Water pollution and distribution of the black fly (Diptera: Simuliidae) in the Atlantic Forest, Brazil / Contaminación del agua y distribución de la mosca negra (Díptera: Simuliidae) en el bosque Atlán&tico, Brasil

Abstract: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 Teresópolis, 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 rela&tion 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. inscrustatumand S. pertinaxwere significantly associated with intermediate values of most of the variables, and then to intermediate impacted sites. On the other hand, Lutzsimulium hirticosta, S. subnigrumand Simuliumsp. 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. hirticostaand Simuliumsp. A, while others may be good bioindicators of moderately impacted streams, such as S. pertinax, S. subnigrumand S. subpallidum.

Resumen:Aunque las moscas negras tienen importancia médica debido a que algunas de sus especies son vectores de la Oncocercosis y Mansonelosis, su ecología y su potencial como bioindicadores es aún poco estudiado en la Región Neotropical. En Brasil el uso de bioindicadores se centra principalmente en un índice ecológico multimétrico, en este estudio investigamos la distribución espacial de las moscas negras y su relación con los factores abióticos, para su utilización como indicadores de la integridad de los sis&temas lóticos. En este sentido, hemos probado la hipótesis de que los cambios ambientales relacionados con la urba&nización conducen a la disminución de la abundancia y la pérdida de especies de la mosca negra. El muestreo se llevó a cabo en la región montañosa del Estado de Río de Janei&ro, Brasil, en 10 zonas urbanas y 10 arroyos conservados durante la estación seca (agosto-septiembre) de 2012. Los arroyos se caracterizaron por sus condiciones de integridad del ambiente y las propiedades físico-químicas de agua. Las moscas negras se muestrearon en sustratos rocosos con un kick-net sampler.El material se separó y las larvas se ordenaron por morfotipos y más tarde los especímenes en último estadio se disectaron e identificaron con la ayuda de la literatura taxonómica a nivel de especie. Una abundancia total de 488 larvas de nueve especies fueron recolectadas, 5 (1.02 %) en arroyos muy afectados, 470 (96.31 %) en intermedios y 13 (2.66 %) en conservados. La evaluación visual (HII) difiere de la físico-química del agua, en la que se observó una mayor variación. En el Análisis Correspon&dencia Canónica, Simulium subpallidum, S. inscrustatumy S. pertinaxestaban asociadas significativamente con sitios de impacto intermedio, para la mayoría de las variables. Por otro lado, Lutzsimulium hirticosta, S. subnigrumy Simuliumsp. A se asocian con valores bajos de las varia&bles químicas, relacionado a sitios más conservados. La mayoría de los estudios sobre el potencial bioindicador de Simuliidae tienden a enfocarse en los impactos agrícolas, mientras que nuestros resultados, por otro lado, sugieren que las especies de Simuliidae están presentes en arroyos con impactos intermedios de contaminación urbana, pero ausentes en los sitios fuertemente afectados. Por lo tanto, nuestros datos sugieren que algunas especies tales como L. hirticostay Simuliumsp. A están asociadas a lugares de reproducción más prístinos, mientras que otras pueden ser bioindicadores de arroyos moderadamente afectados, como S. pertinax, S. subnigrumy S. subpallidum.

Description of microsporidia in simulids: molecular and morphological characterization of microsporidia in the larvae of Simulium pertinax Kollar (Diptera: Simuliidae)

