害虫综合治理模型及其最优控制

针对最优害虫综合治理问题,首先建立农作物药效模型,与害虫-天敌动态模型结合起来,建立喷洒杀虫剂和释放天敌的脉冲控制模型,并分析周期解的稳定性.然后利用最优控制理论,求出最适杀虫剂药量和喷洒时间间隔,使得杀虫剂药量在农作物的残留最少,同时使害虫数量控制在经济危害阈值以下,给出一个利用杀虫剂控制农业害虫的最佳方案.最后,通过数值模拟解释这一方案的执行.     

三化螟种群系统的最优管理决策

以三化螟Tryporyza invertulas(Walker)种群动态模型和水稻产量损失预测模型为基础,根据水稻插植期、品种抗性,保护利用自然天敌和杀虫剂多次使用等控制措施以及它们的各种不同组合对该虫种群动态、水稻产量损失串和净收益的影响,以净收益最大为目标函数,研究三化螟种群的最优管理决策。其中,对昆虫种群动态模拟方法作了一点改进,它综合了前人所提出的种群动态模型的优点。建立的系统模型能够提供包括农业防治、生物防治和化学防治措施在内的、对三化螟种群实施有效管理的最优决策方案。     

稻纵卷叶螟种群系统动态模拟

本文组建了稻纵卷叶螟种群系统模似模型,它由系统亚模型和总模型二个部分组成.系统亚模型包括发育、死亡和繁殖三个子模块.系统总模型是作者提出的新模型,它综合了前人所提出的种群模型的优点,以差分方程形式给出,以生理时间为单位,考虑了种群内个体间发育速率的差异,不仅能模拟种群数量动态,而且能模拟种群年龄结构,同时能预测发生期.模型有效性检验表明,模拟结果基本上能吻合实测结果.文中还对5个影响因子进行了灵敏性分析.     

稻纵卷叶螟种群系统动态模拟

本文组建了稻纵卷叶螟种群系统模似模型,它由系统亚模型和总模型二个部分组成.系统亚模型包括发育、死亡和繁殖三个子模块.系统总模型是作者提出的新模型,它综合了前人所提出的种群模型的优点,以差分方程形式给出,以生理时间为单位,考虑了种群内个体间发育速率的差异,不仅能模拟种群数量动态,而且能模拟种群年龄结构,同时能预测发生期.模型有效性检验表明,模拟结果基本上能吻合实测结果.文中还对5个影响因子进行了灵敏性分析.     

棉铃虫抗药性的生理生化机制研究

本文报道了棉铃虫Helicoverpa armigera田间抗性种群对杀虫剂抗药性的生理生化机制。抗性种群(HJ-R)5龄幼虫羧酸酯酶、谷胱甘肽转移酶、多功能氧化酶活力均明显高于相对敏感种群(HD-S)。两种群乙酰胆碱酯酶对杀虫剂敏感性没有显著差异。HJ-R种群的腹神经索对氰戊菊酯表现了2-3倍的神经不敏感性。HJ-R种群对氨基甲酸酯类杀虫剂的抗性主要是由代谢机制引起,其中多功能氧化酶可能起主导作用;对菊酯的抗性是由多功能氧化酶、酯酶、以及神经不敏感性几个因子综合作用的结果。     

贵州菜蚜对杀虫剂的敏感性监测

【目的】持续监测菜蚜田间种群对杀虫剂的敏感性,是菜蚜防治与抗药性治理的重要措施,本研究旨在探析贵州菜蚜对十字花科蔬菜地常用杀虫剂的敏感性【。方法】采用叶片浸渍法测定了2017-2018年贵州省贵阳市花溪区、修文县、毕节市黔西县、遵义市播州区桃蚜Myzus persicae、甘蓝蚜Brevicoryne brassicae和萝卜蚜Lipaphis erysimi田间种群对10余种常用药剂的敏感性,并分别以物种、年份、地区和杀虫剂为变量进行数据比较和统计分析。【结果】3种菜蚜对杀虫剂的敏感性差异显著,桃蚜对杀虫剂的敏感性明显低于甘蓝蚜和萝卜蚜(分别相差12.7倍和15.5倍);贵州不同地区间同种蚜虫对杀虫剂敏感性差异不明显,贵阳、黔西和息烽甘蓝蚜对杀虫剂敏感性没有差异;贵阳和遵义萝卜蚜对杀虫剂敏感性也没有差异。年度间同种蚜虫对杀虫剂敏感性发生变化,从2017-2018年桃蚜和甘蓝蚜敏感性分别下降了2.2倍和1.9倍;其中贵阳市桃蚜种群对烯啶虫胺、噻虫啉、噻虫嗪、毒死蜱、噻虫胺和溴氰虫酰胺的敏感性下降了5.6-115.0倍;贵阳市甘蓝蚜种群对功夫菊酯、氟啶虫胺腈、毒死蜱、吡虫啉和噻虫嗪的敏感性也有2.1-6.7倍不同程度的下降。【结论】多数药剂对甘蓝蚜和萝卜蚜的毒力较高,可用于这2种蚜虫的防治,优先推荐噻虫嗪和溴氰虫酰胺等交替轮换使用;桃蚜对多数杀虫剂很不敏感,且抗性上升很快,推荐氟啶虫胺腈、吡虫啉和抗蚜威等药剂暂时还可以用于防治贵州桃蚜,急需寻找新型高效药剂来交替轮换使用。     

