The field experiments were carried out at the experimental farm of Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, Egypt to study the influence of both chemical composition and molecular variations of sugar beet cultivars on the population of Scrobipalpa ocellatella and Cassidavittata in 2020-2021 and 2021-2022 seasons. Results showed that Celnne cultivar harbored higher population of S. ocellatella (16.50 and 18.67 larvae/ 5 plants) in February and C. vittata (54.87 and 55.40 larvae and adults/ 5 plants) in March, with significant differences, than Heliospoly cultivar during the two investigated seasons, respectively. These differences may be due to the direct proportion between protein content and insect populations. A maximum standard of DNA polymorphism was found out by RAPD-PCR technique for both cultivars appearance certain positive and negative markers linked with plant afford to insect offensive. The RAPD-PCR techniqueof both cultivars revealed that Heliospoly was more resistant; while Celnne was more sensitive to these insects. The present study could be utilized by breeders and entomologists to develop sugar beet cultivars resistant to the two insects.