Pupal Exuviae Research Articles

New records of chironomids (Chironomidae: Diptera) from Slovakia / Nové nálezy pakomárov (Chironomidae: Diptera) zo Slovenska

Abstract Five chironomid species: Thienemannimyia vitellina (Kieffer, 1916), Orthocladius (Pogonocladius) consobrinus (Holmgren, 1869), Parachironomus danicus, Lehmann 1970, Tanytarsus norvegicus (Kieffer 1924) and Tanytarus smolandicus, Brundin 1947 were recorded in Slovakia for the first time. The pupal exuviae were collected in 2012-2013 from 9 water reservoirs. Details on finding with the notes on distribution and ecology are presented.

Trace DNA from insect skins: a comparison of five extraction protocols and direct PCR on chironomid pupal exuviae

Insect skins (exuviae) are of extracellular origin and shed during moulting. The skins do not contain cells or DNA themselves, but epithelial cells and other cell-based structures might accidentally attach as they are shed. This source of trace DNA can be sufficient for PCR amplification and sequencing of target genes and aid in species identification through DNA barcoding or association of unknown life stages. Species identification is essential for biomonitoring programs, as species vary in sensitivities to environmental factors. However, it requires a DNA isolation protocol that optimizes the output of target DNA. Here, we compare the relative effectiveness of five different DNA extraction protocols and direct PCR in isolation of DNA from chironomid pupal exuviae. Chironomidae (Diptera) is a species-rich group of aquatic macroinvertebrates widely distributed in freshwater environments and considered a valuable bioindicator of water quality. Genomic DNA was extracted from 61.2% of 570 sampled pupal exuviae. There were significant differences in the methods with regard to cost, handling time, DNA quantity, PCR success, sequence success and the ability to sequence target taxa. The NucleoSpin(®) Tissue XS Kit, DNeasy(®) Blood and Tissue kit, andQuickExtract(™) DNA Extraction Solution provided the best results in isolating DNA from single pupal exuviae. Direct PCR and DTAB/CTAB methods gave poor results. While the observed differences in DNA isolation methodson trace DNA will be relevant to research that focuses on aquatic macroinvertebrate ecology, taxonomy and systematics, they should also be of interest for studies using environmental barcoding and metabarcoding of aquatic environments.

Use of Chironomidae (Diptera) Surface-Floating Pupal Exuviae as a Rapid Bioassessment Protocol for Water Bodies.

Rapid bioassessment protocols using benthic macroinvertebrate assemblages have been successfully used to assess human impacts on water quality. Unfortunately, traditional benthic larval sampling methods, such as the dip-net, can be time-consuming and expensive. An alternative protocol involves collection of Chironomidae surface-floating pupal exuviae (SFPE). Chironomidae is a species-rich family of flies (Diptera) whose immature stages typically occur in aquatic habitats. Adult chironomids emerge from the water, leaving their pupal skins, or exuviae, floating on the water's surface. Exuviae often accumulate along banks or behind obstructions by action of the wind or water current, where they can be collected to assess chironomid diversity and richness. Chironomids can be used as important biological indicators, since some species are more tolerant to pollution than others. Therefore, the relative abundance and species composition of collected SFPE reflect changes in water quality. Here, methods associated with field collection, laboratory processing, slide mounting, and identification of chironomid SFPE are described in detail. Advantages of the SFPE method include minimal disturbance at a sampling area, efficient and economical sample collection and laboratory processing, ease of identification, applicability in nearly all aquatic environments, and a potentially more sensitive measure of ecosystem stress. Limitations include the inability to determine larval microhabitat use and inability to identify pupal exuviae to species if they have not been associated with adult males.

Use of Chironomidae (Diptera) Surface-Floating Pupal Exuviae as a Rapid Bioassessment Protocol for Water Bodies

Rapid bioassessment protocols using benthic macroinvertebrate assemblages have been successfully used to assess human impacts on water quality. Unfortunately, traditional benthic larval sampling methods, such as the dip-net, can be time-consuming and expensive. An alternative protocol involves collection of Chironomidae surface-floating pupal exuviae (SFPE). Chironomidae is a species-rich family of flies (Diptera) whose immature stages typically occur in aquatic habitats. Adult chironomids emerge from the water, leaving their pupal skins, or exuviae, floating on the water’s surface. Exuviae often accumulate along banks or behind obstructions by action of the wind or water current, where they can be collected to assess chironomid diversity and richness. Chironomids can be used as important biological indicators, since some species are more tolerant to pollution than others. Therefore, the relative abundance and species composition of collected SFPE reflect changes in water quality. Here, methods associated with field collection, laboratory processing, slide mounting, and identification of chironomid SFPE are described in detail. Advantages of the SFPE method include minimal disturbance at a sampling area, efficient and economical sample collection and laboratory processing, ease of identification, applicability in nearly all aquatic environments, and a potentially more sensitive measure of ecosystem stress. Limitations include the inability to determine larval microhabitat use and inability to identify pupal exuviae to species if they have not been associated with adult males.

