instead, ~24 terrestrial insect genomes have been sequenced for every aquatic insect genome. This discrepancy is even more dramatic if the quality of genomic resources is considered; for instance, while no aquatic insect genome has been assembled to the chromosome level, 29 terrestrial insect genomes spanning four orders have. We argue that a lack of aquatic insect genomes is not due to any underlying difficulty (e.g., small body sizes or unusually large genomes), yet it is severely hampering aquatic insect research at both fundamental and applied scales. By expanding the availability of aquatic insect genomes, we will gain key insight into insect diversification and empower future research for a globally important taxonomic group.

New Species and New Records of Caddisflies (Insecta: Trichoptera) from India

In the publication by Kaur et al. (2020), the depository for the holotype of Chimarra gangtokensis new species was given as "(NPC)", but no corresponding explanation for this acronym was provided in that publication. Therefore, the name of the species is unavailable (International Code of Zoological Nomenclature 1999, Art. 16.4.2). We clarify here that the holotype is a male deposited in the National Pusa Collection, Division of Entomology, Indian Agricultural Research Institute, Pusa, New Delhi (NPC). The purpose of this note is to validate the name of the new species from the publication date of this erratum by a reference to the original description and diagnosis as an indication (International Code of Zoological Nomenclature 1999, Art. 13.1.2).

PVC and PET microplastics in caddisfly (Lepidostoma basale) cases reduce case stability

Caddisfly larvae occur in streams and rivers, and many caddisfly species build protective cases using material from their habitat such as sand grains. At the same time, microplastics (MPs) are regularly deposited in aquatic sediments and are incorporated into caddisfly (Lepidostoma basale) cases in the field. However, it is unknown what the effects of MP incorporation into cases might be on the health of the caddisfly larvae. Hence, we offered two commonly used MPs (polyvinyl chloride (PVC) and polyethylene terephthalate (PET)) to L. basale larvae during a laboratory experiment. Both plastic types have a high density and co-occur with L. basale larvae in benthic habitats. In our experiment, L. basale actively used sand, PET and PVC MPs for building tube-like portable or emergency cases. The latter is a temporary shelter under which the larva can hide for immediate protection. Furthermore, case stability decreased with increasing PVC and PET particle content in the cases, suggesting that MPs may threaten caddisflies by destabilising cases. When case stability is reduced, the protective function of the cases is limited and the larvae may be more prone to predation. Additionally, larvae may be washed away by the current as plastic is lighter than sand. Both effects could limit the caddisfly's survival, which could have far-reaching consequences as caddisfly larvae are important primary consumers in aquatic ecosystems. Graphical abstract.

Avoidance and aggregation create consistent egg distribution patterns of congeneric caddisflies across spatially variable oviposition landscapes

Amongst oviparous animals, the spatial distribution of individuals is often set initially by where females lay eggs, with potential implications for populations and species coexistence. Do the spatial arrangements of oviposition sites or female behaviours determine spatial patterns of eggs? The consequences of spatial patterns may be context independent if strong behaviours drive patterns; context dependent if the local environment dominates. We tested these ideas using a guild of stream-dwelling caddisflies that oviposit on emergent rocks, focussing on genera with contrasting behaviours. In naturally occurring oviposition landscapes (riffles with emergent rocks), we surveyed the spatial arrangement and environmental characteristics of all emergent rocks, identified and enumerated egg masses on each. Multiple riffles were surveyed to test for spatially invariant patterns and behaviours. In landscapes, we tested for spatial clumping of oviposition sites exploited by each species and for segregation of congeneric species. At oviposition sites, we characterised the frequency distributions of egg masses and tested for species associations. Genus-specific behaviours produced different spatial patterns of egg masses in the same landscapes. Congregative behaviour of Ulmerochorema spp. at landscape scales and an aggregative response at preferred oviposition sites led to clumped patterns, local aggregation and species overlap. In contrast, avoidance behaviours by congeners of Apsilochorema resulted in no or weak clumping, and species segregation in some landscapes. Spatial patterns were consistent across riffles that varied in area and oviposition site density. These results suggest that quite different oviposition behaviours may be context independent, and the consequences of spatial patterns may be spatially invariant also.

