甘薯天蛾过冷却点变化与生化成分的关系

测定长沙地区甘薯天蛾Agrius convolvuli L.在发育过程中不同时期的过冷却点、虫体水分和粗脂肪含量,并对其动态变化和相互之间的相关性进行分析。结果表明:不同世代甘薯天蛾过冷却点均随发育进程显著升高,在蛹期明显下降;2龄幼虫的过冷却点均为-11℃左右,蛹的过冷却点在越冬代过冷却点为-7·38℃,比其他世代蛹低2~3℃。甘薯天蛾虫体含水量随发育进程不断降低,粗脂肪含量则不断升高,其越冬代蛹粗脂肪含量占其干重高达30·23%。甘薯天蛾过冷却点与虫体水分含量呈正相关;而与虫体粗脂肪含量呈负相关,且在第2、3代和越冬代均呈显著负相关。甘薯天蛾在发育过程中通过调节水分和粗脂肪含量可能是其抵抗低温的生理机制之一。     

Geographic variation in cold hardiness of eggs and neonate larvae of the yellow-spotted longicorn beetle Psacothea hilaris

Cold hardiness of eggs and neonate larvae of the yellow-spotted longicorn beetle, Psacothea hilaris (Pascoe) was examined using six geographical populations in Japan. Particular attention was paid to cold hardiness of eggs and neonate larvae of the subtropical population (Ishigaki), because the east Japan populations are considered to have been introduced from a subtropical area, and the overwintering stage in the east Japan populations is incidentally shifted from the original mature larval stage to the egg or neonate larval stages. When the eggs were exposed to low temperatures for 1 h, the decrease in hatchability became significant at –12°C in the southernmost two populations (Ishigaki and Naze), and at –16°C in the northern populations. After 1 h exposure to –20°C, few eggs could hatch in the Ishigaki population, whereas 27–55% of the eggs survived in the northern populations. Pre-chilling of the eggs at 10°C for 10 days enhanced the cold hardiness in all populations. This effect was particularly distinct in the subtropical population; the eggs of the Ishigaki population became as cold hardy as those of the northern populations after acclimation. These results suggest that the subtropical population is capable of establishing itself in east Japan, where the winter is cold.     

温度变化对休耕期冬水田天敌捕食猎物的影响及天敌耐冷性分析

为评估冬水田休耕季节长达6-8个月温度变化对稻田主要捕食性天敌通过觅食策略维持其种群发生的影响,在室内测定了两种代表性温度下青翅蚁形隐翅甲Paederus fuscipes成虫、拟水狼蛛Pirata subpiraticus和拟环纹豹蛛Pardosa pseudoannulata成蛛、亚成蛛对天台刺齿虫兆Homidia tiantaiensis和白翅叶蝉Thaia rubiginosa成虫的捕食功能反应、搜寻效应、自身密度干扰效应以及捕食偏好性;测定了这些捕食者在这两种温度诱导下的过冷却点（Supercooling point,SCP）和结冰点（Freezing point,FP）。结果表明,温度变化显著影响了捕食性天敌的捕食功能反应、对猎物的搜寻效应以及自身密度的干扰反应。在22℃和12℃下,捕食者对刺齿虫兆和叶蝉的捕食功能反应均符合Holling II模型。由捕食功能反应可知,22℃下捕食者对两种猎物的捕食量均高于12℃下的捕食量,两种温度下捕食者对刺齿虫兆的捕食量要显著高于对叶蝉的捕食量。22℃下捕食者对两种猎物的瞬时攻击率、最大捕食量和a/T_h值均相应地高于12℃下的值,而22℃下它们对两种猎物的处理时间则相应地小于12℃下的处理时间。在同一猎物相同温度下,狼蛛和豹蛛亚成蛛的瞬时攻击率、最大捕食量和a/T_h值均相应地高于狼蛛和豹蛛成蛛的值,它们的处理时间则明显小于其成蛛的处理时间。隐翅甲的最大捕食量和a/T_h值在12℃叶蝉试验中均最大,而其处理时间则最小;其它条件下的隐翅甲参数值通常介于狼蛛和豹蛛成蛛、亚成蛛各参数值之间。捕食者对两种猎物的搜寻效应与猎物密度呈负相关;温度变化对捕食者搜寻效应的影响程度与捕食者和猎物的种类有关;22℃下的搜寻效应值均高于12℃下的搜寻效应值。捕食者对两种猎物的捕食作用均随自身密度升高而下降,22℃下对两种猎物和12℃下对刺齿虫兆的搜寻常数和干扰系数值均以狼蛛和豹蛛亚成蛛的为最高,而12℃下对叶蝉的这2个值以豹蛛亚成蛛和隐翅甲的为最高。两种温度下捕食者对这两种猎物存在选择偏好性,更嗜食刺齿虫兆,但温度变化没有对捕食者的这种猎物偏好性产生影响。在这两种温度快速冷驯化下这些捕食者间的SCP和FP均差异显著,通常温度降低能诱导亚成蛛的SCP和FP下降,而成蛛的升高,隐翅甲的变化很小或下降,说明不同捕食者适应温度降低的耐冷特性与其捕食作用间存在一定相关性。     

