In recent years the cultivation of white mustard (Sinapis alba) has been promoted as a winter alternative crop in the Pampas. Previous studies related to mustard entomofauna, denote the presence of Microtheca ochroloma, a specific chrysomelid of Brassicaceae family, causing significant defoliation. The objectives of this study were to evaluate whether the presence of M. ochroloma varies according to different genetic materials and white mustard phenological stages and describe some parameters of its life cycle feeding on this crop. The studies were carried out in the Experimental field and Laboratory of Agricultural Zoology of Universidad Nacional de Luján. Genetic materials of different origins of white mustard, were sampled weekly in the number of plants infested with larvae and adults of M. ochroloma during a growing season. The development cycle was studied under laboratory conditions (24 ± 2 ºC, 60 ± 10 % RH, photoperiod 10L: 14O) from a cohort of eggs. The larvae were fed with the origin Canada and recorded development time of each stage. Pupae were sexed and then formed pairs to estimate the pre-oviposition period and fecundity for 30 days. Both larvae and adults were recorded in all genetic material, although the number of infected plants showed no significant differences between origins and between phenological stages. The average cycle length was 29.1 days. Females oviposit a mean of 74.9 eggs into several groups. These results suggest that M. ochroloma interchangeably used as a food source to all genetic material evaluated and successfully completes its life cycle feeding on S. alba.