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Pre-imaginal black fly assemblages in streams of Eastern Spain: environmental and substrate requirements

DOI:10.1007/s10750-020-04206-0
Authors:
David López-Peña at University of Valencia
David López-Peña
Eduardo M. García-Roger at University of Valencia
Eduardo M. García-Roger
Ricardo Jiménez Peydró at University of Valencia
Ricardo Jiménez Peydró
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Abstract and Figures

A growing interest in the importance of simuliids in health and animal welfare in certain areas in Europe, such as around the Mediterranean basin, together with the fact that there is fragmentary ecological information on the pre-imaginal stages of these dipterans has led to the need to carry out further research. We studied the abundance and distribution of pre-imaginal stages—mainly the pupae—of simuliid species, and examined their assemblages in relation to environmental gradients identified in Mediterranean basins of eastern Spain. We report a total of 21 black fly species from the set of studied streams, where largely the most common species were Simulium (Simulium) intermedium and Simulium (Simulium) ornatum, two species of medical and veterinary concern. We found that pre-imaginal simuliid assemblages were strongly related to elevation, water temperature and turbidity, dissolved oxygen concentration and water velocity. The analysis of the optima and tolerances for these environmental factors suggests differences in ecological requirements of the pre-imaginal stages of the reported simuliid species. Likewise, it was found that the pupae of some species were strongly associated with specific substrates. We hope that our research results on autoecology of black fly species will contribute to the improvement of pest management programs.
Principal components analysis (PCA) biplot of stream environmental variables. Streams are represented by symbols: (asterisk) Algar, (squared times) Amadorio, (circled plus) Cenia, (diamond with dot) Cervol, (open triangle) Júcar, (times symbol) Mijares, (inverted open triangle) Montnegre, (plus symbol) Palancia, (open diamond) Serpis, and (open circle) Turia
Principal components analysis (PCA) biplot of stream environmental variables. Streams are represented by symbols: (asterisk) Algar, (squared times) Amadorio, (circled plus) Cenia, (diamond with dot) Cervol, (open triangle) Júcar, (times symbol) Mijares, (inverted open triangle) Montnegre, (plus symbol) Palancia, (open diamond) Serpis, and (open circle) Turia
… 
Map of the study area showing the sampling sites
Map of the study area showing the sampling sites
… 
Simuliid species accumulation curves for the studied watercourses. Only those watercourses for which n > 5 were plotted
Simuliid species accumulation curves for the studied watercourses. Only those watercourses for which n > 5 were plotted
… 
a Canonical correspondence analysis (CCA) ordination biplot of simuliid pupae assemblages in the sampling sites, represented by grey circles. Scores for simuliid species are represented by black crosses in the rectangular area delimited by a dashed line. Species scores are at the centroid (weighted average) of the sampling points where each species occurs (i.e., the samples that contain a particular species are scattered around that species’ point in the diagram). Environmental variables were selected using forward selection and Monte Carlo permutation tests (see “Materials and methods”). b Zooming on the rectangular area delimited by a dashed line with standardized names for simuliid species. Perpendiculars drawn from species scores to environmental arrows give approximate ranking of species response to that variable, and whether species has higher-than-average or lower-than average optimum on that environmental variable
a Canonical correspondence analysis (CCA) ordination biplot of simuliid pupae assemblages in the sampling sites, represented by grey circles. Scores for simuliid species are represented by black crosses in the rectangular area delimited by a dashed line. Species scores are at the centroid (weighted average) of the sampling points where each species occurs (i.e., the samples that contain a particular species are scattered around that species’ point in the diagram). Environmental variables were selected using forward selection and Monte Carlo permutation tests (see “Materials and methods”). b Zooming on the rectangular area delimited by a dashed line with standardized names for simuliid species. Perpendiculars drawn from species scores to environmental arrows give approximate ranking of species response to that variable, and whether species has higher-than-average or lower-than average optimum on that environmental variable
… 
