榆属（榆科）一新种——绵竹榆

绵竹榆的花秋季开放,翅果柱头面被毛,其两侧的翅较果核为窄,果核位于翅果上端接近缺口处,与榔榆(Ulmus parvifolia Jacq.)相似,但树皮深灰色,不规则鳞块状浅裂,叶片先端渐尖,花被片裂至基部,宿存,边缘上部生纤毛,翅果狭椭圆形,中部最宽,向两端渐变窄,果梗与花被等长,长约2 mm,果序梗长约1 mm,而明显不同。     

木虱啮小蜂对木虱分泌物脂溶性物质的嗅觉行为反应

利用Y-型嗅觉仪测定了木虱啮小蜂Tetrastichussp.对枸杞木虱Paratrioza sinicaYangetLi分泌物脂溶性物质的嗅觉行为反应。结果表明木虱啮小蜂的嗅觉行为反应不仅与脂溶性物质有关,而且与每一种物质的浓度也有关系。同一种脂溶性物质因浓度不同对木虱啮小蜂的作用可为吸引、排斥和无反应3种情况。浓度为0.76%正十四烷、1.52%正十四烷、1.84%正十七烷和0.49%正十八烷对木虱啮小蜂吸引作用显著(P<0.01)。0.76%(+)长叶烯、1.52%(-)长叶烯、1.14%正二十烷、2.28%正二十烷1、.22%正二十一烷以及0.62%正二十二烷对木虱啮小蜂吸引作用较前4者弱,显著水平为P<0.05。0.76%正壬烷、0.64%正十三烷、1.96%正十八烷、0.53%正十九烷及1.24%正二十二烷对木虱啮小蜂有显著的排斥作用。苯并噻唑、正十一烷和正十六烷对木虱啮小蜂无作用。浓度为0.49%正十八烷和0.57%正二十烷对木虱啮小蜂有吸引作用,而浓度为1.96%正十八烷和2.28%正二十烷对寄生蜂却有排斥作用。     

Structural and Functional Grounds for Ephedra sinica Expansion in Mongolian Steppe Ecosystems

Morphological and structural characteristics of photosynthetic organs, diurnal changes in photosynthetic and transpiration rates, and the efficiency of water use were studied in three plant species from mountain-steppe ecosystems in Mongolia, Ephedra sinica Stapf, Stipa glareosa P. Smirn., and Allium polyrhizum Furcz. ex Regel. The species studied differed in the structural and functional mechanisms for the adaptation of photosynthetic apparatus to arid conditions. E. sinica has thick, vertical assimilating shoots, which are characterized by a high density (620 mg/cm³) and a small proportion of photosynthetic tissues (13%). The proportion of meso-phyll in the leaves of A. polyrhizum and S. glareosa was two and three times higher, respectively. The low content of phototrophic tissues in E. sinica shoot was compensated for by a high photosynthetic activity of single chloroplasts (25 mg CO₂/(10⁹ chloroplast h)), which was six times higher, than in two other species. Daily course of photosynthesis and transpiration inE. sinica differed from those of A. polyrhizum and S. glareosa by the absence of the midday depression. E. sinica had the highest efficiency of water use (45 mg CO₂/g H₂O) due to a low transpiration rate (0.25 g/g fr wt h). It is concluded that, in E. sinica, the main strategy for adaptation to arid stress is to develop in the shoot a few photosynthesizing cells of high assimilation activity. Such structural organization of photosynthetic organs in ephedra contributes to its higher efficiency of water use and stability of physiological characteristics under changing environmental conditions. These specific features of the structure of assimilating organs and their functional features contribute to a greater expansion of E. sinica with increasing climate aridization in Mongolia.     