Seasonal variation in Chironomid emergence from coastal pools

Understanding the phenology of emergences can be useful in determining seasonal chironomid life cycle patterns, which are often influenced by ice cover and temperature in cold climates. Lake Superior is the largest lake in North America and with a mean surface temperature of 3.9 °C influences regional climate. Coastal pools at Isle Royale, a wilderness archipelago in the northern part of the lake, occur in dense patches on low-gradient volcanic bedrock between the lakeshore and forest, creating variable microhabitats for Chironomidae. Four sites were sampled monthly from April to October, 2010. Surface-floating pupal exuviae were collected from a series of pools in two zones: a lower zone near the lake influenced by wave splash, and an upper zone near the forest and influenced by upland runoff. We used Jaccard’s and Whittaker’s diversity indexes to test community similarity across months. Temperature loggers in pools collected hourly readings for most of the study. Assemblage emergences were stable in upper pools, with significant similarity across late spring and summer months. Assemblages were seasonally variable in lower pools, with significant dissimilarity across spring, summer, and fall months. Few species in either zone were unique to spring or fall months. However, many summer species in the splash zone had a narrow emergence period occurring during calm weather following distinct increases in mean water temperature. Regardless of input of cold lake water to the lower zone, pools from both zones generally had corresponding temperature trends.

Even more Chironomid species for classifying lake nutrient status

The European Union Water Framework Directive (WFD) classifies ecological status of a waterbody by the determination of its natural reference state to provide a measure of perturbation by human impacts based on taxonomic composition and abundance of aquatic species. Ruse (2010; 2011) has provided methods of assessing anthropogenic perturbations to lake ecological status, in terms of nutrient enrichment and acidification, by analysing collections of floating pupal exuviae discarded by emerging adult Chironomidae. The previous nutrient assessment method was derived from chironomid and environmental data collected during 178 lake surveys of all WFD types found in Britain. Canonical Correspondence Analysis provided species optima in relation to phosphate and nitrogen concentrations. Species found in less than three surveys were excluded from analysis in case of spurious association with environmental values. Since Ruse (2010) an additional 72 lakes have been surveyed adding 31 more species for use in nutrient status assessment. These additional scoring species are reported here. The practical application of the Chironomid Pupal Exuvial Technique (CPET) to classify WFD lake nutrient status is demonstrated using CPET survey data from lakes in Poland.

First record of a Chironomidae pupa in amber

A pupal exuviae of a non-biting midge (Chironomidae) is recorded in Eocene Rovno amber from Ukraine. The exuviae belongs to an Orthocladiinae species. It possesses several traits characteristic for terrestrial species including non-fringed anal lobes without macrosetae, tergites with only minute shagreen, bare conjunctives, and absence of thoracic horns and frontal warts. Up to now, this is the earliest record of a preimaginal stage of Orthocladiinae, and the only record of a chironomidae pupal exuviae from amber.

First Report of the Invasive Crane Fly, Tipula oleracea, Associated with Turfgrass in Utah

This is the first report of Tipula oleracea L. (the common crane fly, also marsh crane fly) in Utah. Tipulid larvae were collected from a putting green in Tooele County in fall 2012. Pupal exuvia and adult crane flies were seen flying on golf courses in Salt Lake, Davis, and Utah counties in 2013, but adults were not captured or identified as the exotic species until fall 2014. The detection of T. oleracea in Utah is somewhat surprising, given the species’ association with moist environments. A statewide survey is needed to better understand the spread and potential impact of T. oleracea on the turfgrass industry in Utah and the surrounding Intermountain West region.

The presence of species of Pseudochironomus Malloch 1915 (Diptera: Chironomidae) in watercourses of Chaco Serrano Ecoregion (Argentina, South America).

