B型烟粉虱和温室白粉虱在温度逆境下的生存特性比较

为了明确B型烟粉虱和温室白粉虱在温度逆境下的生存特性对其种群发展的影响,通过进行高温和低温暴露试验,研究了B型烟粉虱和温室白粉虱卵、伪蛹、成虫在37℃,39℃,41℃,43℃,45℃下暴露1～2 h后的存活率,以及这两种粉虱卵、2～3龄若虫、伪蛹和成虫在2℃下暴露1～12 d后的存活率。结果表明：两种粉虱的卵、伪蛹和成虫在37℃～45℃下暴露1～2 h,其存活率均随着温度的上升而降低;但在相同处理条件下B型烟粉虱3种供试虫态的存活率要高于温室白粉虱。B型烟粉虱在2℃下暴露2～12 d,各供试虫态的存活率迅速下降,卵、2～3龄若虫、伪蛹在2℃下暴露12 d后均不能存活,成虫在2℃下暴露4 d后也全部死亡;而温室白粉虱卵、伪蛹在2℃下暴露12 d后其存活率还能超过45%,成虫在2℃下暴露7 d后仍有80.9%能够存活。结果说明,B型烟粉虱和温室白粉虱对温度逆境的适应性存在差异,B型烟粉虱对高温的适应性要高于温室白粉虱;温室白粉虱对高温敏感,但对低温的适应性要显著高于B型烟粉虱。据此推测,两种粉虱对温度逆境适应性的差异是导致其种群发生存在差异的一个重要原因。     

不同温度下吡虫啉对B型烟粉虱毒杀活性的研究

分别采用浸卵法、浸渍法和浸叶法测定了22、25、28、31和34℃下吡虫啉对B型烟粉虱Bemisia tabaci B - biotype不同虫态的控制效果.结果表明,随着温度的升高,吡虫啉对B型烟粉虱不同虫态的控制效果也逐渐上升,当温度上升至34℃时,60 mg/L浓度药液处理下卵、低龄若虫、高龄若虫及成虫死亡率分别...     

温度和降水对蔬菜烟粉虱的影响

为了探讨温度胁迫和降水对蔬菜烟粉虱种群的影响,分别利用冬季零度以下的低温、夏季高温闷棚,以及降水量和降水程度与烟粉虱种群数量的关系,研究温度和降水对蔬菜烟粉虱的种群影响。结果发现,冬季低温强度和低温时间对翌年烟粉虱的种群数量有明显的影响,温度越低、低温时间越长,翌年春夏烟粉虱的种群数量越低。翌年春夏烟粉虱的种群数量和低温当量的相关关系符合下列方程:y=-63.16ln(x)+177.2(R~2=0.9102)。夏季高温闷棚后棚内温度迅速上升,闷棚1 d后,棚内地面以上10 cm的空气最高温度迅速上升到63.97℃,此后5 d闷棚期间最高温度一直保持在64℃以上;闷棚1 d后,辣椒上烟粉虱的虫口减退率达到60.41%,处理5 d后成虫全部死亡。闷棚后棚内土温迅速上升,闷棚1 d后,地下20 cm处的温度达到了39.53℃,随着闷棚时间的延长,土温一直保持在40℃以上。降雨量和降雨时间对烟粉虱种群数量有明显的影响,降雨量3.33 mm/12 h的烟粉虱的虫口减退率达到84.72%,11.67 mm/12 h的烟粉虱的虫口减退率达到96.32%。3.33 mm/12 h的降雨强度处理下,处理1.5 h、2.0 h后烟粉虱的虫口减退率分别为92.93%和95.42%。结果表明,冬季低温、夏季高温和降水对蔬菜烟粉虱种群数量有抑制作用。     