上海地区红棕象甲的耐寒性研究

红棕象甲Rhynchophorus ferrugineus (Olivier)是我国危害棕榈科植物的重要入侵害虫, 为探明其越冬抗寒性, 利用过冷却点测定仪测定了红棕象甲上海种群不同虫态的过冷却点, 在低温箱内测定了该虫不同虫态的耐寒性, 然后结合田间越冬模拟试验、气象资料和寄主分布情况, 初步确定了红棕象甲在我国的越冬北界。结果表明： 红棕象甲过冷却点随虫态的发育程度的升高而下降, 卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫的平均过冷却点分别为-5.92, -6.42, -7.19, -7.43和-11.84℃, 过冷却点由高到低的顺序依次为: 卵>幼虫>成虫。在6, 24, 48和72 h 4个时间处理下, 各虫态在低温与存活率之间呈显著或极显著的logistic回归, 半致死温度（Ltemp₅₀）均随处理时间的延长而上升, 不同虫态在处理72 h 后, 卵、1龄幼虫、5龄幼虫、9龄幼虫和成虫之间的Ltemp₅₀分别为1.61, -1.67, -2.39, -2.40和-0.40℃, 各虫态耐寒性由弱到强的顺序依次为: 卵<成虫<幼虫。红棕象甲不同发育阶段的过冷却点与其耐寒性并不完全相关, 幼虫和成虫均可能是该虫的越冬虫态。连续两年的田间模拟越冬试验表明, 在上海地区, 红棕象甲的幼虫和成虫的越冬存活率均在60％以上, 说明红棕象甲在上海地区是可以越冬的。根据这些结果, 结合寄主分布情况, 初步将红棕象甲在我国的越冬北界定于北纬35°附近, 即1月份0℃等温线左右。     

The Use of High-resolution Infrared Thermography (HRIT) for the Study of Ice Nucleation and Ice Propagation in Plants

Freezing events that occur when plants are actively growing can be a lethal event, particularly if the plant has no freezing tolerance. Such frost events often have devastating effects on agricultural production and can also play an important role in shaping community structure in natural populations of plants, especially in alpine, sub-arctic, and arctic ecosystems. Therefore, a better understanding of the freezing process in plants can play an important role in the development of methods of frost protection and understanding mechanisms of freeze avoidance. Here, we describe a protocol to visualize the freezing process in plants using high-resolution infrared thermography (HRIT). The use of this technology allows one to determine the primary sites of ice formation in plants, how ice propagates, and the presence of ice barriers. Furthermore, it allows one to examine the role of extrinsic and intrinsic nucleators in determining the temperature at which plants freeze and evaluate the ability of various compounds to either affect the freezing process or increase freezing tolerance. The use of HRIT allows one to visualize the many adaptations that have evolved in plants, which directly or indirectly impact the freezing process and ultimately enables plants to survive frost events.     

An insect introduction to the maritime Antarctic

Although several invertebrates have been introduced by Man into the Antarctic, no holometabolous insects have survived to colonize terrestrial habitats successfully. Data are presented on the survival of populations of a chironomid midge, together with an enchytraeid worm, for 17 years in a maritime Antarctic site at Signy Island, South Orkney Islands. Both species are thought to have been introduced on plant material transplanted from either South Georgia or the Falkland Islands or both in 1967. Population densities average 25718m^-2 for the dipteran larvae and 3243 m^-2 for the worms. Successful completion of the midge's life cycle was indicated by emergence of brachypterous adults and oviposition (the population is parthenogenetic with only females present). Although both taxa are capable of supercooling to between -13 and -26°C, this capacity may not be sufficient in a severe winter to avoid lethal freezing. Four potential cryoprotectants were found in insect extracts, but in concentrations (< 1 % fresh weight) unlikely to influence cold hardiness. Both invertebrates appear to be pre-adapted for survival in much harsher conditions than they normally experience, by the extension of existing physiological mechanisms. It is concluded that the main limitations to invertebrate colonization of suitable Antarctic land areas by soil-dwelling species are geographical.     

