Tubes and tube-building in a lotic Chironomid (Diptera) community

The use of particles for the construction of tubes by a community of stream-dwelling midge (Chironomidae) larvae was investigated. It was shown that the particles present in the larval tubes occurred in the same proportions as those present on the surfaces of stones in the stream. Small particles were principally of detritus, medium-sized particles mainly of detritus and diatoms, and a a variety of types of particles, including filamentous algae and sand grains, occurred in the large size category. The absence of particle selection in the field was reflected in laboratory experiments. It is suggested that competition for suitable available space in which to build tubes and the quantity of building material are likely to be of more significance to the larval community in upland streams than particle size or type.     

Fungal and oomycete parasites of Chironomidae,Ceratopogonidae and Simuliidae (Culicomorpha,Diptera)

Members of the families Chironomidae (chironomids or non-biting midges), Ceratopogonidae (ceratopogonids or biting midges) and Simuliidae (simulids or blackflies) are ubiquitous dipterans of the infraorder Culicomorpha. They are extremely diversified in ecological strategies. Their larvae play major roles in aquatic food webs as detritivores or predators, whereas their adults can be general predators (Chironomidae), hemolymphagous or hematophagous predators (Ceratopogonidae and Simuliidae) or pollinators. Both larval and adult stages are commonly infected by bacteria, viruses, protists, nematodes, true fungi and oomycetes. These phylogenetically diverse assemblages of microorganisms can simultaneously infect multiple species of chironomids, ceratopogonids and simulids, and each host may become trophically interrelated with other hosts by sharing their parasites. Here, we review the information on fungal and oomycete parasites of these dipteran groups with special reference to the natural regulation of host populations, the impact of parasitism in food webs, and the potential of these parasites as biocontrol agents.     

Maritime midge radiations in the Pacific Ocean (Diptera: Chironomidae)

Maritime chironomid midges (Diptera) are diverse, yet these ‘pearls of the ocean’ are little known. Emphasizing Pacific Ocean taxa, we used six genetic markers (18S, 28S, CAD1, CAD4, FolCOI and COI) and fossil calibrations to produce Bayesian time-calibrated phylogenies to date eight independent marine transitions in three subfamilies. Deep nodes involve subfamily Telmatogetoninae (originating mid-Cretaceous, 101–128, 114 Ma), with sister genera Telmatogeton Schiner and Thalassomya Schiner splitting later in the Cretaceous (56–82, 69 Ma). Two transitions in Orthocladiinae involve Clunio Haliday and Pseudosmittia Edwards, dating from the upper Cretaceous, both with Eocene crown groups. In subfamily Chironominae, transitions to marine occur in two tribes. Four transitions occur within the otherwise nonmarine crown groups Kiefferulus Goetghebuer, Dicrotendipes Kieffer, Polypedilum Kieffer and Ainuyusurika Sasa & Shirasaka. Two separate robust clades in tribe Tanytarsini involve: (1) a minor radiation within Paratanytarsus dated to the mid-Eocene around 43 Ma; and (2) an unexpected but fully supported diversification in Pontomyia Edwards plus Yaetanytarsus Sasa dated to around 47 Ma, with separation of Pontomyia from Yaetanytarsus around 40 Ma. Crown Pontomyia, represented by three species, was estimated to have diverged around 19 Ma, whereas the crown radiation of Yaetanytarsus, with 12 sampled species, dates to the mid-Eocene. In a comprehensive global review we concisely document new synonymies and new combinations revealed by the study. The evolutionary timing estimate provides insights into the frequency of marine transitions and diversifications in the Chironomidae in association with dynamic oceanic changes during the Oligocene and Miocene.     

