›› 2010, Vol. 53 ›› Issue (2): 147-153.doi:

• RESEARCH PAPERS •

### Responses of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) adults to cold acclimation and the related changes of activities of several enzymes in their bodies

ZHAO Jing, CHEN Zhen-Zhen, QU Jian-Jun, ZHANG Fan, YIN Xiang-Chu, XU Yong-Yu

• Online:2010-03-25 Published:2010-02-20

Abstract: In order to clarify the effects of cold acclimation on cold tolerance of adult Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), we investigated the survival rate, supercooling point (SCP), water content and reproduction capability of adults under low temperature in the laboratory condition. Adults of H. axyridis were cold acclimated at 5℃ successively for 1, 3, 5 and 10 d prior to cold stress. The results showed that the survival rate of the adults exposed to -5℃ for 3 d was improved from 46% of the control (without prior cold stress) to 60% and 67% when adults were acclimated for 3 d and 5 d, respectively, but decreased to 51% after the cold acclimation for 10 d. Returning of the adults to 25℃ caused a loss of cold acclimation within 7 d. The SCP and the water content decreased as the duration of cold acclimation prolonged. Shortterm (5, 10 d) exposure to 5℃ did not decrease the SCP even though it significantly decreased water content in the body. The pre-oviposition period of the female was delayed after acclimation. Acclimation significantly decreased the fecundity within 72 h, but did not affect the number of eggs laid in the first cluster. The effects of cold acclimation on several enzyme activities were examined, and the results showed that superoxide dismutase (SOD) and catalase (CAT) activities increased whereas lactate dehydrogenase (LDH) and Na+, K+-ATPase activities decreased after cold acclimation. These results indicate that cold acclimation is a complex physiological and biochemical process, which is very important to the survival and reproduction of H. axyridis.