The effect of aeration on the vertical distribution of grain beetles (Coleoptera) in wheat

Abstract

In order to see if aeration causes grain beetles to become peripherally distributed in bulks of grain, the positions of adults were recorded 7–10 days after they had been placed in the middle of vertical columns of wheat 1200 mm long and 80 mm in diameter. The columns were held at 10 or 25°C, and a downward current of air was passed through half of them. At 10°C, there were more adults of Oryzaephilus surinamensis (L.) at the ends and fewer at the centre of aerated than unaerated tubes when a high airflow was used, and at 25°C, a similar difference occurred when aeration caused cooling, dampening or drying of the grain. Dampening at 10°C and drying at 25°C caused there to be fewer adults of Sitophilus granarius (L.) at the ends and more at the centre of aerated than unaerated tubes. However, vibration at 10°C encouraged the dispersion of weevils. Rhyzopertha dominica (F.) scarcely moved at 10 or 25°C under either aerated or unaerated conditions.