Optima (modes) and tolerances (error bars) for a elevation, b temperature, c NTU, and d dissolved oxygen concentration for the pupae of the 21 simuliid species found in this study. Species are arranged on the y axis by increasing optima for each variable
+2
Optima (modes) and tolerances (error bars) for a elevation, b temperature, c NTU, and d dissolved oxygen concentration for the pupae of the 21 simuliid species found in this study. Species are arranged on the y axis by increasing optima for each variable
… 
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PRIMARY RESEARCH PAPER
Pre-imaginal black fly assemblages in streams of Eastern
Spain: environmental and substrate requirements
David Lo
´pez-Pen
˜a.Eduardo M. Garcı
´a-Roger .Ricardo Jime
´nez-Peydro
´
Received: 6 November 2019 / Revised: 5 February 2020 / Accepted: 11 February 2020 / Published online: 27 February 2020
ÓSpringer Nature Switzerland AG 2020
Abstract A growing interest in the importance of
simuliids in health and animal welfare in certain areas
in Europe, such as around the Mediterranean basin,
together with the fact that there is fragmentary
ecological information on the pre-imaginal stages of
these dipterans has led to the need to carry out further
research. We studied the abundance and distribution of
pre-imaginal stages—mainly the pupae—of simuliid
species, and examined their assemblages in relation to
environmental gradients identified in Mediterranean
basins of eastern Spain. We report a total of 21 black
fly species from the set of studied streams, where
largely the most common species were Simulium
(Simulium) intermedium and Simulium (Simulium)
ornatum, two species of medical and veterinary
concern. We found that pre-imaginal simuliid assem-
blages were strongly related to elevation, water
temperature and turbidity, dissolved oxygen
concentration and water velocity. The analysis of the
optima and tolerances for these environmental factors
suggests differences in ecological requirements of the
pre-imaginal stages of the reported simuliid species.
Likewise, it was found that the pupae of some species
were strongly associated with specific substrates. We
hope that our research results on autoecology of black
fly species will contribute to the improvement of pest
management programs.
Keywords Ecological gradients Mediterranean
streams Optima Simuliidae Spain Tolerance
Introduction
Black flies, also known as simuliids (Diptera: Simuli-
idae), are a relatively homogeneous family within
nematoceran dipterans, and ubiquitous to flowing
water (Currie & Adler, 2008). They are holometabo-
lous insects with pre-imaginal developmental stages
(i.e., larvae and pupae) settling in a variety of
submerged substrates in running waters, where they
can attain very high population densities of more than
500,000 individuals per m
2
(Palmer, 1994) and feed by
filtering particles of organic matter dragged by water
flow (Adler & McCreadie, 1997; Currie & Adler,
2008). Their high abundance means that simuliid
larvae and pupae are a source of food for many
Handling editor: Vero
´nica Ferreira
Electronic supplementary material The online version of
this article (https://doi.org/10.1007/s10750-020-04206-0) con-
tains supplementary material, which is available to authorized
users.
D. Lo
´pez-Pen
˜a(&)E. M. Garcı
´a-Roger
R. Jime
´nez-Peydro
´
Institut Cavanilles de Biodiversitat i Biologia Evolutiva,
Universitat de Vale
`ncia (Estudi General), C/ Catedra
´tic
Jose
´Beltra
´n Martı
´nez, 2, Paterna, 46980 Valencia, Spain
e-mail: David.Lopez@uv.es
123
Hydrobiologia (2020) 847:1521–1538
https://doi.org/10.1007/s10750-020-04206-0(0123456789().,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... The ecological characterization of blackfly breeding habitats has been intensified in Europe since the 1980s (Hansford & Ladle, 1979;Rivosecchi, 1986;Leclercq, 1987;Ignjatović-Ćupina et al., 2006) and in the north of Africa (Arigue et al., 2016;Belqat et al., 2018), but there is still a paucity of data concerning some European regions, such as the Mediterranean region. This is especially true in Spain, where populations of pest species including Simulium (Boophthora) erythrocephalum (De Geer, 1776), S. (Simulium) ornatum (Meigen, 1818), S. (S.) reptans (Linnaeus, 1758), S. (Wilhelmia) equinum (Linnaeus, 1758), S. (W.) lineatum (Meigen, 1804) and S. (W.) pseudequinum (Séguy, 1921), have recently increased their population sizes and geographical ranges and have thus become an emerging issue of public health and veterinary concern (López- Peña & Jiménez-Peydró, 2017;López-Peña et al., 2020), although the increase in their annoyance to humans may be explained by other factors such as increasing anthropophagic tendencies, changes in species compositions, decreased tolerance by people, increased knowledge resulting in more frequent reporting of the problem, etc. ...
