食蚜瘿蚊全虫态形态记述

【目的】基于实验室饲养的食蚜瘿蚊Aphidoletes aphidimyza (Rondani)进行个体发育的形态特征描述。为食蚜瘿蚊的鉴定提供基本信息。【方法】在野外采集幼虫,温度(25±1)℃、相对湿度65%±5%、光照16 L∶8 D的室内条件下饲养获得食蚜瘿蚊卵、幼虫、蛹和成虫的全部虫态。通过数码采集和电子显微镜详细描述了各虫态的发育特征。【结果】食蚜瘿蚊卵的发育历期为2 d,幼虫期有3个龄期,发育历期5-8 d,蛹期7-10 d以及成虫期3-4 d。【结论】食蚜瘿蚊个体发育特征对食蚜瘿蚊的鉴定和分类有指导意义。     

不同温度对食蚜瘿蚊生长发育和幼虫捕食能力的影响

【目的】明确不同温度对食蚜瘿蚊Aphidoletesaphidimyza(Rondani)幼虫生长发育、捕食能力及控蚜效能的影响。【方法】在实验室不同温度条件下,测定了食蚜瘿蚊从卵到老熟幼虫的发育历期和日捕食量,并测定了食蚜瘿蚊3龄初幼虫的捕食功能反应。【结果】随着温度的升高,食蚜瘿蚊卵和幼虫发育速度加快,捕食天数减少,总捕食量增加,各温度间的总捕食量差异显著。温度为22-30℃时,食蚜瘿蚊幼虫在第3-4天开始捕食蚜虫,随后的1-2d内日捕食量达到高峰,随猎物密度增加,3龄初幼虫捕食量有明显的逐级上升趋势。每个温度下食蚜瘿蚊幼虫对玉米蚜Rhopalosiphum maidis (Fitch)的捕食功能反应均符合HollingⅡ型方程,18-30℃最大捕食量分别为30.9、33.0、35.2、48.9头,食蚜瘿蚊幼虫瞬时攻击率26℃时最高为0.99,单头猎物处理时间在30℃时最短为0.02 d。食蚜瘿蚊的控蚜能力30℃时最强,当温度降低时,其控蚜能力相应减弱。【结论】较高的温度有利于食蚜瘿蚊幼虫的发育、捕食和对蚜虫的控制。     

食蚜瘿蚊对莴苣指管蚜的捕食作用

【目的】为明确食蚜瘿蚊Aphidoletes aphidimyza对莴苣指管蚜Uroleucon formosanum的控害潜能。【方法】本研究在室内条件下测定食蚜瘿蚊对莴苣指管蚜的捕食功能反应,并利用室外笼罩法模拟食蚜瘿蚊对莴苣指管蚜的田间控害潜能。【结果】食蚜瘿蚊3龄幼虫对1-5龄莴苣指管蚜的捕食功能反应符合HollingⅡ模型,对1-2龄莴苣指管蚜的瞬时攻击率(a)和捕食能力(a/T_h)均最高,分别为0.466和12.90;搜寻效应随莴苣指管蚜密度的增大而下降;食蚜瘿蚊3龄幼虫对1-5龄莴苣指管蚜的日均捕食量随自身密度的增加而增大,但捕食作用率随其密度的增加而逐渐降低,其种内干扰方程分别为：E_1–2=0.304P^﹣1.148、E₃=0.226P^﹣1.155、E₄=0.177P^﹣1.094、E₅=0.128P^﹣1.028;在捕食偏好选择中,食蚜瘿蚊3龄幼虫对莴苣指管蚜1-2龄及3龄若蚜的...     

