光周期对歧阜异针蟋若虫发育的影响

研究了光周期对歧阜异针蟋若虫生长发育的影响.结果表明:25C条件下,歧阜异针蟋若虫发育明显受光周期的影响,长日条件下的若虫发育明显快于短日条件下的若虫发育.当若虫由短日条件转移至长日条件时,能够显著促进若虫的发育,并且转移越早促进效果越明显,而反方向的转移则对若虫发育无明显影响.这表明歧阜异针蟋若虫存在滞育现象,短日条件诱导滞育,长日条件解除滞育,并且低龄若虫对长日条件比较敏感.     

小悍蟋若虫滞育的光周期调控及其季节适应策略

就光周期对小悍蟋T a rta rog ry llusm inuscu lus若虫发育及成虫繁殖的影响进行了调查.结果表明,在30℃恒定长日(LD16 h∶8 h)条件下,小悍蟋若虫63 d内全部供试个体完成羽化,而在恒定短日(LD 12 h∶12 h)条件下,小悍蟋若虫120 d之内仍只有90%的个体完成羽化;将孵化后第7 d和第35 d的若虫自短日条件向长日条件转移,能够促进小悍蟋若虫的发育,而反方向的转移则对小悍蟋若虫的发育几乎不起影响.这表明小悍蟋若虫存在滞育现象,短日条件诱导滞育,长日条件解除滞育,并且低龄若虫对长日条件比较敏感.光周期不仅影响小悍蟋若虫发育,而且也影响成虫的繁殖.长日条件下的成虫产卵量显著多于短日条件下的成虫产卵量.但是,光周期对成虫产卵前期间无明显影响.     

小悍蟋若虫发育的光周期反应模式

对小悍蟋若虫发育的光周期反应模式进行了探讨.结果表明:25℃条件下,小悍蟋若虫发育明显受光周期的影响,长日条件下的若虫发育明显快于短日条件下的若虫发育.当若虫先于LD 12∶12 h条件下发育后转移至LD 14∶10 h、LD 16∶8 h,能够显著促进若虫发育,反方向的转移则会抑制若虫发育.但LD 14∶10 h与LD 16∶8 h之间的光周期变化对小悍蟋若虫发育几乎不起影响.变化光周期对小悍蟋若虫发育的影响与光周期变化的时间、变化方向及低龄若虫感受的光周期类型有关.     

光周期和温度对美凤蝶滞育诱导的影响

对光周期和温度对美凤蝶峨眉种群滞育诱导的影响进行了研究,结果表明:光周期对美凤蝶滞育的诱导作用与温度有关,在20℃的恒温条件下,光照在12～13 h范围内,随着光照时间的缩短,滞育个体增加,在光照时间短于12.5 h后达到100%;在25℃时,光照时间在11～13.5 h范围内,随光照时间的缩短,滞育率增加,但没有出现全部个体滞育的情况,最高滞育率为94.5%;在30℃时,在实验光周期范围内没有出现滞育个体.温度对滞育的影响受光周期的影响,在相同光照条件下,在一定温度范围内,随着温度的上升,滞育率下降,当温度上升幅度达到30℃,无论长短光照条件下均不出现滞育个体.只有在短光照条件下,低温才有利于滞育,而长光照和高温则有利于个体的发育而抑制滞育产生.短光照对滞育的诱导作用具有累积效应.在20℃恒温条件下,美凤蝶的临界光周期为LD 13 h 11 min:10 h 49 min;而在25℃恒温条件下,美凤蝶的临界光周期为LD 12 h 49 min:11 h 11 min.随着温度的升高,临界光照长度缩短.美凤蝶对光周期的敏感期为5龄幼虫.     