Project overview: Intricate bodies in the boundary layer - bridging fluid mechanics, morphology and ecology in larval Drusinae (Insecta: Trichoptera)

This paper summarizes the layout, the three work packages and the intended outcome of the project 'Intricate bodies in the boundary layer P 31258-B29', funded by the Austrian Science Fund (FWF ; project start: October 2018).

Annotated Draft Genomes of Two Caddisfly Species Plectrocnemia conspersa CURTIS and Hydropsyche tenuis NAVAS (Insecta: Trichoptera)

Members of the speciose insect order Trichoptera (caddisflies) provide important ecosystem services, for example, nutrient cycling through breaking down of organic matter. They are also of industrial interest due to their larval silk secretions. These form the basis for their diverse case-making behavior that allows them to exploit a wide range of ecological niches. Only five genomes of this order have been published thus far, with variable qualities regarding contiguity and completeness. A low-cost sequencing strategy, that is, using a single Oxford Nanopore flow cell per individual along with Illumina sequence reads was successfully used to generate high-quality genomes of two Trichoptera species, Plectrocnemia conspersa and Hydropsyche tenuis. Of the de novo assembly methods compared, assembly of low coverage Nanopore reads (∼18×) and subsequent polishing with long reads followed by Illumina short reads (∼80-170× coverage) yielded the highest genome quality both in terms of contiguity and BUSCO completeness. The presented genomes are the shortest to date and extend our knowledge of genome size across caddisfly families. The genomic region that encodes for light (L)-chain fibroin, a protein component of larval caddisfly silk was identified and compared with existing L-fibroin gene clusters. The new genomic resources presented in this paper are among the highest quality Trichoptera genomes and will increase the knowledge of this important insect order by serving as the basis for phylogenomic and comparative genomic studies.

When barcoding fails: development of diagnostic nuclear markers for the sibling caddisfly species Sericostoma personatum (Spence in Kirby & Spence, 1826) and Sericostoma flavicorne Schneider, 1845

The larval stages of the central European sibling caddisfly species Sericostomapersonatum (Spence in Kirby and Spence, 1826) and S.flavicorne Schneider, 1845 are morphologically similar and can only be distinguished by differences in coloration in late larval instars. Identification using the mitochondrial barcoding gene, i.e., the Cytochrome c Oxidase 1, is impossible, as both species share the same highly differentiated haplotypes due to introgression. Nuclear gene markers obtained through double digest restriction site associate sequencing (ddRAD seq), however, can reliably distinguish both species, yet the method is expensive as well as time-consuming and therefore not practicable for species determination. To facilitate accurate species identification without sequencing genome-wide markers, we developed nine diagnostic nuclear RFLP markers based on ddRAD seq data. The markers were successfully tested on geographically distinct populations of the two Sericostoma species in western Germany, on known hybrids, and on another sericostomatid caddisfly species, Oecismusmonedula (Hagen, 1859) that sometimes shares the habitat and can be morphologically confounded with Sericostoma. We describe a simple and fast protocol for reliable species identification of S.personatum and S.flavicorne independent of the life cycle stage of the specimens.

Exploring the underwater silken architectures of caddisworms: comparative silkomics across two caddisfly suborders

Caddisfly (Trichoptera) larvae assemble a variety of underwater structures using bioadhesive silk. The order is divided into two primary sub-orders distinguished by how the larvae deploy their silk. Foraging Integripalpia larvae construct portable tube cases. Annulipalpia larvae construct stationary retreats, some with suspended nets to capture food. To identify silk molecular adaptations that may have contributed to caddisfly diversification, we report initial characterization of silk from a net-spinner genus, Parapsyche, for comparison with the silk of a tube case-maker genus, Hesperophylax. Overall, general features of silk structure and processing are conserved across the sub-orders despite approximately 200 Ma of divergence: the H-fibroin proteins comprise repeating phosphoserine-rich motifs, naturally spun silk fibres contain approximately 1 : 1 molar ratios of divalent metal ions to phosphate, silk fibre precursors are stored as complex fluids of at least two types of complexes, and silk gland proteins contain only traces of divalent metal ions, suggesting metal ions that solidify the fibres are absorbed from the aqueous environment after silk extrusion. However, the number and arrangement of the repeating phosphoserine blocks differ between genera, suggesting molecular adaptation of H-fibroin through duplication and shuffling of conserved structural modules may correspond with the radiation of caddisflies into diverse environments. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.

