朱砂叶螨对阿维菌素及高温的交互耐性

以朱砂叶螨敏感种群(SS)、抗阿维菌素种群(RA)和耐高温种群(RH)为材料,应用生物测定方法以及荧光实时定量PCR技术,研究朱砂叶螨抗药性和耐高温间存在的交互耐性及机制.结果显示:46℃高温下RH和RA种群的半致死时间(LT50)显著长于SS种群,其顺序依次是:RHRASS,阿维菌素对朱砂叶螨的半致死浓度(LC50)各种群间的顺序依次是:RARHSS,其中,RH和RA种群显著高于SS种群.这表明长期的高温胁迫能诱导其对阿维菌素药剂的抗性,同样对阿维菌素的抗药性也能诱导其对高温的耐性.SS、RA和RH经阿维菌素处理后体内O2?(超氧自由基)含量分别是对照的2.08、1.85和2.00倍,SOD(超氧化物歧化酶)活性分别是对照的3.81、4.84和4.26倍,CAT(过氧化氢酶)和POD(过氧化物酶)活性也都高于对照;经高温(40℃)和低温(4℃)处理后,O2?及SOD、CAT和POD活性也表现出相同的趋势.说明朱砂叶螨虫体内的O2?、SOD、CAT和POD与阿维菌素药物和热(冷)刺激有关,RA和RH在长期阿维菌素或高温胁迫作用下对保护酶活性的诱导能力加强.朱砂叶螨Tc HSP90 mRNA在正常情况下的表达是RA和RH高于SS,分别是SS的1.64倍和1.29倍,经阿维菌素、高温(40℃)和低温(4℃)处理后,RA和RH的表达量显著高于SS,表明朱砂叶螨HSP90在抗药性和耐热性方面发挥了作用.

Cross tolerance of carmine spider mite,Tetranychus cinnabarinus,to abamectin and high temperature

The susceptible strain (SS), the abamectin resistant strain (RA) and the high temperature tolerant strain (RH) from Tetranychus cinnabarinus were used to study cross tolerance to abamectin and high temperature using the methods of bioassay and fluorescent real time quantitative PCR. The results showed that, under high temperature (46 ℃), median lethal time (LT_(50)) and median lethal concentration (LC_(50)) of abamectin toxicity to T. cinnabarinus were in the order of RH>RA>SS and RA>RH>SS, respectively, which of the strains RH, RA were significantly higher than SS, indicating that the long-term heat stress could induce abamectin-resistance and heat-resistance. The contents of free radicals (O_2~-·) of SS, RA, and RH treated with abamectin were 2.08, 1.85, and 2.00-fold higher than those of their untreated controls, respectively, and the superoxide dismutase (SOD) activities were 3.81, 4.84, and 4.26-fold higher, and the activities of catalase (CAT) and peroxidase (POD) were higher than those of their untreated controls. The free radical contents and the activities of SOD, CAT and POD in T. cinnabarinus exhibited the same tendency at high temperature (40 ℃) and low temperature (4 ℃). The result above showed that the O_2~-·, the activities of SOD, CAT and POD in T. cinnabarinus were related to abamectin and hot (cold) stimulates, and the induced abilities of RA and RH to protect the enzyme activity were strengthened under long-term abamectin or high temperature stress. Under the normal condition, the mRNA level of TcHSP90 was 1.64 and 1.29-fold higher in the RA and RH than that in SS, respectively. After treatment of abamectin, high temperature (40 ℃) and low temperature (4 ℃), the TcHSP90 mRNA levels of RA and RH were also significantly higher than SS, indicating that HSP90 played an important role in the drug-resistance and heat-resistance.