The interferon (IFN)-inducing capacity of different isolates of vesicular stomatitis virus (VSV) of the Indiana (IN) and New Jersey (NJ) serotypes were measured to assess the extent of variability of this phenotype. Over 200 preparations of wild-type field isolates, laboratory strains, and plaque-derived subpopulations were examined. Marked heterogeneity was found in the ability of these viruses to induce IFN, covering a 10,000-fold range. A good fit to a normal distribution for the log of the IFN yields suggests a continuum of incremental changes in the viral genome may govern the IFN-inducing capacity of consensus populations derived from independently arising infections. A broad range in the magnitude of these changes, skewed towards inducers of high IFN yields, is consistent with a comparable series of ribonucleotide changes in the VSV genome, a sine qua non of a quasispecies population. Plaque- or vesicle-derived populations displayed standard deviations less than the mean IFN yields, though skewed to higher yielders, whereas populations from field and laboratory samples which differed widely in time and origin of isolation gave standard deviations greater than the means. The plaque isolation of IFN-inducing particles of VSV-IN, normally masked in populations by the predominance of non-IFN-inducing particles that suppress IFN induction, and the isolation of potent wild-type IFN-inducing VSV-IN from cows during an outbreak of vesicular stomatitis in a region that had yielded only virus expressing the non-IFN-inducing phenotype in prior and subsequent years, supports the view that genetic bottlenecks are operative in the natural transmission of this disease.

Interferon Induction as a Quasispecies Marker of Vesicular Stomatitis Virus Populations

Although correct taxonomy is paramount for disease control programs and epidemiological studies, morphology-based taxonomy of black flies is extremely difficult. In the present study, the utility of a partial sequence of the COI gene, the DNA barcoding region, for the identification of species of black flies from Mesoamerica was assessed. A total of 32 morphospecies were analyzed, one belonging to the genus Gigantodax and 31 species to the genus Simulium and six of its subgenera (Aspathia, Eusimulium, Notolepria, Psaroniocompsa, Psilopelmia, Trichodagmia). The Neighbour Joining tree (NJ) derived from the DNA barcodes grouped most specimens according to species or species groups recognized by morphotaxonomic studies. Intraspecific sequence divergences within morphologically distinct species ranged from 0.07% to 1.65%, while higher divergences (2.05%-6.13%) in species complexes suggested the presence of cryptic diversity. The existence of well-defined groups within S. callidum (Dyar & Shannon), S. quadrivittatum Loew, and S. samboni Jennings revealed the likely inclusion of cryptic species within these taxa. In addition, the suspected presence of sibling species within S. paynei Vargas and S. tarsatum Macquart was supported. DNA barcodes also showed that specimens of species that are difficult to delimit morphologically such as S. callidum, S. pseudocallidum Diaz Najera, S. travisi Vargas, Vargas & Ramirez-Perez, relatives of the species complexes such as S. metallicum Bellardi s.l. (e.g., S. horacioi Okazawa & Onishi, S. jobbinsi Vargas, Martinez Palacios, Diaz Najera, and S. puigi Vargas, Martinez Palacios & Diaz Najera), and S. virgatum Coquillett complex (e.g., S. paynei and S. tarsatum) grouped together in the NJ analysis, suggesting they represent valid species. DNA barcoding combined with a sound morphotaxonomic framework provided an effective approach for the identification of medically important black flies species in Mesoamerica and for the discovery of hidden diversity within this group.

/pdf/dna-barcoding-of-neotropical-black-flies-diptera-simuliidae-4ih6wwi52t.pdf

DNA barcoding of Neotropical black flies (Diptera: Simuliidae): Species identification and discovery of cryptic diversity in Mesoamerica

