Metagenomics, paratransgenesis and the Anopheles microbiome: a portrait of the geographical distribution of the anopheline microbiota based on a meta-analysis of reported taxa

Anophelines harbour a diverse microbial consortium that may represent an extended gene pool for the host. The proposed effects of the insect microbiota span physiological, metabolic and immune processes. Here we synthesise how current metagenomic tools combined with classical culture-dependent techniques provide new insights in the elucidation of the role of the Anopheles-associated microbiota. Many proposed malaria control strategies have been based upon the immunomodulating effects that the bacterial components of the microbiota appear to exert and their ability to express anti-Plasmodium peptides. The number of identified bacterial taxa has increased in the current “omics” era and the available data are mostly scattered or in “tables” that are difficult to exploit. Published microbiota reports for multiple anopheline species were compiled in an Excel® spreadsheet. We then filtered the microbiota data using a continent-oriented criterion and generated a visual correlation showing the exclusive and shared bacterial genera among four continents. The data suggested the existence of a core group of bacteria associated in a stable manner with their anopheline hosts. However, the lack of data from Neotropical vectors may reduce the possibility of defining the core microbiota and understanding the mosquito-bacteria interactive consortium.

Seasonal prevalence & resting behaviour of Anopheles minimus Theobald & An. fluviatilis James (Diptera: Culicidae) in east-central India.

Background & objectives: Anopheles minimus has recently been reported to have re-appeared in Keonjhar district of Orissa after a period of about 45 years of launching the malaria eradication programme. An. minimus and An. fluviatilis were the incriminated major malaria vectors in the district, endemic for falciparum malaria. The information on seasonal prevalence and resting behaviour of the vectors is crucial for implementing appropriate malaria control measures. Therefore, a study was undertaken on seasonal prevalence and resting behaviour of An. minimus and An. fluviatilis in this district. Methods: Seven randomly selected villages of Keonjhar district, Orissa, were studied during August 2005 to November 2007. Daytime resting collections indoors and outdoors were made covering three seasons of the year. The Anopheles mosquitoes obtained from different habitats were identified. Collections were maintained separately according to different sites as well as heights of the walls in human dwellings. Results: Among the indoor collections, the densities of An. minimus and An. fluviatilis were higher in human dwellings than cattle sheds. An. fluviatilis was the predominant (41.5%) species followed by An. minimus (26.3%) in human dwellings. The density of both the vector species in human dwellings peaked during rainy and winter seasons followed by summer. Walls were the most preferred site by these vectors for resting and the maximum number was collected at a height of 3 to 4 ft. Interpretation & conclusions: The resting behaviour of the vector species increases their contact with the sprayed walls and therefore, a quality residual spraying of human dwellings focusing indoor walls could interrupt the malaria transmission in this area.

Studies on mosquito borne dieases in Egypt and Qatar

Mosquitoes identification, distribution and densities in representative Egyptian Governorates and five Qatarain Municipalities [Al Rayyan, Doha, Al Daayan, Al Khor and Al Zahakira and Al Shamal] were studied. In Qatar the larvae were Culex pipiens complex, C. univettatus, C. pusillus, Aedes caspies, Anopheles multicolor and A. stephensi. C. pipiens and C. univettatus were mainly in Al Rayyan, Doha, and Al Khor and Al Zahakira. C. pusillus was in Doha and Al Daayan while A. caspies was in Al Daayan and Al Shamal. Anopheles multicolor and A. stephensi were mainly in Al Shamal with low density in Al Rayyan [only in Ain- Khalid locution]. The Egyptian mosquitoes were C. pipiens, C. antennatus, C. thelerei, C. univittatus, C. perexiguus, C. poicilipes, C. pusillus, Aedes caspius, Ae. detritus, A. sergentii, A. pharoensis, A. multicolor, A. detail, A. algeriensis, A. tene-brosus, A. gambiae [formerly], A. superpictus, A. tarkhadi, A. hispaniola, A. rhodesiensis, A. stephensi, A. coustani and Culiseta longiareolata. As an example in Sharkia Governorate, larvae were C. pipiens [68.77%], Ae. caspius [15.75%], Culiseta sp. [=Theobaldia] and C. pusillus. In Greater Cairo, parts of Qualyoubia G., C. pipiens was the most dominant and the least was C. perexiguus. In parts of Giza G., C. pipiens was the most dominant and least was Cs. longiareolata. In Cairo G., C. pipiens was the most dominant and least was Ae. caspius. The overall in Greater Cairo was C. pipiens [61.74%], Cs. longiareolata [15.56%], Ae. caspius [15.3%], C. pusillus [4.0%] and C. perexiguus [3.16%]

Effect of entomopathogenic fungus, Beauveria bassiana on larvae of three species of mosquitoes.

