Chironomidae Research Articles

Swarming Insects May Have Finely Tuned Characteristic Reynolds Numbers

Over the last few years, there has been much effort put into the development and validation of stochastic models of the trajectories of swarming insects. These models typically assume that the positions and velocities of swarming insects can be represented by continuous jointly Markovian processes. These models are first-order autoregressive processes. In more sophisticated models, second-order autoregressive processes, the positions, velocities, and accelerations of swarming insects are collectively Markovian. Although it is mathematically conceivable that this hierarchy of stochastic models could be extended to higher orders, here I show that such a procedure would not be well-based biologically because some terms in these models represent processes that have the potential to destabilize insect flight dynamics. This prediction is supported by an analysis of pre-existing data for laboratory swarms of the non-biting midge Chironomus riparius. I suggest that the Reynolds number is a finely tuned property of swarming, as swarms may disintegrate at both sufficiently low and sufficiently high Reynolds numbers.

Sediment Core DNA-Metabarcoding and Chitinous Remain Identification: Integrating Complementary Methods to Characterise Chironomidae Biodiversity in Lake Sediment Archives.

Chironomidae, so-called non-biting midges, are considered key bioindicators of aquatic ecosystem variability. Data derived from morphologically identifying their chitinous remains in sediments document chironomid larvae assemblages, which are studied to reconstruct ecosystem changes over time. Recent developments in sedimentary DNA (sedDNA) research have demonstrated that molecular techniques are suitable for determining past and present occurrences of organisms. Nevertheless, sedDNA records documenting alterations in chironomid assemblages remain largely unexplored. To close this gap, we examined the applicability of sedDNA metabarcoding to identify Chironomidae assemblages in lake sediments by sampling and processing three 21-35 cm long sediment cores from Lake Sempach in Switzerland. With a focus on developing analytical approaches, we compared an invertebrate-universal (FWH) and a newly designed Chironomidae-specific metabarcoding primer set (CH) to assess their performance in detecting Chironomidae DNA. We isolated and identified chitinous larval remains and compared the morphotype assemblages with the data derived from sedDNA metabarcoding. Results showed a good overall agreement of the morphotype assemblage-specific clustering among the chitinous remains and the metabarcoding datasets. Both methods indicated higher chironomid assemblage similarity between the two littoral cores in contrast to the deep lake core. Moreover, we observed a pronounced primer bias effect resulting in more Chironomidae detections with the CH primer combination compared to the FWH combination. Overall, we conclude that sedDNA metabarcoding can supplement traditional remain identifications and potentially provide independent reconstructions of past chironomid assemblage changes. Furthermore, it has the potential of more efficient workflows, better sample standardisation and species-level resolution datasets.

Spatial correlations in laboratory insect swarms.

In contrast with flocks of birds, schools of fish and herds of animals, swarms of the non-biting midge Chironomus riparius do not possess global order and under quiescent conditions velocities are only weakly correlated at long distances. Without such order it is challenging to characterize the collective behaviours of the swarms which until now have only been evident in their coordinated responses to disturbances. Here I show that the positions of the midges in laboratory swarms are maximally anticorrelated. This novel form of long-range ordering has until now gone unnoticed in the literature on collective animal movements. Here, its occurrence is attributed to midges being, in nearly equal measure, attracted towards the centre of the swarm and repelled by one another. It is shown that the midge swarms are poised at the cusp of a stable-unstable phase transition.

