红脂大小蠹 Dendroctonus valens （ Coleoptera, Scolytidae ）和大唼蜡甲Rhizophagus grandis （Coleoptera, Rhizophagidae）的耐寒性

红脂大小蠹 Dendroctonus valens LeConte (Red turpentine beetle,RTB)是近年来在中国爆发的入侵生物,在我国主要以老熟幼虫在油松伐桩和立木的根部越冬.室内测定昆虫的过冷却点(SCP)和短时间致死低温(LLT)是评价昆虫耐寒能力的重要方法.实验结果显示,红脂大小蠹越冬幼虫的平均过冷却点为一11.98±2.55℃,是一种耐冰冻的昆虫.红脂大小蠹的过冷却点在不同地理分布区的种群问有明显差异,老熟幼虫的过冷却点明显低于低龄幼虫,在越冬前和越冬后的幼虫问没有明显差异.红脂大小蠹幼虫在冬季至少町以忍受-23.5℃的大气温度安全越冬.从2001年开始引入我国的云杉大小蠹的捕食者大唼蜡甲(Rhizophagus grandis cyll.)幼虫的过冷却点为-18.05±2.76℃,低于红脂大小蠹所有虫态的过冷却点,说明比红脂大小蠹有更强的耐寒能力.

The cold-hardiness of Dendroctonus valens (Coleoptera, Scolytidae) and Rhizophagus grandis (Coleoptera, Rhizophagidae)

Dendroctonus valens LeConte(Red turpentine beetle,RTB) was recently found in outbreak in China.Its elder instars and mature larvae mainly over-winter under the roots of the pine stumps and standing trees in China.The cold tolerant capabilities of the pest was estimated in the laboratory by SU-per-cooling points (SCP) and short-term lower lethal temperatures (LLT).The results show that the lowest mean super-cooling point of the RTB over-wintering larvae is-11.98 ± 2.55℃ and it is a species of tolerant-freezing insect.The SCP of RTB is significantly different between different geographical populations,the elder stage larvae have lower cold-hardiness than younger ones,but no significantly different between the larvae in early winter and later winter.The RTB larvae could spend its life in winter below the atmospheric temperie temperature which being lower more than-23.5℃ at least.In contrast,Rhizophagus grandis Gyll.,as a predator of Dendroctonus micans,was introduced to China against RTB since 2001.The mean SCP of Rhizophagus grandis larva is-l8.05 ±2.76℃ which being lower temperature more than ones of any stage of RTB.