Larval control of Anopheles (Nyssorhinchus) darlingi using granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon Rainforest

• Main Authors: Allan Kardec Ribeiro Galardo, Robert Zimmerman, Clícia Denis Galardo
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Medicina Tropical (SBMT) 2013-09-01
• Series: Revista da Sociedade Brasileira de Medicina Tropical
• Subjects: Anopheles darlingi; Bacillus sphaericus; Gold-miners; Malaria
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0037-86822013000200172
• ISSN: 0037-8682; 1678-9849

INTRODUCTION: Use of a Bacillus sphaericus based mosquito larvicide was evaluated as an intervention for malaria vector control at a mining site in Amap&#225;, Brazil. Impacts on larval and adult densities of the primary vector Anopheles darlingi were measured over the course of a 52 week study period. METHODS: In Cal&#231;oene, State of Amap&#225;, gold mining activity occurs in 19 mining sites in gold-miners of Louren&#231;o. Large pools are formed in mining sites and naturally colonized by Anopheles darlingi. During one year, the impact of applications of VectoLex(r) CG to these larval sources was evaluated. Applications of 20kg/ha were made as needed, based on 10 immature (3rd, 4th instars and pupae) surveillance of health and established thresholds. RESULTS: One hundred percent initial control was observed 48h after each treatment. The pools received from 2-10 (5.3&#177;1.6) treatments during the year. The average re-treatment interval in productive pools was 9.4&#177;4.3 weeks. During weeks 3-52 of the study, mean density of late stage larvae was 78% and pupae were 93% lower in the treated pools than in untreated pools (p< 0.0001, n=51) while reduction of adult mosquitoes was 53% in comparison to the untreated area during the last five months of the study, which were the rainy season (p<0.001). CONCLUSIONS: VectoLex(r) CG reduced immature Anopheles darlingi infestation levels during the entire study period, and reduced adult mosquito populations during the rainy season.