Beauveria bassiana, an entomopathogenic fungus, was evaluated for its potential against second and third instar larvae of Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. Conidiospores of this fungus were effective in causing infection leading to mortality of different larval instars. Larvae of Cx. quinquefasciatus were more susceptible to infection than An. stephensi and the second instar larvae of these two species were more susceptible than third instar larvae. Larvae of Ae. aegypti were resistant to infection by B. bassiana.

Biological control of malaria vectors.

A comprehensive review is presented of the potentiality of biocontrol agents viz. entomophagus bacteria (Bacillus thuringiensis var. israelensis and Bacillus sphaericus), fungi, microsporidians, predators and parasites against malaria vectors in the field condition. Unlike insecticides, these control agents are host specific and safer to the environment. However, barring fishes which are being used in certain situations, other biocontrol agents have not yet reached the operational stage. Two spore forming bacteria B. thuringiensis var. israelensis and B. sphaericus have been extensively tested against malaria vectors in the field. Though they are effective in suppressing anopheline larval population, their recycling capacity and availability of toxin hearing spores on the water surface are limited. Therefore, there is a need for developing improved formulations through bio-engineering techniques for enhancing their residual activity and availability of spores for anopheline larvae which feed mostly on the water surface. The biocontrol potentiality of other agents in the field condition is yet to be explored fully. The use of biocontrol agents for malaria control also poses certain operational constraints in view of the vastness of the anopheline breeding habitats and less acceptance for their use in domestic environments. However, there is a scope for using these biocontrol agents in conjunction with other control methods in integrated control programmes.

Dengue in Gujarat state, India during 1988 & 1989.

Following the reports of epidemics of febrile illness from several rural and urban areas of Gujarat state (India) in 1988, epidemiological investigations were carried out and dengue (DEN) virus activity was demonstrated in large cities such as Surat and Rajkot as well as several villages in Sabarkantha district. Two strains of dengue type-2 each were isolated from human sera from Surat city and a village in Sabarkantha district. Six strains of dengue virus were isolated from Aedes aegypti mosquitoes collected at Chotasan village, two of which were confirmed as DEN type-2. Of the 560 patients' sera tested from different areas (including villages and townships), 122 showed evidence of dengue infection and another 236 showed a broader reaction with flaviviruses. Entomological investigations showed a widespread distribution of Ae. aegypti both in urban and rural areas. In the household conditions this mosquito was found to breed predominantly in containers with non-potable water. Amongst these, cement containers manufactured in towns and distributed to the villages seem to play an important role in the spread of this species. In non-residential areas prolific breeding of Ae. aegypti was observed in automobile tyre dumps, and varied types of scrap, in towns and villages. Distribution and relative prevalence of the species were studied in 46 towns and villages, covering the spectrum of rural-urban-continuum. These studies provide an indication regarding the mechanism of the spread of DEN virus through peoples' movement, transport, the process of urbanisation etc.

Seasonal abundance of dengue vectors in Manila, Republic of the Philippines.

The dengue vectors Aedes aegypti and Ae. albopictus were surveyed within the city of Manila from August 1985 to July 1987. Survey techniques included ovitraps, indoor resting collections, Fay traps, and larval surveys. Aedes aegypti was the principal container breeder within the residential areas, while Ae. albopictus predominated in cemeteries. The ovitrap was very effective in detecting the presence of Ae. aegypti, but not in measuring population changes during the year. Indoor resting and Fay traps show a low population of Ae. aegypti from February through May, during the dry season, and higher populations from June through September, during the rainy season. The most common indoor containers holding larvae were flower vases, while metal or glass containers were the most common outdoors. Dengue transmission appears to be closely related to rainfall, with cases increasing about 2 months following the onset of the rainy season.