我国特有植物缙云卫矛濒危机理分析

缙云卫矛为我国二级保护植物,仅分布于重庆北碚缙云山和统景镇东温泉公园,皆为旅游胜地。缙云卫矛常以伴生种存在于慈竹林。伴随着旅游业的发展,适宜于缙云卫矛生存的空间环境越来越小,致使该物种处于濒危状态。导致缙云卫矛濒危的原因主要有：(1)物种的生态幅较小,适宜生长在水热条件良好的环境中,(2)形态可塑性较差,对生境的适应能力差;(3)生长发育缓慢,竞争能力较弱;(4)种子萌发率低;(5)人为干扰严重。此外,还讨论了缙云卫矛保护对策。     

国产丽豆属2个种的比较形态及其生态学特性和地理分布

对国产丽豆属间断分布的 2个种丽豆 Calophaca sinica 和新疆丽豆 C.soongorica 进行了形态、地理分布及其生态学特性的研究 ,其中包括叶表皮微观结构、花粉和果皮形态、种皮特征以及分布现状、生态学适应性等 ,结合古地理、气候、植被等的变迁 ,探讨了丽豆属的起源、形态分化及其环境解释以及现代分布式样的成因 ,并对其资源利用与保护方面的有关问题提出了相关措施和建议     

Reproductive biology of Magnolia sinica (Magnoliaecea), a threatened species with extremely small populations in Yunnan,China

Magnolia sinica is one of the most threatened trees endemic to Southeast Yunnan. Based on our investigations, only 52 individuals and eight populations are found in the wild. M. sinica has been categorized as Critically Endangered on the IUCN Red List and identified as a “Plant Species with Extremely Small Populations (PSESP)”. Its fruit/seed set is very low and seedlings are rarely found in the wild. It is hypothesized that it may encounter obstacles to reproductive success. This study, therefore, focuses on its reproductive biology, knowledge of which is essential for effective conservation. Flowers of this species are protogynous and nocturnal, and possess a two-day rhythm of sexual presentation. For the first night of anthesis, the flowers are in the pistillate stage during which tepals open at dusk and close approx. 1 h later (except for the open outer ones). They remain closed until the next afternoon, when flowers, now in the staminate stage, re-open and remain so until the tepals drop. Nocturnal beetles enter into the flowers and remain trapped throughout the night as the flower closes, during which time they feed on tepals. Pollen-gathering bees are found to visit the re-opened flowers and the beetles are released during this stage. Two species of Pleocomidae and Curculionidae beetles appear to be effective pollinators.M. sinica is a self-compatible, pollinator-dependent species, and its fruit/seed set can be significantly increased by hand-pollination. No functional seed dispersers have been found in its extant natural habitats. These findings suggest that it may face both pollination and seed disperser insufficiencies in its current fragmented habitats, which may account for its low regeneration. Here we propose conservation strategies based on our findings.     

光周期对中华通草蛉自然越冬成虫及实验种群幼虫耐寒能力的影响

【目的】滞育诱导期进行短光照处理可影响昆虫耐寒性。为明确光周期对中华通草蛉Chrysoperla sinica (Tjeder)耐寒性的影响, 针对中华通草蛉滞育解除过程及非滞育虫态的耐寒性进行了一系列研究。【方法】测定了中华通草蛉自然越冬成虫的过冷却点（supercooling point, SCP）以及长光周期（15L∶9D）和短光周期（9L∶15D）条件下自然越冬成虫在滞育解除过程中在-12℃下的死亡率, 并测定了室内长、 短两种光周期下实验种群2龄和3龄幼虫的过冷却点（SCP）、 结冰点（freezing point, FP）以及-7℃下的死亡率。【结果】中华通草蛉12月份的自然越冬成虫SCP集中在-10~-14℃之间。SCP低于-12℃的个体占43.70%, 且-12℃处理1 d死亡率为62.00%。-12℃处理1 d条件下的长、 短光周期处理自然越冬成虫, 除处理0 d外, 长光周期处理死亡率均高于短光周期处理的, 且在处理15 （P=0.012）, 20 （P=0.01）和25 d （P=0.001）差异显著。中华通草蛉试验种群相同龄期幼虫在短光周期下的SCP和FP均高于长光周期下, 但差异不显著(P>0.05); 但在-7℃下, 2龄幼虫短光周期下的低温死亡率为67.00%±4.04%, 显著低于长光周期下的低温死亡率（78.00%±1.33%）（P=0.011）, 3龄幼虫短光周期条件下低温死亡率为24.33%±1.33%, 显著低于长光周期下的低温死亡率（53.00%±3.46%）（P=0.002）。【结论】中华通草蛉为结冰敏感型, 诱导滞育的短光照处理可提高其幼虫期及滞育解除过程中成虫的耐寒能力。     

