This study aimed to evaluate the toxicity of Bacillus thuringiensis (Bt) transconjugants harboring chitinase genes against larval stage of Tuta absoluta . Bacillus licheniformisand Serratia marcescens were used as donors against Bt  . Bacillus transconjugants were evaluated for chitinase activity depending on hydrolysis zone appeared on chitin agar medium. Parental strains and their recombinants significantly reduced the number of survived larvae if compared with untreated larvae. Mortality rate was gradually increased to reached a maximum ratio after six days of treatments. Most bioinsecticides including parental strains and their transconjugants significantly losses larval body weight daily if compared with untreated larvae.Bioinsecticides, as well as, bioinsecticide concentrations and the interaction between both factors showed negative significant effect on larval body weight at most time intervals of larval age.In addition, Bt recombinants , as well as, their parental strains has exhibited a great potential effect for controlling and suppress the feeding of larval stage on the host plants.