Search

Various insects utilise hydrophobic biological surfaces to live on the surface of water, while other organisms possess hydrophilic properties that enable them to live within a water column. Dixidae larvae reside, without being submerged, just below the water surface. However, little is known about how these larvae live in such an ecological niche. Herein, we use larvae of Dixa longistyla (Diptera: Dixidae) as experimental specimens and reveal their characteristics. A complex crown-like structure on the abdomen consists of hydrophobic and hydrophilic elements. The combination of these contrasting features enables the larvae to maintain their position as well as to move unidirectionally. Their hydrophobic region leverages water surface tension to function as an adhesive disc. By using the resistance of water, the hydrophilic region serves as a rudder during locomotion., Suzuki, Takaku, Hariyama and colleagues report on a crown-like structure found on the heads of midge larvae. This structure, analysed using scanning electron microscopy and experimental methods, enables subsurface adhesion and aids in control of locomotion in this region of the water column.

The Mediterranean stripe-necked terrapin is a freshwater turtle widely distributed in southwestern Europe and northwestern Africa, but whose natural history is little known. In this study we investigated the ecology of a population in northern Algeria (Reghaïa Lake Ramsar Reserve), with special emphasis on its phenology, demographic structure and diet, based on capture and recapture methods. Our results indicated that there is a short inactivity period in January and possibly the activity is also reduced during the month of August. The best Jolly-Seber model indicated that the population within the survey station had a minimum size of 653 specimens. The population contained a higher proportion of males (0.68 - 0.76) and a proportion of juveniles between 0.02 - 0.16. Females were larger and relatively heavier than males. Analysis of stomach contents showed that M. leprosa feeds with high frequency on aquatic arthropods. Specifically, we found insects: Diptera (Chironomidae, Culicidae, Dixidae, Syrphidae), Heteroptera (Corixidae, Notonectidae) and Coleoptera (Dytiscidae), crustaceans (Branchiopoda, Ostracoda), plant matter (Typha angustifolia), fish (Gambusia holbrooki), and unidentified materials.

Invertebrate surveys in Croatia conducted between 2005 and 2018 included 39 sampling sites yielding bycatch samples of Dixidae (Diptera). All records of this family from the territory of Croatia are summarized, including previously unpublished data. Collections contained six species ofDixaMeigen –D.dilatataStrobl,D.maculataMeigen,D.nebulosaMeigen,D.nubilipennisCurtis,D.puberulaLoew, andD.submaculataEdwards, withDixadilatatareported from Croatia for the first time. Information relating to the ecoregions in which species were found and specific species traits are provided. Compared to neighbouring countries, the Croatian species assemblage is most similar to the fauna of Italy and least similar to that of Serbia and Montenegro.

Dixidae (Insecta, Diptera) are an interesting ecological component in freshwater ecosystems. They are merolimnic insects with larvae and pupae living in aquatic habitats while adults live in terrestrial habitats in close proximity to water. The goals of this study were to determine the phenology patterns of Dixidae and what influences them, to analyse their preference for microhabitats, and to determine the main ecological factors that have an influence on the composition of Dixidae. Adult Dixidae were collected monthly in the period from 2007 to 2008 at 10 sites, from 2009 to 2010 at four sites, and from 2011 to 2014 at three sites in the Plitvice Lakes National Park. Adult specimens were collected using pyramid-type emergence traps. A total of 1271 Dixidae were collected during eight years of study belonging to five species of the genus Dixa. Dixa submaculata was most abundant species at the spring and upper reach of Bijela rijeka Stream and the upper reach of Crna rijeka Stream. Dixa nebulosa was most numerous at the Kozjak-Milanovac tufa barrier site. Dixa puberula was the dominant species at the rest of the sites. Dixa puberula and Dixa submaculata were univoltine, bivoltine or trivoltine, depending on the site, while Dixa nebulosa was only univoltine. The highest diversity was recorded at the tufa barrier Kozjak-Milanovac, and the highest number of species, four species, was found at the upper reach of the Crna rijeka Stream. The greatest number of specimens was recorded at the Labudovac tufa barrier, 128 specimens in 2014. Water temperature is the main ecological factor that influences the phenology of Dixidae at the tufa barriers and lower streams. Discharge affected the abundance of Dixidae. Dixa puberula prefers moss as a substrate and a faster water velocity.

