Table 2.

Toxicity to fourth instar Culex quinquefasciatus of Bacillus thuringiensis subsp. israelensis (Bti) strains that produce high levels of the B. sphaericus (Bs) binary toxin in comparison with wild-type Bti and Bs

Bacterial strainToxin compositionLC50 (ng ml−1)Improvementa
Bti IPS-82 + Bs BinCry4A + Cry4B + Cry11A + Cyt1A + Bs Bin1.5±0.413×
Bti 4Q7 + Bs BinBs Bin1.4±0.410×
Bti IPS-82Cry4A + Cry4B + Cry11A + Cyt1A19.5±3.5
Bs 2362Bs Bin15.0±3.4
  • a Improvement represents the factor by which the toxicity per unit mass of lyophilized fermentation product is improved compared with that of the wild-type strains. The Bti IPS-82 + Bs Bin strain is compared with Bti IPS-82, a wild-type strain, and the Bti 4Q7 + Bs Bin strain is compared with Bs 2362, a wild-type strain.