Introduction Microsporidia constitute the most common black fly pathogens, although the species' diversity, seasonal occurrence and transmission mechanisms remain poorly understood. Infections by this agent are often chronic and non-lethal, but they can cause reduced fecundity and decreased longevity. The objective of this study was to identify microsporidia infecting Simulium (Chirostilbia) pertinax (Kollar, 1832) larvae from Caraguatatuba, State of São Paulo, Brazil, by molecular and morphological characterization. Methods Larvae were collected at a single point in a stream in a rural area of the city and were kept under artificial aeration until analysis. Polydispyrenia spp. infection was characterized by the presence of at least 32 mononuclear spores measuring 6.9 ± 1.0 × 5.0 ± 0.7µm in persistent sporophorous vesicles. Similarly, Amblyospora spp. were characterized by the presence of eight uninucleate spores measuring 4.5 × 3.5µm in sporophorous vesicles. Results The molecular analysis confirmed the presence of microsporidian DNA in the 8 samples (prevalence of 0.51%). Six samples (Brazilian larvae) were related to Polydispyrenia simulii and Caudospora palustris reference sequences but in separate clusters. One sample was clustered with Amblyospora spp. Edhazardia aedis was the positive control taxon. Conclusions Samples identified as Polydispyrenia spp. and Amblyospora spp. were grouped with P. simulii and Amblyospora spp., respectively, corroborating previous results. However, the 16S gene tree showed a considerable distance between the black fly-infecting Amblyospora spp. and the mosquito-infecting spp. This distance suggests that these two groups are not congeneric. Additional genomic region evaluation is necessary to obtain a coherent phylogeny for this group. .

Simulium (Chirostilbia) brunnescens (Diptera: Simuliidae) - new species from the Brazilian cerrado, Manso Dam, state of Mato Grosso, Brazil

A new species of Simuliidae, Simulium (Chirostilbia) brunnescens, was discovered at Chapada dos Guimarães, state of Mato Grosso, Brazil, and nearby municipalities (Paranatinga, Rosário do Oeste and Nobres). This species is described here based on the adults, pupae and larvae. This species is closely related to Simulium (C.) subpallidum Lutz, but could be differentiated in all stages: females, leg colour pattern and frontal dilatation size; males, gonostyle shape; pupae, number of gill filaments; larvae, body size and colour, postgenal cleft, ratio between antenna and stalk of labral fan.

Diversity and microdistribution of black fly (Diptera: Simuliidae) assemblages in the tropical savanna streams of the Brazilian cerrado

We describe the abiotic factors affecting the distribution of black flies at a microhabitat scale, rather than at the regional scale usually present in the literature on the Neotropics. Black fly larvae were sampled from the Tocantins River and three tributaries, located in the Brazilian savanna (state of Tocantins, Brazil) during six bi-monthly sampling periods from October 2004-August 2005. At each sampling site, 15 random quadrats (30 x 30 cm) were sampled each period and for each quadrat were determined mean water velocity, predominant substrate type (rocks, riffle litter or riparian vegetation) and depth detrended correspondence analysis (DCA) was used to determine associations with current velocity, whereas correspondence analysis (CA) was used to estimate site specific current velocity associations. Canonical correspondence analysis (CCA) was used to identify general microhabitat associations. The CCA showed that most species had a trend towards riffle litter, except for Simulium nigrimanum associated with rocky substrate and Simulium cuasiexiguum associated with riparian vegetation. The DCA showed a well defined pattern of water velocity associations. The CA revealed that the species showed different speed associations from one site to another, suggesting different competitive pressures resulting in the occurrence of different realized niches.

The phylogeny of Simulium (Chirostilbia) (Diptera: Simuliidae) and perspectives on the systematics of the genus in the Neotropical Region

Recently, knowledge of Neotropical Simuliidae has been accumulating quickly. However, information about supra-specific relationships is scarce and diagnoses of Simulium subgenera are unsatisfactory. To investigate the relationships among Simulium (Chirostilbia) species and test the subgenus monophyly, we performed a cladistic analysis. The ingroup included all species of this subgenus and the outgroup included representatives of the 17 species groups of Neotropical Simulium and three Holarctic species. The study was based on a data matrix with 31 terminal taxa and 45 morphological characteristics of adult, pupa and larva. The phylogenetic analysis under equal weights resulted in eight most-parsimonious trees (length = 178, consistency index = 34, retention index = 67). The monophyly of the S. (Chirostilbia) was not supported in our analysis. The Simulium subpallidum species group was closer to Simulium (Psilopelmia) and Simulium (Ectemnaspis) than to the Simulium pertinax species group. Additionally, we describe the three-dimensional shape of the terminalia of male and female of Simulium (Chirostilbia) for the first time and provide comments about the taxonomic problems involving some species of the subgenus: Simulium acarayense, Simulium papaveroi, S. pertinax, Simulium serranum, Simulium striginotum and S. subpallidum.