Ultrastructure of mediodorsal setae in biting midge larvae of the genus Atrichopogon Kieffer with notes on their biological significance (Diptera: Ceratopogonidae)

The ultrastructure of the strong mediodorsal setae in terrestrial stage IV larvae of Atrichopogon (Meloehelea) oedemerarum and A. (M.) meloesugans was examined using light, scanning and transmission electron microscopy. Serrated setae placed on prominent processes are distributed in pairs on all thoracic and abdominal segments. Setae are innervated by a single dendrite and their surface has no pores. The trichogen cell is not retracted from the setal lumen on completion of the hair-forming process but fills the mediodorsal seta also when the larval cuticle is fully sclerotised. Such a phenomenon was previously reported in terrestrial larvae of the genus Forcipomyia. We suggest that the mediodorsal setae described in Atrichopogon are plesiotypic mechanoreceptors for the subfamily Forcipomyiinae. They are preserved in the truly terrestrial larvae of Atrichopogon, but modified to secretory setae in the genus Forcipomyia. Both genera bearing distinct mediodorsal setae have developed functional tracheal gills, unknown in other biting midges.     

Phenology and life history of Belgica antarctica, an Antarctic midge (Diptera: Chironomidae)

ABSTRACT.

• 1 An account of the life-history with emphasis on phenology and number of instars is presented for Belgica antarctica Jacobs, the southernmost holometabolous insect.
• 2 Contrary to earlier reports, Belgica has four instars, in common with most other chironomids. Mean head capsule lengths varied between different populations but no overlap was found between discrete size classes of successive instars.
• 3 Belgica overwinters in all four instars.
• 4 Relative frequency of different instars from samples taken through the season indicates that a 2-year life-span is the commonest pattern.
• 5 Emergence of adults is relatively synchronous. Belgica exhibits protandry, which may be established at the time of pupation.

     

Archaeochlus Brundin: a midge out of time (Diptera: Chironomidae)

Abstract. Archaeochlus , a plesiomorphic genus of Podonominae (Chironomidae), is revised and two new species (biko from Namibia and brundini from southwestern Australia) described. The systematic status of the genus and the tribe Boreochlini is reassessed. Biogeographic evidence, sustained by a fossil record, dates the genus at least to the Upper Jurassic. The ecology of early Chironomidae is suggested to be eurythermic and hygropetric rather than cold stenothermic in lotic waters.     

Density and distribution in laboratory populations of midge larvae (Chironomidae: diptera)

The troglobitic amphipod crustacean Crangonyx antennatus occupies mud-bottom pools and small, gravel-bottom streams in caves in the southern Appalachians. One large, mud-bottom pool population in Lee Co., Virginia was observed periodically from 1967 to 1975. Amphipods in this population frequently burrowed into the soft mud substrate, where they were able to survive desiccation during periods when the pool dried up. Animals kept in the laboratory also burrowed and survived desiccation during an experiment which simulated drought conditions similar to those observed in caves. Amphipods collected from both pool and stream habitats burrowed, thereby indicating that stream-adapted populations of this species still retain sufficient flexibility to survive under variable environmental conditions that might be encountered in nature. It is concluded that burrowing provides a means of survival for C. antennatus when it is sometimes exposed to drought conditions in cave pool habitats and also provides protection from potential terrestrial predators under similar conditions. Burrowing also offers amphipods protection from aquatic predators (such as salamander larvae) during normal water levels and possibly allows juveniles a means of escaping cannibalism by adults.     

Food preferences of tanypodinae larvae (Diptera: Chironomidae)

Analyses of the gut contents of larvae of three species of Tanypodinae, collected from four sites in north-east England and Scotland, invariably showed small particles (1–10 µm²), predominantly of detritus, to be more abundant than large particles (10–100 µm²), mostly algae and diatoms. No animal remains, such as carapaces, head capsules and chaetae, or vascular plant fragments were found in any of the intestines. In contrast, food-choice and growth experiments suggested that animal food (particularly Tubificidae and Chironominae larvae) was important in the tanypod diet. In the food-choice experiments, six different foods offered to small (4–7 mm long) and to large (8–12 mm long) larvae of Procladius choreus Meigen, were chosen in the following order: live Tubificidae spp.; detritus; live Chironominae larvae; a mixture of algae and diatoms; live Ostracoda spp.; and live Cladocera spp. However, when the results of the individual choices were examined, it was clear that the small larvae had consumed greater amounts of the small types of food (i.e. detritus, algae and diatoms) in comparison to the large larvae. In the growth experiment, those larvae of P. choreus reared solely on Tubificidae, detritus or Chironominae larvae thrived, while those fed on algae and diatoms, ostracods or cladocerans grew more slowly and fewer survived the experimental period.It was concluded that although Tanypodinae larvae are primarily predators with definite food preferences in ideal foraging conditions, in adverse conditions they will utilize a range of available stand-by foods, the most important of which appears to be detritus.     

