Effects of cold acclimation on the biochemical content and survival of Steinernema litorale
Author of the article:ZHANG Xu-Xia;HAN Lan-Lan;ZHAO Kui-Jun;LI Dong-Po;GAO Yun-Lei;DENG Shi-Qun;LIU Fan
Author's Workplace:College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China;College of Agriculture, Northeast Agricultural University, Harbin 150030, China
Key Words:Steinernema litorale, cold acclimation, freezing survival rate, storage stability, biochemical materials
Abstract:
[Objectives] To clarify the potential value of S.
litorale as a biological control agent, we studied the appropriate low
temperature characteristics of this species in rhizosphere soil from under elms in the Xiangfang district,
Harbin city. [Methods] S. litorale were exposed to
several temperature treatments, including 25 ℃ (6 d), 10 ℃ (6 d), 4 ℃ (6 d) and 25 ℃ (2 d)-10 ℃ (2 d)-4 ℃ (2 d), and their freezing survival
rate, low temperature dormancy, and biochemical (soluble sugar, glycogen,
trehalose, lipid and protein) content, measured and compared. [Results] The freezing survival rates of S.
litorale were 0.9%, 23.6%, 20.0% and 49.2% after cold acclimation at 25 ℃ (6 d), 10 ℃ (6 d), 4 ℃ (6 d) and
25 ℃ (2 d)-10 ℃ (2 d)-4 ℃ (2 d),
respectively, followed by a 36 h -20 ℃ freezing treatment. The freezing survival rates of S. litorale after 25 ℃ (2 d)-10 ℃ (2 d)-4 ℃ (2 d) was significantly higher than those of the other
three temperature treatments. Staged cooling significantly improved cold
tolerance. The survival rates of nematodes in the four treatment
groups were all above 65% and were not significantly different (P < 0.05) after they had been
kept at 4 ℃ for 7 months.
Mortality in the 25 ℃ (6 d) treatment group was significantly
lower than that in the other three treatment groups. The soluble sugar, lipid
and trehalose contents of the
25 ℃ (2 d)-10
℃ (2 d)-4 ℃ (2 d) treatment groups
were the highest; significantly higher than those of the 25 ℃ (6 d) treatment group.
The protein and glycogen content of the 25 ℃ (6 d) treatment group were not significantly different from those of the
other three treatment groups. [Conclusion] Cold acclimation by staged temperature reduction improves the cold
tolerance of S. litorale and can be used to maintain these animals in a
dormant state for prolonged periods.