Simulium (Psilopelmia) virescens, a new black-fly species (Diptera: Simuliidae) from the southwestern region of the state of Bahia, Brazil

The last-instar larva, pupa, male and female of Simulium virescens sp. nov. are described and illustrated. This species has a peculiar larva, which has an elongated head capsule and light-green colour. The first thoracic segment has tubercle on its dorsal region and the third thoracic segment has one pair of tubercles; the first to the fourth abdominal segments have one pair of tubercles on each segment. Until now this new species had only been collected at the type locality, which is on the middle stretch of the Correntina River in the southwestern portion of the state of Bahia, Brazil. Females were voraciously biting humans during the field work. This new species represents the second species of Simulium(Psilopelmia) in Brazil and the first registered outside of the Brazilian Amazon Region.

Investigation of the occurrence of Mansonella ozzardi in the State of Rondônia, Western Amazonia, Brazil / Investigação da ocorrência da Mansonella ozzardi no Estado de Rondônia, Amazônia Ocidental

INTRODUCTION: Mansonella ozzardi, a human filarial nematode transmitted by Diptera Simuliidae flies (black flies), is widely spread in the Amazon, while the occurrence of mansonelliasis in the State of Rondônia (Western Amazonia) has not been reported thus far. The existence of this parasitic disease in this state is investigated in this study. METHODS: A total of 4,452 people who lived alongside the Madeira, Mamore, Guapore, Machado and Preto Rivers, in the State of Rondônia, were examined using the thick blood smear method. Alongside the Machado and Guapore rivers, 2,112 adult simuliid specimens were captured. RESULTS: Infected people were not reported, although simuliids with vector potential such as Cerqueirellum pydanielli, C. argentiscutum and C. amazonicum were found. CONCLUSIONS: This study registered no infected people. This finding may be explained by the individuals' low level of microfilaremia that is below the limit of detection of the diagnostic method used in the study or insufficient migration of people infected with M. ozzardi from endemic areas, making it impossible to introduce the disease into Rondônia. Further studies using more sensitive diagnostic techniques could shed light on this question.

INTRODUÇÃO: Mansonella ozzardi é uma filária humana que tem como vetor dípteros simulídeos e é amplamente distribuída na Amazônia. Não há informações sobre a ocorrência de casos de mansonelose no Estado de Rondônia, e neste trabalho procurou-se investigar a situação epidemiológica desta parasitose em áreas urbanas e ribeirinhas na Amazônia Ocidental. MÉTODOS: Foram examinados 4.452 moradores às margens dos rios Madeira, Mamoré, Guaporé, Machado e Preto em Rondônia, através da técnica da gota espessa de sangue. Capturou-se às margens do rio Machado e Guaporé 2.112 simulídeos adultos das espécies Cerqueirellum pydanieli e Chirostilbia pertinax. RESULTADOS: Não foram encontradas pessoas infectadas com M. ozzardi e foram encontradas diferentes espécies de simulídeos com potencial de transmissão da mansonelose. CONCLUSÕES: Não foram encontrados indivíduos infectados com M. ozzardi neste estudo. Este fato pode ser explicado pela existência de pacientes com baixas microfilaremias, associado à técnica diagnóstica de baixa sensibilidade utilizada no estudo. Pode-se ainda aventar a possibilidade de ter ocorrido migração insuficiente de pacientes infectados de áreas endêmicas, impossibilitando a implantação da endemia. Estudos posteriores com técnicas diagnósticas mais sensíveis podem ajudar a esclarecer esta questão.

