Simuliid Larvae Research Articles

The Molecular Classification Of Blackfly (Diptera: Simuliidae) Species Which Pose a Problem in Nevşehir Part of Central Kızılırmak Basin

This study was carried out to determine the molecular characterization of simuliid species which cause a problem in the part of Kızılırmak passes from Ürgüp and Gülşehir districts of Nevşehir. Between May and September 2011, totally 150 simuliid larvae were sampled. Morphological identifications of the collected larvae specimens were done before the molecular analyses. Genomic DNA extractions were utilized on 7 larvae specimens which were selected from morphologically identified samples and the sequence and phylogenetic analyses were performed after the amplification of the partial mitochondrial cytochrome oxidase subunit 1 (mt-COI) and ribosomal complete internal transcript spacer 2 and partial 28S (ITS-2/28S) gene regions. Eighty-five, 46 and 19 out of 150 morphologically examined specimens were identified as Simulium (S.) Wilhelmia sp., S. Wilhelmia lineatum and S. Wilhelmia balcanicum, respectively. Among the amplified samples with respect to mt-COI and ITS-2/28S gene regions, sequence analyses were performed on 3 and 2 isolates from S. Wilhelmia sp. and both S. lineatum and S. balcanicum. The isolates were found to be clustered together depending on the species for both gene regions phylogenetically and the sequence heterogeneity was found to be higher in S. lineatum. When comparing with the other species under the Wilhelmia subgenus, S. lineatum and S. balcanicum were determined to be more close to each other. Scientific data on the molecular characterization and phylogeny of blackfly species under the S. Wilhelima subgenus which pose a problem in the Central Kızılırmak Basin were provided with this study.

Influence of Some Water Physicochemical Parameters on the Distribution of Black Fly (Diptera, Simuliidae) in Some Rivers in Nasarawa State, Nigeria

Changes in the distribution of simuliid species and their disease transmission pattern may occur in response to climatic and environmental factors. Simuliid larvae were prospected in 34 rivers of Nasarawa State from January 2010 to December 2010. A total of 198,420 simuliid larvae collected were found to belong to six species as follows: S. damnosum s.l. (72.13%), S. adersi (24.31%), S. ruficorne (2.52%), S. cervicornutum (0.69%), S. alcocki (0.68%), and S. schoutedeni (0.17%). The monthly sample indicated continuous breeding throughout the year with peaks in July, August and September. The density of black fly larvae was estimated from samples collected on water plants per 1 dm2 of water plant surface. The study showed that both physicochemical and ecological parameters influenced the density of simuliids. Correlation analysis showed a significant relationship between simuliids density and the environmental factors. Data on prevalence and distribution of simuliids in Nasarawa State are sparse and scanty. Therefore, the result of this study provides additional information on the distribution and density of simuliids in Nasarawa State, Nigeria.

Book Review

Book Review

Identification Keys to the Larvae and Pupae of New Jersey Black Flies (Diptera: Simuliidae)

Multichotomous identification keys are provided to the black fly larvae and pupae of New Jersey and neighboring states. Control of black flies is targeted at the aquatic immature stages, making proper identification of larvae and pupae vital for suppression purposes. The key includes 40 species known from NJ and an additional 24 species from surrounding states. A species confirmation table is also included to increase identification accuracy. Diagnostic images of simuliid pupae and larvae are also provided.

Mermithids (Nematoda: Mermithidae) Parasitizing Different Blackfly (Diptera: Simuliidae) Populations in Quebec: Environmental Parameters Related to Their Presence or Absence in the Studied Brooks

Specimens of Isomermis wisconsinensis, Gastromermis viridis, Mesomermis flumenalis, and Mesomermis camdenensis have been found in 14 out of 28 studied sites. Their hosts were the following blackfly species: Cnephia dacotensis, Cnephia mutata, Prosimulium sp., Simulium decorum, Simulium tuberosum, Simulium venustum/verecundum complex, and Simulium vittatum. Superparasitism was observed in several simuliid larvae and, occasionally, with 2 different mermithid species. The prevalence of different mermithid species varies according to seasons: Mesomermis genus is more abundant during winter, whereas Isomermis and Gastromermis are found in higher number during summer. The study of environmental parameters related to mermithid presence or absence shows that only stream depth makes a difference.