Mid-Devensian climate and landscape in England: new data from Finningley, South Yorkshire

While there is extensive evidence for the Late Devensian, less is known about Early and Middle Devensian (approx. 110-30 ka) climates and environments in the UK. The Greenland ice-core record suggests the UK should have endured multiple changes, but the terrestrial palaeo-record lacks sufficient detail for confirmation from sites in the British Isles. Data from deposits at Finningley, South Yorkshire, can help redress this. A channel with organic silts, dated 40 314-39 552 cal a BP, contained plant macrofossil and insect remains showing tundra with dwarf-shrub heath and bare ground. Soil moisture conditions varied from free draining to riparian, with ponds and wetter vegetated areas. The climate was probably low arctic with snow cover during the winter. Mutual climatic range (MCR), based on Coleoptera, shows the mean monthly winter temperatures of -22 to -2°C and summer ones of 8-14°C. Periglacial structures within the basal gravel deposits and beyond the glacial limits indicate cold-climate conditions, including permafrost. A compilation of MCR reconstructions for other Middle Devensian English sites shows that marine isotope stage 3-between 59 and 28 ka-experienced substantial variation in climate consistent with the Greenland ice-core record. The exact correlation is hampered by temporal resolution, but the Finningley site stadial at approximately 40 ka may correlate with the one of the Greenland stadials 7-11.

Caddisfly Assemblages in Metal Contaminated Rivers of the Tikhaya Basin, East Kazakhstan

The Ulba river basin is one of the most industrialized regions of Kazakhstan. The development of mining and metallurgical industries has increased pollution of the basin's surface waters by heavy metals, primarily zinc and copper. The taxonomical structure of Trichoptera was studied in reference and impacted reaches of the river basin. A significant decrease in Trichoptera species richness was recorded in the most polluted areas. A total of 35 species were identified at the reference site of the Breksa River, but only 14 in the impacted sites. Ceratopsyche newae, Dicosmoecus palatus, Glossosoma altaicum and Rhyacophila sibirica showed a significant reduction at sites with high heavy metal concentrations.

Survival under anthropogenic impact: the response of dragonflies (Odonata), beetles (Coleoptera) and caddisflies (Trichoptera) to environmental disturbances in a two-way industrial canal system (central Poland)

Ecological metrics and assemblages of three orders of aquatic insects (Odonata, Coleoptera and Trichoptera—OCT) in an industrial canal system affected by dredging were studied. Five sites (a river as a control site and canals) along the Vistula River in Central Poland were sampled during six sampling periods (2011 and 2013). Canonical correspondence analyses (CCA) was used to assess the influence of environmental variables on the distribution of 54 insect species in the following system of habitats—a river feeding the canals, river-fed inlet canals and outlet canals with cooling waters. Additionally, before and after control impact (BACI) was used to test for the impact of canal dredging in 2011 on the insect response metrics. Non-metric multidimensional scaling analysis differentiated insect assemblages of the three habitats and similarity percentage (SIMPER) indicated the species most responsible for the faunistic dissimilarities. Temperature was found to be a key factor governing the presence of insects in the outlet canals with cooling water. CCAs revealed that electrolytic conductivity (EC) and salinity had the greatest influence on the OCT fauna in the river and the inlet canals, whilst it was the dissolved oxygen and the level of development of aquatic plants that proved most important in the outlet canals. Modified ANOVAs showed that dredging significantly affected the mean species richness and the dominance in the canals. The changes in OCT species composition were highly informative. The comparison between tolerance patterns of the OCT orders against the five parameters (temperature, EC, total dissolved solids (TDS), pH and current) revealed that caddisflies are the most sensitive group, followed by Coleoptera while Odonata proved the most resistant. Dragonflies have the greatest potential to serve as bioindicators of industrially heated waters. The OCT fauna responded specifically to different environmental factors and stressors, it is strongly recommended to track the responses on different levels, not only metrics, but above all, species.