粘虫抗寒力的初步研究

【目的】本研究旨在初步探索粘虫的抗寒力,以期能够为粘虫Mythimna separata(Walker)预测预报提供依据。【方法】测定粘虫不同发育期、不同光周期下的过冷却点,并计算虫体含水量;测定0、5、10℃下处理不同时间时粘虫老熟幼虫和蛹的死亡率。【结果】蛹的过冷却点、结冰点和含水量最低,并且粘虫不同发育期的过冷却点、结冰点和含水量差异显著(P0.05);不同光周期下粘虫的过冷却点和含水量并无显著差异;在0、5、10℃条件下,粘虫老熟幼虫和蛹的死亡率均随着温度降低而增加,老熟幼虫的死亡率均小于蛹;雌雄蛹对低温的抵抗力有差异,温度较低并且处理时间较短时,对雌蛹的死亡率影响较大,而温度稍高或处理时间较长时,对雄蛹的死亡率影响较大。【结论】粘虫蛹的抗寒力最强,低温以及低温的持续时间影响蛹的性比以及老熟幼虫和蛹的死亡率,光周期对粘虫的抗寒力无显著影响。     

沙葱萤叶甲的过冷却能力与抗寒性

【目的】沙葱萤叶甲Galeruca daurica Joannis于2009年开始在内蒙古草原暴发成灾, 发生地区不断扩大, 危害日趋严重, 严重影响内蒙古草原畜牧业的可持续发展和生态安全。低温是影响昆虫生长发育和存活的关键因子, 而昆虫对低温的耐受性决定了其越冬存活率。了解沙葱萤叶甲的过冷却点及抗寒能力有助于预测其分布范围及种群数量动态。【方法】采用热电偶法, 在室内测定了沙葱萤叶甲各发育阶段的过冷却点; 比较了幼虫在不同低温条件下（-6~-14℃）暴露2 h及在-5℃低温条件下暴露不同时间（0.5~8 d）的存活率。【结果】沙葱萤叶甲不同发育阶段的过冷却点存在显著差异, 从低到高依次为卵（-29.8℃）、 1龄幼虫（-14.6℃）、 2龄幼虫（-13.3℃）、 蛹（-12.1℃）、 3龄幼虫（-10.2℃）和成虫（-9.0℃）; 越冬卵12月和1月的过冷却点最低, 2月的过冷却点最高。随着处理温度的降低和处理时间的延长, 幼虫的存活率降低。1, 2和3龄幼虫在-5℃下的半致死时间（Ltime₅₀）分别为3.84, 3.80和2.28 d, 低温处理2 h后半致死温度（Ltemp₅₀）分别为-10.1, -9.1和-8.5℃, 高于其过冷却点。【结论】说明沙葱萤叶甲幼虫为不耐寒冷型(chill-intolerant)。     

异色瓢虫不同色斑型成虫的耐寒性研究

【目的】研究异色瓢虫Harmonia axyridi不同色斑型成虫的耐寒能力,以明确其色斑型比例所呈现的季节性变化的适应意义。【方法】本文测定了异色瓢虫实验种群和自然种群不同色斑型成虫的过冷却点(Supercooling point,SCP)及低温存活率。【结果】同一发育温度下异色瓢虫实验种群不同色斑型成虫的SCP和低温存活率均没有显著性差异(P>0.05),但是低温暴露中饲养在25℃下成虫的存活率下降更为剧烈。异色瓢虫自然种群黑底型与黄底型成虫的SCP呈现出明显的季节性变化,其SCP在7月份最高,分别为﹣8.2℃和﹣7.5℃;在1月份达到最低,分别为﹣16.8℃和﹣18.2℃。越冬开始(11月)黑底型成虫的SCP低于黄底型成虫的,整个越冬期间黄底型成虫的SCP一直低于黑底型成虫的,但是异色瓢虫黑底型与黄底型越冬成虫的低温存活率却没有显著性差异(P>0.05)。【结论】越冬期间异色瓢虫黄底型成虫的SCP低于黑底型的,这样可以通过体液过冷却的方式来避免结冰造成的伤害,以增强其越冬种群的耐寒能力,这也可能是越冬期间异色瓢虫黄底型成虫数量显著上升的一个原因。     

