烟草疫霉菌的培养及大量产生游动孢子囊和游动孢子方法的研究

烟草疫霉菌(Phytophthora nicothianae)在燕麦培养基上生长良好 ,菌丝在滴加了土壤浸出液的皮氏培养液中 ,可在 3d内产生大量的游动孢子囊 ,游动孢子囊经低温处理后再培养 2 4h可产生大量游动孢子     

氟啶虫胺腈对枸杞棉蚜室内毒力及田间防效研究

明确氟啶虫胺腈对枸杞棉蚜的室内毒力及田间防效。采用浸虫法进行室内毒力测定,在田间进行小区药效试验。氟啶虫胺腈对枸杞棉蚜的LC₅₀值为77.6215 mg/L。50%氟啶虫胺腈水分散粒剂在田间对枸杞棉蚜表现出较好的速效性和持效性,55.56、83.33、111.11 mg/L在药后3、7、14 d的防效分别为72.38%～78.96%、80.15%～92.59%、79.71%～93.09%。药后7 d低剂量处理防效低于对照处理,其他处理的防效均显著高于对照药剂吡虫啉的防效,且各剂量处理均对枸杞树安全。50%氟啶虫胺腈水分散粒剂对枸杞棉蚜有较好的防治效果。     

氟啶虫胺腈对麦蚜的防治效果

测定了河南许昌、山东汶上、江苏邗江3地两种麦蚜对吡虫啉、啶虫脒和氟啶虫胺腈的抗性水平,并在3地开展了田间防效试验。室内抗性监测结果表明,禾谷缢管蚜种群对吡虫啉处于敏感至低水平抗性状态(抗性倍数0.30~7.00倍),对氟啶虫胺腈处于敏感状态;麦长管蚜种群对吡虫啉、氟啶虫胺腈都处于敏感状态。田间试验结果表明,在河南许昌、山东汶上、江苏邗江3地试验田50%氟啶虫胺腈WG对麦蚜田间防治效果药后3d为81.6%~88.0%,药后7d为79.2%~89.7%,明显优于对照药剂10%吡虫啉WP、5%啶虫脒WP的防治效果。结合室内抗药性监测和田间防治效果,说明氟啶虫胺腈作为新型杀虫剂品种,可作为轮换或替代药剂用于麦蚜的抗性治理。     

亚致死浓度氟啶虫胺腈对棉蚜生物学特性及生长发育基因的影响

为明确氟啶虫胺腈对棉蚜Aphis gossypii的亚致死效应,利用生命表和实时荧光定量PCR技术测定亚致死浓度氟啶虫胺腈处理后父代(F₀)及其F₁和F₂子代棉蚜的生物学参数及生长发育相关基因的表达量。结果显示,氟啶虫胺腈对成蚜的LC₁₀和LC₃₀分别为0.48μg/m L和1.53μg/m L。LC₁₀和LC₃₀氟啶虫胺腈处理后F₀代棉蚜成蚜寿命分别为12.62 d和13.19 d,显著高于对照(10.03 d),LC₁₀处理后F₀代产蚜量为27.84头,显著高于对照(23.13头),而LC₃₀处理后F₀代产蚜量为21.18头,与对照差异不显著。与对照相比,LC₁₀和LC₃₀处理后F₁代的若蚜发育历期和总寿命显著延长,产蚜前期显著缩短;LC₁₀     

溴虫氟苯双酰胺与氟啶虫胺腈桶混防治黄瓜蓟马田间药效试验

【目的】蓟马是黄瓜的重要害虫之一,严重影响其产量及质量。通过进行溴虫氟苯双酰胺与氟啶虫胺腈桶混药效试验明确其对蓟马的防控效果。【方法】利用喷雾法测定溴虫氟苯双酰胺与氟啶虫胺腈桶混对黄瓜蓟马的防治效果。【结果】第1次施药后溴虫氟苯双酰胺10 g/L SC单剂处理,以及含有溴虫氟苯双酰胺10 g/L SC的桶混处理均与对照药剂乙基多杀菌素60g/LSC差异不显著,且随着药后时间的延长差异逐渐缩小。第2次施药后各药剂处理防治效果均有不同程度的提升,药后10 d,溴虫氟苯双酰胺10 g/L SC单剂处理及其他含有溴虫氟苯双酰胺10 g/L SC的桶混处理表现出较好的防效,防治效果显著高于对照药剂乙基多杀菌素60 g/L SC,或与之差异不显著。【结论】实际应用中可推荐溴虫氟苯双酰胺10 g/L SC+氟啶虫胺腈22%SC,用量为每667 m2(9+3)～(18+6)g,m L。视虫害发生情况,间隔5～7 d,至少连续施用2次。     