... This directly targets one of the most challenging questions in biological control regarding whether natural antagonists provide enough limitation of the abundance of a pest due to the effects of competition for a shared resource, in this case substrate availability, or not. Previous studies have suggested no particular substrate preference for the set of species studied here (López-Peña et al., 2020), so competition may occur for any empty space on the riverbed. ...
... This result is consistent with the pupal habitat analysis of the local abiotic variables. Previous studies have highlighted the role of both meteorological and topographic factors, such as temperature and elevation, in shaping blackfly assemblages (McCreadie & Adler, 2006Ya'cob et al., 2016;López-Peña et al., 2020), however we did not include elevation in the set of variables used in the CCA as it was included in the dataset of abiotic variables and it showed a high negative correlation with annual average temperature (R 2 > 0.8, P value <0.001). Regarding the other landscape variables, our results suggest that breeding sites of S. (W.) equinum are positively associated with the presence of pig farms within a radius of 35 km around sampling sites, whereas those of S. (S.) reptans were found closer to cattle farms and within shorter distances from them. ...
Environmental drivers of breeding sites in blackfly species of medical and veterinary importance in eastern Spain
Article
Full-text available
  • Feb 2022
Geographical distribution and abundance of the pupae of six blackfly species of medical and veterinary concern were studied in eastern Spain according to three different sets of explanatory variables including in-stream variables, both (i) abiotic (i.e., physicochemical) and (ii) biotic (i.e., richness and abundance of either taxonomically or ecologically close related taxa), as well as (iii) meteorological and landscape variables. The results showed specific habitat requirements for pupation in Simulium (Boophthora) erythrocephalum (De Geer, 1776) and Simulium (Wilhelmia) equinum (Linnaeus, 1758), two of the six species studied regarding elevation and temperature. While the rest of the species showed a certain degree of ecological overlap, co-occurrence was in general low, which suggested that antagonistic biotic factors may be important in structuring blackfly assemblages. In effect, biotic predictors explained a high proportion (50%–70%) of the variability in the abundance of the pupae of the most generalist blackfly species, although further studies are needed to disentangle the sign of interspecific interactions. At the landscape level, S. (W.) equinum and S. (W.) pseudequinum Séguy, 1921 breeding habitats were associated with the presence of pig farms, and S. (Simulium) reptans (Linnaeus, 1758) and S. (B.) erythrocephalum with the presence of cattle.
... Finally, simuliid species with obligate hematophagy of biomedical and veterinary importance [27] such as S. erythrocephalum are generalist species regarding the type of habitat in which they develop, Therefore, these species are capable of tolerating a wide range of ecological conditions. Under this premise and given the current climate change scenario in which certain authors and institutions predict a decrease in coldwater river habitats and greater environmental variability [28], it would be expected that the resulting conditions would favor the distribution and colonization of S. erythrocephalum to new geographic areas, increasing its harm to the well-being of citizens. ...