椰心叶甲的耐寒力测定

测定椰心叶甲Brontispalongissima(Gestro)的过冷却点和结冰点。各虫态中过冷却点值以卵和蛹最低,分别为-9.8℃和-9.0℃,成虫较高,雌、雄成虫分别为-5.9℃和-5.5℃;幼虫的过冷却点最高,平均为-4.5℃。结冰点由高到低依次为2龄幼虫、5龄幼虫、4龄幼虫、1龄幼虫、3龄幼虫、雄成虫、雌成虫、蛹和卵,分别为-0.3,-0.8,-1.1,-1.3,-1.3,-2.4,-2.7,-5.4和-5.5℃。综合分析认为,蛹、卵的耐寒能力最强。根据广东地区常年平均气温分析了在自然条件下该虫各虫态越冬情况,但由于生物学特性的限制,越冬虫态主要是成虫、蛹。     

粘虫抗寒力的初步研究

【目的】本研究旨在初步探索粘虫的抗寒力,以期能够为粘虫Mythimna separata(Walker)预测预报提供依据。【方法】测定粘虫不同发育期、不同光周期下的过冷却点,并计算虫体含水量;测定0、5、10℃下处理不同时间时粘虫老熟幼虫和蛹的死亡率。【结果】蛹的过冷却点、结冰点和含水量最低,并且粘虫不同发育期的过冷却点、结冰点和含水量差异显著(P<0.05);不同光周期下粘虫的过冷却点和含水量并无显著差异;在0、5、10℃条件下,粘虫老熟幼虫和蛹的死亡率均随着温度降低而增加,老熟幼虫的死亡率均小于蛹;雌雄蛹对低温的抵抗力有差异,温度较低并且处理时间较短时,对雌蛹的死亡率影响较大,而温度稍高或处理时间较长时,对雄蛹的死亡率影响较大。【结论】粘虫蛹的抗寒力最强,低温以及低温的持续时间影响蛹的性比以及老熟幼虫和蛹的死亡率,光周期对粘虫的抗寒力无显著影响。     

瓜实蝇耐低温相关生理指标的测定

【目的】了解瓜实蝇Bactrocera cucurbitae(Coquillett)对低温的耐受性,分析其不同发育阶段耐寒力差异。【方法】以不同发育阶段瓜实蝇为实验材料,分别测定并比较了过冷却点、水分、脂肪、甘油和糖类含量的变化情况。【结果】其不同龄期的过冷却点差异显著,5日龄蛹的过冷却点最低,为﹣17.04℃,1日龄幼虫的过冷却点最高,为﹣11.82℃,同一日龄的雌、雄成虫之间的过冷却点无显著差异;其幼虫期和蛹期虫体的含水量随着龄期的增长而下降,从1日龄幼虫79.64%下降到5日龄蛹65.31%,5日龄蛹的含水量显著低于其他龄期瓜实蝇,成虫期各龄期雌成虫含水量均显著高于雄成虫;5日龄幼虫脂肪含量最高,为32.90%,1日龄雄成虫和14日龄雄成虫脂肪含量最低,均为15%;幼虫期甘油含量随着龄期的增长而下降,从3.32μg/mg下降到1.12μg/mg,而蛹期逐渐上升,14日龄雌成虫甘油含量最高,为5.90μg/mg;1日龄幼虫总糖、海藻糖和糖原含量均最高,分别为7.51、0.94和1.93μg/mg,显著高于其他龄期瓜实蝇,蛹期糖类含量逐渐下降,而成虫期糖类含量随龄期增长而逐渐升高。【结论】本研究结果可为正确评估瓜实蝇的地理适应性和低温检疫处理提供依据。     

