Emigration Activity in Lesser Grain-Borer Rhyzopertha dominica in the Initial Stage of Infesting Stored Wheat Grain (Coleoptera: Bostrichidae)
The subject of the study is a population of lesser grain-borer Rhyzopertha dominica (Fabricius 1792), a dangerous pest of stored grain. Laboratory experiments were conducted in order to determine the emigration activity of R dominica in the initial stage of wheat grain storage infestation. The studies were carried out at a temperature of 28°C and 60±5 % relative humidity (RH). The assessment of emigration activity was based on the analysis of population numbers and sex ratios. It was found that the lesser grain-borer population displays very intensive emigration activity independent of population-related and environmental factors. It was also found that R dominica females manifest a higher emigration drive than males. This is particularly harmful because fertilized females move quickly within grain heaps, attacking and contaminating new batches of stored cereal grain.