This study aimed to determine the relationship between the population density of pest and other species of white grubs (Coleoptera: Melolonthidae) occurring in cultivated and uncultivated fields in the planalto region, in northern Rio Grande do Sul. Sampling was carried through 23 municipalities, from July to September 2009 and 2010 in two areas, one cultivated and another noncultivated, In each area, trenches of 50x25x30cm were opened. Melolontid larvae collected were identified and gathered in two groups: "pest-species" and "other species". Populational density (no of larvae m-2) of the two groups were compared between cultivated and noncultivated areas. The "other species" density was higher than pest community in both cultivated (9,0 e 3,9 larvae m-2) and noncultivated areas (6,6 e 3,9 larvae m-2 respectively). There is no difference between means of pest species population density between cultivated and noncultivated areas
winter crops; populational density; identification; integrated pest management; Melolonthidae; occurrence