Prevalence of Mansonella ozzardi among riverine communities in the municipality of Lábrea, State of Amazonas, Brazil / Prevalências de Mansonella ozzardi entre comunidades ribeirinhas do município de Lábrea, Estado do Amazonas

INTRODUCTION: Estimate the prevalence of Mansonella ozzardi infection and calculate the parasitic infection rate (PIR) in simuliid black flies in the municipality of Lábrea, State of Amazonas, Brazil. METHODS: Prevalence was measured using the thick blood smear method collected from the fingers and was related to age, sex and occupation. Simuliidae were collected with a suction apparatus, then stained with hematoxylin and dissected to verify the PIR. RESULTS: The average prevalence rate of M. ozzardi among the 694 individuals examined was 20.7 percent. Infection was higher in men (27.6 percent) than in women (14.3 percent) (p < 0.001) and occurred in most age groups, with the highest prevalence in the following age groups: 38-47 (40 percent), 48-57 (53.1 percent) and >58 (60.5 percent). The highest prevalence rates were observed in the retired (64 percent), followed by farm workers (47.1 percent). Infection by M. ozzardi was only identified in Cerqueirellum amazonicum (Simuliidae) with a PIR of 0.6 percent. CONCLUSIONS: This study showed a high prevalence of M. ozzardi in the riverine communities of Lábrea due to the lack of policies regarding the treatment of microfilaremic individuals in the region and an abundance of competent vectors for M. ozzardi.

INTRODUÇÃO: Estimar as prevalências de Mansonella ozzardi, e calcular a taxa de infecção parasitária nos simulídeos no município de Lábrea, Estado do Amazonas. MÉTODOS: As prevalências foram obtidas através do método de gota espessa a partir do sangue coletado da polpa digital e foram relacionadas com a idade, sexo e ocupação. Os simulídeos foram coletados com capturador de sucção, posteriormente foram corados com hematoxilina e dissecados para se obter a taxa de infecção parasitária. RESULTADOS: A prevalência de M. ozzardi entre as 694 pessoas examinadas foi de 20,7 por cento. A infecção foi maior nos homens (27,6 por cento) do que nas mulheres (14,3 por cento) (p < 0,001) e ocorreu na maioria das faixas etárias com maiores prevalências nos indivíduos entre 38-47 (40 por cento), 48-57 (53,1 por cento) e >58 (60,5 por cento) anos. As maiores prevalências foram observadas nos aposentados (64 por cento) e agricultores (47,1 por cento). Somente Cerqueirellum amazonicum (Simuliidae) foi encontrado infectado com M. ozzardi com uma taxa de infecção parasitária de 0,6 por cento. CONCLUSÕES: Este trabalho mostra elevadas prevalências de M. ozzardi nas comunidades ribeirinhas de Lábrea devido à ausência de políticas de tratamento dos microfilarêmicos na região e a abundância de vetores competentes.

Simulium (Inaequalium) marins, a new species of black fly (Diptera: Simuliidae) from inselbergs in Brazil

A new species of black fly, Simulium (Inaequalium) marins (Diptera: Simuliidae), is described based on the male, female, pupa and larva. This new species was collected from two localities: a small stream on the Pico dos Marins, a high mountain with granite outcrops in Piquete County, state of São Paulo, and in a small stream in the Serra dos Órgãos National Park, state of Rio de Janeiro, Brazil.

