How does the red flour beetle, Tribolium castaneum, obtain chill hardiness under room conditions in Kyoto, Japan?

Abstract

Adult beetles of Tribolium. castaneum were exposed to 5 ℃ after being in unheated seasonal room conditions in a concrete apartment building or constant temperature conditions of 27 ℃ in 2013 and 2014 in Kyoto. No beetles in the room could tolerate the chill treatment for 75 days when the minimum room temperature decreased from 21 to 14 ℃ from Nov. 3 to Dec. 16. However, 42.5% of beetles at 27 ℃ could survive the 75-day chill treatment after being exposed to minimum room temperatures of 12–14 ℃ for 40 days. These results suggest that the beetles need to be exposed to temperatures lower than 14 ℃ for a certain period in order to overwinter in Kyoto.