... In this way, the knowledge of the bioecology of the species will play a crucial role when it comes to implementing treatment plans for preimaginal states, minimizing the sizes of their populations and reducing their incidences in public health. In the case of S. erythrocephalum, it is important to know that it is a species whose preimaginal development optimum is 20°C, tolerates values higher than 25°C, shows a narrow range of altitudinal tolerance with its optimum around 75 meters above sea level (masl), so that its distribution in the Valencian Autonomous Region is restricted to elevations between 5 and 240 masl [27]. Likewise, some authors ecologically described this species as preferring lentic and warm waters typical of the middle and lower sections of rivers [30]. ...
Health Risks of Simulium (Boophthora) erythrocephalum (De Geer, 1776) in the Valencian Autonomous Region, Eastern Spain
Article
Full-text available
  • Nov 2021
The presence and distribution of Simulium erythrocephalum (De Geer, 1776) in the Valencian Autonomous Region is analyzed, an arthropod of medical-sanitary importance due to the marked anthropophilic characteristics exhibited and the tendency to carry out massive attacks. The increasing incidence registered in certain areas as a consequence of their hematophagy, and the meager availability of epidemiological, fauna, bioecological, and distribution data, have led to this study. A field study of 137 samplings was carried out from 2013 to the present in the 14 hydrographic basins of the Valencian Autonomous Region. The study variables were the presence or absence of preimaginal states, environmental and physical-chemical parameters of the water, bite data from the Generalitat Valenciana, population density and incidence of bites by municipality, and geographic location of the population areas. A scarce and reduced presence of the aforementioned species is revealed in the study area. Risk maps of human populations near the detected breeding areas are provided, and the epidemiological interest is discussed due to its vector capacity to transmit pathogens that cause disease. The number of bites registered between 2015, 2016, 2017, and 2018 in the seven health departments involved is provided. The general trend toward an increase in the number of cases is observed year after year, where the highest peaks in the number of cases coincide with the months of June, July, and August, and eventually, September and October. Surveillance and control programs to minimize the problem in the Spanish health system are needed.
... Finally, simuliid species with obligate hematophagy of biomedical and veterinary importance [27] such as S. erythrocephalum are generalist species regarding the type of habitat in which they develop, Therefore, these species are capable of tolerating a wide range of ecological conditions. Under this premise and given the current climate change scenario in which certain authors and institutions predict a decrease in coldwater river habitats and greater environmental variability [28], it would be expected that the resulting conditions would favor the distribution and colonization of S. erythrocephalum to new geographic areas, increasing its harm to the well-being of citizens. ...
... In this way, the knowledge of the bioecology of the species will play a crucial role when it comes to implementing treatment plans for preimaginal states, minimizing the sizes of their populations and reducing their incidences in public health. In the case of S. erythrocephalum, it is important to know that it is a species whose preimaginal development optimum is 20°C, tolerates values higher than 25°C, shows a narrow range of altitudinal tolerance with its optimum around 75 meters above sea level (masl), so that its distribution in the Valencian Autonomous Region is restricted to elevations between 5 and 240 masl [27]. Likewise, some authors ecologically described this species as preferring lentic and warm waters typical of the middle and lower sections of rivers [30]. ...
Health Risks of Simulium (Boophthora) erythrocephalum (De Geer, 1776) in the Valencian Autonomous Region, Eastern Spain
Article
  • Nov 2021
... Finally, simuliid species with obligate hematophagy of biomedical and veterinary importance [27] such as S. erythrocephalum are generalist species regarding the type of habitat in which they develop, Therefore, these species are capable of tolerating a wide range of ecological conditions. Under this premise and given the current climate change scenario in which certain authors and institutions predict a decrease in coldwater river habitats and greater environmental variability [28], it would be expected that the resulting conditions would favor the distribution and colonization of S. erythrocephalum to new geographic areas, increasing its harm to the well-being of citizens. ...
... In this way, the knowledge of the bioecology of the species will play a crucial role when it comes to implementing treatment plans for preimaginal states, minimizing the sizes of their populations and reducing their incidences in public health. In the case of S. erythrocephalum, it is important to know that it is a species whose preimaginal development optimum is 20°C, tolerates values higher than 25°C, shows a narrow range of altitudinal tolerance with its optimum around 75 meters above sea level (masl), so that its distribution in the Valencian Autonomous Region is restricted to elevations between 5 and 240 masl [27]. Likewise, some authors ecologically described this species as preferring lentic and warm waters typical of the middle and lower sections of rivers [30]. ...