Simuliid silk pads enhance tufa deposition

Simuliid silk pads and their effect on tufa deposition and biofilm development with respect to current velocity and time of exposure have been studied during the winter on tufa barriers in Plitvice Lakes (Croatia). Analysis of silk pad types on artificial substrates showed that moderate velocity substrates were slightly more favourable for simuliid larvae as landing attachment site, while they strongly preferred high velocity substrates as wandering attachment sites and exclusively as long term attachment sites for feeding. Although silk covered only 0.78% of surface area on glass slides, it accumulated 17% of diatoms and 56% of individual calcite crystals under moderate velocity conditions and 13% of diatoms and 41% of individual calcite crystals under high velocity conditions, thus proving that silk influence periphyton development and serves as biomediator in early stages of tufa formation. Diatom and calcite densities were mainly functions of time, with higher densities of both under moderate velocity. Maximum dimension of calcite crystals wasn’ t affected by the two month time of exposure, with larger crystals found under moderate velocity. We conclude that low winter temperature inhibited intensive calcite precipitation so tufa deposition during winter time happened mainly by trapping and binding microcrystalline calcite. Increased current velocities resulted in a poorer periphyton development and a lesser accumulation of calcite crystals.

Xenochironomus ceciliae (Diptera: Chironomidae), a new chironomid species inhabiting freshwater sponges in Brazil

Chironomids living inside freshwater sponges are scarcely known, particularly in the Neotropical region where most of them are to be described. Here, male and female adults, pupa and 4th instar larva of Xenochironomus ceciliae sp. n., living in freshwater sponges of the Parana River (Brazil) are described. The larval labrum with its several densely setose or combed structures somewhat resembling the filtering structures of simuliid larvae and the predominance of fine detritus in the larval gut contents, may indicate that the larvae of Xenochironomus ceciliae sp. n. are collector-filterers and they might be favored by the aquifer systems of the sponges.

The Simuliidae (Diptera) of the Republic of São Tomé and Príncipe, including the description of a new species

Identifications were made of 1122 simuliid larvae and pupae (including neonate adults) collected from 29 localities during November 1998, on the islands of Sao Tome and Principe in the Gulf of Guinea. Three species, including one new species, were found on Sao Tome. Simulium (Pomeroyellum) santomi sp. n. was particularly abundant in the eastern part of the island, whereas the western part was dominated by Simulium (Anasolen) dentulosum Roubaud. In the north-eastern corner Simulium (Pomeroyellum) alcocki Pomeroy was also found. On Prಥncipe only S. dentulosum was found. Findings are briefly discussed in relation to speciation on oceanic islands and vis-a-vis human onchocerciasis (river blindness).

Levantamento das espécies de Simulium (Diptera, Simuliidae), Riacho dos Padres, município de Almirante Tamandaré, Paraná, Brasil

De janeiro a agosto de 2002, quinzenalmente, foi levada a efeito a coleta de simulídeos imaturos em substratos naturais e antrópicos no Riacho dos Padres. O trabalho visou proceder ao inventário das espécies e verificar as freqüências relativas. A área de propriedade particular localizada na Região Metropolitana de Curitiba constitui uma microempresa de agronegócio, com criação de peixes, coelhos, ovinos, bovinos, aves domésticas e, ainda, área de lazer com eqüinos para cavalgada de visitantes. A presença constante de animais hospedeiros e a ração fornecida aos peixes garantiram farta alimentação aos simulídeos, o que favoreceu a explosão desta praga. Em todos os substratos foram coletadas 24.021 pupas e um total de 197.812 larvas. A partir de pupas, foram identificadas com as seguintes freqüências: Simulium inaequale (55,24%), Simulium perflavum (16,81%), Simulium pertinax (13,93%), Simulium orbitale (8,03%), Simulium subnigrum (4,92%), Simulium distinctum (1,03%) e Simulium incrustatum (0,04%). Verificou-se também a quantidade de larvas que colonizaram todos os substratos.

