The vira-like chitinase gene, one of the genes involved in the formation of chitin and concerned with development of insect. PCR- RFLP technique was used in the present study to compare the effect of sub-lethal doses of two IGRs, flufenoxuron (cascade) as a chitin synthesis inhibitor and tebufenozide (mimic) as a moulting hormone agonist, on this gen in Spodoptera littoralis pest. As the 2nd instar larvae were treated with sublethal doses LC25, LC50 and LC90 of the two tested IGRs. The endonucleases Spel, EcoRI and Bbsl were used to detect the molecular changes in the gene at different time intervals 6, 12, 24 and 48 hours post treatment. Bioinformatical obtained results showed significant changes in the gene sequences (mutations) of the treated groups which were dose and time dependants. For each studied group, the RNA secondary structure stems nucleotide sequences; positions and free energy were recorded.