During the last years, the enlargement of areas sown with oil seed rape ensures its permanent participation in the modern crop-rotation lands. The application of different technologies of cultivation is related with specific soil treatments. The aim of the present investigation is to establish the influence of the crop-rotation and soil treatments on the density of harmful and useful insect species by oil seed rape. The experiments were provided during the years 2003 - 2006 and they include three regions in Bulgaria, Plovdiv, Rakovski and Yambol. The insects` density was established using standard entomological methods. On the base of that investigation, it was established that the insects` density in the different regions varies depending on the soil treatments type and the crop-rotation. [BG].
Influence of crop-rotation and soil treatments on the density of harmful and useful insects by oil seed rape