Movement of adult rusty grain beetles, Cryptolestes ferrugineus (Coleoptera: Cucujidae), in wheat in response to 5°C/m temperature gradients at cool temperatures

Abstract

Abstract The direction and speed of movement of adult rusty grain beetles in 12 and 24 h at 2.5–27.5°C (standard error was ±0.2°C in all of the experiments) were determined in 100×100×1000 mm 3 wheat (14.5±0.2% moisture content) columns with or without 5°C/m temperature gradients. At 5°C or less, adults could not move more than 5 cm in 24 h. At 7°C or less, 98% of adults could not move more than 5 cm in 24 h. Between 5°C and 27.5°C, the beetles preferred warmer areas and increasing temperature caused an increased number of insects to move towards the warmer areas both in vertical and horizontal columns. Insects moved faster in the vertical direction than in the horizontal direction and the maximum absolute speed of the beetles was