刺桐姬小蜂对低温胁迫的耐受性评价

摘要

刺桐姬小蜂是我国的重要的外来林业有害生物之一, 目前仍具有向高纬度或高海拔入侵的潜在风险. 以刺桐姬小蜂福建种群的不同虫态为对象, 分别测定其在低温条件下的过冷点(SCP)和死亡率;并利用逻辑斯蒂模型Ⅰ、 Ⅱ(改进型)拟合其死亡率与低温累积的关系, 并进一步测算各虫态的致死中有效伤害低温累积(LSIT50). 研究结果表明: 幼虫、 蛹、 雌成虫和雄成虫的过冷却点均小于-10.0 ℃, 仅雌成虫与其它虫态之间差异极为显著(P<0.01), 属耐结冰型;各虫态死亡率均随着温度降低而增加, 且在5 ℃以下超过80%的个体死亡,表明5 ℃以下低温对各虫态的存活影响最大, 其中以雄、 雌成虫耐受性最弱, 幼虫的耐受性最强;两个逻辑斯蒂模型均能很好地拟合低温暴露死亡率与低温累积的关系(R2>0.98, P<0.01), 分别测算各虫态的LSIT50值分别为: 幼虫>蛹>雌成虫>雄成虫, 从理论上也验证了幼虫对低温耐受性最强;虽然模型Ⅱ的LSIT50值仅略高于模型Ⅰ的理论值, 由于前者兼顾了昆虫冷伤害的上限温度(ULCIZ)对害虫的影响, 较真实地模拟自然条件下昆虫所经历的持续降温过程, 更适于定量评价昆虫耐寒性. 上述研究结果对预测害虫的适生分布范围具有重要意义.%Quadrastichus erythrinae Kim is currently one of the most dangerous invasive pests in Fujian Province, However, it has the ability potentially to be a dangerous species in the circumpolar latitude area and high altitude area in China.To evaluate cold tolerance of Q.erythrinae, Super-cooling point (SCP) of different stages including larvae, pupae, adults and the total population was measured under low temperature rooms.Then, two logistical models were conducted to fit the relationship between mortality of Q.erythrinae and accumulation of low temperatures, and compared the LSIT50 (median lethal sum of injurious temperature) value of different stages.The results indicated that the average SCP of adults (female and male), pupae and larvae were below-10.0 ℃, respectively (P<0.01), and there was only remarkable difference between females and all other treatments, these pests belonged to type of high tolerance to freeze.The mortality of different stages and the total population increased with the decrease of temperature.More than 80% individuals were dying under 5 ℃, which indicated most individuals did not have the cold tolerance to temperatures under 5 ℃, of which the larvae stage was the strongest cold tolerance.In addition, the correlation between the mortality and accumulation of low temperatures was fitted through 2 kinds of similar logistic model (R2>0.98, P<0.01), and which was used to predict the LSIT50 of different stages and the total population, and the fitted results also showed the order of LSIT50 volues was the larvae, pupae, female adults and male adults respectively.Moreover, the model Ⅱ was better than model Ⅰ because the former was very closer to practical environment, taking ULCIZ into consideration and adding one index into model Ⅱ.All above results will be very helpful to predict their potential biography and analyze their adaptation under the extreme circumstance.