Health Risks of Simulium (Boophthora) erythrocephalum (De Geer, 1776) in the Valencian Autonomous Region, Eastern Spain
Article
  • Nov 2021
The presence and distribution of Simulium erythrocephalum (De Geer, 1776) in the Valencian Autonomous Region is analyzed, an arthropod of medical-sanitary importance due to the marked anthropophilic characteristics exhibited and the tendency to carry out massive attacks. The increasing incidence registered in certain areas as a consequence of their hematophagy, and the meager availability of epidemiological, fauna, bioecological, and distribution data, have led to this study. A field study of 137 samplings was carried out from 2013 to the present in the 14 hydrographic basins of the Valencian Autonomous Region. The study variables were the presence or absence of preimaginal states, environmental and physical-chemical parameters of the water, bite data from the Generalitat Valenciana, population density and incidence of bites by municipality, and geographic location of the population areas. A scarce and reduced presence of the aforementioned species is revealed in the study area. Risk maps of human populations near the detected breeding areas are provided, and the epidemiological interest is discussed due to its vector capacity to transmit pathogens that cause disease. The number of bites registered between 2015, 2016, 2017, and 2018 in the seven health departments involved is provided. The general trend toward an increase in the number of cases is observed year after year, where the highest peaks in the number of cases coincide with the months of June, July, and August, and eventually, September and October. Surveillance and control programs to minimize the problem in the Spanish health system are needed.
... Our results also illustrate the broad tolerance to water current velocity conditions of taxa such as S. rubzovianum and S. intermedium s.l. (Gallardo-Mayenco and Toja 2002;L opez-Peña et al. 2020), and provide evidence that S. angustitarse and S. trifasciatum are found across the widest ranges of current velocities. For those taxa, common in this study and that of L opez- Peña et al. (2020) in the Iberian Peninsula, for which more ecological information is available, the rank distribution regarding water velocity was quite similar (Spearman's r ¼ 0.636). ...
... (Gallardo-Mayenco and Toja 2002;L opez-Peña et al. 2020), and provide evidence that S. angustitarse and S. trifasciatum are found across the widest ranges of current velocities. For those taxa, common in this study and that of L opez- Peña et al. (2020) in the Iberian Peninsula, for which more ecological information is available, the rank distribution regarding water velocity was quite similar (Spearman's r ¼ 0.636). Simulium lineatum was found in higher occurrence at lower values of TDS (Figure 5b), while in L opez-Peña et al. (2020), this was found to be the case for S. carthusiense (unrecorded in the UK), while S. equinum showed the widest TDS range but in L opez-Peña et al. (2020), this was true (for turbidity) of S. bezzi (unrecorded in the UK). ...
Ecological characteristics of pre-imaginal stages of blackflies (Diptera: Simuliidae) in Southern England
Article
  • Sep 2021
Data on pre-imaginal stages of blackflies obtained in southern England during the summer and early autumn of 2020 were supplemented by additional surveys and analysed in relation to environmental factors. Fourteen taxa from 29 locations were recorded. Of these, seven are of medical and/or veterinary importance: Simulium (Wilhelmia) equinum (Linnaeus, 1758), S. (Boophthora) erythrocephalum (De Geer, 1776), S. (Simulium) intermedium Roubaud, 1906 sensu lato (s.l., a complex of species), S. (W.) lineatum (Meigen, 1804), S. (S.) morsitans Edwards, 1915, S. (S.) noelleri Friederichs, 1920 and S. (S.) ornatum (Meigen, 1818) s.l. Analyses of a variety of environmental factors recorded at the insects’ breeding sites showed that, by considering larvae and pupae together, the differences in the assemblages of blackfly species were explained by four variables: river depth, temperature, conductivity and elevation.