A Microcosm Analysis of Species-Specific Responses of Chironomidae on Heavy Metal Pollution in The Nyanza Gulf of Lake Victoria

The Chironomidae family, known as "non-biting midges" in their adult stage and "bloodworms" in their larval stage, consists of diverse dipteran insects inhabiting various global aquatic environments. Despite extensive global research, data on Chironomidae in the polluted Nyanza Gulf of Lake Victoria, Kenya, is scarce, and molecular identification methods have not been explored. This study aimed to quantify heavy metal concentrations in water, sediment, and insect samples and assess their impact on Chironomid species identified using mitochondrial DNA barcoding of the cytochrome oxidase subunit 1 (COI) gene. Analysis of Variance was used to determine if there were any statistically significant differences in heavy metal concentrations across different sample types or locations along the pollution gradient. Chironomids were collected from Nyanza Gulf, focusing on a pollution gradient. Results showed that concentrations of arsenic (As), lead (Pb), and cadmium (Cd) in insect, water, and sediment samples exceeded standard limits, while mercury (Hg) concentrations were within limits. Significant variations (p ≤ 0.05) in Pb levels were observed in water samples, and heavy metal concentrations in sediment samples varied significantly (p ≤ 0.05), with Pb showing the highest variation (p ≤ 0.0001). Insect samples exhibited significant differences (p ≤ 0.0001) in As and Hg contents. Genetic analysis identified two known species: Chironomus transvaalensis at the heavily polluted Kisumu station and Chironomus pseudothummi at the moderately polluted Kendu Bay and Homa Bay stations. Additionally, a unique Chironomus species was found on Ndere Island, a relatively clean site with restricted human activities. Sequence comparisons indicated proximity to global data but also highlighted the evolutionary significance and uniqueness of the identified species. This study demonstrated the potential use of genetic methods in determining Chironomid species diversity, community structure, and abundance in relation to heavy metal concentration. It suggests that heavy metal pollution may act as a selective pressure, driving the evolution of Chironomid species. The study recommends combining genetic approaches with other pollution sources for a comprehensive understanding of using this species in monitoring pollution

Why insect swarms seem unduly complicated

Mating swarms of flying male insects are a form of collective behaviour, albeit one different from flocks and schools as they do not display ordered collective movements. In recent years, much progress has been made in uncovering the emergent mechanical-like and thermodynamic-like of such swarms. Nonetheless, two basic properties of this swarming behaviour remain unexplained. Namely, why do individual insects have erratic rather than regular flight patterns? And why are the swarms elliptical rather than circular? Here I account for this seemingly undue complexity. I show that regular flight patterns weaken an individual’s attraction to the swarm centre, making swarms less resilient to the presence of environmental disturbances. I then show that the elliptical shape of swarms of the non-biting midge Chironomus riparius optimizes the trade-off between maximizing swarm size (target size for females) and maximizing swarm stability. Finally, I show that the observed excess velocity kurtosis of swarming C. riparius maximizes swarm cohesiveness. Taken together the new results provide the first tentative evidence for fine-tuning in insect mating swarms driven by selection pressure for advantageous behaviours.Graphic abstract

First Australian amber fossil of Podonominae (Diptera: Chironomidae) from the late Middle Eocene

A non-biting midge of the cosmopolitan family Chironomidae (Podonominae) is recorded in amber from the Anglesea Coal Measures, southeastern Australia. The new morphotype is likely a new species but is not formally described here because of insufficient diagnostic character states. To date, only five amber deposits in the Northern Hemisphere have yielded fossils of Podonominae, making our discovery the first amber-hosted representative of the group from the Southern Hemisphere. The single adult male individual has been assigned to the subfamily Podonominae, and shows similarities to the Austrochlus cluster group including small size, the lack of veins R2 + 3, and the distally located cross-vein m-cu. Synchrotron X-ray microtomographic imaging reveals some internal structures of the wing musculature and brain capsule, highlighting the taphonomic significance of this unique specimen. Maria Blake* [ maria.paulsen@monash.edu ], School of Earth, Atmosphere and Environment, 9 Rainforest Walk, Monash University, Clayton, Victoria, 3800, Australia Enrique Peñalver [ e.penalver@igme.es ], Instituto Geológico y Minero de España, CSIC, Valencia, Spain Jeffrey D. Stilwell [ jeffrey.stilwell@monash.edu ], School of Earth, Atmosphere and Environment, 9 Rainforest Walk, Monash University, Clayton, Victoria, 3800, Australia, and Australian Museum, Australian Museum, 1 William Street, Sydney, NSW 2010, Australia Joseph J. Bevitt [ jbv@ansto.gov.au ], Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia Daniel J. Bickel [ Dan.Bickel@australian.museum ] Australian Museum, 1 William Street, Sydney, New South Wales, 2000, Australia.