Intraspecific food resource partitioning in Atlantic salmon ( Salmo salar) parr in a subarctic river

The food utilisation and partitioning between three age-groups of Atlantic salmon parr were studied in the subarctic river Tana (70° N, 27° E) by analysis of fish stomach contents and invertebrate composition in the three main lotic feeding habitats: bottom substratum, water column and surface. The salmon parr exhibited large seasonal variation in their food choice, but the different age-groups had a similar diet, dominated by mayfly and stonefly nymphs in May, flying insects and simuliid larvae and pupae in July, and caddis fly larvae in August and September. Some differences in the food resource use of the three age-groups were however also observed, mainly related to size-dependent differences in feeding abilities, but partly also to different use of feeding habitats. Small-sized stonefly and mayfly nymphs and simuliid larvae and pupae decreased in importance with increasing fish age, whereas Trichoptera larvae and flying insects increased. The low resource partitioning between the different age-groups of salmon parr suggests that intraspecific competition for food may occur. All age-groups mostly fed on prey types associated with the bottom habitat, and substantial drift feeding was only observed in July, probably due to low drift rates throughout most of the summer season in this subarctic river.

Phenotypic plasticity in the labral fan of simuliid larvae (Diptera): effect of seston load on primary-ray number

The number of primary rays in the labral fan of filter-feeding black fly (Diptera: Simuliidae) larvae has been used by some authors to aid in species identification. We examined the number of primary labral fan rays in field-collected last-instar larvae of Simulium rostratum and Simulium decorum. Significant inter- and intra-specific differences were found both spatially and temporally. Simulium rostratum and S. decorum larvae were also reared to last instar (from eggs or first- or second-instar larvae) under three feeding regimes to test the effect of seston load on the number of primary labral fan rays. In both species the fan-ray number decreased when the food supply was increased. We conclude that the primary fan ray number should be used cautiously in species diagnosis because it is a phenotypically plastic trait that varies with seston load. A potential feedback mechanism to explain the observed differences in fan-ray number is hypothesised.

Fall and Winter Diets of Juvenile Coho Salmon in a Small Stream and an Adjacent Pond in Washington State

ABSTRACT The diets of coho fry in Baker Creek, Bellingham, Washington, and an adjacent pond were examined in November through January, 1988–89. Fry in both habitats had the larger numbers of prey in early December after heavy rain, when springtails comprised more than 70% of their food items in both habitats. In January, when rainfall was low, both populations fed more on benthic invertebrates, such as taeniopterygid nymphs and simuliid larvae in the creek, and chironomid larvae in both habitats. High rainfall and flooding played an important role in making available food for juvenile coho salmon in both off-channel and creek habitats in late fall and early winter.

Phenotypic plasticity in the labral fan of simuliid larvae (Diptera): effect of seston load on primary-ray number

Phenotypic plasticity in the labral fan of simuliid larvae (Diptera): effect of seston load on primary-ray number

Diel emigration and colonization responses of blackfly larvae (Diptera: Simuliidae) to ultraviolet radiation

1. Total counts of blackfly larvae densities over 30‐ and 57‐h periods in experimental channels during May of 1996 & 1997 indicate that ultraviolet radiation (UV; 290–400 nm) may be important in stimulating emigration.2. Under experimentally controlled solar UV exposure, larval densities at dawn in UV‐shielded channels were 161% and 168% higher than in the UV‐exposed channels. Larval densities in UV‐exposed channels then decreased by 68.2% and 81.1% between dawn and early afternoon of the two days; density decreases in UV‐shielded channels were slight, and not statistically significant, during the same periods.3. Larvae within UV‐exposed channels occupied shaded microhabitats during hours of intense solar radiation, suggesting that simuliid larvae can detect and respond to UV radiation over very short periods of time.4. A cyclical pattern of UV‐induced emigration during hours of increasing solar flux (06.30–13.30) and net immigration in the hours of decreasing solar flux and at night emerged. Thus stream invertebrates may be very sensitive to environmental changes, resulting in either increased UV flux or decreased shading of streams. Diel cycles in invertebrate densities should be taken into account in research designs and sampling protocols in order to identify and interpret correctly results of both periodic surveys and experiments.