DNA barcoding of blackflies (Diptera: Simuliidae) as a tool for species identification and detection of hidden diversity in the eastern regions of Spain
Article
Full-text available
  • Aug 2018
Background: Blackflies have negative impact on public and animal health due to the haematophagous habit of females. In recent times, in some regions in Spain, blackfly outbreaks are becoming more and more frequent, threatening the public health. However, there is still a paucity of data concerning the Spanish blackfly fauna. Correct identification of species is of paramount importance in order to provide correct information on species distribution, biology and behaviour, so that control measures could be implemented appropriately. Methods: Blackflies specimens (larvae, pupae, reared adults and biting females) were collected in the period 2015-2017 in and near rivers and streams from different regions in Spain. A modified Hotshot technique was used for the DNA extraction and the cox1 DNA barcoding region of the cytochrome c oxidase subunit 1 was sequenced from the specimens collected. Results: In total, we collected 239 specimens representing 22 species. Of these, six species are new records for the Aragón region: P. tomosvaryi, S. bertrandi, S. galloprovinciale, S. lineatum, S. rubzovianum and S. xanthinum. Cox1 DNA barcode sequences for 21 species were recovered, including four species of the genus Prosimulium and 17 species of the genus Simulium [Boophthora (1 species), Eusimulium (1 species), Nevermannia (4 species), Simulium (s.s.) (6 species), Trichodagmia (1 species) and Wilhelmia (4 species)]. For the first time the complete DNA barcodes for five species (P. tomosvaryi, S. carthusiense, S. brevidens, S. monticola and S. sergenti) were registered. Most of the specimens belonging to the same recognized species were clustered together in the neighbour-joining tree, except for S. argyreatum, S. monticola and S. variegatum. The overall genetic distance in the dataset was 0.14%. The average of the intraspecific genetic divergence within the different taxa was 1.47% (0.05-3.96%). In contrast, the interspecific divergence varied between 2.50-22.0%. Conclusions: In this study we assessed the use of the cox1 DNA barcoding region for the identification of species of blackflies in Spain. Our results showed that combining DNA barcoding with morphology enhanced our taxonomic rationale in identifying the blackflies in the country.
Are there so many congeneric species of chironomid larvae in a small stream?
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  • Jun 2018
The co-occurrence of larvae of congeneric chironomid species is common in natural stream assemblages, and raises the problem of finding mechanisms to explain the co-existence of species with similar ecological requirements. In this contribution, we explored the co-occurrence of chironomid larvae belonging to congeneric species within four genera of chironomids: Cricotopus, Eukiefferiella, Orthocladius and Rheocricotopus (with 2, 7, 2 and 4 species, respectively) in the headwaters of a small Mediterranean calcareous stream. Due to the intrinsic, natural spatial and temporal variability in these habitats, we studied three different sites at two different seasons within the annual hydrological cycle (spring vs summer samples), and each microhabitat unit was surveyed with an effort proportional to its cover at the sampling site. The Outlying Median Index method was used to distinguish the niches of the different chironomid species in relation to the hydraulic features and substrates within each site. Our results showed that hydraulic features helped to improve discrimination between the niches of five congeneric species of Eukiefferiella, and the same occurred within the species belonging to Cricotopus and Orthocladius, although niche overlap was high in general. One Rheocricotopus species was associated to algal substrate. Schoener’s co-occurrence at the microhabitat scale was low among the congeneric species found in our study, suggesting exclusion mechanisms. Flow regime, substrate type and shifts in environmental conditions may favor the settlement of some species to the detriment of other congeneric ones, but other mechanisms such as lottery competition, diffusion competition or predation should be considered in further studies.
Updated checklist and distribution maps of blackflies (Diptera: Simuliidae) of Spain
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An updated checklist of the cited simuliids' species in Spain is presented, together with maps, which show the provincial distribution of each of the known species. The Simuliid Bulletin (previously, The British Simuliid Group Bulletin) ISSN 2397-5075 (Online) http://simuliid-bulletin.blogspot.co.uk/p/archive_30.html .