Cold-hardiness and development of eggs of Rhopalosiphum insertum

Abstract. 1. The eggs of Rhopalosiphum insertum (Walker) showed a seasonal increase in cold-hardiness under field conditions. Their supercooling point fell from -35°C in November to below -40°C in January, then rose to-35°C or above by March.
2. Laboratory experiments demonstrated that both temperature and date affected cold-hardiness of the eggs. The supercooling points of eggs kept at 16 h photoperiod or in darkness did not, however, differ significantly.
3. Eggs brought from the field into warm, long-day conditions would not hatch until after mid-January. After this date, per cent hatch was significantly greater in 16 h photoperiod than in darkness; it did not differ between eggs kept at 5 or 0°C, but was reduced at -5°C.
4. It is concluded that eggs of Rinserturn are in diapause until mid-January, and that hatching rate and cold-hardiness are determined by separate environmental factors.     

Survival at low temperature of larvae of the pine processionary moth Thaumetopoea pityocampa from an area of range expansion

1 Larvae of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) develop throughout the winter, although their feeding activity and survival can be impaired by adverse climatic factors. The present study investigated the survival at low temperature of larvae originating from a population with range expansion in an alpine valley in Northern Italy.
2 The supercooling point of individually analysed larvae averaged at −7 °C. This value insufficiently described the cold hardiness of the larvae; 39% of the tested larvae were alive when returned to room temperature immediately after freezing. When larval colonies inside their nest were exposed to −17 °C for 1 h after gradual temperature decrease, survival was 70.4%.
3 Rearing of larvae in the laboratory at different day/night temperatures indicated an effect of cumulative chill injury on larvae. A logistic regression explained the relationship between negative thermal sum (h°C below 0 °C) received in the laboratory experiment and larval survival. A similar relationship was demonstrated between negative thermal sum and survival of larval colonies in the field.
4 In the laboratory experiment, some tested larvae were able to survive for up to 8 weeks without feeding depending on rearing temperature. As expected, feeding occurred only when larvae were reared at temperatures of 9 °C day/0 °C night.
5 We classify the larvae of T. pityocampa as being moderate freezing tolerant. The winter behaviour allows this species to track climate warming by a rapid expansion into those areas that become compatible with the insect's development.     

红脂大小蠹幼虫和成虫耐寒能力及耐寒物质的研究

为明确红脂大小蠹Dendroctonus valens LeConte的耐寒能力以及主要耐寒物质,对越冬期幼虫和成虫的过冷却点及冰点进行了测定,同时对越冬期及非越冬期幼虫和成虫体内的抗冻保护物质进行了测定.结果表明,越冬期幼虫和成虫的过冷却点差异不显著,分别为-18.34±0.26℃和-18.59±0.63℃,冰点差异...     

宁夏赤霞珠葡萄不同发育期晚霜冻害阈值试验研究

【目的】葡萄霜冻温度阈值是葡萄霜冻监测、预测、评估与防御的基础。对贺兰山东麓主栽酿酒葡萄‘赤霞珠’不同发育期低温忍耐力进行研究分析,建立葡萄霜冻温度阈值体系,旨为贺兰山东麓地区酿酒葡萄霜冻预测、防御提供理论依据。【方法】于2022年4—5月采用野外霜冻试验箱原位试验方法对贺兰山东麓主栽酿酒葡萄品种‘赤霞珠’不同发育期绒球、芽、新叶、新梢进行低温处理,测定其过冷却点、相对电导率（REC）及半致死温度（LT50）,同时对低温胁迫后的受冻指数进行田间跟踪调查,利用受冻率与低温建立关系模型,计算不同发育期轻、中、重度受冻温度阈值。对不同发育期过冷却点、半致死温度（LT50）及霜冻指标温度阈值进行综合分析,确定不同发育期霜冻温度阈值。【结果】结果表明：不同低温对‘赤霞珠’绒球期、芽开放期、展叶期和新梢生长期的影响程度不同,温度越低,各发育期的受冻率越大;随发育进程推进,‘赤霞珠’过冷却点温度、半致死温度逐渐升高;绒球期的低温耐受性最强,芽开放期、展叶期次之,新梢生长期最弱。【结论】研究认为：-7.70℃是绒球期重度受冻的起始温度;芽开放期遭受重度霜冻的临界温度为-4.49℃;展叶期在-2.79℃即遭受不可逆伤害;新梢生长期出现低于-1.62℃以下的低温,会造成严重的霜冻。