Changes In The Physiological And Biochemical Mechanisms Under Temperature Change And Clone Of CDNA Fragment Of HSP70 In Gomphocerus Sibiricus(Oorthoptera: Acrididae)

Recent warming climate has beening causing persistent outbreaks of Siberian grasshopper, Gomphocerus sibiricus(L.) in Xinjiang. This study aims to explore the potential physiological and biochemical mechanisms of G. sibiricus exposed to high temperatures. The survival rate,the ratio of free water and bound water and the contents of trehalose, glycerine, oleic acid, linoleic acid, and linolenic acid in adult grasshoppers were measured after grasshoppers beening treated under consistent temperature ranges of 24-42℃ at 3℃ intervals for 4 h. And using the RT-PCR method, the partial cDNA sequences of heat shock protein 70 genes of G. sibiricus were cloned and analyzed. From 24 to 30℃, no grasshopper appears dead. With the temperature going up, the survival rate significantly decreased. When the grasshoppers were treated at 39℃ and 42℃, the adult survival rate went down to 44% and 8%, respectively. The ratio of free water and bound water rose when the grasshoppers were exposed from 24 to 33℃, and reached the peak at 33℃,at which the ratio is 40.11. With temperature going up further, the ratio began to decrease and reached the lowest value(30.82) at 42℃.The contents of trehalose, glycerine, oleic acid, linoleic acid, and linolenic acid increased during from 24 to 30℃, and reached the peak at 30℃, with the contents of 18.691μg/g, 261.432μg/g, 79.063mg/g, 78.664 and 227.593mg/g, respectively. The contents of the five substances began to decrease with the temperature rising further, and reached the lowest values at 42℃, with the contents of 18.218μg/g, 104.588μg/g, 4.383mg/g, 3.093mg/g and 11.067mg/g, respectively. The accumulation rates of these five substances were different with temperature rising. The content of linolenic acid dramatically increased(832.189%) while that of trehalose slightly increased(0.893%). The content of linoleic acid had a significant decrease(63.988%) while that of trehalose had a slight decrease(0.224%). One fragment of 471 bp was amplified of G. sibiricus, and deduced amino acid sequence contains 153 residues. Results showed that the homology of amino acid sequence between G. sibiricus, and Locusta migratoria L. is 99.3%. The higher the temperature is more than 30℃, the higher the grasshopper survival rate is decreasing. This study demonstrated that G. sibiricus can adapt to higher temperatures by regulating the contents of stress resistant substances in certain temperature ranges, especially the unsaturated fatty acids, which indicates the grashopper is still a serious pest to the steppe in Xinjiang under the trend of climate warming.