Abstract

Saad Aied AlOtaibi

In this study twelve Bacillus strains and 20 transconjugants resulted from nine matings between strains that having the opposite genetic markers were used in this work. This study aimed to evaluate accumulative mortality, as well as, body weight yielding of surviving larvae, after intoxication with Bt recombinants. The results appeared that recombinant crystals from transconjugants number Tr-B and Tr-D were more toxic if compared with other Bt toxins used in this study. This is because they were appeared in the lower LT50 which reached to 4.09 and 5.30 days, respectively. In addition, recombinant crystals + endospores derived from transconjugants; Tr- B and Tr- D were more toxic if compared with other Bt, this because they appeared the lower values of LT50 than other isolates of Bt. The LT50 of Tr-B and Tr-D were 2.87 and 2.44 day, respectively. The results indicated that mortality percentage increased with increasing feed period but decreased with increasing larval age. The yield in body weight of surviving larvae treated with Bt. increased above that in untreated larvae. In addition, the yield in mortality percentage increased above that in control experiment. Although, yield in mortality percentage was increased when the larvae was treated with crystals + endospores than that treated with crystals alone. The results indicated that wider application of this technology will necessitate the testing of a broad range of insects encompassing agriculturally important pests and also beneficial insects to ascertain the full efficacy and safety of these recombinant proteins. This article sets the stage for developing an alternative strategy via using transgenic Bt in controlling important insect pests in a sustainable manner. The results demonstrated that B. thuringiensis - induced accumulative mortality depending on the components of bioinsecticides.