The swarming behaviour of the Scottish biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae)

Abstract.

• 1 Swarms of Culicoides impunctatus males were examined in the field in Scotland. Most swarms were close to midge emergence/breeding grounds over a variety of vegetation, some of which clearly acted as swarm markers. Low light (0–1000 lux) and still/humid conditions favoured swarming.
• 2 Swarm size ranged between less than 10 and more than one thousand midges. The modal size was 200 individuals. The smallest swarms were usually columnar in shape and the larger swarms ovoid.
• 3 Midges behaved individually within swarms, moving in an elliptical manner characteristic of other dipterans in swarms.
• 4 Swarms were classified as either ‘persistent’ or ‘transient’ in terms of their shape, size and stability. Wind was the most influential factor in disrupting swarms.
• 5 Swarms were confirmed as mating sites for C.impunctatus.

     

A new Andean species of Ablabesmyia Johannsen from Colombia (Diptera: Chironomidae) with an updated taxonomic key for Neotropical species

ABSTRACT

Ablabesmyia

is a speciose genus, with about 90 species distributed worldwide, 37 of which occurring in the Neotropical region. In Colombia, A. metica is the only species of the genus recorded so far, which was initially described with material collected in the Colombian Orinoquia and more recently recorded in the southeastern Brazil. In the present study, Ablabesmyia opita sp. n. from the Colombian Andes is described and illustrated based on adult males collected at the inter-andean valley of Magdalena river basin. In addition, an updated taxonomic key for Neotropical species and a map of Ablabesmyia records in Colombia are provided. The male of the new species is similar to that of A. laurindoi but can be easily distinguished by the coloration patterns of the legs, the shape of the sternapodeme and by the number of antepronotals.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:A9FD43D5-7018-4B3F-925B-E843B82D71E6     

Afrochlus Freeman: an African gondwanan midge and the phylogeny of the Podonominae (Diptera: Chironomidae)

The immature stages and male adult of Afrochlus harrisoni Freeman are described for the first time, from the type locality, a granite outcrop in Zimbabwe. A phylogenetic position within the subfamily Podonominae as sister to South African-western/central Australian genus Archaeochlus Brundin, suggested in 1966 by Brundin from the adult female alone, is confirmed by cladistic analysis of all life history stages combined. Within the Podonominae, the tribes Boreochlini and Podonomini erected by Brundin are monophyletic only if Trichotanypus Kieffer is transferred from the former to the latter. Little or none of the structure provided by the combined evidence from all stages is retrieved by cladistic analyses of characters derived solely from the adult stage. The implications of erection of monotypic genera for adult-only taxa are discussed.     

Semiocladius Sublette and Wirth: taxonomy and ecology of an estuarine midge (Diptera: Chironomidae: Orthocladiinae)

Abstract Semiocladius Sublette and Wirth, described from adult midges from south-western Pacific Ocean shores, has the Australian Camptocladius crassipennis Skuse as its type. Immature stages previously known only from Semiocladius kuscheli Sublette and Wirth from sub-Antarctic New Zealand were associated tentatively, by co-occurrence. For the first time, the immature stages for the Australian species are associated definitively by rearing. Larvae rear to a pupa identical to a speculatively associated exuviae of Semiocladius from Lord Howe Island. Adults conform to the described S. crassipennis . Larval Semiocladius are distinctive and previous diagnoses are confirmed. In contrast, the putatively associated pupa of S. kuscheli is indistinguishable from that of the marine intertidal Thalassosmittia Strenke and Remmert, whereas the newly associated S. crassipennis pupa is distinct. The pupa of S. kuscheli may have been misassociated. Semiocladius live in the mesohaline of the salinity gradient of the Clyde River estuary, south-east Australia and the genus appears to be a distinctive western Pacific saline/mesohaline taxon.     