Contribución al conocimiento de las moscas negras (Diptera, Simuliidae) en la cuenca hidrográfica del Júcar
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Contribution to the knowledge of the black flies (Diptera, Simuliidae) in the Júcar River Basin. The present work aims to expand the knowledge of the fauna, distribution and biology of Diptera Simuliidae in the Júcar River (Valencia, Spain). Examining the material collected in the river as well as in 8 of its main tributaries: Albaida, Barcheta, Cabriel, Clariano, Magro, Mariana, Sellent and Verde, 16 species have been identified: Simulium angustipes, Simulium angustitarse, Simulium cryophilum, Simulium equinum, Simulium erythrocephalum, Simulium intermedium, Simulium lineatum, Simulium ornatum, Simulium petricolum, Simulium pseudequinum, Simulium quadrifila, Simulium reptans, Simulium sergenti, Simulium trifasciatum, Simulium velutinum y Simulium xanthinum. 14 of these species constitute new records from the province of Valencia and 10 from the Valencian Community.
Human-landing rate, gonotrophic cycle length, survivorship, and public health importance of Simulium erythrocephalum in Zaragoza, northeastern Spain
Article
Full-text available
  • Apr 2017
Background Simulium (Boophthora) erythrocephalum (De Geer, 1776) is one of the blackfly species responsible for major public health problems in Europe. Blackfly outbreaks of this species are becoming more frequent, threatening public health in Spain. In the present study, bionomic parameters of S. erythrocephalum in northeastern Spain were estimated. Methods Simulium erythrocephalum was collected from May through June 2015 in Zaragoza, Spain, using the human-landing-collection (HLC) method. Daily pattern of total and parous landing activity was estimated, as was the gonotrophic cycle (GC) length and survivorship (S) rate, using time series analysis. ResultsHost-seeking females of S. erythrocephalum showed a bimodal human-landing activity pattern, with a minor and major peak at dawn and dusk, respectively; there was a significant negative association between human daily landing rate and temperature (P = 0.003) and solar radiation (P < 0.001). Overall, a daily landing rate (DLR) of 34 lands/person/day was estimated. Series of sequential data analysis on parity showed the highest significant (P < 0.001) correlation indices (r = 0.45 and r = 0.39 for raw and filtered data) for a 2-day time lag, indicating that the GC length corresponded to 2 days. Daily survivorship and parity rate were 0.85 and 0.72, respectively. Conclusions Simulium erythrocephalum was confirmed as a nuisance species in Zaragoza, using the HLC method for the first time in Spain. The data offer insights into the ecology of S. erythrocephalum, which can improve management strategies of this pest in Spain.
Black flies (Diptera, Simuliidae) as ecological indicators of stream ecosystem health in an urbanizing area (Rome, Italy)
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  • Apr 2016
Introduction: The effectiveness of Simuliidae (Diptera, Nematocera) as indicators of stream health was tested in the urbanizing area of Rome, Central Italy. Methods: 108 sampling sites were investigated in the spring to acquire data on environmental variables and black fly species. Results and discussion: The comparison of sampling and literature data highlighted the disappearance of some species (Simulium reptans, S. vernum, S. liriense), possibly due to water pollution and land use changes. Correspondence analysis confirms altitude as the main factor influencing black fly species' distribution. However, water quality becomes predominant when considering exclusively plain sites: "ornatum" and "equinum" species groups show the greatest tolerance to chemical pollution. The high course of the Aniene river and its tributaries were sampled bimonthly, confirming the spatial-temporal black fly successions previously observed in central Apennines. The results also indicate that S. ornatum may supplant all other species in areas where the rural use is substituted by urban landscape. Conclusion: In conclusion, black flies can be considered good environmental indicators to assess ecological health of both watercourses and surrounding landscapes.