光周期和温度诱导美国白蛾滞育

【目的】探究光周期和温度对美国白蛾滞育的影响,明确诱导美国白蛾滞育的主控因子和幼虫敏感龄期,为深入研究光周期诱导美国白蛾滞育的分子机制和开发新型防治技术奠定基础。【方法】设置4个温度(21、23、25和27℃)和7个光周期(L8∶D16、L10∶D14、L12∶D12、L13∶D11、L14∶D10、L15∶D9和L16∶D8),统计和比较28种不同处理条件下美国白蛾的滞育结果,阐明光周期和温度对美国白蛾滞育和临界光周期的影响; 23℃条件下,在美国白蛾幼虫不同发育阶段分别给予长光照(L16∶D8)和短光照(L10∶D14)交替饲养处理,统计和比较32种不同处理下美国白蛾的滞育结果,明确光周期诱导美国白蛾滞育的敏感龄期。【结果】在21、23、25和27℃条件下,光照时间小于13 h,可导致美国白蛾滞育发生,光照时间达到16 h,美国白蛾个体继续发育而无滞育发生,光照时间在13～16 h之间时,滞育同时受光周期和温度调控,且滞育率随光周期增长或温度升高均呈下降趋势。21、23、25和27℃条件下的临界光周期分别为14 h 58 min∶9 h 02 min(L∶D)、14 h 45 min∶9 h 15 min(L∶D)、14 h35 min∶9 h 25 min(L∶D)和14 h 24 min∶9 h 36 min(L∶D),临界光周期随温度升高逐渐缩短。短光照对美国白蛾滞育诱导具有累积效应,美国白蛾幼虫3龄、4龄和5龄对光周期诱导滞育最为敏感。【结论】美国白蛾属典型的长日照发育-短日照滞育型昆虫,光周期在美国白蛾滞育诱导中发挥主导作用,温度伴随光周期发挥作用,低温和短光照利于滞育发生;临界光周期受温度调控,随温度升高逐渐缩短;美国白蛾对光周期诱导滞育具有累积效应,感受光周期最敏感的阶段为幼虫3～5龄。     

昆虫滞育诱导的因素

本文主要论述昆虫滞育诱导的诸多环境因素。对昆虫滞育诱导起作用的有光周期、温度、湿度、食料、激素等，其中光周期和温度是主要因素，昆虫对光周期的反应有长日照型、短日照型和中间型，同时昆虫对光周期的反应存在着地理差异，而对温度的反应则有冬滞育和夏滞育两种类型。     

温度和光照对美国白蛾越夏蛹发育的影响

在实验室内,采用人工饲养的方法测定了美国白蛾越夏蛹的发育与温度和光照之间的关系,结果表明:在相对湿度80％、光周期LD12∶12条件下,25,28,30℃饲喂化蛹的美国白蛾,蛹滞育率分别为35.48％,42.71％,0,蛹的死亡率分别为25.81％,14.58％,8.91％.30℃的饲养条件下不能解除已经进入滞育状态的蛹,在全暗条件下滞育蛹可解除滞育,但蛹期明显加长.     

豫西地区中华松针蚧生物生态学特性初步研究

中华松针蚧Sonsaucoccus sinensis Chen雌雄异型，1a发生1代，雌虫2龄，终生被蜡质蚧壳，不爬出壳外。雄虫3龄，3龄若虫爬出壳外化蛹，进而羽化成虫。滞育期在6月下旬至8月中旬，滞育期解除后1龄寄生若虫蜕变为2龄无肢若虫，继续危害至10月份，并以2龄无肢若虫越冬。各虫态出现期因海拔和气温变化而有差异。海拔高、气温低发育迟，反之发育早。该虫主要是通过风、雨和人为活动等途径传播。化学防治的有利时机在初孵若虫期。     

温度对黄脸油葫芦卵滞育解除的影响

黄脸油葫芦在我国分布广泛,对农作物造成一定程度的危害.调查了温度对江苏泗洪地区黄脸油葫芦卵滞育的影响,检测了低温对其卵滞育的解除效果及高温对促进滞育解除的影响.结果表明:黄脸油葫芦的卵在30、25、20℃的温度条件下均进入滞育;8℃处理40 d以上对黄脸油葫芦的卵滞育具明显的解除效果,但要完全解除其滞育需经8℃处理100 d以上;8℃低温处理20 d尚未能有效解除黄脸油葫芦卵的滞育,但8℃低温处理20 d后再30℃加温,卵的孵化虽然很不整齐,但在60 d内孵化率可达100%;同样,8℃低温处理20 d后经30℃处理7 d以上也会显著提高其孵化率,说明高温具促进黄脸油葫芦卵滞育解除的效果.高温对黄脸油葫芦卵滞育解除的促进作用,在维持其生活史的整齐性,并使其发育与季节保持同步方面具有重要的生态意义.     