Organic matter processing by chironomid larvae (Diptera: Chironomidae)

In laboratory experiments, we used fluorescent dye markers to investigate processing of organic matter by larvae of Psectrocladius limbatellus (Holm.) (Diptera: Chironomidae). 59% of the organic matter used was incorporated into tubes, 39% was present in faecal pellets (both after 24 h), and 2% was found in the larval gut at the end of experiments. Ingested matter passed through the gut rapidly, resulting in the gut being emptied more than 20 times each day. Further 24-h experiments using dye-marked faecal pellets showed that 6% of pellets produced were re-ingested and 12% were incorporated into tubes. There was no preference for conditioned faecal pellets as food over those that had recently been egested and tubes also provided a food reserve on which larvae feed. Chironomid larvae recycle organic matter resulting in its mineralization and their ‘engineering’ has a dramatic effect on the substratum. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chironomidae (Insecta: Diptera) from four protected areas in the state of Pernambuco,Brazil

New records and distributional notes of Chironomidae (Insecta, Diptera) are provided for four protected areas in the state of Pernambuco, northeastern Brazil. Additionally, we also present new records and update of distributional ranges from Brazil and the Neotropical Region. In total, 810 specimens belonging to 35 genera within the subfamilies Chironominae (22 taxa), Tanypodinae (11 taxa) and Orthocladiinae (2 taxa) were found. The subfamilies Chironominae and Tanypodinae predominated. Axarus Roback, 1980 Roback, S.S. (1980), ‘New name for Anceus Roback nec Anceus Risso’, Entomological News, 91, 32.[Web of Science ®] , [Google Scholar] and the Tanytarsus ortoni-group were recorded for the first time in the state of Pernambuco, while Nanocladius Kieffer, 1913a Kieffer, J.J. (1913b), ‘Nouvelle étude sur les Chironomides de l'Indian Museum de Calcutta’, Records of the Indian Museum, 9, 119–197. [Google Scholar] was recorded for the first time in the Northeast Region of Brazil. Our results make evident how much and where current knowledge of the northeastern Brazil chironomids remains fragmentary.     

Production of the predaceous midge tribes Sphaeromiini and Palpomyiini (Diptera: Ceratopogonidae) in Lake Norman,North Carolina

Production and P/B ratios of predaceous midges of the tribes Sphaeromiini and Palpomyiini (Diptera: Ceratopogonidae) collected from sublittoral and littoral depths in Lake Norman, North Carolina, were estimated by the size-frequency method. Production estimates in g dry wt/m²/yr at eight sampling locations ranged from 0.002 to 0.022. The littoral zone as a whole was more productive (0.015 g/m²/yr) than the sublittoral zone (0.006 g/m²/yr). The P/B ratios ranged from 2.37 to 3.78 among all stations and depths.     

Biology ofChironomus piger Str. (Diptera: Chironomidae) and its role in the self-purification of a river

Chironomus piger larvae are widespread in small rivers and canals strongly polluted with domestic sewage. Despite this, almost nothing is known concerning the biology of the species under natural conditions and its role in the process of river self-purification. For two years, benthic samples were collected in the Sestra River at a site about 250 m downstream of the effluent discharge drains of a sewage treatment installation where the greatest concentrations of the larvae occurred. The number and biomass ofC. piger larvae were subject to marked fluctuations,viz. 96,000–348,000 ind m^–2 and 420–1,800 g m^–2. 460 degreedays (on average) was required for development of one generation.C. piger has 5 or 6 generations per year depending on the hydrometeorological conditions during the growing season.C. piger larvae play an important role in self-purification of the river. They utilize precipitating seston for food and for building their dwelling tubes. According to our calculations the amount of organic matter assimilated in the area of maximum larval concentration ranged 80–177 g wet weight m^–2 day^–1, and 32–71 g wet weight m^–2day^–1 was mineralized.     

