Aktywność migracyjna populacji kapturnika zbożowca Rhyzopertha dominica (F) (Coleoptera, Bostrychidae)

Abstract

The migratory activity of lesse grain borer Rhyzopertha dominica (F.) Coleoptera, Bostrychidae, the pest of cereal grain crops, was studied. We found that although the adult individuals showed highly specialised morphological features which limit relocation, favourable circumstances may nevertheless promote migration. Our experiments indicated that in populations with a high migratory activity, the direction of movements is non- random. Unidirectional emigration index ranges from 62% to 84%, whereas indices of two-directional migration are lower (42% to 62%), resulting in a uniform dispersion of the population. Moreover, moevements led to differentiation of the population structure, which differed between the migrant groups. The experiments revealed differences in sex ratio, mortality indices and colonisation rate. The prevalence of the females among the migrants and their higher rate of substrate colonisation were responsible for the population expansion and high reproductive rate of these seemingly immobile pests.