Distribution pattern of black fly (Diptera: Simuliidae) assemblages along an altitudinal gradient in Peninsular Malaysia
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Full-text available
  • Apr 2016
Background Preimaginal black flies (Diptera: Simuliidae) are important components of the stream ecosystem. However, there has been limited research undertaken on the vertical distribution of preimaginal black flies and their associated ecological factors. Stream conditions are generally variable along the altitudinal gradient. Therefore, we conducted an in-depth entomological survey to investigate the simuliid distribution pattern along an altitudinal gradient in Peninsular Malaysia. MethodsA total of 432 collections were performed in this study (24 samplings at each of 18 fixed-streams at monthly intervals) from February 2012 to January 2014. Larvae and pupae attached on aquatic substrates such as grasses, leaves and stems, twigs, plant roots and rocks were collected by hand using fine forceps. Stream depth (m), width (m), velocity (m/s), water temperature (°C), acidity (pH), conductivity (mS/cm) and dissolved oxygen (mg/L) were measured at the time of each collection. ResultsA total of 35 black fly species were recorded in the present study. The most frequently collected species were Simulium tani (31.7 %) and S. whartoni (21.5 %), while the relatively common species were Simulium sp. (nr. feuerborni) (16.2 %), S. decuplum (15.5 %), S. angulistylum (14.8 %), S. bishopi (13.2 %) and S. izuae (11.8 %). Total estimated species richness ranged between 39.8 and 41.3, which yielded more than 80 % of sampling efficiency. Six simuliid species were distributed below 500 m, whereas eight species were distributed above 1400 m. Simulium sp. (nr. feuerborni) and S. asakoae were found from middle to high altitudes (711–1813 m). Simulium whartoni, S. brevipar and S. bishopi were distributed widely from low to high altitudes (159–1813 m). Regression analysis between species richness and PCs revealed that the species richness was significantly associated with wider, deeper and faster streams at low altitude, normal water temperature (23–25 °C), low conductivity, higher discharge, more canopy cover and riparian vegetation and with larger streambed particles (F = 20.8, df = 1, 422, P < 0.001). Forward logistic regression indicated four species were significantly related to the stream variables (S. whartoni, Simulium sp. (nr. feuerborni), S. tani and S. angulistylum). Canonical correspondence analysis indicated that the temperature, stream size and discharge were the most important factors contributing to the separation of the stream sites from different altitude and hence are the predictors for the distribution of black fly species assemblages. Conclusions This study has provided insight into the distribution pattern of preimaginal black fly assemblages along an altitudinal gradient in Peninsular Malaysia. This study could deepen our knowledge on the ecology and biology of the specialised taxa in response to environmental changes.
Modelos de distribución de Plecópteros, efemeropteros, tricópteros y simúlidos en el rio Ter
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The influence of turbidity and water temperature on black fly species in the middle and lower Orange River, South Africa
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  • Jan 2018
Water clarity in the Orange River of South Africa alternates between highly turbid and clearer conditions. Multiple ecological effects result from this that affect aquatic community structure and species composition, including switching of dominant black fly species and growth of benthic algae. Fourteen sites in the middle and lower Orange River were sampled for black fly species and abundances, presence of benthic algae, and water quality and turbidity seasonally between November 2015 and December 2016. Logistic regression models, time series analyses, and multivariate ordinations showed that clearer water favours benthic algae and the minor pest black fly species Simulium adersi Pomeroy, 1922 and Simulium nigritarse Coquillett, 1902, while high turbidity favours the major pest black fly species Simulium chutteri Lewis, 1965 and Simulium damnosum Theobald, 1903. Moreover, these switches appear to be less frequent under post-impoundment conditions. We conclude that black fly species composition is dynamic and reflects changes in flow and turbidity levels. Flow regulation has resulted in a trade-off between improved water supply and ecological costs resulting from reduced ecosystem variability.
Aspects of the life history of Simulium chutteri and S. bovis (Diptera; Simuliidae) in relation to changing environmental conditions in South African rivers
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