Non-alkaloid Constituents of Buxus sinica (Buxaceae)

From the aerial parts of Buxus sinica, ten non- alkaloid compounds were isolated and identified as cleomiscosin A ( 1 ), 3, 5-dihydroxyl-4', 6, 7-trimethyl flavone-3′- O-β- D-glucopyranoside ( 2 ), 3, 5, 3', 4′tetrahydroxyl-3, 6, 7-trimethyl flavone (3 ) , cleomiscosin A-4′- O-β- D-gluco-pyranoside (4 ), 3, 5-dimethoxybenzoicacid-4- O-β- D-glucopyranoside (5 ), 4′, 5-dihydroxyl-3, 6, 7-trimethyl flavone (6), lupine (7), ( + )-pinoresinol- O-β- D-glucopyranoside (8 ), β-sitosterol (9), and daucosterol (10). Their structures were identified by spectral evidence.     

百合科寄主植物对韭菜迟眼蕈蚊的生物效应

室内分别用百合科韭菜、大葱、大蒜和圆葱饲喂韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang幼虫,研究了4种寄主植物对其生长发育和繁殖的影响;用气-质谱联用分析技术,检测了人工合成大蒜素及大蒜、圆葱和韭菜的乙醇提取物的主要化学成分。结果表明,4种供试寄主植物对韭菜迟眼蕈蚊生长发育和繁殖的影响存在差异,幼虫取食韭菜最有利于其生长发育和繁殖;取食大蒜和圆葱对其生长发育和繁殖表现出明显的不利性,主要表现为幼虫死亡率增加,幼虫期延长,蛹重减轻,单雌产卵量降低;而取食大葱的影响介于取食韭菜与取食大蒜和圆葱之间。大蒜、圆葱的乙醇提取物和人工合成的大蒜素均对韭菜迟眼蕈蚊1龄幼虫有不同程度的杀虫活性,大蒜和圆葱的乙醇提取物（干粉,2 g/mL）稀释100和200倍,处理后48 h对1龄幼虫的校正死亡率分别达54.7%、28.0%和49.4%、22.7%;10%大蒜素稀释500和1 000倍,处理后48 h校正死亡率达100%和80.0%。成分分析表明硫醚类化合物可能是大蒜和圆葱中含有的杀虫活性物质之一。     

有害赤潮生物球形棕囊藻对卤虫的毒性研究

利用1997年10月和1998年6月分别在广东汕头饶平海域和香港海域分离到的球形棕囊藻,即球形棕囊藻香港株(Phaeocystis globosastrain HK)和球形棕囊藻汕头株(Phaeocystis globosastrain ST),在实验室条件下研究其对四日龄卤虫(Artemia sinica)的急性毒性。结果表明,对数生长期的HK株藻液24h对卤虫LC₅₀约为2.9×10⁵cell·mL^-1。对数期的ST株对卤虫的毒性难以达到半致死浓度,衰亡期的ST株24h对卤虫LC₅₀约为9.89×10⁶cell·mL^-1。在上述浓度下两者半致死时间分别为20.91h和26.62h,而对数生长期的HK株和衰亡期的ST株的培养物过滤液24h对卤虫LC₅₀则分别为7.1×10⁵cell·mL^-1和1.457×10⁷cell·mL^-1,且在该浓度下的半致死时间分别为26.56h和28.02h。实验表明,HK株藻液和滤液的毒性均大于ST株,且藻液的毒性均大于滤液。