Ecology of mosquitos (Diptera: Culicidae) at a site endemic with Japanese encephalitis on Luzon, Republic of the Philippines.

A 2-year study of the ecology of mosquitos was conducted in a rice-growing area in the Philippines. Forty-four species in 8 genera were collected using 6 techniques, with Culex vishnui being most abundant. Of all the Anopheles collected, most species were exophagic, while most of the Culex species collected were endophagic. Anthropophilic or zoophilic feeding patterns were estimated using man-to-animal biting ratios. Peak periods of mosquito abundance occurred several months after the onset of both the rainy season and the rice irrigation period. Seasonal populations of the more abundant species revealed 3 distinct patterns: 1) populations are high during the rainy season and low during the irrigation period; 2) populations are equally strong during both periods; and 3) populations are highest during the irrigation period. Species' biting activity was grouped into 2 patterns: 1) those that feed primarily from 1800-0000; and 2) those that feed evenly throughout the night. Mosquito abundance and Japanese encephalitis virus activity were related to rainfall and rice-growing practices.

Caracterizaçäo e relacionamento antigênico de três novos Bunyavirus no grupo Anopheles A (Bunyaviridae) dos arbovirus / Characterization and antigenic relationship of three new Bunyavirus in the Anopheles A serogroup (Bunyaviridae) of arboviruses

Säo descritos o isolamento e a caracterizaçäo de três novos arbovirus isolados na regiäo da Usina Hidro-Elétrica de Tucuruí (UHE-TUC). Os três novos arbovirus pertencem ao grupo Anopheles A(ANA), genêro Bunyavirus (família Bunyaviridae). Os vírus Tucuruí (TUC), Caraipí (CPE) e Arumatena (ART) säo relacionados entre si e com o vírus Trombetas (TBT), formando dentro do grupo ANA um complexo chamado Trombetas. Os arbovirus TUC, CPE, e ART foram obtidos a partir de lotes de mosquitos Anopheles (Nyssorhynchus) sp capturados em Tucuruí, nas proximidades da usina hidrelétrica de Tucuruí, Estado do Pará, nos meses de fevereiro, agosto e outubro de 1984, respectivamente. Até o final de 1990 os vírus TUC, CPE e ART foram isolados 12, 32 e 28 vezes respectivamente, sempre na regiäo da UHE-TUC, exceçäo feita ao vírus TUC, do qual se obteve uma amostra procedente de Balbina, onde também foi contruída uma hidroelétrica. Até o presente, esses vírus só foram isolados a partir de mosquitos do grupo An. (Nys) principalmente, a partir de espécies An. (Nys) nuneztovari e An. (Nys) triannulatus também consideradas vetores secundários da malária na Amazônia Brasileira. Testes sorológicos executados com soros humanos e de diversas espécies de animais silvestres foram negativos, com execeçäo de um soro de um carnívoro de espécie Nasua nasua que neutralizou a amostra TUC em títulos de 2.6 índice logarítmico de neutralizaçäo (ILN)

Biologia de anofelinos. XI. Estudos em populaçöes de anopheles e controle da malária em Ariquemes (Rondônia)

Säo apresentados dados sobre inquérito entomológico para espécies de Anopheles realizado no Município de Ariquemes e discutida a incidência da malária neste Município e no Estado de Rondônia. Os resultados do inquérito entomológico na zona urbana de Ariquemes evidenciaram a diversidade de espécies nos diferentes Setores, possibilitando verificar o grau de penetraçäo dos anofelinos na cidade. Säo correlacionados casos autóctones de malária e a presença do principal vetor da malária humana na Amazônia, o Anopheles darlingi. A dinâmica da transmissäo da malária na zona urbana é enfocada, discutindo-se os riscos verificados para cada Setor e säo apresentadas estratégias de controle, ao nível do vetor, fundamentadas no manuseio do habitat. Na zona rural estäo sendo estudados parâmetros populacionais realcionados (1) `a atividade de picar, abrigo natural, sítios de reproduçäo e deslocamento para hematofagia; e (2) comportamento das populaçöes para atividade hematófoga e preferências alimentares. Os resultados, embora preliminares, evidenciam variaçöes na densidade populacional e na diversidade de espécies, as quais devem estar relacionadas `a mudanças estacionais. Variaçöes nas preferências alimentares das espécies também foram verificadas, sendo constatada elevada antropofilia de A. darlingi. Dois parâmetros relevantes na atividade hematófaga de A. darlingi foram detectados, observando-se que os anofelinos estäo penetrando nas habitaçöes pelas partes inferiores e que näo estäo pousando nas paredes com DDT. Na vegetaçäo circundante `as habitaçöes, está havendo preferência para locais de pouso, que podem ser alternativamente alto e baixo

