Efeitos da aplicação de Bacillus sphaericus (Neide, 1904) sobre anofelinos e entomofauna associada em tanques de piscicultura na periferia de Manaus, AM

Abstract

The Amazon region is considered malaria endemic area and has a large variety of anopheline breeding sites, arising from the environmental conditions of the tropics. Fish breeding incentive policies in the state of Amazonas have led to the occurrance of a new type of breeding site, namely fish ponds. These places have become breeding sites for malaria vector - Anopheles darlingi, sharing the environment with other aquatic associated insects. The present work has analyzed the effects of Bacillus sphaericus (Vectolex / dose 11kg/ha) on larvae of Anopheles and on the aquatic associated insects with this environment. Five peri-urban area breeding sites were used for the experiments. A total of seven samples were obtained from each site and Bacillus sphaericus (Bs) was applied and reapplied 15 days later. Samples were collected at: 24 hours prior to application, 24h post-application and on the 5th and 15th day after application so as to evaluate Bs effects on anopheline aquatic associated entomofauna. Anopheles larvae were collected during 20min. in each pond at three random points. Anophelines larvae associated insect fauna was collected with an entomological aquatic net (rapiché) at four random points, for 30sec. at each point. Anopheles abundance (%), larvae reduction (%) and larval density (ILHH) and aquatic associated insects abundance (%), richness (Jackknife 1st Order), Shannon diversity (H') and subsequently functional trophic groups were analysed so as to evaluate the Bs effects. We collected 904 Anopheles larvae, distributed in five species: A. darlingi, A. albitarsis, A. braziliensis, A. triannulatus and A. nuneztovari. A. darlingi (54%) and A. albitarsis (1%) showed to be the most and the least abundant species, respectively. The larval density of breeding sites ranged from 0.65 to 6.35. Larval reduction data (%) indicated rapid Bs effect 24 hours following its application. We collected 5328 aquatic associated insects, divided into six orders and 23 families. Diptera and Chironomidae showed to be the most abundant order and family, respectivelly. Richness (r ² = 0.22), diversity (r ² = 0.24) regression analysis indicated there being no relationship between studied variables and Bs application. Thus, the results showed no biolarvicide effect on the anophelines aquatic associated insects present in the analyzed fish breeding pond.