New isolate of Bacillus thuringiensis effective against the fall armyworm

Com o objetivo de encontrar princípios ativos que possam ser usados no controle da lagarta-do-cartucho, Spodoptera frugiperda (Smith, 1797), foram testados 205 isolados de Bacillus, provenientes de diferentes regiões brasileiras, contra larvas deste inseto. Apenas um isolado de B. thuringiensis subsp. kurstaki, denominado S93, causou 100% de mortalidade. A CL50 da mistura esporos-cristais do isolado S93 para larvas de 3o estádio de S. frugiperda foi de 37,0 ng/mL, enquanto a da estirpe HD-1 de B. thuringiensis subsp. kurstaki isolada do produto Dipel foi de 177,73 mg/mL, demonstrando ser o novo isolado muito mais tóxico contra a lagarta-do-cartucho do que HD-1-Dipel.Aiming to identify active ingredients that can be used to control the fall armyworm, Spodoptera frugiperda (Smith, 1797), 205 isolates of Bacillus from samples of different Brazilian regions were assayed against this insect. Only one isolate of B. thuringiensis subsp. kurstaki, designed S93, caused 100% mortality. The LC50 of spores-crystals mixture of S93 against 3th instar larvae of S. frugiperda was 37.0 ng/mL, while the LC50 for the strain HD-1 of B. thuringiensis subsp. kurstaki, isolated from the product Dipel, was 177.73 mg/mL, showing that this new isolate is much more active against the fall armyworm than the HD-1-Dipel