Species richness and distribution of blackflies (Diptera: Simuliidae) in the Chapada Diamantina region, Bahia, Brazil / Riqueza e distribuição de espécies de borrachudos (Diptera: Simuliidae) na região da Chapada Diamantina, BA

Taxonomically, blackflies (Simuliidae) are among the best-known aquatic insects in Brazil. However, information on their distribution is lacking for many regions. We sampled simuliids in 50 streams in the Chapada Diamantina region, State of Bahia, located in three distinct geographical areas, 20 at Lençóis, 18 at Mucugê, and 12 at Rio de Contas. We analyzed simuliid species richness and distribution in the Chapada Diamantina area as a whole, as well as in each of the three distinct geographical areas. We collected 20 species, three of which were not yet described and two were described after our sampling. The three areas are distinct in relation to environmental variables, mainly owing to differences in altitude and water pH. Four species were restricted to Rio de Contas, while four other species were restricted to Mucugê. Sixteen species were present in Mucugê and fifteen in Rio de Contas. Only twelve species were present in Lençóis, despite the higher sampling effort. Rio de Contas appears to be the area that harbors the highest species richness. Species richness was related to environmental factors only when evaluated on a small spatial scale (i.e. when each area was analyzed separately). Although we have not tested for causal relationships, our findings agree with other studies that showed that pH and altitude are important factors with which species richness and species distribution appear to be associated.

A família Simuliidae é taxonomicamente uma das mais conhecidas entre os insetos aquáticos no Brasil. No entanto, faltam informações relativas à sua distribuição em muitas regiões do Brasil. Foram coletadas larvas e pupas de borrachudos em 50 riachos na região da Chapada Diamantina, BA, localizados em três regiões geográficas distintas, 20 em Lençóis, 18 em Mucugê e 12 em Rio de Contas. Foram analisadas a riqueza e distribuição de espécies da área da Chapada Diamantina como um todo, bem como em cada uma das três áreas geográficas distintas. Coletamos 20 espécies, das quais três ainda não foram descritas e duas foram descritas após este estudo. As três áreas são distintas em relação às variáveis ambientais, principalmente devido às diferenças de altitude e pH da água. Quatro espécies foram coletadas apenas em Rio de Contas, enquanto outras quatro apenas em Mucugê. Dezesseis espécies foram encontradas em Mucugê e quinze em Rio de Contas, enquanto em Lençóis encontramos apenas doze espécies, mesmo com o maior esforço de amostragem exercido naquela região. Rio de Contas parece ser a região que abriga a maior riqueza de espécies. A riqueza de espécies foi relacionada a fatores ambientais apenas quando avaliada em pequena escala espacial (ou seja, quando cada área foi analisada separadamente). Apesar de não ter sido realizado um teste causal, os resultados aqui obtidos corroboram outros estudos que mostraram que o pH e altitude são fatores importantes com os quais a riqueza e a distribuição de borrachudos podem estar associadas.

New records of the black fly fauna (Diptera: Simuliidae) in two rivers of the western Amazonia, Brazil / Novos registros da simuliofauna (Diptera: Simuliidae) em dois rios da Amazônia Ocidental, Brasil

Our goal was to verify the presence and the composition of black floy species in the Antimari and Acre rivers, located in the end of Western Amazonia, where this entomological inquiry was accomplished. Along the Antimari and Acre rivers, 19 localities were studied and 133 larvae and 197 pupae were collected, totalizing 330 black floy immatures. The following species are recorded for the first time in this area: Simulium (Psaroniocompsa) amazonicum Goeldi, Simulium (Psaroniocompsa) oyapockense Floch & Abonnenc, Simulium (Psaroniocompsa) quadrifidum Lutz, Simulium (Psilopelmia) lutzianum Pinto, Simulium (Psilopelmia) perfloavum Roubaud and Simulium (Notolepria) exiguum Roubaud. Our data suggest that S. amazonicum, S. oyapockense and S. quadrifidum have a wide geographical distribution as well as population density.

