不同寄主松树对松突圆蚧耐寒性的影响

通过测定过冷却点和低温暴露试验,比较不同寄主松树上松突圆蚧的耐寒性.寄生黑松和马尾松松突圆蚧雌成虫的过冷却点比寄生湿地松和火炬松的显著较高,2类过冷却点的平均值相差0.9～2.3℃,但寄生黑松和马尾松的雌成虫之间、寄生湿地松和火炬松的雌成虫之间均无显著差异.寄生马尾松2龄性分化后雌若虫的过冷却点比寄生湿地松的显著较高(高2.08℃);而2龄性分化后雄若虫则无显著差异.寄生马尾松的初孵若虫、1龄若虫、2龄性分化前若虫、2龄性分化后雌若虫、2龄性分化后雄若虫、雌成虫及种群总体,对低温暴露致死的起始敏感温度和-20℃低温暴露的死亡率,均比寄生湿地松的相应虫态和种群总体更低;寄生马尾松松突圆蚧种群的致死中有效伤害低温累积(LSIT50)比寄生湿地松种群的低;2种寄主松树松突圆蚧各虫态及种群总体在低温暴露下死亡率的变化规律均符合改进后的双变量逻辑斯谛模型.研究结果说明:寄主松树能够影响松突圆蚧的过冷却点和低温暴露死亡率,寄生湿地松种群的耐寒性比寄生马尾松种群的弱.

Effects of Different Host Pines on the Cold Tolerance of the Pine Scale Insects

The super cooling point (SCP) and mortality of the pine scale insect ( Hemiberlesia pitysophila) that hosted on four different pines of Pinus massoniana, P. elliottii, P. taeda and P. thunbergii were investigated when being exposed to a designated and regulated low temperature. Results showed that a significant effect of pines on SCP of female adults was observed, and the SCPs on P. massoniana and P. thunbergii were 0.9 ~ 2.3℃ higher than that on the other two pines. The mean SCP of the second instar female nymph on P. massoniana after sex differentiation was 2.08℃ higher than that on P. elliottii. However, a separate experiment showed no remarkable difference in the SCPs of the second instar male nymph after sex differentiation between on the two pines. Relations between low temperature and mortality of all insect developing stages and the populations on P. massoniana and P. ellwttii all exhibited a revised double-variable Logistic model. Nevertheless, the incipient sensitively low lethal temperature and mortality of these developing stages and the population exposed at - 20℃ were all lower on P. massoniana than that on P. elliottii. The semi-lethal sum of injurious temperature of the population was lower on P. massoniana than on P. elliottii. The results suggested that the SCP and mortality of Hemiberlesia pitysophila exposed to low temperature were significantly affected by host pines, and its cold tolerance on P. elliottii was lower than that on P. massoniana.