Black flies have medical importance because some species are vectors of the Onchocerciasis and Mansonelosis, nevertheless, their ecology and potential use as bioindicators is still poorly studied in the Neotropical Region. In Brazil, bioindicators use is strongly focused in a multimetrical ecological index approach; this way, we investigated the black fly spatial distribution, in relation to abiotic factors correlated to water quality, to provide baseline information for their utilization as standalone indicators of lotic systems integrity. We have tested the hypothesis that environmental changes related to urbanization, lead to decreased abundance and loss in the number of species of the black fly fauna. The sampling was conducted in 10 urban and 10 preserved streams during the dry season (August-September) of 2012, in the mountainous region of Teresopolis, State of Rio de Janeiro, Brazil. The streams were characterized for their environmental integrity conditions and physico-chemical properties of water. In each stream, five different rapid points were sampled in a section of 50 meters, 10 meters apart from each other. The black flies were sampled with a kick-net sampler on rocky substrates. The material was separated and the larvae were sorted in morphotypes, and later, the final instar specimens were dissected and identified with the help of taxonomical literature at species level. A total abundance of 488 larvae from nine species were collected, 5 (1.02 %) in extremely impacted streams, 470 (96.31 %) in intermediate streams and 13 (2.66 %) in preserved streams. The visual evaluation (HII) differed in relation to the water physico-chemical evaluation, in which more variation in the characterization of the sampling sites was observed. In Canonical Correspondence Analysis Simulium subpallidum, S. inscrustatum and S. pertinax were significantly associated with intermediate values of most of the variables, and then to intermediate impacted sites. On the other hand, Lutzsimulium hirticosta, S. subnigrum and Simulium sp. A were associated to low values of chemical variables, and then to more preserved sites. Most studies on the bioindicator potential of Simuliidae have suggested an approach to agricultural impacts, while our results, on the other hand, showed that Simuliidae species were present in streams with intermediate urban pollution impacts, but absent in heavily impacted sites. Thus, our data suggested that some species are associated to more pristine breeding sites, such as L. hirticosta and Simulium sp. A, while others may be good bioindicators of moderately impacted streams, such as S. pertinax, S. subnigrum and S. subpallidum.

/pdf/water-pollution-and-distribution-of-the-black-fly-diptera-4pzshcaldf.pdf

Water pollution and distribution of the black fly (Diptera: Simuliidae) in the Atlantic Forest, Brazil

Background 
The abundance of onchocerciasis vectors affects the epidemiology of disease in Sudan, therefore, studies of vector dynamics are crucial for onchocerciasis control/elimination programs. This study aims to compare the relative abundance, monthly biting-rates (MBR) and hourly-based distribution of onchocerciasis vectors in Abu-Hamed and Galabat foci. These seasonally-based factors can be used to structure vector control efforts to reduce fly-biting rates as a component of onchocerciasis elimination programs.


Methods 
A cross-sectional study was conducted in four endemic villages in Abu-Hamed and Galabat foci during two non-consecutive years (2007–2008 and 2009–2010). Both adults and aquatic stages of the potential onchocerciasis vector Simulium damnosum sensu lato were collected following standard procedures during wet and dry seasons. Adult flies were collected using human landing capture for 5 days/month. The data was recorded on handheld data collection sheets to calculate the relative abundance, MBR, and hourly-based distribution associated with climatic factors. The data analysis was carried out using ANOVA and Spearman rank correlation tests.


Results 
Data on vector surveillance revealed higher relative abundance of S. damnosum s.l. in Abu- Hamed (39,934 flies) than Galabat (8,202 flies). In Abu-Hamed, vector populations increased in January-April then declined in June-July until they disappeared in August-October. Highest black fly density and MBR were found in March 2007 (N = 9,444, MBR = 58,552.8 bites/person/month), and March 2010 (N = 2,603, MBR = 16,138.6 bites/person/month) while none of flies were collected in August-October (MBR = 0 bites/person/month). In Galabat, vectors increased in September-December, then decreased in February-June. The highest vector density and MBR were recorded in September 2007 (N = 1,138, MBR = 6,828 bites/person/month) and September 2010 (N = 1,163, MBR = 6,978 bites/person/month), whereas, none appeared in collection from April to June. There was a significant difference in mean monthly density of S. damnosum s.l. across the two foci in 2007–2008 (df = 3, F = 3.91, P = 0.011). Minimum temperature showed significant correlation with adult flies counts in four areas sampled; the adult counts were increased in Nady village (rs = 0.799) and were decreased in Kalasecal (rs = - 0.676), Gumaiza (rs = - 0.585), and Hilat Khateir (rs = - 0.496). Maximum temperature showed positive correlation with black fly counts only in Galabat focus. Precipitation was significantly correlated with adult flies counts in Nady village, Abu-Hamed, but no significance was found in the rest of the sampled villages in both foci. Hourly-based distribution of black flies showed a unimodal pattern in Abu-Hamed with one peak (10:00–18:00), while a bimodal pattern with two peaks (07:00–10:00) and (14:00–18:00) was exhibited in Galabat.