Exploring the interplay between water quality parameters and aquatic fauna in a human-dominated stream network in Iran

Rivers and streams are dynamic linear features that undergo numerous disturbances from nearby human activities. This is particularly evident in Iranian arid regions, where agricultural activities are concentrated along these water bodies to harness their freshwater resources. This study utilized 12 stations in the Maharlu stream network to assess the impact of human activities on its water quality and aquatic fauna. Results indicated that severe nutrient pollution attributed to a high mean nitrate concentration (67.77 ± 79.72 mg/L). By employing PCA analysis, three main principal components were extracted, explaining a variance of 82.61%. PC1 exhibited high positive loadings for dissolved oxygen (DO), while PC2 showed an elevated salt concentration. Midges and non-biting mosquitoes, predominantly from the Chironomidae family, emerged as the dominant taxon, contributing to over 98% of the total species abundance. Furthermore, integrated PCA–CCA analysis revealed downstream shifts in species composition toward more tolerant species, driven by decreasing DO levels and increasing salt concentrations. These shifts in trends found in water quality parameters and species composition were linked to agricultural runoff carrying substantial amounts of fertilizers, pesticides, and organic matter from livestock farming. Consequently, there is an urgent need to implement conservation measures to mitigate their adverse effects.

Genome-wide annotation and comparative analysis revealed conserved cuticular protein evolution among non-biting midges with varied environmental adaptability

Chironomidae, non-biting midges, a diverse and abundant insect group in global aquatic ecosystems, represent an exceptional model for investigating genetic adaptability mechanisms in aquatic insects due to their extensive species diversity and resilience to various environmental conditions. The cuticle in insects acts as the primary defense against ecological pressures. Cuticular Proteins (CPs) determine cuticle characteristics, facilitating adaptation to diverse challenges. However, systematic annotation of CP genes has only been conducted for one Chironomidae species, Propsilocerus akamusi, by our team. In this study, we expanded this annotation by identifying CP genes in eight additional Chironomidae species, covering all Chironomidae species with available genome data. We identified a total of 889 CP genes, neatly categorized into nine CP families: 215 CPR RR1 genes, 272 CPR RR2 genes, 23 CPR RR3 genes, 21 CPF genes, 16 CPLCA genes, 19 CPLCG genes, 28 CPLCP genes, 77 CPAP genes, and 37 Tweedle genes. Subsequently, we conducted a comprehensive phylogenetic analysis of CPs within the Chironomidae family. This expanded annotation of CP genes across diverse Chironomidae species significantly contributes to our understanding of their remarkable adaptability.

Benthic Macroinvertebrates as Indicators of Organic Pollution in Upstream Batena River, Hossana, Central Ethiopia

Benthic macro invertebrates are insects and other organism without a back bone that can be seen without magnification and that live in the bottom of all water bodies. They are bio monitor species in determining the water quality in fresh water and other aquatic ecosystems as they are indicator of environmental change of aquatic ecosystem and fresh water ecosystem. The aim of this study was to assess Organic pollution by using benthic macro invertebrate as indicator in upstream parts of Batena River and implication to the water quality of the river. Benthic Macro invertebrates were collected using Scrubber net and sieve with mesh size of 1mm. A total of 57 individual within 4 families belong to 4 orders and one class was identified during the study period. Most dominant group was Hemiptera 29(50.8%), Diptera14 for Chironomidae (Red) (24.56%) and for Diptera family chironomidae (Pale) (19.3%). Sphendiea, Psephyendiea and class of Turbilaria accounts the same percentage (1.75%) and their total abundance was also similar. The pollution level of the river was assessed using Hillsenhoff Family Biotic Index (HFBI) and the value was 7.96. Over all study showed that the river is polluted and have poor water quality as result of diverse Organic pollutant agents. Therefore, the local people and administration of the river should work hard to prevent further deterioration of the river quality by raising public awareness, prevention of waste disposal and treat the waste water before discharging it directly to the river.