A checklist of the families Chaoboridae, Dixidae, Thaumaleidae, Psychodidae and Ptychopteridae (Diptera) recorded from Finland is given. Four species, Dixella dyari Garret, 1924 (Dixidae), Threticus tridactilis (Kincaid, 1899), Panimerus albifacies (Tonnoir, 1919) and Panimerus przhiboroi Wagner, 2005 (Psychodidae) are reported for the first time from Finland.

Background: Given the importance of arthropods in medical and life sciences and information on the composition of such arthropods in this study was conducted during 2010 in the Kashan. Methods: Descriptive study and sampling at 13 locations and over 39 times in 2303 on the number of larvae, nymphs, Pupa and adults were collected from Lentic and Lotic waters. Samples collected after the transfer to the laboratory using a Stereo microscope and identified using morphological keys used were identified. Results: Total 2303 samples over 39 times the sampling of the Order Diptera, with 1,287 cases (55.8%), crustaceans, with 579 samples (25.2%), Order Trichoptera with 158 samples (6.9%), Order Ephemeroptera 153 samples (6.7%), Order Odonata with 61 samples (2.6%), Order Heteroptera with 26 samples (1.1%), Order Coleoptera with 26 samples (1.1%), Order Plecoptera with 13 sample (0.6) were identified. From Crustacea Class, three orders of the, Amphipoda to 405 numbers (70%) of Lotic water, Ostracoda to 144 (24.9%), Copepoda to 30 (5.1%) from the Lentic waters was collect-ed. Conclusion: In This study, for the first time, from Crustacea subphyllum, order of Ostracoda and Diptera order, Ceratopogonidae, Eryphidae, Dixidae families are reported .Therefore can be concluded that the aquatic arthropods Fauna Kashan is very rich. Considering that some of these insects have a role in the transmission or harassment of human and environmental balance are important, and with molecular methods is recommended that more specific studies done in this field. DOI: http://dx.doi.org/10.3329/bjms.v13i3.15448 Bangladesh Journal of Medical Science Vol.13(3) 2014 p.306-310

A new species of meniscus midge is reported from western Michigan. Adults of Dixella fraxina Taber appear in spring in tussock sedge, Carex stricta Lamarck, understory of black ash, Fraxinus nigra Marshall, swamp. No new species of this genus have been discovered in the United States in the last 40 years. Dark wing coloration suggests a close relationship to Dixella marginata (Loew) but characters in both sexes distinguish this fly from that species and from its other 18 congeners occurring in the United States, half of which occur in the western and southwestern states.

Larval water mites are parasites of various insect species. The main aim of the present study was to analyse the host range of spring dwelling water mites. The investigation focuses on seven spring sites in Luxembourg. Some 24 water mite species were recorded either from the benthos or as parasites attached to flying insects captured in emergence traps. For 20 mite species 35 host species from four Nematocera (Diptera) families were recorded. About 80% of the host species and over 90% of the host individuals were Chironomidae, the others were Limoniidae, Dixidae and Simuliidae. For all water mite species recorded we present the observed host spectrum and/or potential hosts as well as the intensity of parasitism and the phenology of the mites. For 10 mite species the hosts were previously unknown. For another ten species the known host spectrum can be confirmed and extended. The host spectrum ranged from one host species (e.g. for Sperchon insignis) to at least 10 host species (for Sperchon thienemanni, Ljania bipapillata), but the effective host range could not be definitively estimated due to the lack of corresponding data. The hypothesised host preference of the water mites, of which most are strictly confined to spring habitats, for similarly spring-preferring hosts could not be proven. The mean intensity of parasitism was highest for Thyas palustris (10.8 larvae/host) and lowest for Sperchon insignis and Hygrobates norvegicus (1.2 larvae per host for each). The hydryphantid mite Thyas palustris occurred at maximal intensity (41 larvae per host) and the two abdominal parasites Ljania bipapillata and Arrenurus fontinalis showed higher mean intensities than the thoracic parasites did. Larval water mites parasitising chironomids did not exhibit a preference for host sex. The phenology of the larval mite species was varied, some species were only present in samples early in the year and others exclusively in the summer. Another species showed two peaks of occurrence, springtime/early summer and late summer/autumn. In conclusion, the water mite larvae in the studied springs showed differences in host spectra and phenology but there are no clear evidences in both for host partitioning. Maybe, the relative low species diversity of water mites in individual springs and the low inter-specific competition for suitable hosts in combination with the high host abundances and species richness makes springs such favourable habitats for the mites.