不同宿主植物和饲养密度对蠋蝽生长发育和生殖力的影响

为促进蠋蝽规模化养殖,在室内测定不同宿主植物和饲养密度对蠋蝽若虫存活率、发育历期和成虫生殖力的影响,并利用Weibull分布函数S(t)=exp(-btc)拟合蠋蝽若虫在不同饲养密度下的存活率曲线。结果表明:蠋蝽若虫的存活率、发育历期和成虫生殖力因不同的饲养条件而异。宿主植物为榆树幼苗时,蠋蝽若虫存活率最高,平均为82.09%;无宿主植物时若虫存活率最低,平均仅达16.38%。不同宿主植物对若虫发育历期无显著影响,而无宿主植物时若虫发育历期延长。不同宿主植物对蠋蝽成虫生殖力影响显著,宿主为榆树时成虫产卵量最大,平均每雌产卵量可达330.89粒,无宿主植物时产卵量仅为96.64粒。以榆树作为宿主植物,不同饲养密度对蠋蝽若虫存活率影响较大,较低密度饲养时,其存活率差别不大,均达85.56%以上;但饲养密度超过每罩40头时,其存活率显著降低。不同饲养密度对蠋蝽若虫各龄发育历期的影响无规律。不同饲养密度对蠋蝽生殖力有不同程度的影响,密度过高或过低都显著降低其生殖力。     

Wirkungen der Fotoperiode und Temperatur auf die Entwicklungsstadien von Acrotylus insubricus Scop. (Orthopt., Acrididae)

Effect of photoperiod and temperature on the developmental stages of Acrotylus insubricus Scop. (Orth., Acrididae) The effect of different temperatures and photoperiods on the developmental stages ofAcrotylus insubricus Scop. was studied. The species has no embryonic or nymphal diapause. The relatively low temperature of the winter months prolonges the incubation period as well as the nymphal development. By rising temperature both eggs and nymphs began to continue their development. The shortest nymphal duration at 27 °C (63.9 days) was obtained when rearing nymphs at long photoperiod (16L:8D), while the longest duration (92 days), was recorded at short photoperiod (8L:16D). In intermediate photoperiod (12L:12D), the nymphal duration was 82.8 days, between the long and the short photoperiods. At 37 °C, the nymphal durations were shorter than at 27 °C and still the shortest at a long day (4310 days) than the two other conditions. The total nymphal mortality was higher at short day-length than that at the other photoperiods tested. The incubation period as well as the percentage of hatching were not affected by the different photoperiodic regimes while the low temperature prolonges the incubation period and nymphal development. The higher temperature (37 °C) tended to mask or abolish the effect of the photoperiod while the moderate temperature (27 °C) clarified this effect when the two factors were combined together.     

A molecular marker associated with low-temperature induction of dormancy in red osier dogwood (Cornus sericea)

Dormancy induction in temperate deciduous plants is thought to be regulated by short photoperiods, but low temperature has been shown to eliminate the short photoperiod requirement in northern ecotypes. An F2 population (191 plants) red osier dogwood (Cornus sericea L.) derived from a polycross of an F1 population produced from reciprocal crosses of the parental clonal ecotypes, Northwest Territories (NWT, 62 degrees N) and Utah (42 degrees N), was examined to identify molecular markers of temperature-induced endodormancy. Dormancy induction curves were generated for each individual in the F2 population and a standard point prior to vegetative maturity (i-VM) was inferred from the change in slope of the dormancy acquisition curve. Under Saskatoon, Saskatchewan field conditions (52 degrees N), the NWT ecotype entered i-VM on average 5-6 weeks before the Utah ecotype. Two sub-populations of the F2 population were distinguishable based on VM acquisition on exposure to low temperature but not to short photoperiods. A sequence characterized amplified region (SCAR) marker was developed that correctly (> 92%) identified individual plants within the F2 subpopulation that were responsive to low-temperature induction of VM. Timing of bud break was strongly associated with the timing of VM in the geographical ecotypes but not in the F2 population, indicating that these are separate traits under genetic control.     