A multigenerational study can detect the evolutionary response to BaP exposure in the non-biting freshwater midge Chironomus riparius

The release of polycyclic aromatic hydrocarbons (PAHs) into the environment is posing a threat to ecosystems and human health. Benzo(a)pyrene (BaP) is considered a biomarker of PAH exposure and is classified as a Group 1 carcinogen. However, it was not known whether BaP is mutagenic, i.e. induces inherited germline mutations. In this study, we used a recently established method, which combines short-term mutation accumulation lines (MAL) with whole genome sequencing (WGS) to assess mutagenicity in the non-biting midge Chironomus riparius. The mutagenicity analysis was supplemented by an evaluation of the development of population fitness in three successive generations in the case of chronic exposure to BaP at a high concentration (100 μg/L). In addition, the level of ROS-induced oxidative stress was examined in vivo. Exposure to the higher BaP concentration led to an increase in germline mutations relative to the control, while the lower concentration showed no mentionable effect. Against expectations, BaP exposure decreased ROS-level compared to the control and is thus probably not responsible for the increased mutation rate. Likewise, the higher BaP concentration decreased fitness measured as population growth rate per day (PGR) significantly over all generations, without signs of rapid evolutionary adaptations. Our results thus highlighted that high BaP exposure may influence the evolutionary trajectory of organisms.

Shared Features Underlying Compact Genomes and Extreme Habitat Use in Chironomid Midges.

Nonbiting midges (family Chironomidae) are found throughout the world in a diverse array of aquatic and terrestrial habitats, can often tolerate harsh conditions such as hypoxia or desiccation, and have consistently compact genomes. Yet we know little about the shared molecular basis for these attributes and how they have evolved across the family. Here, we address these questions by first creating high-quality, annotated reference assemblies for Tanytarsus gracilentus (subfamily Chironominae, tribe Tanytarsini) and Parochlus steinenii (subfamily Podonominae). Using these and other publicly available assemblies, we created a time-calibrated phylogenomic tree for family Chironomidae with outgroups from order Diptera. We used this phylogeny to test for features associated with compact genomes, as well as examining patterns of gene family evolution and positive selection that may underlie chironomid habitat tolerances. Our results suggest that compact genomes evolved in the common ancestor of Chironomidae and Ceratopogonidae and that this occurred mainly through reductions in noncoding regions (introns, intergenic sequences, and repeat elements). Significantly expanded gene families in Chironomidae included biological processes that may relate to tolerance of stressful environments, such as temperature homeostasis, carbohydrate transport, melanization defense response, and trehalose transport. We identified several positively selected genes in Chironomidae, notably sulfonylurea receptor, CREB-binding protein, and protein kinase D. Our results improve our understanding of the evolution of small genomes and extreme habitat use in this widely distributed group.

On the Hydrofauna of the First Batabat Water Reservoir

For the first time generalized data on hydrofauna of the First Batabat reservoir are given. In the fauna 6 species of zooplanktonic organisms are revealed, with absolute predominance of large predatory copepod Hemidiaptomus rylovi Charin, 1928. The mean body length of fertilized egg-bearing female crustaceans was 3.6 mm to the furca and 5.1 mm to the tip of the telson. In the ecosystem, Daphnia pulex Leydig, 1860 typically produces its last parthenogenetic generation in September. In the macrozoobenthos of the reservoir, 40 species of macrobenthic organisms were found, with the Heteroptera (9 species) and the Chironomidae family (9 species) predominating in terms of the number of species. According to all its ecological indicators Gammarus lacustris (Sars, 1863) is the dominant bottom organism of the ecosystem. The maximum number of population individuals — 346 spec./m2 and biomass — 2804 g/m2 was calculated in the last decade of June 2017. Being a detritophage with a wide food spectrum, individuals of the higher crayfish have an abundant food base in the reservoir. The first Batabat reservoir located in the high mountainous region of the autonomous republic and having favorable natural and geographical conditions is characterized by high biological productivity.