Male imagos of Pseudochironomus viridis (Kieffer) are redescribed, the immature stages are described and figured for the first time. During this study, larva and pupal exuviae associated to P. richardsoni (Malloch) were recorded for the first time for South America. The specimens were collected from a stream and a river in the Pampasic Hills System in the Chaco Serrano ecoregion of Argentina.

Philornis downsi (Diptera: Muscidae), an Avian Nest Parasite Invasive to the Galapagos Islands, in Mainland Ecuador

ABSTRACT Philornis downsi (Dodge and Aitken) is a bird-parasitic muscid fly native to mainland South America that recently invaded the Galapagos Islands where it is parasitizing Darwin's finches and other land birds. This parasite was previously known only from Argentina, Brazil, and Trinidad and Tobago. The first report of P. downsi from mainland Ecuador is provided, supporting the hypothesis that the invasion route of P. downsi from its native range to the Galapagos Islands includes mainland Ecuador. Four different morphologies of pupal exuviae, which belong to different fly species, were uncovered. Dipteran puparia were found in 20% of naturally occurring nests collected in 2013 and in 27% of nests in 2014 at the two sites in western Ecuador. P. downsi accounted for 74% and 40% of the puparia in 2013 and 2014, respectively. Two new bird host species for the genus Philornis were recorded: the streak-headed woodcreeper (Lepidocolaptes souleyetii) and the fasciated wren (Campylorhynchus fasciatus). The le...

Characterization of Chironomidae (Diptera) surface-floating pupal exuviae sample sort time from coastal tropical aquatic systems.

Many studies either ignore chironomids or only identify specimens to subfamily or tribe due to the associated difficulty and high cost with processing and identifying larvae. An efficient form of sampling chironomids involves collections of surface-floating pupal exuviae (SFPE). SFPE sample sorting has been shown to be more time efficient than traditional dip-net methods in temperate urban and peri-urban streams. However, no published studies have tested the time efficiency of SFPE sample sorting from coastal tropical aquatic systems. We calculated sort times for SFPE samples collected from a coastal tropical stream and an estuary and used multiple linear regression analysis to quantify the relationship between sample sort time and number of specimens, average body length of specimens, and dry weight of sample residue. The average amount of time required to sort very small samples was 69.3min, while moderate samples averaged 85.6min and large samples averaged 153.5min. However, on average, small samples were nine times more time consuming per specimen than large samples. Additionally, dry weight of small-sized residue and the number of specimens contributed significantly to sort time. Therefore, we recommend collecting larger samples, which can be achieved by sampling for 20min over 200-m reaches for stream sites and 500- to 1,000-m reaches for riverine and estuarine sites. Also, we suggest collecting during periods of low wave action and disturbance by boat wake to reduce the amount of sample residue. This research will enhance project planning and budgeting of future studies using the SFPE method to monitor coastal tropical aquatic systems.

Zonal stratification and geographic clustering of a species-rich chironomid community in freshwater coastal rock pools

Chironomidae are typically abundant in freshwater habitats and can be good indicators of ecological health. Coastal rock pools of barrier islands were sampled to determine how communities varied spatially between two horizontal zones, defined by wave disturbance and distance from shore, and from island-to-island. Pupal exuviae were collected monthly from pool surfaces to assess species composition, true community richness, and alpha and beta diversity. Cluster analyses were used to determine geographic community variation. A majority of species were rare, while three species dominated relative abundances. Zonal differences were significant, diversity was greater in near-shore pools overall, and few species occurred in both zones. Communities were more species-rich than expected based on prior studies in similar habitats. Community clusters were not strongly differentiated but suggested increased dispersal challenges at wider gaps between islands. Higher diversity near the shore and geographic clustering of communities are important to consider when planning for remediation activities following pollution events such as ship groundings or oil spills. In general, baseline coastal studies and conservation planning should consider aquatic invertebrates when pool habitats are present.