Phylogenetic relationships between the families of the infraorder Culicomorpha were investigated by using partial 28S ribosomal RNA gene sequences. All families traditionally placed in this infraorder were investigated and confirmed as clades. On the other hand, some of the morphological relationships between these families were found to be in disagreement with phylogenies based on molecular characters. Our results did not support the generally accepted division of the Culicomorpha into two superfamilies, the Culicoidea (Culicidae + Corethrellidae + Chaoboridae + Dixidae) and the Chironomoidea (Chironomidae + Ceratopogonidae + Simuliidae + Thaumaleidae). Precisely, if the sister-group relationship between Culicidae, Chaoboridae and Corethrellidae was clearly confirmed, the Dixidae, traditionally considered as closely related to these two families, were not placed close to them on our trees. On the other hand, strong evidence was found for grouping together the Simuliidae and the Thaumaleidae, in spite of the cytological and morphological differences between these two families. The position of the Ceratopogonidae was uncertain, and the Chironomidae appeared as a possible sister group to the rest of Culicomorpha. The phylogenetic positions of the groups characterized by feeding on vertebrate blood or insect haemolymph (the Culicidae, Chaoboridae, Ceratopogonidae and Simuliidae) suggest that haematophagy has appeared at least twice in the evolution of Culicomorpha.

The sperm tail from representatives of several families of Diptera has been examined by high resolution electron microscopy and a computer analysis that improved the visualization of recorded patterns. A considerable variability in sperm tail structure is found within Diptera, and is actually greater than that of any other insect order. The ‘generalized insect sperm axoneme’. which is characterized as a 9+9+2 axoneme and by the accessory microtubules having 16 protofilaments, was found only in some dipterans; these are members of Mycetophilidae. From this fact we conclude that Mycetophilidae is likely to be the most primitive extant dipteran group. Another mycetophilid, Boletina, was seen to have accessory tubules with 15 protofilaments as have members of families Dixidae, Chironomidae, Culicidae, and Bibionidae. The last two families have spermatozoa of a type designated as 9+9+‘1’ there is a central rod rather than two microtubules. We regard this 9+9+‘1’pattern with 15 protofilaments to represent a synapomorphic feature. Representatives of the neatoceran families Tipulidae and Trichoceridae have accessory tubules with 13 protofilaments as do examined members of several brachyceran families. Brachycera is hence likely to be derived from the vicinity of the tipulid family. The intertubular material is small in Mycetophilidae and most nematoceran groups, whereas in Tipulidae and Brachycera it is enlarged; here it bridges the space between the accessory tubules and contains various inclusions.

SUMMARY. Larvae of Dixa, especially D. puberula Loew., were a significant component of the invertebrate drift in the Walla Brook in southwest England, the Wilfin Beck and the River Duddon in the English Lake District, and the River Estibere in the French Pyrenees. The drifting of the larvae increased markedly at night and showed a definite diel periodicity with maximum numbers usually in the early hours of the night. Seasonal peaks in the density of larvae in the drift frequently occurred in months when adults and especially pupae were present. Most drifting larvae were in the fourth and final instar, and their drift rate usually increased when they were searching for suitable pupation sites.