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。     

扶桑绵粉蚧的过冷却点和体液结冰点测定

本文测定了扶桑绵粉蚧Phenacoccus solenopsis Tinsley除卵期以外其它各虫态的过冷却点和结冰点.结果表明,该虫过冷却点以1龄若虫最低,为-24.02℃;雄虫预蛹次之,为-22.13℃;雄虫蛹、雄虫2龄若虫、雌虫3龄若虫、雄成虫、雌虫2龄若虫、雌成虫过冷却点逐渐升高,分别为-21.08℃、-20.25℃、-19.05℃、-18.42℃、-17.91℃、-16.89℃.体液结冰点也以1龄若虫最低,为-23.2℃;雄虫预蛹次之,为-19.09℃;雄虫蛹、雄虫2龄若虫、雌虫3龄若虫、雌虫2龄若虫、雌成虫、雄成虫体液结冰点逐渐升高,分别为-16.64%、-15.81℃、-13.92℃、-13.20℃、-12.85℃、-12.79℃.试验结果表明扶桑绵粉蚧过冷却点低,耐寒性较强,可能适宜在中国北部更广泛的区域生存.     

Isoelectric points of viruses

Viruses as well as other (bio‐)colloids possess a pH‐dependent surface charge in polar media such as water. This electrostatic charge determines the mobility of the soft particle in an electric field and thus governs its colloidal behaviour which plays a major role in virus sorption processes. The pH value at which the net surface charge switches its sign is referred to as the isoelectric point (abbreviations: pI or IEP) and is a characteristic parameter of the virion in equilibrium with its environmental water chemistry. Here, we review the IEP measurements of viruses that replicate in hosts of kingdom plantae, bacteria and animalia. IEPs of viruses are found in pH range from 1·9 to 8·4; most frequently, they are measured in a band of 3·5 < IEP < 7. However, the data appear to be scattered widely within single virus species. This discrepancy is discussed and should be considered when IEP values are used to account for virus sorption processes.     

Isoelectric points of multi-domain proteins

Although the distribution of protein isoelectric points is multi-modal, large proteins show isoelectric points less variable than small proteins and their isoelectric points tend to converge to a unique value, close to the pH of the milieu in which the proteins are functional, as far as the protein dimension increases. This study demonstrates that large proteins, which contain more than a single domain, do have isoelectric points less variable than small proteins, which contains a single domain. However, the distribution of the isoelectric points of the single domains, contained in large proteins, resembles that of small proteins, which contain a single domain. Thus, large proteins can be soluble even if their pI is very close to the pH of the milieu, in which they perform their function, since they can contain several domains, the electrostatic properties of each of which mirror those of small proteins.     

Four forward-looking guidance points

Four key guidance points in the UNAIDS guidance document, Ethical Considerations in HIV Preventive Vaccine Research, are compared with analogous statements in three other recently issued documents dealing with international research. Those documents are: the Declaration of Helsinki, as revised in 2000; the report of the U.S. National Bioethics Advisory Commission, issued in 2001; and a current (2001) draft revision of the 1993 CIOMS International Ethical Guidelines for Biomedical Research Involving Human Subjects. The four guidance points compared with statements on similar issues in the other three documents are Guidance Point 2, which deals with making available a safe and effective vaccine after trials are completed; the second half of Guidance Point 4, which requires that the desired outcome should potentially benefit the population from which research participants are drawn; Guidance Point 11, which discusses what should be provided to a control group in a vaccine trial; and Guidance Point 16, which addresses the care and treatment to be provided for trial participants who become infected with HIV during the trial. The analysis and comparison concludes that the UNAIDS guidance points are at least as ethically sound as analogous points in these other documents, and for the most part are ethically superior in providing greater benefits to research participants and to others. Nevertheless, they are subject to the criticism that they are too 'aspirational' and not sufficiently 'pragmatic'.     

Human chromosome hot points

Summary A chromosome hot point, 3p14, in healthy peasants, mentally retarded patients (MR), and epileptic patients (EP) was studied. The frequency of the hot point, 3p14 break, was significantly higher in EP. It may be caused by folic acid reduction in patients' serum induced by the antiepileptic drugs. The difference between hot point and fragile site is discussed.