This study is a part of an extended investigation that aims to clarify the nemastatic activity of two commercial formulations of resistance inducers; Bio-arc and Nemastrol against Meloidogyne incognita infected sugar-beet in vitro and in vivo. Generally, data indicate that the ability of all individuals of the stage juveniles to penetrate the roots and develop into the next stage with a shortage of the duration of the life cycle in sandy soil compared to clayey soil. The results showed that Nemastrol caused a significant reduction in the percentage of penetration of M. incognita at the second-stage juveniles. Bio-arc ranked the second one comparing to control in clayey and sandy soil. The duration of developmental four juvenile stages, as well as egg-laying females, have a clear reduction with Nemastrol in clayey and sandy soil more than Bio-arc comparing to control. The length of the life cycle varies, as treatments by Nemastrol were longer than Bio-arc in clayey and sandy soil (2-24 and 9-24 days), respectively. Besides, Nemastrol showed a poor formation of irregular giant cells devoided from the cytoplasm and contained less number of nuclei.