Isolation and distribution of mosquito-larvicidal cry genes in Bacillus thuringiensis strains native to Saudi Arabia

A total of 157 environmental samples were collected from 11 ecological regions across Saudi Arabia to isolate native Bacillus thuringiensis (Bt) strains. Bt isolates (n=103) were recovered by the 50% (v/v) ethanol treatment method with Bt index range of 0.01 to 0.4. Most of Bt isolates showed spherical crystals (54%), while, irregular, bi-pyramidal, and sporeattached crystal constituted 27, 16 and 3% respectively. PCR analysis with eight general and specific dipteran primers of Cry and Cyt genes, revealed positive amplification for cry4 & cyt1, and cry4A, cry4B and cyt2, and cry 10 and cry 11 genes in 28%, 26%, 22%, and 25% of tested strains respectivel