Conclusion 
Transmission of onchocerciasis in both foci showed marked differences in seasonality, which may be attributed to ecology, microclimate and proximity of breeding sites to collection sites. The seasonal shifts between the two foci might be related to variations in climate zones. This information on black fly vector seasonality, ecology, distribution and biting activity has obvious implications in monitoring transmission levels to guide the national and regional onchocerciasis elimination programs in Sudan.

/pdf/seasonal-variation-in-biting-rates-of-simulium-damnosum-3cy9cnkkt4.pdf

Seasonal Variation in Biting Rates of Simulium damnosum sensu lato, Vector of Onchocerca volvulus, in Two Sudanese Foci.

Costa Rica hosts an extraordinarily high biodiversity and is among the best studied neotropical countries. Insects represent the most diverse group of organisms, not only in terrestrial but also in aquatic, especially freshwater, habitats. Among the most diverse aquatic insect orders are the Trichoptera, Diptera and Coleoptera; although Ephemeroptera can locally also be very abundant and diverse. In Costa Rica, the taxonomically best known orders of aquatic insects are the caddisflies (Trichoptera), dragonflies (Odonata) and stoneflies (Plecoptera) and within the Dipterans, groups of medical importance have received special attention. The interest in aquatic insects has been constantly growing in Costa Rica over the past 10 years, but scientific publications are widely dispersed and often difficult to locate. Due to the importance of aquatic organisms in environmental impact studies and biomonitoring of freshwater habitats, there is an urgent need for comprehensive studies and publications that are locally available. In this sense, the present paper tries to give an overview on the state of knowledge and the literature published to date on the aquatic insects of Costa Rica, taking in account taxonomic, biological and ecological studies. Rev. Biol. Trop. 56 (Suppl. 4): 273-295. Epub 2009 June 30.

Aquatic insect diversity of Costa Rica: state of knowledge

In the Western Hemisphere there are listed 61 species of black flies which are recorded as biting man in the Neotropical Region and 37 in the Nearctic Region. Five neotropical species, Simulium quadrivittatum, S. metallicum, S. callidum, S. baematopotum and S. paynei, were collected while biting rates in Costa Rica. The greatest biting rates in Costa Rica were at altitudes of 0 to 1500 m.

https://revista-ciencia-tecnologia.ucr.ac.cr/index.php/rbt/article/download/26090/26363

Bionomics of black flies (Diptera: simuliidae) in Costa Rica. I. Species biting man, with an epidemiological summary for the Western Hemisphere

Studies on black fly larval populations in five streams in the Central Valley of Costa Rica during July 1968 to July 1969 indicated that a single observation on a stream would not necessarily evaluate its relative importance as a black fly producer and that more than one sampling is needed to obtain reliable and representative data.Among the subgenera studied (Hemicnetha, Psilopelmia and Simulium) information on larval size, maturity and population levels established that hatching of larvae continued during both dry and rainy seasons. Although the population levels dropped during the dry sea son in three of the five study streams, there was no consistent seasonal influence on larval populations and the differences observed were greater between streams than between seasons.

https://revista-ciencia-tecnologia.ucr.ac.cr/index.php/rbt/article/download/25703/26078

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. III. Larval population dynamics in five selected streams

Se estudio las poblaciones de simulidos en 100 corrientes de Costa Rica por un periodo de dos anos. En los ejemplares colectados en el campo se encontro larvas y pupas del subgenero Hearlea . La comparacion de material disponible de Hearlea de Canada, Mexico, Guatemala y Panama con el de Costa Rica permitio clasificar el costarricense como Simulium (H.) chiriquiense Field, 1967. Este constituye el primer informe de la presencia, ecologia y distribucion de este subgenero y especie en Costa Rica.

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. VII. Genus Simulium subgenus Hearlea.

Observation on 100 streams in Costa Rica over a two-year period indicated no strong correlations of either larval populations al biting adults with such stream factors as substrate, tcmperaturc, altitudc. water speed and turbulence, pollution of shade. Small differences and sorne reversals in the datasuggest only trends.

B. V. Travis

Papers

Bionomics of black flies (Diptera: simuliidae) in Costa Rica. I. Species biting man, with an epidemiological summary for the Western Hemisphere

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. III. Larval population dynamics in five selected streams

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. VII. Genus Simulium subgenus Hearlea.

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. VI. Correlations with ecological factors.