O objetivo deste trabalho foi verificar a presença e composição de simulídeos nos rios Antimari e Acre, localizados no extremo oeste da Amazônia Ocidental. Foram levantados 19 pontos de coleta ao longo dos rios Antimari e Acre, onde foram coletadas 133 larvas e 197 pupas, totalizando 330 imaturos de simulídeos. As seguintes espécies foram encontradas pela primeira vez na região: Simulium (Psaroniocompsa) amazonicum Goeldi, Simulium (Psaroniocompsa) oyapockense Floch & Abonnenc, Simulium (Psaroniocompsa) quadrifidum Lutz, Simulium (Psilopelmia) lutzianum Pinto, Simulium (Psilopelmia) perfloavum Roubaud e Simulium (Notolepria) exiguum Roubaud. Os resultados sugerem que S. amazonicum, S. oyapockense e S. quadrifidum têm distribuição geográfica mais ampla e são mais frequentes nessa região.

Mansonella ozzardi in Brazil: prevalence of infection in riverine communities in the Purus region, in the state of Amazonas

This study was undertaken to investigate the prevalence of Mansonella ozzardi infection and to estimate the parasitic infection rate (PIR) in simuliid black flies in the municipality of Pauini, Amazonas, Brazil. We used thick blood films to examine 921 individuals in 35 riverine communities along the Pauini and Purus Rivers. Simuliids were caught in several communities. Flies were identified, stained with haematoxylin and dissected. Overall, 44 (24.86 percent) of 177 riverines were infected in communities on the Pauini River and 183 (24.19 percent) of 744 on the Purus. The prevalence was higher in men (31.81 percent and 29.82 percent) than in women (17.98 percent and 19.18 percent) and occurred in most age groups. The prevalence increased sharply in the 28-37 (50 percent and 42.68 percent) age group and increased in the older age classes. The highest prevalence was in farmers (44 percent and 52.17 percent, respectively) in the Pauini and Purus Rivers. Only Cerqueirellum amazonicum (Simuliidae) transmits M. ozzardi in this municipality, and we found a PIR of 0-8.43 percent and infectivity rate of 0-3.61 percent. These results confirm that rates of M. ozzardi infection are high in Pauini and suggest that its prevalence may be far greater than has been previously reported due to the absence of a program for treating the population.

Local distribution of blackfly (Diptera, Simuliidae) larvae in two adjacent streams: the role of water current velocity in the diversity of blackfly larvae / Distribuição local de larvas de simulídeos (Diptera, Simuliidae) em dois rios adjacentes: O papel da velocidade da correnteza na diversidade de larvas de simulídeos

This study aimed to evaluate the influence of water velocity speed on the local distribution and taxocenosis structure of blackfly larvae. The larvae were collected from two adjacent streams located in the municipality of Angra dos Reis (RJ): Caputera River and one of its tributaries. Riffle litter patches were sampled randomly using a 30 x 30 cm quadrat. Four blackfly species were found: Simulium incrustatum s. l. Lutz, 1910; Simulium (Inaequalium) sp. ; Simulium pertinax s. l. Kollar, 1832 and Simulium subpallidum s. l. Lutz, 1909. Among these species, Simulium pertinax s. l. was clearly associated with higher water current speeds, while Simulium subpallidum s. l. showed association with lower water velocities, and Simulium (Inaequalium) sp. had a relatively constant distribution along the water current gradient.

Este estudo teve como objetivo avaliar, nos criadouros de simulídeos, a influência da velocidade da água sobre a ocorrência de suas larvas e estrutura de suas taxocenoses. Para obtenção da amostragem foram utilizados "quadrats" de madeira distribuídos aleatoriamente no rio Caputera e um de seus tributários. Foram encontradas quatro espécies: Simulium incrustatum sl. Lutz, 1910; Simulium (Inaequalium) sp. ; Simulium pertinax sl. Kollar, 1832 e Simulium subpallidum sl. Lutz 1909. S. (Inaequalium) sp. teve uma distribuição quase constante ao longo do gradiente de correnteza. S. pertinax se mostrou fortemente associada às velocidades mais altas de correnteza, enquanto que S. subpallidum se mostrou associado às velocidades mais baixas.

