Genetic improvement of Bacillus thuringiensis against the cotton bollworm, Earias vitella (Fab.) (Lepidoptera: Noctuidae), to improve the cotton yield in Pakistan

Abstract

In the present study, CryIAc (Crystal protein) gene was cloned under Cry3A promoter, which is known to express vegetatively as a sporulation independent promoter, transformed into acrystalliferous strain of Bacillus thuringiensis. Its potential was evaluated as a strain to be used for formulation development against the spotted cotton bollworm Earias vitella (Fab.) (Lepidoptera: Noctuidae), the major pest of cotton, the important cash crop in Pakistan. The crystal protein produced in a new strain, i.e., Bt1, had comparable potency as of crystal protein produced during sporulation. The new strain Bt1 had the maximum expression of Cry1Ac protein during the vegetative stage, i.e., in the first 24 h, thereby reducing the growth period until crystal protein production, from 72 to 24 h. In addition, crystal protein produced during vegetative stage under Cry3A promoter remained encapsulated within the cells, which could protect them from UV degradation and was independent of sporulation; therefore; it did not produce spores and thus is not a source to spread Bt spores in the environment. It can, therefore, be called as an environmentally friendly pesticide to control cotton pest especially bollworms and ultimately improve the yield of cotton.