Host plants as reservoirs of the main oil-producing cabbage crops pests in the eastern forest-steppe of Ukraine

Abstract

Considering the geographical position of Ukraine, which is Such biotic factor as the vegetation distribution, which is the forage base for most insects, influences their spreading greatly. This connection is strongly expressed among the harmful herbivorous insects. The presence and distribution of the plants which are cultivated or used by humans and on which the insects are fed is certainly the first and basic condition for the emergence of a zone or a breeding ground of harmfulness. The presence of the most preferred by the insects fodder plants often leads to the formation of a zone or a center of the greatest damage (in the presence of other favorable conditions for the existence and reproduction of the pest). In the course of the researches concerning the identification of the host plants as reservoirs of the main oil producing cabbage crops pests which have been conducted in 2011–2014 in the communities (meadows, roadsides of highways and field perimeters) of the Kharkiv district of the Kharkiv region it has been found out the host plants as reservoirs for the dominant pests of the oil producing cabbage crops were dandelion, caustic buttercup, field mustard, hedge mustard, tansy mustard, yellow rocket and field shepherd’s purse. The largest number of species of the host plants as reservoirs was found on the roadsides of highways and along the field perimeters (6 species) and on the meadows (2 species).The cruciferous fleas, rape blossom beetles and cruciferous bugs visited such crops as field mustard, hedge mustard and yellow rocket most often. Field shepherd’s purse was the least significant among the identified host plants as reservoirs. Only a small amount of the cabbage fleas fed on this crop. This fact can be explained by the small white flowers that do not attract the rape blossom beetles and rose chafers as well as by a ground flat leaf rosette, which is always covered with dust and prevents the fleas and bugs from feeding.