Detection of Onchocerca volvulus (Nematoda: Onchocercidae) infection in vectors from Amazonian Brazil following mass Mectizan™ distribution

Detection of Onchocerca volvulus in Simulium populations is of primary importance in the assessment of the effectiveness of onchocerciasis control programs. In Brazil, the main focus of onchocerciasis is in the Amazon region, in a Yanomami reserve. The main onchocerciasis control strategy in Brazil is the semi-annually mass distribution of the microfilaricide ivermectin. In accordance with the control strategy for the disease, polymerase chain reaction (PCR) was applied in pools of simuliids from the area to detect the helminth infection in the vectors, as recommended by the Onchocerciasis Elimination Program for the Americas and the World Health Organization. Systematic sampling was performed monthly from September 1998 to October 1999, and a total of 4942 blackflies were collected from two sites (2576 from Balawaú and 2366 from Toototobi). The molecular methodology was found to be highly sensitive and specific for the detection of infected and/or infective blackflies in pools of 50 blackflies. The results from the material collected under field conditions showed that after the sixth cycle of distribution of ivermectin, the prevalence of infected blackflies with O. volvulus had decreased from 8.6 to 0.3 percent in Balawaú and from 4 to 0.1 percent in Toototobi.

Cytotaxonomy of Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz (Diptera: Simuliidae) in Brazilian Amazonia

Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz are widely distributed in the Amazon region and are morphologically similar at the larval and pupal stages. Chromosomally, these species are readily distinguished by the position of the nucleolar organizer, which is in the short arm of chromosome I in S. cauchense and in the long arm of chromosomes III in S. quadrifidum. They also differ by three fixed inversions. Sex chromosomes are undifferentiated in both species. Chromosomal resolution of the two species allowed us to evaluate four structural features previously used as diagnostic aids at the larval stage. Characters that distinguish larvae of the two species are the number of branches and branching patterns of the dorsal abdominal setae and the dark band on each primary fan. Branching patterns of the gill histoblasts were often diagnostic, with S. quadrifidum exhibiting more proximal branching and S. cauchense more distal branching. Sites where both species occurred sometimes had larvae with one petiole branching proximally and the other distally; in these cases examination of the chromosomes permitted assignment of the specimen to species. Pigmentation patterns of larvae, on the other hand, are highly variable. Color typically is sex linked in both species.

Black flies (Diptera: Simuliidae) of French Guiana: cytotaxonomy and a preliminary list of species

The objectives of the present study were to broaden the survey of simuliid species in French Guiana and to cytologically analyze the species in the Simulium perflavum species group. Twelve species of Simulium were collected from which S. goeldii, S. quadrifidum, S. trombetense, S. near incrustatum, S. metallicum (s.l.) sp1, S. metallicum (s.l.) sp2 and S. ochraceum (s.l.) are reported for the first time for this region. The only species collected in the S. perflavum group was S. rorotaense; 34 larvae of this species were cytologically analyzed, all of which had the standard sequence. S. metallicum (s.l.), S. ochraceum (s.l.), S. guianense (s.l.) and S. oyapockense (s.l.) are involved with transmission of onchocerciasis in Central and South America, however, in French Guiana these species were not found biting humans during the sampling period. With the few collections made during this study, we increase the number of simulid species known in French Guiana from 6 to 13. It is clear that more simuliid species can be expected to be found when more sampling is done, including collections in other ecoregions in French Guiana

Simulium cuasiexiguum, a new blackfly species (Diptera: Simuliidae) from the Minaçu area in the State of Goiás, Central Brazil

During studies of Simuliidae at a suspected new focus of human onchocerciasis in central Brazil a new species of Simulium was found. Full descriptions of the adults and pupae of this species, S. cuasiexiguum, are described here, its affinities to closely related species in the subgenus Notolepria are discussed and its distribution in Brazil recorded

Simulium (Psaroniocompsa) tergospinosum new species (Diptera: Simuliidae) in siolii group from the Southern part of the State of Amazonas, Brazil

