Field evaluation of effectivity of Bacillus sphaericus against Anopheles aquasalis Curry (Diptera: Culicidae) larvae in natural breeding-sites of Sucre State, Venezuela

Resumen

Anopheles aquasalis Curry is the main vector of malaria in northeastern Venezuela. A study of its biological control was carried out in the Sucre State. The aim of this study was to evaluate the field effectivity and persistence of a granular formulation of Bacillus sphaericus against larval populations of An. aquasalis. The main breeding-sites of An. aquasalis are the semi-permanent freshwater wetlands with herbaceous emergent vegetation (Eleocharis mutata). In field trials, two comercial concentrations (2 and 3 g/m²) of a granular formulation (Vectolex® CG 7.5%) of Bacillus sphaericus were evaluated in the typical breeding habitat of An. aquasalis. The granular formulation provided very good larval control. The two dosages had the same effectivity against larvae in breedingsites exposed to sunlight radiation, with acid pH and herbaceous emergent vegetation, producing a larval reduction greater than 91% during 7 days post-treatment (2 g/m² and 3 g/m²), equal to 94 % during 14 days (3 g/m²) and equal to or greater than 66% during 21 days post-treatment (2 g/m² and 3 g/m²).