福建省烟粉虱种群消长动态及影响因素分析

【目的】为了探究福建省烟粉虱Bemisiatabaci(Gennadius)种群消长动态及其影响因素,提高监测与防控水平。【方法】选择代表福建南北两地的漳州和建瓯蔬菜生产地开展露地和温室大棚烟粉虱种群数量的系统调查,并在室内测定了不同温度对烟粉虱生长发育及繁殖的影响。【结果】漳州露地烟粉虱周年发生,种群季节性消长呈现两个高峰,即6月中下旬-7月上中旬的夏季高峰和11月上中旬的秋季高峰;建瓯大棚内烟粉虱亦周年发生,且与漳州露地种群消长动态基本同步;建瓯露地烟粉虱始见期为3月下旬,种群夏季高峰在7月中下旬,秋季高峰期在10月中下旬。烟粉虱卵、1龄若虫、2龄若虫、3龄若虫和4龄若虫+拟蛹的发育起点温度分别为13.77、14.98、9.60、7.97、12.56℃,有效积温分别为77.25、29.13、49.62、65.03和65.13日·度,结合2015-2017年气象资料,推算出烟粉虱在建瓯和漳州年发生代数分别为11-12代和13-14代。【结论】气温是影响烟粉虱种群消长的关键因子,21-27℃是B型烟粉虱发育的适宜温度,低于20℃和高于30℃均不利于烟粉的生长发育和繁殖。当旬平均气温稳定在20℃以上时种群数量快速上升,当旬平均气温持续保持在30℃以上时种群数量呈回落态势。     

球孢白僵菌HFW-05对烟粉虱的致病力及组织病理影响

环境温湿度是影响白僵菌菌株致病力的关键因素,本文测定了不同温、湿度下白僵菌Beauveria bassiana HFW-05对烟粉虱Bemisia tabaci若虫及卵的致病力,同时观察了烟粉虱感病若虫的组织病理变化。结果表明,各浓度下烟粉虱若虫的校正死亡率随时间变化曲线基本一致,接种3-4 d时出现死亡高峰,白僵菌HFW-05对烟粉虱1龄、2龄、3龄若虫的LC_(50)分别为5.94×10~4、1.06×10~5、5.08×10~5孢子/mL,LT50分别为2.54 d、2.68 d、3.18 d;白僵菌HFW-05对卵的致病力很低,1×108孢子/mL接种浓度下,卵的6 d感染率仅为24.9%。在25℃、30℃下,HFW-05对烟粉虱若虫表现出最强的致病力,高于或低于此温度时,烟粉虱若虫死亡速度减慢,死亡率降低。相对湿度发生变化时,烟粉虱若虫死亡速度和死亡率明显不同,相对湿度高于90%时,烟粉虱若虫死亡速度最快,死亡率最高,相对湿度介于70%-90%时,白僵菌HFW-05对烟粉虱若虫的致病力无明显差异,但校正死亡率显著低于环境湿度大于90%的处理,相对湿度低于70%时,烟粉虱死亡率也达到60%左右。组织病理学观察显示尾部舌状突是HFW-05侵染烟粉虱若虫的关键部位。研究结果表明白僵菌HFW-05在烟粉虱的生物防治中有较大的潜力。     

京冀地区烟粉虱的早春扩散特征

掌握烟粉虱Bemisia tabaci(Gennadius)温室内种群动态过程和早春扩散规律,是从源头治理大田烟粉虱的关键。通过对京冀地区烟粉虱冬季温室(番茄)种群动态调查发现,烟粉虱在温室的发生呈现先逐渐下降后又上升的趋势。进一步对早春扩散的调查表明,其大棚内的寄主植物为番茄、甜瓜、黄瓜、豆角、冬瓜,5月中上旬为华北烟粉虱从大棚向外扩散高峰期,以在大棚周围(0m)处的数量最多,且随着距温室虫源距离的增加,虫口密度逐渐减小,烟粉虱从虫源大棚逐渐向外扩散。根据其种群动态和扩散规律,建议在5月中上旬重点在大棚周围控制烟粉虱,以防止其对外扩散。     