The larva, pupa, male and female of Simulium tergospinosum n. sp. are described and illustrated. The adults of this new species share many characters with species in the subgenus Psaroniocompsa, where it is placed. The larva of this species bears dorsal and lateral triangular tubercles on the abdomen and multiply branched scale-like setae on the body, suggesting that it belongs to the S. siolii species group. S. tergospinosum n.sp. was collected along the Juma River, Apuí county, in the southern part of the State of Amazonas, Brazil. The Juma, a black-water river, is a tributary of the Aripuana River in the Madeira River hydrographic basin, on the southern part of Amazonas. Females were collected biting humans along the water courses during the sampling period (in the dry season)

Distribution of the larvae of blackflies (Diptera: Simuliidae) at Doi Inthanon National Park, northern Thailand.

The larvae of seventeen Simulium species consisting of thirteen known species, three unnamed species and one new species were distributed in various localities with different habitats at 400-2,460 meters above sea level in Doi Inthanon National Park, Chiang Mai Province, northern Thailand. Simulium caudisclerum, S. sp G and S. sp H were restricted to the high altitude of 2,460 m at the cool Ang Kha habitat of the summit of Doi Inthanon. On the other hand, S. nakhonense and S. rudnicki occurred only at low altitudes from 400 m-700 m. Some Simulium species such as S. fenestratum, S. asakoae, S. inthanonense and S. sp J were found in the warmer localities at 1,010 m-1,280 m altitudes. Moreover, S. feuerborni and S. rufibasis were widely distributed species at different altitudes from 700 m-2,460 m and 1,010 m-2,300 m respectively. Therefore, the distribution and abundance of Simulium species seem to correlate with altitudes as well as micro-habitat factors such as water temperature and water velocity.

Insecticide resistance in the Simulium damnosum S. L. vectors of human onchocerciasis: distributional, cytotaxonomic and genetical studies

Human onchocerciasis is a debilitating disease caused by the filarial parasite Onchocerca volvulus (Leukart). The parasite is transmitted by dipterous insects of the family Simuliidae. ln West Africa, transmission is by members of lhe Simulium damnosum (Theobald) species complex. The manifestations of the disease are mainly dermal, lymphatic and ocular, the most severe of which is blindness hence the common name 'river blindness'. The disease is found in parts of Latin America, the Yemen and Sub-Sahara Africa. lt affects some 17.7 million people world-wide with 500,000 severely visually disabled and some 27O,00O blind. ln West Af rica, which is the most affected area, there are over 5 million infected with onchocerciasis and about 148,000 blind. ln view of this, the Onchocerciasis Control Programme in West Africa (OCP), one of the biggest vector control operations covering parts of 11 countries was started in 1975 by the World Health Organization to control onchocerciasis as a disease of public health and socio-economic importance. The initial strategy of the OCP was the application of insecticides to the breeding sites of the insect vectors. ln the OCP, temephos an organophosphate insecticide (OP) was the only chemical used for the initial five years due to its selective mode of action. Resistance to temephos first appeared in 1980 in a population of S. soubrense/S.sanctipauli on the Bandama river in Southern Côte d'lvoire. Later, similar resistant populations of the same species were identified in other river basins in the C6te d'lvoire. ln 1981 Chlorphoxim, also an OP, was used as a replacement for temephos in areas where resistance to temephos had been detected but a similar pattern of resistance was soon detected against chlorphoxim Careful monitoring of resistance to temephos has shown that it has spread to all river basins and different species of the S. damnosum complex at one time or another within the OCP area. Resistance to insecticides demands that large quantities and more novel and toxic chemicals have to be used in the fight against insects and other arthropod pests. This has important economic, operational and environmental demands. ln the West African vector control programme mentioned above, a rotation of 6 insecticides is used to manage insecticide resistance. This strategy places a major constraint on the operations of the Programme (OCP) due to the logistic need of stocking insecticides in the field