Estudio biosistemático y ecológico de anopheles aquasalis (Diptera: Culicidae) y sus implicaciones para el control de la malaria en el estado Sucre: III-control biológico y manejo integrado / Study biosystematic and ecologic of anopheles aquasalis (diptera: culicidae) and it's implications for the control of the malaria in the Sucre state: III biologic control and integrated management

El principal objetivo del presente trabajo fue evaluar el impacto de la introducción de Bacillus thuringiensis israelensis (Bti) sobre las poblaciones larvarias de anopheles aquasalis Curry, principal vector de la malaria en el oriente de Venezuela. Para ello, se evaluaron tres formulaciones comerciales de Bti en diferentes tipos de criaderos de este vector. En condiciones de campo y aplicadas a la CL95, establecida previamente en el laboratorio,, Vectobac-G y Teknar tuvieron la misma efectividad contra Anopheles spp., en los criaderos totalmente exppuestos a la luz solar, con un bajo contenido de oxigeno disuelto y abundante vegetación emergente (Typhaceae y Cyperaceae). En criaderos con alta salinidad como el manglar, Teknar y Vectobac-AS fueron los más efectivos, produciendo una mortalidad mayor del 80 por ciento a los 8 días del tratamiento. La concentración de Teknar recomendada por el fabricante fue bastante efectiva para reducir la densidad larvaria durante 8 días; mientras que las concentraciones recomendadas para Vectobac-AS, solamente fueron efectivas durantre las primeras 48 horas post-tratamiento. El impacto de un proyecto piloto de control vectorial también fue evaluado en el estado Sucre (municipio Libertador). Usando la información de un estudio ecológico sobre An.aquasalis, se implementó un proyecto de control integrado basado en las aplicaciones espaciales de insecticidas alrededor de las casas y en el uso de larvicidas (Bti). Los resultados preliminares sugieren un significativo descenso en la densidad, la paridad y la expectativa de vida del vector, justamente a partir del inicio de esta nueva estrategia de control

Spatial and temporal distribution of anopheline larvae in two malarious areas in Sucre State, Venezuela

The spatial and temporal distribution of anopheline larvae was studied in two coastal malarious areas of Sucre, State, Venezuela. Seven habitat types were sampled in the village of Guayana and eight species of Anopheles were collected. Anopheles aquasalis was the predominant species collected and was most abundant in the brackish marsh habitat (71 larvae per 100 samples). It was most abundant during the rainy season. At the second location, Santa F e, six habitat types were sampled and four anopheline species were collected. Habitats where An. aquasalis was most abundant were temporary freshwater ponds (34 larvae per 100 samples) and mangroves (10.5 larvae per 100 samples). At this location it was also most abundant in the rainy season. During the dry season it was collected in small numbers in river pools (1.3 larvae per 100 samples) along with large numbers of An. pseudopunctipennis (479 larvae per 100 samples). Larval control could be an important component of the malaria control program because major habitats could be defined and presence and abundance of larvae was limited to specific times of year

Adult abundance, biting behavior and parity of Anopheles aquasalis, Curry 1932 in two malarious areas of Sucre State, Venezuela

The principal vector of malaria in eastern Venezuela, Anopheles aquasalis, is exophagic and exophilic. Control using indoor insecticide house sprays has failed to lower the number of malaria cases. Therefore, studies were initiated in two villages of the eastern coastal state of Sucre to better understand this vector's biology and develop a more integrated control program. An. aquasalis was found to have a crepuscular biting behavior with a major peak at dusk and a minor peak at dawn. Mosquitos were collected more outdoors than indoors. Forty-seven percent of the biting took place before people went to bed (22:30 hr) and 69 per cent of the mosquitos biting during this time period bite outdoors. Outdoor biting could be the reason why indoor spraying alone did not lower malaria cases. Seasonal abundance was greater in the rainy season compared to the dry season. Seasonal parous rates were high (78.3 per cent -100 per cent ) and similar indoors and outdoors and between dry and wet season in Santa F e. In Guayana, the seasonal parity was lower (34.6 per cent -42.2 per cent ) than Santa F e with indoor parity slightly higher than outdoors. Malaria cases were higher in Santa F e, but adult mosquito density was much lower than in Guayana. This difference could have been due to higher parity in Santa F e compared to Guayana. The greater distance to the nearest breeding site and presence of alternative hosts in Guayana can not be discounted as factors which contributed to the difference in malaria transmission between locations. We concluded that knowledge on seasonal occurrence, biting activity, resting behavior and breeding site location can be used to design a new control strategy for this vector