EN
The insects' behaviour and development of pest populations are closely related to the host plant separation in respect of the time or space. The more food-specialization of pests could mean the greater possibilities to control them and may affect less damages of host plants, when they are growing together with non-host plants. Monophagous insects, strictly connected with one species very often couldn't find out their food, shelter and oviposition requirements within the crops consisted of different species. Population densities of olygophagous insects (botanical family is spectrum of hosts) are strongly restricted by the mixtures composed with taxonomically unrelated species, such as Poaceae and Papilionaceae. For example, the cereal leaf beetles - dangerous pest for all cereal species may damage about 50% more cereal plants in pure stand than in the cereal-leguminous mixtures. The numerous empirical data and several theoretical arguments are presented that suggest that the differences in pest abundance between diverse and simple annual crops can be accounted for by the response of herbivore host-finding behaviour to the patterns of recourse availability rather than the activities of natural enemies. The multicropping systems, especially inter-species mixtures, may provide short-term benefits such as: - reduced insect-pest populations, - decreased losses of plant yield, - decreased pest control costs.