RESUMEN
The presence of pathogens or predators in water may alter oviposition behaviour of gravid female Aedes aegypti mosquitoes. We evaluated the oviposition behaviour of A. aegypti in recipients containing larvivorous fish (Betta splendens and Poecilia reticulata). In four breeders, fish specimens were placed in 15 l of dechlorined water. Four control breeders only contained dechlorined water. Breeders with eucatex ovitraps and approximately 100 male and female mosquitoes were placed in wire netting cages. During a period of 7 weeks, eggs on the ovitraps were counted weekly. The median number of eggs laid in recipients with B. splendens (32.5/week) was lower than in those with P. reticulata (200.5/week) and the control group (186.5/week; P < 0.0001). The oviposition activity index (OAI) for P. reticulata did not show any considerable difference between posture in deposits with and without fish (-0005). Deposits with B. splendens showed a lower position than those used as controls (-0627). We conclude that B. splendens can be used to effectively prevent gravid A. aegypti females from laying eggs in large water containers.
Asunto(s)
Aedes/anatomía & histología , Peces , Insectos Vectores , Oviposición , Control Biológico de Vectores/métodos , Animales , Dengue/prevención & control , FemeninoRESUMEN
Canindé apresenta uma população de 71.235 habitantes. Em abril de 2001 iniciou a utilização de peixes larvófagos em tanques de cimento, localizados ao nível do solo, como forma de controle biológico para larvas de Aedes aegypti. Durante a visita do agente, ao invés de se tratar os tanques com larvicida, colocou-se um espécime do peixe Betta splendens por depósito. O presente trabalho teve como objetivo avaliar os resultados desta intervenção. Com os levantamentos do número de imóveis e depósitos existentes, estimou-se este número mês a mês determinando então o número de depósitos existentes por imóvel. Com esta estimativa e o número de imóveis visitados mensalmente analisou-se a infestação deste tipo de depósito. Em janeiro de 2001, 70,4 por cento dos tanques examinados apresentavam larvas; e apenas 7,4 por cento em janeiro de 2002. Em dezembro de 2002 este índice caiu para 0,2 por cento. Demonstrou-se com clareza a capacidade do Betta splendens como agente de controle biológico, em tanques de cimento, reduzindo 320 vezes a infestação deste tipo de recipiente de grande volume.
Asunto(s)
Animales , Aedes , Control Biológico de Vectores/métodos , Peces , Insectos Vectores , Brasil , Dengue/prevención & control , Larva , Densidad de Población , Abastecimiento de AguaRESUMEN
Canindé has a population of 71,235 inhabitants. In April 2001, the city started using larvivorous fish in cement water tanks, as a means of biological control of Aedes aegypti larvae. During house-to-house visits by health agents, instead of treating the water tank with larvicide, a Betta splendens fish was introduced into each tank. The number of houses and the number of tanks was estimated by monthly surveys. Then, the number of tanks per house was determined. Taking into account this estimated number and the number of houses visited, the infestation level for each kind of deposit was analyzed. In January 2001, 70.4% of the water tanks presented mosquitoes. Following the intervention, in January 2002 only 7.4% were positive and by December 2002 the rate had dropped to 0.2%. The efficacy of Betta splendens as a biological control agent in cement water tanks was clearly demonstrated, by achieving a 320 times reduction in the infestation level.