Comparative bioassays of Tolypocladium cylindrosporum Gams (Californian strain) against four species of mosquitoes in Malaysia.

Comparative laboratory bioassays of Tolypocladium cylindrosporum, California strain (Kal) was conducted against third instar larvae of four species of mosquito, viz. Aedes aegypti, Anopheles balabacensis, Culex quinquefasciatus and Mansonia uniformis in Malaysia. Of the four mosquito species tested, Ma. uniformis was found to be the most susceptible, followed by Cx. quinquefasciatus, An. balabacensis and Ae. aegypti, in a decreasing order. The LC50 values for Ma. uniformis, Cx. quinquefasciatus, An. balabacensis and Ae. aegypti after four days of exposure were 1.18 X 10(4), 2.02 X 10(5), 4.76 X 10(5) and 1.84 X 10(7) spores per ml test media, respectively. The high sensitivity of Ma. uniformis and its longer life cycle seems to indicate that T. cylindrosporum Kal has good potential as a biocontrol agent for this species of mosquito. But, for Ae. aegypti, this fungus appears to be less effective.

Mosquito fauna of the Bengkoka Peninsula, Sabah, Malaysia.

A total of 37 species of mosquitoes from seven genera were collected in six villages in the Bengkoka Peninsula, Sabah State, during two visits in 1981 in connection with studies on malaria and filariasis. Fifty-five per cent of the total mosquitoes collected were Mansonia. An. collessi constituted a new record of the species from Sabah. An. balabacensis was found to be naturally infected with sporozoites. Ma. bonneae was found to be naturally infected with Brugia, probably B. malayi. Parous rates of An. balabacensis and Ma. bonneae were very high with consequent high probability of survival ideally suiting transmission of malaria and filariasis.

Anofelinos de Cordoba (Buenaventura, Colombia) / Anophelines from Cordoba (Buenaventura, Colombia)

En Cordoba, corregimiento de Buenaventura (Valle), en la region de la Costa del Pacifico, donde hay un foco de malaria endemica, se estudiaron los mosquitos para conocer los anofelinos presentes y su papel en la transmision de la enfermedad. Las investigaciones se efectuaron mediante capturas con cebo humano, tanto dentro de los domicilios como en el peridomicilio. Tambien se hicieron capturas con cebo animal en una trampa-establo. Se encontraron 6 generos de mosquitos, ademas de Anopheles. De estos se reconocieron 9 especies y de ellas 4 (A. evansi, A. oswaldoi, A. rangeli y A. atrodei) constituyen nuevos registros para el Valle del Cauca. A. nuneztovari fue el mas abundante (48.0%) en las capturas con cebo humano, mientras A. apicimacula tuvo el primer lugar (98.3%) entre los que se capturaron en la trampa-establo. Se discuten e ilustran las variaciones en la densidad de poblacion para los anofelinos obtenidos con mayor frecuencia. No se pudo comprobar cuales especies transmiten la malaria en Cordoba, pues las disecciones de estomagos y glandulas salivales de casi 200 anofelinos capturados con cebo humano fueron negativas

Additional isolations of Japanese encephalitis virus from the Philippines.

Japanese encephalitis virus was isolated from Culex tritaeniorhynchus, Culex bitaenorhynchus and Anopheles annularis mosquitoes collected from San Jose, Nueva Ecija, South Central Luzon in the Philippines. This is the second report of the isolation of the virus from mosquitoes in the Philippine Islands.