Imaging natural history museum collections from the bottom up: 3D print technology facilitates imaging of fluid-stored arthropods with flatbed scanners

Availability of 3D-printed laboratory equipment holds promise to improve arthropod digitization efforts. A 3D-printed specimen scanning box was designed to image fluid-based arthropod collections using a consumer-grade flatbed scanner. The design was customized to accommodate double-width microscope slides and printed in both Polylactic Acid (PLA) and nylon (Polyamide). The workflow with two or three technicians imaged Trichoptera lots in batches of six scanning boxes. Individual images were cropped from batch imagess using an R script. PLA and nylon both performed similarly with no noticeable breakdown of the plastic; however, dyed nylon leeched color into the ethanol. The total time for handling, imaging, and cropping was ~8 minutes per vial, including returning material to vials and replacing ethanol. Image quality at 2400 dpi was the best and revealed several diagnostic structures valuable for partial identifications with higher utility if structures of the genitalia were captured; however, lower resolution scans may be adequate for natural history collection imaging. Image quality from this technique is similar to other natural history museum imaging techniques; yet, the scanning approach may have wider applications to morphometrics because of lack of distortion. The approach can also be applied to image vouchering for biomonitoring and other ecological studies.

The complete mitochondrial genome of the giant casemaker caddisfly Phryganea cinerea (Insecta: Trichoptera: Phryganeidae)

The rush sedge caddisfly Phryganea cinerea Walker, 1852 (Phryganeidae, the giant casemakers), is a widespread and adaptable North American caddisfly. Genome skimming by Illumina sequencing permitted the assembly of a complete 15,043 bp circular mitogenome from P. cinerea consisting of 78.2% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the ancestral insect gene order. Phryganea cinerea COX1 features an atypical CGA start codon and COX1, NAD1, NAD4, and NAD5 exhibit incomplete stop codons completed by the addition of 3' A residues to the mRNA. Phylogenetic reconstruction reveals a monophyletic Order Trichoptera and Family Phyrganeidae.

Updated checklist of the Michigan (USA) caddisflies, with regional and habitat affinities

Based on examination of ~180,000 specimens from 695 collections of 443 localities collected from the 1930s to 2015 we report 295 species of caddisflies from Michigan. Of these, 41 are reported from the state for the first time. Another 18 species previously reported from Michigan are listed as doubtful. The 11 most abundant species collectively represented over half of all specimens collected. Conversely, 80 species were known from <10 specimens, and 27 species from a single specimen. The Michigan fauna is similar to those of Minnesota and Ohio, adjacent states with comparable recent collecting effort. Regional and habitat affinities for each Michigan species are reported herein. Due to the high level of species discovery over the last few years, despite a >80-year collecting history, it is likely that additional species remain undiscovered in the state.

DNA barcode-based survey of Trichoptera in the Crooked River reveals three new species records for British Columbia

Anthropogenic pressures on aquatic systems have placed a renewed focus on biodiversity of aquatic macroinvertebrates. By combining classical taxonomy and DNA barcoding we identified 39 species of caddisflies from the Crooked River, a unique and sensitive system in the southernmost arctic watershed in British Columbia. Our records include three species never before recorded in British Columbia: Lepidostoma togatum (Lepidostomatidae), Ceraclea annulicornis (Leptoceridae), and possibly Cheumatopsyche harwoodi (Hydropsychidae). Three other specimens may represent new occurrence records and a number of other records seem to be substantial observed geographic range expansions within British Columbia.

Our love-hate relationship with DNA barcodes, the Y2K problem, and the search for next generation barcodes