Incidence of Mentum Deformities in Midge Larvae (Diptera:Chironomidae) from Northern Nova Scotia, Canada

Deformities in the mouthparts of larval Chironomidae, particularly of the teeth on the mentum, have been proposed as a bioindicator of sediment quality and environmental stress. Most work to date has concentrated on relatively few abundant, responsive genera common in soft-bottom lakes. We examined mentum deformities in 25 genera of Chironominae, Orthocladiinae and Diamesinae (one genus) from streams and a lake in rural Nova Scotia where farming and forestry are the principal land uses. Incidence of deformity at similar stream sites varied across genera from zero to >10%. Average frequencies of deformity across all three subfamilies at sites with no known sources of contamination ranged from <4% to 8%, and increased to nearly 15% at a site receiving treated municipal sewage effluent. Differences in chironomid community structure and rates of leaf litter decomposition above and below the sewage effluent outfall were congruent with the difference in mentum deformities. Frequencies of deformity observed here are an order of magnitude greater than in similar studies of rural areas. Low-level stress from agriculture or forest harvesting may be widespread in rural regions even in aquatic ecosystems that are seemingly free of industrial discharges or sediment contamination.     

Incidence of deformed chironomid larvae (Diptera: Chironomidae) in Swedish lakes

The occurrence of deformed mouth parts in recent and subfossil material of mostly Chironomus, Micropsectra and Tanytarsus increased from less than 1 % of the larvae at unpolluted sites or time periods to figures in the range of approx. 5–25% at strongly polluted sites. Deformities occurred in species that are widely separate in taxonomic position and way of living. Several heavy metals are suspected causative agents. Deformities in various mouth parts are illustrated by SEM photographs.     

Some carotenoids in Chironomus annularius Meig. larvae (Diptera : Chironomidae)

Summary The author investigated the presence of various carotenoids in the body of the larvae of the Chironomus annularius MEIG. moquito (Diptera: Chironomidae) by means of columnar and thin-layer chromatography.The investigations revealed the presence of the following carotenoids in the larvae: -carotene, -carotene, canthaxanthin, cryptoxanthin, lutein, astacene and a kind of xanthophyl which was not possible to identify more closely.     

Sex ratio in relation to season and host plant quality in a monogenous stem-galling midge (Diptera: Cecidomyiidae)

Abstract.  1. The sex determination mechanism in gall midges is little understood, although it is known that the females of several species primarily or exclusively produce unisexual broods throughout their lifetime.
2. The gall midge Izeniola obesula Dorchin is a multivoltine species, inducing multi-chambered stem galls on the salt-marsh plant Suaeda monoica . Each gall contains 5–70 individuals, all being the progeny of a single female. Sampling of more than 450 galls, from which adult midges were reared, suggested that I .  obesula exhibits strict monogeny, resulting in galls that contain either all female or all male progeny.
3. Characterisation of the growth pattern of young S .  monoica shoots revealed that shoots in apical positions grew more rapidly than shoots in more basal positions. Galls that were induced on such shoots were larger and yielded more adult midges.
4. No difference in the site of gall induction was found between male and female galls, with galls of either sex being mainly induced on more rapidly growing shoots. It is concluded that I .  obesula females cannot control the sex of their progeny, and that both female-producers and male-producers strive to maximise their reproductive success by choosing the faster-growing shoots for gall induction.
5. Female galls were larger and more abundant than male galls at almost all times. The sex ratio among galls fluctuated throughout the year, ranging from 4:1 in spring to 1:1 in winter. The skewed sex ratio among galls possibly results from greater mortality rates among male galls than among female galls, due to either primary or secondary factors. Alternatively, it is possible that the number or fitness of male-producers in the population is reduced relative to female-producers.