Toxicity of an Isolate of Bacillus thuringiensis Subspecies darmstadiensis to Adults of the Mexican Fruit Fly (Diptera: Tephritidae) in the Laboratory

Centrifugation pellets obtained from an isolate of Bacillus thuringiensis subspecies darmstadiensis (Guat 1) cultured from a Guatemalan soil sample were found to be toxic to Anastrepha ludens (Loew) adults in the laboratory. We developed a bioassay diet that consisted of a mixture of the bacterium, a protein source, and sugar. A pH of 4.1 of the mixture was needed to obtain maximum adult mortality. One meal of the diet, which lasted from 30 s to 4 min, was enough to cause > 70% mortality of both fed or starved adults. Mortality of fed adults was 70-75% following a feeding period of 60 min and mortality of starved adults was 80-90% following a feeding period of 30 min. The isolate was toxic to adults from 1 to 21 d old.