Habitat use by Harlequin Ducks breeding in Hebron Fiord, Labrador

Understanding of breeding habitat requirements is vital to recovery plans for the endangered eastern North American population of Harlequin Ducks (Histrionicus histrionicus). I compared habitat characteristics and benthic invertebrate fauna between streams in Hebron Fiord, Labrador, used and unused by Harlequin Ducks in 1996. Used streams were narrower, had higher pH and temperature, a larger substrate, steeper shorelines, and greater vegetation cover on islands and shorelines than unused streams. Greater numbers of invertebrates were recovered from kick samples, simuliid larvae and plecopteran nymphs were more frequent, and chironomid larvae and emphemeropteran nymphs were less frequent in used than in unused streams. Results from this study will help focus future survey and conservation efforts.

Aquatic insects in an estuarine environment: densities, distribution and salinity tolerance

1. Aquatic insects were quantitatively surveyed at five sites along the tidally influenced section of a river‐dominated estuary in North Wales. Site 1 was the furthest upstream and was established as a reference site as it was never inundated by salt water. Site 5 was the furthest downstream and was inundated by all incoming tides. Numerically, insects made up 32% of the estuarine invertebrate fauna.2. Although the densities of most insect taxa decreased towards the estuary mouth, there were significant numbers present downstream for much of the year; for example, in April at site 4 (which was inundated by 81% of all high tides), a mean of 3514 chironomid larvae were recorded per m2 of estuary bed. Even at site 5, which was inundated twice daily, there were 747 larvae per m2. Among the larger aquatic insects, caddisfly and elmid beetle larvae, together with stonefly nymphs, were consistently taken at site 4 (e.g. maxima of forty‐eight caddisfly larvae m–2 in December and seventy elmids m–2 in April), although their densities were lower than upstream.3. There were seasonal shifts in the longitudinal distribution of several taxa, most notably the extension of chironomids down the estuary in April and July, and the concentration of simuliid larvae and mayfly nymphs at site 2 in July. The total freshwater benthos showed a downstream shift between September and December, which was maintained through April and into the summer. The latter was despite peak saltwater inundation (highest tides) in October, November and April. In June and July, when saltwater intrusion was lowest, the ranges of many aquatic insects had contracted to sites 1 and 2.4. Laboratory experiments showed that virtually all individuals of nineteen species of insects collected from site 1 (freshwater) survived a 4‐h immersion in 8.75‰ saltwater (25% strength seawater). Immersion in progressively more saline solutions reduced the survivorship of first the mayflies, followed by the caddisflies Glossosoma conformis and Hydropsyche instabilis. After 4 h in full strength seawater, all specimens of the stonefly Dinocras cephalotes, over half of the Perla bipunctata, and some individuals of nine species of caddisfly were alive. Four species of caddisfly (Sericostoma personatum, Odontocerum albicorne, Potamophylax cingulatus and Adicella reducta) survived a 24‐h simulated tidal cycle of immersion. With the exception of P. cingulatus, a few individuals of these caddisfly species survived immersion in full‐strength seawater for 24 h. For some individual species there was good agreement between their observed longitudinal distribution in the estuary and laboratory‐measured salinity tolerance; however, there was no significant correlation, overall, for the fauna.