Physiological responses of three deciduous conifers (Metasequoia glyptostroboides, Taxodium distichum and Larix laricina) to continuous light: adaptive implications for the early Tertiary polar summer

Polar regions were covered with extensive forests during the Cretaceous and early Tertiary, and supported trees comparable in size and productivity to those of present-day temperate forests. With a winter of total or near darkness and a summer of continuous, low-angle illumination, these temperate, high-latitude forests were characterized by a light regime without a contemporary counterpart. Although maximum irradiances were much lower than at mid-latitudes, the 24-h photoperiod provided similar integrated light flux. Taxodium, Larix and Metasequoia, three genera of deciduous conifers that occurred in paleoarctic wet forests, have extant, closely related descendents. However, the contemporary relative abundance of these genera differs greatly from that in the paleoarctic. To provide insight into attributes that favor competitive success in a continuous-light environment, we subjected saplings of these genera to a natural photoperiod or a 24-h photoperiod and measured gas exchange, chlorophyll fluorescence, non-structural carbohydrate concentrations, biomass production and carbon allocation. Exposure to continuous light significantly decreased photosynthetic capacity and quantum efficiency of photosystem II in Taxodium and Larix, but had minimal influence in Metasequoia. In midsummer, foliar starch concentration substantially increased in both Taxodium and Larix saplings grown in continuous light, which may have contributed to end-product down-regulation of photosynthetic capacity. In contrast, Metasequoia allocated photosynthate to continuous production of new foliar biomass. This difference in carbon allocation may have provided Metasequoia with a two fold advantage in the paleoarctic by minimizing depression of photosynthetic capacity and increasing photosynthetic surface.     

Photoperiodic control of seasonal development and dormancy in tropical stem-succulent trees

Tropical stem-succulent trees store large quantities of water in their trunks yet remain leafless during the early and mid dry season. In contrast to most other tropical trees, bud break of vegetative buds is not induced in fully hydrated stem succulents between the winter solstice and the spring equinox by leaf abscission, abnormal rain showers or irrigation. Vegetative buds of leafless trees are therefore in a state of endo-dormancy similar to that of temperate perennial plants during early winter. Highly synchronous bud break regularly occurs soon after the spring equinox, often weeks before the first rainfalls of the wet season. These observations suggested that endo-dormancy and bud break might be induced by declining and increasing photoperiods after the autumn and spring equinoxes, respectively. In phenological field observations, we confirmed highly synchronous bud break after the spring equinox in many trees of five stem-succulent species in the northern and southern hemispheres. Shoot growth of potted saplings of Plumeria rubra L. was arrested by a decline in day length below 12 h after the autumn equinox, but continued in saplings maintained in a 13-h photoperiod. Conversely, exposure to a 13-h photoperiod induced bud break of dormant apical buds in saplings and cuttings in January, whereas plants maintained in the natural day length of < 11.7 h remained dormant. Photoperiodic control of endo-dormancy of vegetative buds in stem succulents is thus supported by field observations and experimental variation of the photoperiod. At low latitudes, where annual variation of day length is less than 1 h, bud dormancy is induced and broken by variations in photoperiod of less than 30 min.     

The abundance of <Emphasis Type="Italic">Orius niger</Emphasis> (Wolf.) and <Emphasis Type="Italic">O. minutus</Emphasis> (L.) in potato fields and their life table parameters when fed on two prey species

Two-spotted spider mite (TSSM) and onion thrips are serious pests of potatoes in the Ardabil region (Iran). In the present study, anthocorid species were identified in potato fields of this region during 2006 and 2007. The results of the abundance study indicate that Orius niger (Wolff) and O. minutus (Linnaeus) are major predators of these pests in potato fields. The life table parameters of these predators were compared when they were fed 2nd instar larvae of onion thrips or female TSSM on potato leaves. In these experiments, O. niger had a lower nymphal mortality, longer oviposition period, higher net reproductive rate (R ₀), and higher intrinsic rate of natural increase (r _m ) when fed thrips instead of mites. O. minutus feeding on mites compare to thrips had a lower nymphal mortality, longer oviposition period, higher net reproductive rate, and higher intrinsic rate of natural increase. Based on these results, it can be concluded that these predators could be useful as biological agents in potato fields.     