A revised, annotated checklist of Mexican non-biting midges (Diptera, Chironomidae).

An updated checklist of Mexican non-biting midges (Chironomidae) is presented. A total of 110 species of Chironomidae are known for Mexico: 52 species in 25 genera belong to the subfamily Chironominae, 30 species in 13 genera to Orthocladiinae, 21 species in nine genera to Tanypodinae, five species in two genera to Telmatogetoninae, and two species in one genus to Diamesinae. In addition, 41 genera without identified species are listed. The highest number of species (29) is recorded from the state of Campeche, while 19 species have been found in Veracruz and 15 in Nuevo León. Few or no records exist for states in Central and Northern Mexico, or those on the Pacific coast. The type localities for 34 species are in Mexico; of these, 27 species (25% of the total number of species recorded in the country) are endemic. Twenty-nine species recorded in Mexico have a Neotropical distribution, 15 a Nearctic distribution, and 39 species are distributed in both the Neotropical and Nearctic regions or more widely. It has been suggested that as many as 1000 species might occur in Mexico; so only a little more than 10% of the expected diversity has so far been recorded.

Land use alters cross-ecosystem transfer of high value fatty acids by aquatic insects

BackgroundMany aquatic insects emerge as adults from water bodies to complete parts of their life cycle in terrestrial ecosystems and are potential prey for riparian predators. The benefits of riparian predators from aquatic insects include higher contents of long-chain polyunsaturated fatty acids (PUFA) compared to terrestrial insects. Aquatic insects are therefore considered a high-quality food. Food containing high levels of PUFA can enhance growth and immune response of spiders. However, agricultural stressors like nutrient increase, pesticides and habitat degradation can affect the biomass of aquatic insects and in turn the diet of spiders. Studies quantifying the influence of land use on fatty acid (FA) profiles of emergent aquatic insects and riparian predators are lacking. We quantified differences in exports of FA, saturated FA, monounsaturated FA, and PUFA, FA profiles of aquatic insects and spiders between forested and agricultural sites over the primary emergence period within one year. The FA export to the riparian food web is crucial to understand energy fluxes between ecosystems. Furthermore, we monitored environmental variables to identify associations between agricultural stressors and FA profiles of aquatic insects and spiders.ResultsWe found differences in FA export and profiles of aquatic insects between land-use types. The quantity of total FA export via aquatic insects was lower in agricultural sites (95% CI 1147–1313 µg m−2) in comparison to forested sites (95% CI 1555–1845 µg m−2), while the biomass export was higher in agricultural sites. Additionally, in spring the PUFA export was significantly lower (up to 0.06 µg d−1 m−2) in agricultural than forested sites. Agricultural stressors explained only little variation in the FA profiles of aquatic insects, e.g., 4% for caddisflies and 12% for non-biting midges. Percentage of shading and pool habitats were identified as most important variables explaining the variation in FA profiles.ConclusionThe quality of aquatic insects as food source for riparian spiders was smaller in agricultural than forested sites, which can decrease the fitness of riparian predators. To improve our capacity to predict potential adverse effects in the riparian food web, future studies should identify the mechanisms underlying a lower PUFA content.

