| Tetranychus cinnabarinus (Boisduval) is widely distributed in China, and often infests seriously, but difficult to control in cotton and many vegetables, particularly in high temperature and dry seasons, the infestation of T. cinnabarinus are often serious. This mite has developed significant resistance to pesticides in many areas in China. In this paper, the resistance strains of T. cinnabarinus to abamectin (Ra) and to high temperature (Rh) were selected, respectively. By constructing the life table of different strains at normal temperature and high temperature, the biology and ecology of different strains were compred, and the fitness of different strains at normal temperature and high temperature were also compared to ascertain the interrelation of resistance to abamectin and to high temperature. This study was supported by National Natural Science Foundation of China (30600598), and the main results are as follows.1 The interrelation of resistance of T. cinnabarinus to abamectin and to high temperatureAfter 24 generations selection with abamectin, T. cinnabarinus developed 4.1494-folds resistance to abamectin. Meanwhile, when the susceptible strain of the mite were reared at 34°C for1 year, the LC50 of this strain against abamectin is 2.1396 folds higher than that of the susceptible strain (S) which was reared at 26°C. When T. cinnabarinus were exposed at 48℃for 1 hour, the mortality of the S and Ra were not significantly different, but both were obviously higher than the Rh. These result indicated that after the T. cinnabarinus were reared at high temperature for long time, the adaptability to high temperature significantly strengthed.2 The Biology and experimental population ecology of T. cinnabarinusAfter T. cinnabarinus developed resistance to abamectin and high temperature, at the normal temperature (26℃), the oviposition period shortened and the fecundity decreased, and these two strains had the reproductive defect, particularly for Rh. The fecundity of Ra did not decrease significantly, maybe it is relative to the low resistance fold to abamectin. At high temperature (34°C), the oviposition period prolonged, the fecundity incecfeased, while oviposition period and fecundity of Rh are not significantly different.The age-specific fecundity and survival curves showed that the fecundity and survival rate of susceptible strain was significantly greater than those of Ra and Rh strains at the normal temperature (26°C), the Rh strain are significant lower than the other strains, maybe this due to the cost of resistance high temperature. While the fecundity and survival rate of Ra strain was significant greater than those of susceptible and Rh strains at the high temperature (34°C), this also suggested that the suitability of T. cinnabarinus to high temperature increased after selection with abamectin, implied that there might exist some links between the tolerance to extreme high temperature and resistance to abamectin. At the same time, when T. cinnabarinus were reared in high temperature for 1 year, the survival rate increase significantly, the suitability to high temperate increased significantly.The fitness (measured with Rn) of Ra and Rh were lower than that of susceptible strain at the normal temperature, but the fitness of Ra strain and Rh was significantly higher than that of susceptible strain at high temperature (34°C), this indicated that when T. cinnabarinus occurred resistance to abamectin, as the same as the Rh, could suitable to survival better at the higher temperatures compared with the susceptible strain, especially the Ra has more fecundity, the suitability are more higher.3 Study of protective enzyme activities of T. cinnabarinusAfter T. cinnabarinus developed resistance to abamectin and high temperature, the Ra's superoxide dismutase (SOD) activity decreased, peroxidase (POD) activity increased; while the Rh's SOD activity increased, POD activity decreased. Treatment with 43℃high temperature, with the time increased, the SOD activity of S and Rh decreased, the activities were restrained. The SOD activity of Ra increased at the first, then deceased slowly. The SOD activity of Ra was always higher than the other strains. The POD activity overall tendency is first reduces then increases with the time increase, possibly the POD activity were restrained at the first, when T. cinnabarinus suit the high temperature for a long time, the activity recover slowly.4 Study of Expression of Heat Shock Protein of T. cinnabarinusHeat shock protein was detected by SDS-PAGE, the results showed that compared with the S, the expression of 28.5 and 26.8 kDa proteins of Ra and Rh was increased. The 97.2kDa protein of Rh strain was expressed differently. When Ra was exposed to 43℃, the 98.6kDa expression was significant increased, while the 54.9kDa expression was the least. When T. cinnabarinus was exposed to 43℃, 75.9kDa expression in all strains was increased, especially for HR. The change of protein expression might be relative to resistance to high temperatures and abamectin. |
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