Evidence from molecules and morphology expands Podonomopsis Brundin (Diptera : Chironomidae : Podonominae) to include ‘genus Chile'

The informal taxon ‘genus Chile’ of Brundin, based solely on pupal exuviae of a podonomine Chironomidae, has remained inadequately known for half a century. New collections reveal life associations, and provide molecular data to hypothesise a precise phylogenetic placement in the austral Podonominae. A densely sampled molecular phylogeny based on two nuclear and one mitochondrial DNA markers shows ‘genus Chile’ to be the sister group to Podonomopsis Brundin, 1966. Within Podonomopsis a clade of South American species is sister to all Australian species. We discuss how to rank such a sister group taxon and treat ‘genus Chile’ as a new subgenus Araucanopsis, subg. nov. with the new species, Podonomopsis (Araucanopsis) avelasse, sp. nov. from Chile and Argentina as genotype of the monotypic subgenus. We describe P. (A.) avelasse in all stages and provide an expanded diagnosis and description of Podonomopsis to include Araucanopsis. A dated biogeographic hypothesis (chronogram) infers the most recent common ancestor (tmcra) of expanded Podonomopsis at 95 million years ago (Mya) (68–122 Mya 95% highest posterior density), ‘core’ Podonomopsis at 83 Mya (58–108) and Australian Podonomopsis at 65 Mya (44–87). All dates are before the South America–Australia geological separation through Antarctica, supporting previous conclusions that the taxon distribution is ‘Gondwanan’ in origin. Podonomopsis, even as expanded here, remains unknown from New Zealand or elsewhere on extant Zealandia. http://zoobank.org/urn:lsid:zoobank.org:act:B242009B-0CEF-41CA-8C78-17B9D3B57025

Chironomidae (Diptera) in Freshwater Coastal Rock Pools at Isle Royale, Michigan

Chironomid pupal exuviae were collected from coastal rock pools at Isle Royale National Park, Michigan, from April to October in 2009 and 2010. Pools in bedrock depressions were separated into those higher on the shore, where desiccation is likely an important disturbance, and lower on the shore, where wave-wash from Lake Superior is likely a fundamental influence. The 102 species collected represent 42 genera in six subfamilies. The distribution and ecology of each species is summarized. Also included are remarks on species with significant range expansions, either with Palearctic or Nearctic disjunct ranges, or novel habitat use among species that are typically considered lotic but occur in splash zone pools at Isle Royale.

Differential efficiencies of dip-net sampling versus sampling surface-floating pupal exuviae in a biodiversity survey of Chironomidae

Relative efficiencies of standard dip-net sampling (SDN) versus collections of surface-floating pupal exuviae (SFPE) were determined for detecting Chironomidae at catchment and site scales and at subfamily/tribe-, genus- and species-levels based on simultaneous, equal-effort sampling on a monthly basis for one year during a biodiversity assessment of Bear Run Nature Reserve. Results showed SFPE was more efficient than SDN at catchment scales for detecting both genera and species. At site scales, SDN sampling was more efficient for assessment of a first-order site. No consistent pattern, except for better efficiency of SFPE to detect Orthocladiinae genera, was observed at genus-level for two second-order sites. However, SFPE was consistently more efficient at detecting species of Orthocladiinae, Chironomini and Tanytarsini at the second order sites. SFPE was more efficient at detecting both genera and species at two third-order sites. The differential efficiencies of the two methods are concluded to be related to stream order and size, substrate size, flow and water velocity, depth and habitat heterogeneity, and differential ability to discriminate species among pupal exuviae specimens versus larval specimens. Although both approaches are considered necessary for comprehensive biodiversity assessments of Chironomidae, our results suggest that there is an optimal, but different, allocation of sampling effort for detecting Chironomidae across stream orders and at differing spatial and taxonomic scales.Article submitted 13. August 2014, accepted 31. October 2014, published 22. December 2014.

Factors affecting decomposition rates of chironomid (Diptera) pupal exuviae

Collections of floating chironomid pupal exuviae are used to monitor water quality and assess ecological conditions. Factors controlling exuviae sinking rates are not well known, although they should have an effect on conclusions that can be drawn from collections. The current study was conducted to determine the rate of sinking under controlled laboratory conditions using water from three streams with different nutrient levels. Sinking rates ranged from less than a day to seven days, depending on microbial activity, nutrient concentrations, temperature and turbulence. Results also varied by genus, with pupal exuviae of Chironomus riparius, Diamesa nivoriunda, Orthocladius (Euorthocladius) thienemanni and Eukiefferiella sp. used in experiments. Four species of bacteria and eight genera of fungi colonized and metabolized exuviae, with bacteria dominant early and fungi dominant later in the decomposition process. Decomposition was faster in lightly chitinized abdominal conjunctive areas, which resulted in exuviae breaking apart and sinking. Examination of untreated, dewaxed and dewaxed-deproteinized exuviae indicated that untreated exuviae sank faster. Waxes appeared important for colonization and initial microbial metabolization was delayed when waxes were removed. Results confirm the importance of biological degradation of exuviae in determining floatation times. We predict that streams and other waterbodies with high dissolved nutrients will result in rapidly sinking exuviae, while exuviae in low nutrient waterbodies will float longer.Article submitted 1. October 2014, accepted 18. November 2014, published 22. December 2014.