Состояние кормовой базы бентосоядных рыб малого водоема на водосборе Онежского озера (Республика Карелия)

Knowledge of the conditions of fish existence, one of the elements of which are the conditions of their fattening, allows us to determine the ways of rational use of fish production resources of the reservoir. The research was carried out by means of complex expedition observations in the summer-autumn period of 2017-2021 in the catchment area of Lake Onega (Lake Munozero, Republic of Karelia). The main criterion for assessing the productivity of reservoir is the indicator of the average biomass of macrozoobenthos. For Lake Munozero, it is equal to 3.6 g/m2 in the littoral zone, and 2.73 in the deep-water part. The average number of bottom organisms reaches 2.73 thousand specimens/m2 in the coastal zone of the reservoir, 1.14 thousand specimens/m2 in the profundal. Gastropods (34.9%) and equal–legged crayfish (22.4%) play a significant role in the composition of the biomass of the coastal zone of the lake. The remaining groups of macrozoobenthos are inferior to Gastropoda and Isopoda. Thus, larvae of large-winged insects make up 12.5% of the total biomass, and larvae of chironomids – 10.7%. Representatives of other groups of aquatic invertebrates: small-scale worms, beetles, mayflies, etc. – in the feed supply, they have practically no value and account for less than 6% of benthos biomass. In the deep-water part of the reservoir, the value of relict crustaceans in the macrozoobenthos should be noted in terms of food. Amphipods in terms of biomass 2.7 g/m2 (98%), with a population of 1 thousand individuals/m2 (89.5% of the total number of macrozoobenthos) significantly exceed all the present groups of benthic fauna, which forms the basis of the food base for the ichthyofauna of Profundal. The main importance in the taxonomic composition of the macrozoobenthos of the reservoir are aquatic insect larvae. Quantitatively, among all groups of zoobenthos, the larvae of chironomids or bell mosquitoes (family Chironomidae) dominate, which are not only widespread in the lake, but at the same time achieve a fairly large qualitative diversity. The data obtained can be used to assess fish stocks in Lake Munozero.

Influence of polarized light, disruptive visual patterns, and chemical cues on oviposition in the aquatic midge, Chironomus riparius (Diptera: Chironomidae).

Chironomid nonbiting midges are common in many waterbodies, occurring at high densities in sediment and also when flying adults emerge. Although important for food webs and ecosystem processes, the mass emergences of chironomid adults make some species nuisance pests. As part of an effort to develop "push-pull" strategies for managing midge populations, we investigated the importance of visual and chemical cues used by gravid females when selecting sites for oviposition. Field and laboratory oviposition choice tests with Chironomus riparius (Meigen) were used to assess the attractiveness of dark container colors and polarized light for females seeking water for egg laying. Females were not sensitive to increased intensity of polarized light, but they laid fewer eggs in containers with white color above the water's edge but black below the surface. A disruptive pattern of vertical black and white stripes at the water's edge reduced egg laying to a similar degree as white. To investigate the importance of olfactory or gustatory cues in oviposition decisions, we tested 3 potential chemical repellents (damaged larvae simulating predator presence, azadiractin, and picaridin) and 5 potential attractants (a tannin-molasses mixture, leaf detritus, live Hydrilla plants, periphyton, and fermented alfalfa infusions used to bait mosquito oviposition traps). Chemical cues appeared to play a weak role, if any, in oviposition choices. Onlyazadiractin (0.02 and 0.11 ppm) reduced the number of egg ropes deposited, but the mechanism may have been from mechanical trapping and drowning, not deterrence.

Combining Passive Sampling and Dosing to Unravel the Contribution of Hydrophobic Organic Contaminants to Sediment Ecotoxicity.

Contaminated sediments are ubiquitous repositories of pollutants and cause substantial environmental risks. Results of sediment bioassays remain difficult to interpret, however, as observed effects may be caused by a variety of (un)known stressors. This study aimed therefore to isolate the effects of hydrophobic organic contaminants from other (non)chemical stressors present in contaminated sediments, by employing a newly developed passive sampling-passive dosing (PSPD) test. The results showed that equilibrium partitioning between pesticides or polyaromatic hydrocarbons (PAHs) in contaminated sediments and a silicone rubber (SR) passive sampler was achieved after 1-3 days. Chlorpyrifos concentrations in pore water of spiked sediment matched very well with concentrations released from the SR into an aqueous test medium, showing that SR can serve as a passive dosing device. Subjecting the 96 h PSPD laboratory bioassay with nonbiting midge (Chironomus riparius) larvae to field-collected sediments showed that at two locations, concentrations of the hydrophobic organic contaminant mixtures were high enough to affect the test organisms. In conclusion, the developed PSPD test was able to isolate the effects of hydrophobic organic contaminants and provides a promising simplified building block for a suite of PSPD tests that after further validation could be used to unravel the contribution of hydrophobic organic chemicals to sediment ecotoxicity.

