河南新乡小麦区荻草谷网蚜的冬季耐寒性研究

为给荻草谷网蚜Sitobion miscanthi的准确预测预报提供理论依据,本研究利用过冷却点(Supercooling point,SCP)、低温暴露死亡率和冷识别温度(80％死亡率时的温度)等昆虫耐寒性指标评价低温条件下不同发育阶段该虫的耐寒能力.结果表明,荻草谷网蚜各发育阶段的SCP变化范围为-27.10～-12.23℃,SCP为1龄若蚜>2龄若蚜>有翅孤雌成蚜>无翅孤雌成蚜>4龄若蚜>3龄若蚜,其中1龄和2龄若蚜的SCP均显著高于3龄和4龄的SCP(P<0.01),3龄和4龄若蚜的SCP无显著性差异(P>0.05),无翅孤雌成蚜与其它发育阶段蚜虫的SCP均无显著性差异(P>0.05);两种虫态的低温存活率和冷识别温度分析表明,在-10～-8℃不同低温下,荻草谷网蚜1龄若蚜低温存活率均显著高于初羽化有翅成蚜的低温存活率(P<0.05),1龄若蚜和初羽化有翅成蚜的冷识别温度分别为-8.5℃和-7.9℃;两种虫态在0℃经过4 h冷驯化后,1龄若蚜和初羽化有翅成蚜在2 h的存活率提升最高,分别为62％和64％,均显著高于无冷驯化的对照组(P<0.05).本研究结果充分说明了荻草谷网蚜具有极强的耐低温适应能力,结合河南新乡近5年冬季极端低温数据,本文推测该虫能在冬季极端低温高于其冷识别温度的年份在当地越冬.     

柑桔大实蝇老熟幼虫和蛹过冷却点和结冰点的测定

为明确柑桔大实蝇Bactrocera minax (Enderlein)老熟幼虫和蛹的抗寒能力,对柑桔大实蝇老熟幼虫、滞育蛹和滞育解除蛹的过冷却点和结冰点进行了测定。结果显示,同一虫态不同个体间其过冷却点和结冰点具有不同程度的变异,但其变异范围均符合正态分布。柑桔大实蝇不同发育状态间的过冷却点和结冰点均具有显著差异,其中,已解除滞育进入发育状态的蛹的过冷却点和结冰点最低,分别为-11.15℃和-9.76℃;其次为滞育蛹,分别为-8.93℃和-7.63℃;而老熟幼虫最高,分别为-7.09℃和-3.43℃。此外,老熟幼虫的结冰点和过冷却点之间的差值最大为3.24℃,显著高于滞育蛹（1.30℃）和滞育解除蛹（1.39℃）。表明,倒春寒对已进入发育状态的柑桔大实蝇蛹不会造成不利影响。     

湖北地区豚草卷蛾发生规律与抗寒性研究

【背景】豚草卷蛾是豚草的一种重要天敌,1993年在湖南临湘野外释放后,迅速扩散至湖北、江西、福建等省,对豚草种群的蔓延与扩张起到了一定的抑制作用。【方法】为明确豚草卷蛾在湖北的发生规律与抗寒性,2009年在湖北各豚草发生区进行野外调查,并将豚草卷蛾越冬态老熟幼虫置于不同低温下观测其存活率。【结果】豚草卷蛾主要分布于鄂东地区。其越冬代成虫于5月下旬至6月上旬发生,第1代幼虫发生高峰在6月下旬至7月上旬,10月中下旬老熟幼虫进入滞育。12月份的调查结果显示,豚草有虫株率为90%,虫口密度为313头.百株-1,存活率为93.3%。越冬老熟幼虫过冷却点为-26.4℃,存活率和存活时间随温度的降低而下降。【结论与意义】豚草卷蛾已广泛分布于湖北地区,且能成功越冬,对豚草可起到持续控制作用。     