DNA barcodes are very useful for species identification especially when identification by traditional morphological characters is difficult. However, the short mitochondrial and chloroplast barcodes currently in use often fail to distinguish between closely related species, are prone to lateral transfer, and provide inadequate phylogenetic resolution, particularly at deeper nodes. The deficiencies of short barcode identifiers are similar to the deficiencies of the short year identifiers that caused the Y2K problem in computer science. The resolution of the Y2K problem was to increase the size of the year identifiers. The performance of conventional mitochondrial COI barcodes for phylogenetics was compared with the performance of complete mitochondrial genomes and nuclear ribosomal RNA repeats obtained by genome skimming for a set of caddisfly taxa (Insect Order Trichoptera). The analysis focused on Trichoptera Family Hydropsychidae, the net-spinning caddisflies, which demonstrates many of the frustrating limitations of current barcodes. To conduct phylogenetic comparisons, complete mitochondrial genomes (15 kb each) and nuclear ribosomal repeats (9 kb each) from six caddisfly species were sequenced, assembled, and are reported for the first time. These sequences were analyzed in comparison with eight previously published trichopteran mitochondrial genomes and two triochopteran rRNA repeats, plus outgroup sequences from sister clade Lepidoptera (butterflies and moths). COI trees were not well-resolved, had low bootstrap support, and differed in topology from prior phylogenetic analyses of the Trichoptera. Phylogenetic trees based on mitochondrial genomes or rRNA repeats were well-resolved with high bootstrap support and were largely congruent with each other. Because they are easily sequenced by genome skimming, provide robust phylogenetic resolution at various phylogenetic depths, can better distinguish between closely related species, and (in the case of mitochondrial genomes), are backwards compatible with existing mitochondrial barcodes, it is proposed that mitochondrial genomes and rRNA repeats be used as next generation DNA barcodes.

Comparison of sensory structures on the antenna of different species of Philopotamidae (Insecta: Trichoptera)

Structure and distribution of sensilla were studied in sixteen species of the caddisfly family Philopotamidae. Their antennae bear numerous curved trichoid and pseudoplacoid sensilla and fewer coronal, styloconic and chaetoid sensilla on the flagellar segments. The most numerous pseudoplacoid sensilla have non-specific localization. The curved trichoid sensilla form clusters ventrally on each antennal segment. Sensilla belonging to coronal, styloconic and chaetoid types have specific positions. Long grooved trichoid sensilla are located nonspecifically in all the studied species. The average number of sensilla per segment decreases from the proximal to distal part of the flagellum. Scapus and pedicellum are devoid of most types of sensilla, however, they bear the Böhm bristles and long trichoid sensilla. A positive correlation between antenna dimensions and its cuticular structures is found.

The complete mitochondrial genome of the long-horned caddisfly Triaenodes tardus (Insecta: Trichoptera: Leptoceridae)

The long-horned caddisfly Triaenodes tardus Milne, 1934 (Leptoceridae), is a widespread herbivorous North American caddisfly found in both lentic and lotic habitats. Whole genome Illumina sequencing allowed the assembly of a complete circular mitogenome of 14,963 bp from T. tardus consisting of 73.4% AT nucleotides, 22 tRNAs, 13 protein-coding genes, two rRNAs and a control region in the ancestral insect gene order. Triaenodes tardus COX1 features an atypical TTG start codon as in some lepdioptera and prokaryotes. Phylogenetic reconstruction places T. tardus as sister to Sericostoma personatum (Sericostomatidae) within a monophyletic Order Trichoptera, which is consistent with previous phylogenetic hypotheses.

Application of Aquatic Insects (Ephemeroptera, Plecoptera And Trichoptera) In Water Quality Assessment of Malaysian Headwater

The Ephemeroptera, Plecoptera and Trichoptera (EPT) community structure and the specific sensitivity of certain EPT genera were found to be influenced by water parameters in the rivers of Gunung Jerai Forest Reserve (GJFR) in the north of peninsular Malaysia. The scores of EPT taxa richness of >10 in all rivers indicated all rivers’ habitats were non-impacted, having good water quality coinciding with Class I and Class II of Malaysian water quality index (WQI) classification of potable water. The abundance of EPT was very high in Teroi River (9,661 individuals) but diversity was lower (22 genera) than Tupah River which was highly diverse (28 genera) but lower in abundance (4,263 individuals). The lowest abundance and moderate diversity was recorded from Batu Hampar River (25 genera). Baetis spp. and Thalerosphyrus spp., Neoperla spp. and Cheumatopsyche spp. were the most common genera found. Classification for all rivers using EPT taxa Richness Index and WQI gave different category of water quality, respectively. The WQI classified Tupah and Batu Hampar rivers into Class II and Teroi River (Class I) was two classes above the classification of the EPT taxa Richness Index.