Mimes of the past: Eocene midges of the tribe Pseudochironomini (Chironomidae, Diptera) reveal their peculiarities.

This is the first study focused on Eocene dipterans of the tribe Pseudochironomini (subfamily Chironominae, family Chironomidae), based on unique materials from Baltic amber. Two new genera and three new species: Eomicromimus gen. nov. with Eomicromimus polliciformis sp. nov. and Eomicromimus serpens sp. nov., and Eoriethia gen. nov. with Eoriethia ursipes sp. nov. are presented. The systematic position of the new taxa is discussed, and an amended key to the identification of adult males of extinct and extant Pseudochironomini genera is provided. The presented analysis of the morphology of the tribe's fossil members allowed us to verify the concepts regarding the origin/homology of male diagnostic structures crucial in defining new taxa, their phylogeny, and to consolidate the terminology used in chironomid research. A new habitual name for Chironomidae, "mime midges", is also proposed.

A Review on Chironomidae (Diptera) of the Eastern Himalayan Region: An Insight into Distribution and Conservation

The Chironomidae (Diptera) commonly known as “midges”, are the most widely distributed and frequently the most abundant group of insects in freshwater ecosystems. Chironomids larvae plays a key ecological role in the maintenance of aquatic ecosystem services, mainly in secondary production and energy flow dynamics [1]. They are the freshwater bio-monitoring indicators of pollution, habitat modifications, and natural changes of water quality [2,3], and is a model which helps to predict diversity and strength of food web of aquatic communities [4]. The objective of the study is to highlight the distribution pattern, biodiversity and the status of conservation of Eastern Himalaya region species of the family Chironomidae. The 'Himalayan Biodiversity Hotspot' is indeed a "store house of biodiversity" because of its rich spectrum of species of flora and fauna including insect species which have been remaining unexplored. This study is a descriptive analysis to assay the main trends on Chironomidae research in freshwater assessments like ecology, palaeolimnology, biogeography, cytology, developmental and eco-toxicological research in Eastern Himalaya region. Finally the review work helps to get a more comprehensive picture of fauna of chironomids in the Eastern Himalayas in relation to those reported earlier from other parts of the globe.

New mitogenomes from the genus Cricotopus (Diptera: Chironomidae, Orthocladiinae): Characterization and phylogenetic implications.

Cricotopus is a large and diverse genus of non-biting midges composed of several subgenera. Complete mitogenome sequences are available for very few Cricotopus species. The subgenus Pseudocricotopus unites species with unusual morphological structures in adult male and pupal stages, however, molecular methods are needed to verify the placement of this subgenus within Cricotopus. We obtained mitogenomes of C. (Pseudocricotopus) cf. montanus and nine other Cricotopus species for phylogenetic analysis, coupled with two Rheocricotopus species and one Synorthocladius species as outgroups. The structure of the mitogenome was similar among these Cricotopus species, exhibiting A+T bias and retaining ancestral gene order. Mutation rate, estimated as Ka/Ks, varied among genes, and was highest for ATP8 and lowest for COI. The phylogenetic relationships among species of Cricotopus, Rheocricotopus and Synorthocladius was reconstructed using Bayesian inference and maximum likelihood estimation. The phylogenetic trees confirmed placement of subgenus Pseudocricotopus, represented by Cricotopus cf. montanus, within Cricotopus. Our study increases the library of chironomid mitogenomes and provides insight into the properties of their constituent genes.