河南省绿盲蝽对有机磷类杀虫剂的抗药性监测

【目的】全面了解河南省绿盲蝽Apolygus lucorum(Meyer-Dür)对有机磷杀虫剂的敏感性变化,可为该虫的有效防治提供科学依据。【方法】采用瓶膜法于2010—2013年系统监测了河南新乡、周口、南阳地区绿盲蝽田间种群对毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷4种常用有机磷杀虫剂的敏感性。【结果】相对于室内敏感种群,2010—2013年河南省各地绿盲蝽种群对不同有机磷杀虫剂表现出不同程度的敏感性变化,但相对毒力比值均小于5倍。其中对毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷的敏感性均未降低,且3个种群对马拉硫磷表现为敏感性增强。【结论】毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷仍是河南省防治绿盲蝽的有效药剂。     

苏云金杆菌预处理棉铃虫二龄幼虫对氰戊菊酯抗性缓解及机理研究(英文)

本文研究了Ｂ．ｔ预处理棉铃虫二龄幼虫对氰戊菊酯抗性缓解及其机理。结果表明,Ｂ．ｔ预处理后的幼虫对氰戊菊酯的敏感性提高。与敏感性种群相比较,在Ｂ．ｔ预处理和未处理两个抗性种群的幼虫对氰戊菊酯的ＬＤ_５０之间纯比值分别大约增加了６２．６％和８０．９％。特异性酶抑制剂对乙酰胆碱酯酶的抑制作用显示,在活体内,马拉氧磷和甲基对氧磷对乙酰胆碱酯酶抑制效率提高了６６．１％和９９．８％;在活体外抑制效率（Ｉ_５０） ６０％和６７．５％及５５．６５％和８６．４％。同时,乙酰胆碱酯酶动力学各因子变化显著。在Ｂ．ｔ预处理的抗性棉铃虫幼虫中,Ｋｍ值从４５．５８％减少到６８．６２％;Ｋｉ值分别增加了２１．２％和４０．９％及３８．２％和６１．５％。这些结果证实Ｂ．ｔ预处理２４ｈ抗性棉铃虫二龄幼虫对氰戊菊酯的敏感性提高,乙酸胆碱酯酶的变化是重要原因之一。这一研究为在ＩＰＭ系统中将微生物杀虫剂和化学杀虫剂协调使用缓解棉铃虫对拟除虫菊酯类杀虫剂的抗性提供理论基础。     

吡虫啉杀虫剂降解菌Ochrobactum BB -1培养条件的研究

目的:研究培养条件对吡虫啉杀虫剂降解菌苍白杆菌BB -1(Ochrobactum sp.BB -1)生长的影响.方法:采用超声波破碎菌体细胞得到粗酶液;应用单因素试验研究培养条件对吡虫啉杀虫剂降解菌 Ochrobactum BB -1生长的影响.结果:降解酶定域试验表明,BB -1吡虫啉降解酶属于胞内蛋白组分.适合Ochrobactum BB -1生长的最佳碳、氮源分别是甘露醇和酵母膏,浓度分别为30g/L和16g/L;最适培养条件为pH 7.0,250mL三角瓶培养基装液量70mL,培养温度30℃.结论:苍白杆菌BB -1(Ochrobactum BB -1)生长条件要求简单,适于进一步研究其对吡虫啉杀虫剂的降解性能.     

瓜实蝇不同寄主种群对4种杀虫剂的敏感性

为探索瓜实蝇Zeugodacus cucurbitae不同寄主种群对杀虫剂的敏感性,本研究在室内通过药膜法测定了瓜实蝇节瓜、黄瓜、丝瓜和苦瓜种群4日龄成虫对4种杀虫剂的敏感性,随后将瓜实蝇不同寄主种群致死中浓度LC50进行比较,计算抗性倍数。结果表明,4个寄主种群对甲维盐的敏感性为节瓜 > 苦瓜 > 丝瓜 > 黄瓜,其中节瓜、苦瓜种群对甲维盐最敏感,其次是丝瓜、黄瓜,LC50值分别为0.250、0.391、0.809和1.035 mg/L。4个寄主种群对灭多威的敏感性表现为节瓜 > 黄瓜 > 苦瓜 > 丝瓜,LC50值分别为0.302、0.318、0.652和0.804 mg/L。对多杀菌素的敏感性大小依次为黄瓜、节瓜、丝瓜、苦瓜,LC50值分别为1.157、1.198、1.232和2.029 mg/L。对啶虫脒的敏感性为苦瓜 > 节瓜 > 黄瓜 > 丝瓜,LC50值分别为17.946、20.166、20.190和21.986 mg/L,其中对甲维盐的敏感性差异幅度最大,为4.140倍,其次是灭多威,为2.654倍,对啶虫脒的敏感性差异幅度最小,为1.225倍。表明寄主植物可引起瓜实蝇对杀虫剂的敏感性变化。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.