Integrative taxonomy by molecular species delimitation: multi-locus data corroborate a new species of Balkan Drusinae micro-endemics

BACKGROUND

Taxonomy offers precise species identification and delimitation and thus provides basic information for biological research, e.g. through assessment of species richness. The importance of molecular taxonomy, i.e., the identification and delimitation of taxa based on molecular markers, has increased in the past decade. Recently developed exploratory tools now allow estimating species-level diversity in multi-locus molecular datasets.

RESULTS

Here we use molecular species delimitation tools that either quantify differences in intra- and interspecific variability of loci, or divergence times within and between species, or perform coalescent species tree inference to estimate species-level entities in molecular genetic datasets. We benchmark results from these methods against 14 morphologically readily differentiable species of a well-defined subgroup of the diverse Drusinae subfamily (Trichoptera, Limnephilidae). Using a 3798 bp (6 loci) molecular data set we aim to corroborate a geographically isolated new species by integrating comparative morphological studies and molecular taxonomy.

CONCLUSIONS

Our results indicate that only multi-locus species delimitation provides taxonomically relevant information. The data further corroborate the new species Drusus zivici sp. nov. We provide differential diagnostic characters and describe the male, female and larva of this new species and discuss diversity patterns of Drusinae in the Balkans. We further discuss potential and significance of molecular species delimitation. Finally we argue that enhancing collaborative integrative taxonomy will accelerate assessment of global diversity and completion of reference libraries for applied fields, e.g., conservation and biomonitoring.

Resource-allocation tradeoffs in caddisflies facing multiple stressors

The replacement of native forests by exotic tree monocultures, such as those of Eucalyptus, decreases the quality of leaf litter inputs to streams and often reduces riparian cover, which can elevate water temperature. The combined effects of these stressors on the survival and performance of detritivores may be important, as detritivore species loss leads to reduced litter breakdown, a key ecosystem process. Potential loss of cased caddisfly larvae is of particular concern because they are the predominant detritivores in many streams, they are sensitive to warming, and they expend energy on building and carrying their cases, which may be an added burden under times of stress. In a microcosm experiment, we tested whether (i) poor‐quality Eucalyptus globulus litter impaired case construction by larvae of Sericostoma pyrenaicum (due to preferential allocation of the scarcer available energy to larval fitness) compared to high‐quality Alnus glutinosa litter; (ii) whether this effect was enhanced by higher temperatures (15 vs. 10°C) resulting in faster metabolism and greater energy expenditure; but (iii) reduced in the presence of chemical cues from a predatory fish (due to greater investment in more protective cases). We found that Eucalyptus had lethal and sublethal effects on larval caddisflies, increasing mortality, reducing growth, and impairing case construction, compared to larvae fed Alnus. Temperature did not reinforce the effects of exotic litter on case construction, but predator chemical cues triggered the construction of more protective cases (i.e., longer and better cemented) despite the lower resource quality, providing evidence for environmentally mediated resource‐allocation tradeoffs.

Realistic pesticide exposure through water and food amplifies long-term effects in a Limnephilid caddisfly

Pesticides are increasingly recognized as relevant stressors in stream ecosystems. Stream biota is exposed to pesticides with low water solubility, e.g. pyrethroid insecticides, via water, habitat, and food. However, long-term effects of simultaneous exposure pathways are unknown. In this context, we conducted a microcosm experiment with the caddisfly Anabolia nervosa exposing the larvae to the pyrethroid insecticide esfenvalerate (EFV) at 0.1 and 1.0μgL^-1 via (i) water, (ii) food or a (iii) combination of water and food. Combined exposure through water and food significantly reduced emergence by 60% and significantly postponed emergence timing at the highest EFV level, whereas none of the single-phase exposures showed significant effects. Moreover, our study revealed that successfully emerged females from the highest biphasic treatment level were characterised by altered composition of storage lipids indicative of reduced energy reserves. Consequently, a realistic test scenario that represents simultaneous exposure of organisms and their food may reveal substantially increased long term effects of pyrethroids when compared with current ecological risk assessment applying only single phase exposure. We recommend that relevant concurrent exposure routes of pesticides should be considered in order to derive realistic regulatory acceptable concentrations of pesticides.