Data on Buchonomyia thienemanni Fittkau (Diptera: Chironomidae) from Slovakia

All known records of Buchonomyia thienemanni Fittkau from Slovakia are summarised below which includes two records from the Žilina Region and one record each from the regions of Levice and Sereď. Bitusik (1987) published the first record of the species for Slovakia from the Rajcianka submontane brook. The species was also found during a study on the longitudinal zonation of chironomid assemblages in the River Hron (Bitusik et al. 2006). Specimens from all localities are based on pupal exuviae collected with drift nets. Details on two previously unpublished records are provided.

Clave para la determinación de exuvias pupales de los quironómidos (Diptera: Chironomidae) de ríos altoandinos tropicales

The Chironomidae is a cosmopolitan family of Nematoceran flies with more than 20,000 species described. However the diversity of genera and species of the family in the Andean region beyond the 2,000 m.a.s.l are scarcely known. We conducted faunal surveys and biomonitoring research in different streams of Colombia, Ecuador and Peru from May 2005 to October 2011. Based on specimens collections, a taxonomic key was developed to identify pupae and pupal exuviae of 46 genera of midges (Diptera, Chironomidae) collected from streams at high altitude areas on the Andean tropical mountains. We included illustrations and brief taxonomic descriptions for all genera, of which several ones have not yet been formally described; in this latter case we used the nomenclature of Roback & Coffman (1983). For two genera, Cricotopus and Genus 1, keys to the most com- mon morphospecies were provided. Results showed that in this area the chironomid assemblages are dominated by the members of the subfamily Orthocladiinae (22 genera) followed by the Chironominae (13). Six genera of Tanypodinae were identified, while only three and two genera were present from subfamilies Podonominae and Diamesinae. This key may be very useful for both studies about drift in streams, and for biomonitoring purposes.

Description of immatures of Mesomphalia gibbosa (Fabricius, 1781) and Mesomphalia turrita (Illiger, 1801) (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini).

Immatures of Mesomphalia gibbosa (Fabricius, 1781) and Mesomphalia turrita (Illiger, 1801) (Coleoptera, Chrysomelidae, Cassidinae, Mesomphaliini) are described based on specimen collections from Rio de Janeiro state, Brazil. The last-instar larva and pupal exuviae of M. gibbosa (Fabricius, 1781) and the eggs, first-instar larva, and pupa of M. turrita (Illiger, 1801) are described, photographed and illustrated, with emphasis on chaetotaxy. Additional notes on their biology are presented.

Spatial Distribution of Grape Root Borer (Lepidoptera: Sesiidae) Infestations in Virginia Vineyards and Implications for Sampling

Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae) is a potentially destructive pest of grape vines, Vitis spp. in the eastern United States. After feeding on grape roots for ≍2 yr in Virginia, larvae pupate beneath the soil surface around the vine base. Adults emerge during July and August, leaving empty pupal exuviae on or protruding from the soil. Weekly collections of pupal exuviae from an ≍1-m-diameter weed-free zone around the base of a grid of sample vines in Virginia vineyards were conducted in July and August, 2008-2012, and their distribution was characterized using both nonspatial (dispersion) and spatial techniques. Taylor's power law showed a significant aggregation of pupal exuviae, based on data from 19 vineyard blocks. Combined use of geostatistical and Spatial Analysis by Distance IndicEs methods indicated evidence of an aggregated pupal exuviae distribution pattern in seven of the nine blocks used for those analyses. Grape root borer pupal exuviae exhibited spatial dependency within a mean distance of 8.8 m, based on the range values of best-fitted variograms. Interpolated and clustering index-based infestation distribution maps were developed to show the spatial pattern of the insect within the vineyard blocks. The temporal distribution of pupal exuviae showed that the majority of moths emerged during the 3-wk period spanning the third week of July and the first week of August. The spatial distribution of grape root borer pupal exuviae was used in combination with temporal moth emergence patterns to develop a quantitative and efficient sampling scheme to assess infestations.