Assessment of toxic potential of local Jordanian Bacillus thuringiensis strains on Drosophila melanogaster and Culex sp. (Diptera)

I. SAADOUN, F. AL‐MOMANI, M. OBEIDAT, M. MEQDAM AND A. ELBETIEHA. 2001. Aims: To assess the toxic potential of different local Jordanian Bacillus thuringiensis isolates on larvae of Drosophila melanogaster and Culex sp. Methods and Results: Scanning electron microscopy revealed the presence of spherical, bi‐pyramidal, and bi‐pyramidal and cuboidal parasporal bodies produced by the toxic isolates. Spherical inclusions dominated. The toxicity of the isolates to the two insects, determined using 24‐well plates or vials, indicated that the 50% lethal concentration (LC50) of the bacterial suspension for D. melanogaster and Culex sp. larvae varied from 4·60 to 8·65, and from 5·30 to 6·74, respectively. Conclusions: Comparison of the LC50 values of isolate 82 with those of the reference strain B. t. israelensis showed that this isolate has a higher toxicity potential. Significance and Impact of the Study: Some local Jordanian B. thuringiensis isolates exhibit toxic potential that could be used to control some important pests, and could replace chemical pesticides.