沙巴拟刀角瓢虫生物学特性研究

探究以烟粉虱Bemisia tabaci Gennadius为食料,沙巴拟刀角瓢虫Serangiella sababensis Sasaji的生物学特性,为利用沙巴拟刀角瓢虫控制烟粉虱提供理论依据。本试验在实验室条件下观察取食烟粉虱的沙巴拟刀角瓢虫各虫态的形态特征、生活习性、不同虫态的发育历期、存活率和繁殖力,并计算沙巴拟刀角瓢虫生命表参数。结果表明,在26±1℃、L∶D=14∶10、相对湿度75%±10%的条件下,以烟粉虱卵和若虫为食的沙巴拟刀角瓢虫的世代历期分别为18.82 d和17.75 d,世代存活率分别为65.53%和75.00%,成虫寿命分别为106.65 d和105.58 d,每雌产卵量分别为286.20粒和366.67粒。以烟粉虱卵和若虫为食的沙巴拟刀角瓢虫的内禀增长率(rm)分别为0.0581和0.0780,净增殖率(R0)分别为107.0338和147.8748,平均世代历期(T)分别为80.3985和64.0385,周限增长率(λ)分别为1.0598和1.0811。研究发现,取食烟粉虱若虫的沙巴拟刀角瓢虫世代发育历期短于取食卵的世代发育历期,繁殖率也高于后者,烟粉虱若虫比烟粉虱卵更适宜作为沙巴拟刀角瓢虫规模化生产的食料。     

短时高温暴露对Q型烟粉虱存活和生殖适应性的影响

在室内将Q型烟粉虱Bemisia tabaci Q-biotype成虫在44℃下暴露1 h后观察成虫的存活率、产卵量、雌雄寿命和后代存活能力,以研究短时高温暴露对Q型烟粉虱生物学特性的影响。结果表明,Q型烟粉虱成虫在44℃下暴露1 h后的存活率为43.5%,暴露热激后的单头雌虫的产卵量为77.2粒,低于常温下(26℃)的产卵量(100.1粒);短时高温可显著缩短Q型烟粉虱成虫的寿命,在44℃下暴露1 h后Q型烟粉虱雌雄虫寿命分别为14.5 d和10.2 d,显著低于常温下(26℃)雌虫20.4 d和雄虫18.2 d;短时高温对Q型烟粉虱后代存活率和雌雄性比无显著影响,但其产卵高峰期延迟,产卵持续期缩短。以上结果表明,短时高温热激可影响Q型烟粉虱的生殖情况,造成Q型烟粉虱产卵量降低和寿命缩短,Q型烟粉虱雌虫耐热性强于雄虫。     

观察球孢白僵菌侵染烟粉虱若虫过程的新方法——荧光显微法

【目的】介绍一种观察白僵菌Beauveria bassiana侵染烟粉虱Bemisia tabaci(Gennadius)若虫的荧光显微方法。【方法】将被白僵菌侵染的烟粉虱若虫用荧光素二乙酸酯(FDA)染色,并于波长为450~490 nm的蓝光下显微观察。【结果】在接种白僵菌12 h和24 h的烟粉虱若虫上分别观察到昆虫表皮上分生孢子的萌发和芽管穿透表皮。结合裸眼和荧光显微观察结果证实了被真菌侵染的烟粉虱若虫体色变红和菌体在虫体内增殖是同时发生的。【结论】应用荧光显微方法能观察到白僵菌在烟粉虱若虫体表和体内的侵染。     

辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响

在实验室条件下研究了辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响.结果表明:辣椒碱对烟粉虱各虫态均有杀虫活性,且随辣椒碱浓度的增大活性增强;辣椒碱浸叶法/浸虫法处理对烟粉虱成虫、卵和若虫的毒力(LC50分别为3525.79、1603.29和1526.27mg·L-1))均高于内吸法处理(LC50分别为5360.04、2359.19和5897.43 mg.L-1),两种处理方法下辣椒碱对烟粉虱卵的毒力均明显高于对成虫的毒力;2000和4000 mg·L-1浓度辣椒碱对烟粉虱成虫具有明显的拒食作用,烟粉虱在该两种浓度辣椒碱处理过的棉花叶上取食24 h的蜜露分泌量均显著低于取食非处理棉花叶后的蜜露分泌量;辣椒碱各试验浓度对烟粉虱成虫均表现出较强的产卵忌避作用,当辣椒碱处理浓度达4000 mg·L-1时,对烟粉虱的选择性产卵忌避率和非选择性产卵忌避率分别高达94.2％和83.0％.500、1000和2000 mg·L-1辣椒碱浸渍处理对烟粉虱存活卵和若虫的发育历期、成虫羽化率均没有影响,但辣椒碱4000mg·L-1处理明显延长烟粉虱若虫发育历期、降低成虫羽化率.不同浓度辣椒碱处理均明显抑制烟粉虱生殖力,且这种抑制作用随辣椒碱浓度的增大而增强.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.