Metabolism and cold tolerance of <scp>C</scp> hinese white pine beetle <i> <scp>D</scp> endroctonus armandi </i> ( <scp>C</scp> oleoptera: <scp>C</scp> urculionidae: <scp>S</scp> colytinae) during the overwintering period

Abstract

Abstract C old hardiness becomes a crucial strategy because temperature change often leads to fluctuations in insect abundance. T he present study investigated the relationship between cold‐tolerance ability in overwintering C hinese white pine beetle D endroctonus armandi T sai and L i larvae and physiological body indices aiming to determine the possible overwintering strategy from S eptember 2013 to M ay 2014. S upercooling points ( SCP ) differed significantly across months, showing a precipitous drop in D ecember 2013 and J anuary 2014. The maximum monthly mean supercooling point was −1.7 ± 0.4 ° C (15 S eptember 2013) and the minimum monthly mean was −7.5 ± 0.2 ° C (15 J anuary 2014). The SCP tended to decrease as the ambient temperature decreased until J anuary, before increasing until the end of the winter. Glycerol, sorbitol and trehalose contents showed a significant negative correlation with the SCP . T he latter results indicate that the cold tolerance ability of the larvae is enhanced by exposure to 4.0 ° C . D endroctonus armandi larvae decreased their mortality at −8.0 ° C after cold acclimation at 4.0 ° C for 24 h.