中华通草蛉自然越冬成虫在两种光周期下滞育解除过程中的生理生化变化

摘要: 光周期在昆虫滞育中起重要作用, 而昆虫光敏感性差异导致了光在昆虫滞育解除过程中作用机制的多样性。为明确光周期在中华通草蛉Chrysoperla sinica (Tjeder)滞育解除过程中的调控机制, 本研究测定了长光周期（15L∶9D）和短光周期（9L∶15D）条件下, 中华通草蛉自然越冬种群成虫在滞育解除过程中的干重、 含水量、 过冷却点（supercooling point, SCP）、 结冰点（freezing point, FP）及蛋白质和糖原含量变化。结果表明： 雌成虫干重在长光照下处理30 d低于短光照下, 其他处理时间的干重均高于短光照下, 但处理间差异不显著（P>0.05）; 雄成虫在长光照下处理5 d的干重高于短光照下, 其余处理时间的干重均低于短光照下, 其中处理30 d 时差异显著（P<0.05）。雌、 雄成虫含水量总体呈上升趋势, 长光照下上升显著（P<0.05）, 短光照下上升不显著（P>0.05）。雌、 雄成虫的SCP、 FP在短光照下处理不同时间均无显著性差异（P>0.05）, 而长光照下表现出先降后升的趋势且处理间差异显著（P<0.05）。成虫蛋白含量在短光照条件下雄虫处理10 d以及雌虫处理15 d均显著低于长光照（P<0.05）, 其他处理之间没有显著性差异。短光照处理成虫体内糖原含量均高于长光照, 且有显著性差异（P<0.05）。多因素方差分析表明, 不同光周期对中华通草蛉成虫滞育解除过程中的SCP、 FP、 糖原变化均有显著性影响（P<0.05）, 而对干重、 含水量及蛋白质含量影响不显著;性别只对成虫FP与糖原有显著影响（P<0.05）; 处理时间对干重、 含水量、 SCP、 FP、 蛋白及糖原含量均有显著影响（P<0.01）。3种因素的交互作用对SCP、 FP、 蛋白及糖原含量均有显著影响, 对干重及含水量影响不显著。初产卵成虫体内物质含量变化测定发现, 长光照（处理10 d）下雌、 雄成虫体内蛋白和糖原含量极显著低于短光照（处理25 d）下（P<0.01）, 雄成虫体内含水量显著高于短光照下（P<0.05）。结果说明, 中华通草蛉自然越冬成虫在长、 短两种光周期下均逐渐解除滞育, 但在滞育解除过程中呈现出不同的生理生化变化。     

Probability distributions of enantiomeric excess in unstirred and stirred crystallization of 1,1'-binaphthyl melt.

Crystallization of 1, l'-binaphthyl from its melt can generate optical activity spontaneously. Since crystallization is a stochastic process, the enantiomeric excess (ee) generated in each crystallization varies randomly. We investigated the qualitative features of probability distribution of the ee for crystallization at two temperatures, 150 degrees C and 152 degrees C, at which conglomerate crystallization occurs. No clear transparent crystals were produced at either temperature, indicating that the solid states formed in the melt were polycrystalline. The ee randomly fluctuated from run to run, with an average of 26.9% and 2.7% when the crystallization was carried out at 152 degrees C, and 150 degrees C, respectively. The spread of the probability distribution is also substantially different. We also studied the probability distribution of ee in stirred crystallization at different stirring RPM. The results show probability distribution's broadening and evolution to a bimodality with increasing stirring RPM--a typical behavior in symmetry-breaking transitions. These results shed light on the nature of enantioselectivity in secondary nucleation and crystal growth.     

Role of latent heat in chiral symmetry breaking transition in the crystallization of 1,1'-binaphthyl

The influence of latent heat dissipated by the crystallization of 1,1'-binaphthyl in its supercooled molten state on the chiral symmetry breaking transition was investigated. Temperature change in the crystallization system was monitored by infrared thermocamera. Temperature rise due to the dissipation of latent heat in the growing front of polycrystalline aggregate was about 2 degrees C in an unstirred crystallization system. The melting point of racemic mixture and racemic compound of 1,1'-binaphthyl is 145 degrees C and 158 degrees C, respectively. The latent heat generated by the crystallization could thus change the crystallization behavior when the initial temperature of the melt was slightly lower than 145 degrees C. The temperature change in both unstirred and stirred crystallization systems was monitored. In the stirred crystallization system, even in the case when the initial temperature of the melt was about 2 degrees C lower than 145 degrees C, the temperature rose by about 4 degrees C immediately after the onset of crystallization. This indicates that the role of stirring as the critical parameter for the chiral symmetry breaking transition is not only to clone the chiral crystals but also to enhance the dissipation of latent heat due to secondary nucleation.     

Cold adaptation in insects of Central Yakutia

The mode of cold hardening was for the first time assessed for 20 insect species living in the extremely cold climate of Yakutia. All insects tested were found to adapt through freeze tolerance, producing ice-nucleating agents that cause the hemolymph to freeze at high subzero temperatures. For the first time ice-nucleating agents were demonstrated in Lepidoptera. Pieris rapae exemplified the possibility of switchover in the survival strategy depending on the climatic conditions.     

Cold tolerance of the invasive larch casebearer and implications for invasion success

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