Foraging behavior predicts age at independence in juvenile Eurasian dippers (Cinclus cinclus)

Timing of foraging independence may be controlled by parents, offspring, or both and may have consequences for dispersal, reproduction, and survival. In a study of juvenile Eurasian dippers {Cinclus cinclus), I examined the relationship between individual differences in parental provisioning, the development of foraging, and the liming of independence. Young dippers forage very differently from adults, specializing on small, stationary prey, such as simuliid larvae (Diptera), and avoiding energetically costly and highly skilled foraging techniques, such as diving, by which adults obtain larger prey. In my Welsh study area, age at independence varied substantially within and between broods. Juveniles that relied more on simuliids and less on larger prey were independent sooner, as were juveniles with higher rates of intake while foraging; the effect was obvious 3—4 days after fledging. Provisioning rate and total caloric intake over the dependent period was unrelated to age at independence, although greater reliance on parental feeding was associated with higher total caloric intake. Higher rates of intake from begging were correlated with reduced foraging time. The results demonstrate that the acquisition of the adult foraging strategy is not a prerequisite for independence or, hence, dispersal. In fact, mastering the skills necessary to capture larger prey may delay independence. Individual juvenile dippers seem to find different solutions to the trade-off between gaining sufficient food (either from begging or from foraging for simuliids) and the eventual necessity of learning to forage like an adult. Kty words: Cinclus cinclus, development, Eurasian dippers, foraging, individual differences, parental provisioning, passerines, skill acquisition. [Bthav Ecol 9:471-477 (1998)]

Diet and dietary overlap in fishes of temporary waters of southwestern Australia

AbstractThe diets of six species of fish occurring in seasonally inundated waters of the southern acid peat flats of southwestern Australia were studied over a 23 month period. Fishes could be allocated to a benthos/lower water column guild or a midwater column/water surface guild. Segregation on the basis of prey size was noted for one species only, and this species had a larger mouth than the remaining species. Seasonal variation in within‐ and between‐guild overlap was observed. Highest overlap occurred in the mid‐wet season when inundation was greatest and all species foraged in extensive areas of very shallow water. Little segregation based on feeding position within the water column was possible, and some prey species (e. g. simuliid larvae) were particularly abundant at this time. Dietary overlap decreased as the dry season progressed and fish became concentrated in smaller areas of habitat. As fish demonstrated lower levels of food acquisition, this change in overlap was suggested to be in response to increased competition for limited food resources.

Size-related shift in feeding strategy and prey-size selection in young grayling (Thymallus thymallus)

Observations of feeding behaviour and analysis of prey-size selection by young grayling revealed a shift in feeding strategy coinciding with a shift in habitat occurring between larval (observed in lateral habitats) and juvenile (observed in the river channel) stages of grayling. The mean number of foraging attempts per minute decreased four times between both stages, while in the same time the mean distance travelled during each foraging attempt decreased from 1.5 body lengths to 1 body length. Gape-limited postemergent larvae fed mainly on small chironomid larvae (<0.5 mm3) but larger larvae and pupae (0.5 – 1 mm3) were consumed with increasing size. The diet spectrum of juveniles >40 mm was characterized by the appearance of very large prey (> 10 mm3), such as simuliid and ephemeropteran larvae, but also by a new increase of the contribution of small chironomid larvae. Changes in the feeding strategy of young grayling are discussed in relation to internal (e.g., morphological limitations) and external (e.g., physical characteristics of habitat) constraints.

Factors influencing invertebrate drift in small forest streams, south-eastern Queensland

Aspects of invertebrate drift were investigated in four small rainforest streams in south-eastern Queensland. Hourly sampling in two streams revealed low drift rates and no distinct diel patterns. This may have been a consequence of the low flows experienced during the study period. The drift was dominated by Simuliidae, Chironomidae and to a lesser extent Tasmanocoenis sp. (Caenidae) and Cheumatopsyche sp. 6 (Hydropsychidae). Additional studies were undertaken to examine why some individuals of particular taxa drift while others (of the same taxa) remain in or on the substratum. Analysis of the relative gut fullness of simuliid and chironomid larvae showed that a higher proportion of non-drifting individuals had full or nearly full guts compared with those in the drift. Hungrier individuals of these two taxa may enter the drift as a food searching mechanism. An analysis of limb loss of hexapod nymphs indicated that a disproportionate number of individuals in the drift had one or more limbs missing compared with those that remained in the benthos. These data support the hypothesis that invertebrates present in the drift are less fit than non-drifters.