Different responses of northern and southern ecotypes of Betula pendula to exogenous ABA application

We investigated responses of northern and southern ecotypes of silver birch (Betula pendula Roth) to exogenous abscisic acid (ABA) under controlled environmental conditions to determine the role of ABA in cold acclimation and dormancy development. Abscisic acid was sprayed on the leaves and changes in freezing tolerance, determined by the electrolyte leakage test, and bud dormancy were monitored. Applied ABA induced cold acclimation but had no effect on growth cessation in seedlings grown in long day conditions (LD, 24-h photoperiod at 18 degrees C). It enhanced freezing tolerance and accelerated growth cessation in seedlings grown in short day conditions (SD, 12-h photoperiod at 18 degrees C), and slightly enhanced freezing tolerance in seedlings grown at low temperature (LT, 24-h photoperiod at 4 degrees C) in both ecotypes. There were distinct ecotypic differences in ABA-induced cold acclimation and dormancy development. The northern ecotype was more responsive to applied ABA than the southern ecotype, resulting in more rapid development of freezing tolerance in all treatments, and earlier dormancy development in SD. When plants were grown in a photoperiod just above the critical photoperiod for the ecotype (defined as the longest photoperiod that induces growth cessation), applied ABA caused growth cessation and dormancy development. Compared with ABA-treated seedlings grown in SD, dormancy development was delayed in ABA-treated seedlings exposed to a near-critical photoperiod, but even in this treatment dormancy developed faster in the northern ecotype than in the southern ecotype.     

Low temperature, but not photoperiod, controls growth cessation and dormancy induction and release in apple and pear

In contrast to most temperate woody species, apple and pear and some other woody species of the Rosaceae family are insensitive to photoperiod, and no alternative environmental seasonal signal is known to control their dormancy. We studied growth and dormancy induction in micropropagated plants of four apple (Malus pumila Mill.) and one pear (Pyrus communis L.) commercial rootstock cultivars in controlled environments. The results confirm that growth cessation and dormancy induction in apple and pear are not influenced by photoperiod, and demonstrate that low temperature (< 12 degrees C) consistently induces both processes, regardless of photoperiodic conditions. Successive stages of the autumn syndrome (growth cessation, formation of bud scales and winter buds, leaf senescence and abscission, and dormancy induction) occurred in response to low temperature. Long days increased internode length at higher temperatures, but had no significant effect on leaf production in any of the cultivars. Chilling at 6 or 9 degrees C for at least 6 weeks (about 1000 h) was required for dormancy release and growth resumption, whereas treatment at 12 degrees C was marginally effective, even after 14 weeks of exposure. We are thus faced with the paradox that the same low temperature conditions that induce dormancy are also required for dormancy release in these species.     

7个美国扁桃品种在河南南阳的引种表现

为了初步筛选出适合河南南阳地区的扁桃品种,为美国扁桃在我国大陆性气候条件下温带地区的引种与发展提供参考,对从美国引进的7个优良扁桃品种All-in-one genetic semi-dwarlf,Nonpareil,Gardenprince,Mission,Neplus,Black butte和Prince在河南南阳地区的表现,从植物学特性、生长特性、结果特性、果实性状等方面,进行观察、对比及分析,并针对其在河南南阳地区的表现,提出在多雨地区发展美国扁桃应注意的事项。     

陕西省长江流域生态地貌功能分区与评价

采用１０个主要生物气候指标，结合地形地貌及相的地带性植被和地带性土壤，对陕西省长江流域３１个县（市）进行动态聚类综合分析，本区可归并为２个森林植物气候带，５个生态地貌功能区。即：低山丘陵区北亚热带常绿落叶阔叶林生物气候区，包括安康盆地，汉中盆地，热暖温带针阔混交林、针叶林生物气候区；包括秦岭南坡东部中山，低山区，秦岭南坡中、西部中、高山区和巴山北坡中山、低山。各生态地貌功能区的生物气候特征明显，符