我国棉蚜对吡虫啉和氟啶虫胺腈抗性水平监测与交互抗性分析

为了解我国不同地区棉蚜Aphis gossypii对吡虫啉和氟啶虫胺腈的抗性现状,对代表性棉区棉蚜田间种群进行抗药性监测,同时通过构建具有R81T及V62I单突变和R81T-V62I共同突变的棉蚜烟碱型乙酰胆碱受体(nicotinic acetylcholine receptor,nAChR)蛋白模型,与吡虫啉和氟啶虫胺腈进行分子对接,分析这些突变在吡虫啉和氟啶虫胺腈抗性中的作用,并分析吡虫啉和氟啶虫胺腈之间是否存在交互抗性。结果显示,不同地区棉蚜对吡虫啉产生了高水平抗性,抗性倍数为174.70～56 409.18,对氟啶虫胺腈产生了低至中等水平抗性,抗性倍数为7.35～44.63,说明不同地区的棉蚜对氟啶虫胺腈的敏感度高于吡虫啉,且吡虫啉抗性和氟啶虫胺腈抗性间不存在相关性。R81T、V62I单突变和R81T-V62I共同突变导致吡虫啉与棉蚜nAChR的亲和力降低,对氟啶虫胺腈与棉蚜n AChR的结合无明显影响。R81T及V62I单突变和R81T-V62I共同突变导致棉蚜对吡虫啉产生靶标抗性,但是对氟啶虫胺腈的抗性无明显影响,这些突变不会导致吡虫啉与氟啶虫胺腈产生靶标突变的交互抗性。     

50％氟啶虫酰胺水分散粒剂对棉蚜的田间防治效果

[目的]明确50％氟啶虫酰胺水分散粒剂对棉花蚜虫的防治效果、最佳使用剂量及其安全性,为生产上使用推广提供指导.[方法]以当地常用药剂70％吡虫啉水分散粒剂为对照药剂,通过田间药效试验测定了50％氟啶虫酰胺水分散粒剂75,60,45 g/hm23种剂量对棉花蚜虫的防治效果.[结果]50％氟啶虫酰胺水分散粒剂3个剂量处理药...     

新型杀菌剂氟醚菌酰胺对辣椒疫霉的作用机制初探

为研究氟醚菌酰胺(N-(3-氯-5-(三氟甲基)吡啶-2-甲基)-2,3,5,6-四氟-4-甲氧基苯甲酰胺)对辣椒疫霉的作用机制,采用生物测定法系统测定了氟醚菌酰胺对辣椒疫霉菌丝生长、游动孢子释放和菌丝生长量的影响,并进一步对药剂处理后的辣椒疫霉菌丝的超微结构进行了观察;同时测定了氟醚菌酰胺对病原菌糖酵解、三羧酸循环和磷酸戊糖3种呼吸代谢途径的影响,以及其对辣椒疫霉菌丝体细胞膜通透性、可溶性蛋白和DNA含量的影响。结果表明:氟醚菌酰胺对辣椒疫霉菌丝生长、游动孢子释放和菌丝生长量的EC50值分别为7.14、16.34和5.12μg/mL;其可使辣椒疫霉菌丝分支增多变短,且出现细胞壁增厚和细胞变形现象;ATP的存在能降低氟醚菌酰胺对辣椒疫霉菌丝的抑制作用,说明氟醚菌酰胺对辣椒疫霉能量产生过程有一定的抑制作用;其对三羧酸循环途径的抑制作用最为明显。电导率法测定结果表明,氟醚菌酰胺处理均能提高辣椒疫霉的细胞膜通透性,用100μg/mL的氟醚菌酰胺处理400 min后,菌株的相对渗率达78.23%。但氟醚菌酰胺对辣椒疫霉生物大分子的影响较小。研究结果初步表明,氟醚菌酰胺有多个作用位点,但主要是通过抑制辣椒疫霉能量产生和细胞膜通透性而起到抑菌作用。     

N-(2,4,5-三氯苯基)-2-氧代环己烷基磺酰胺对灰葡萄孢的抑制作用

研究了新型环烷基磺酰胺类化合物N-(2,4,5-三氯苯基)-2-氧代环己烷基磺酰胺(简称化合物108)对灰葡萄孢菌丝生长、孢子形成和萌发以及菌核产生等不同生育阶段的抑制作用及其对菌丝致病力和形态结构的影响。结果表明:化合物108对灰葡萄孢菌丝生长和孢子形成及孢子萌发具有明显的抑制作用,其EC50值分别为6.90、4.70和4.11μg/mL;菌核形成受到明显抑制,当药剂质量浓度达20μg/mL时,无菌核产生。经化合物108处理后的灰葡萄孢菌丝致病力下降,40μg/mL处理的菌丝致病力显著低于对照。超微结构观察结果表明,化合物108能导致灰葡萄孢菌丝萎缩、塌陷和变形,菌体细胞壁增厚、皱缩及分层。     

三氟啶磺隆除草活性及对棉花的安全性评价

三氟啶磺隆是一种新型、高效、低毒的棉田除草剂,为明确其在我国棉田的应用前景,以嘧草硫醚为对照药剂,采用温室盆栽法对三氟啶磺隆的杀草谱、除草活性及对棉花的安全性进行了评价。结果表明:在有效成分11.25 g/hm2剂量下,三氟啶磺隆对香附子、狗尾草、鳢肠、小藜、画眉草、小飞蓬、千金子、鬼针草、苍耳、鹅肠菜和反枝苋的鲜重防效均在90%以上,且对棉田杂草香附子、苘麻、狗尾草、反枝苋和马齿苋的除草活性均高于嘧草硫醚,以ED50值计,其毒力分别是嘧草硫醚的171、13.6、12.6、10.5和3.82倍;三氟啶磺隆在华棉5号棉花与香附子、狗尾草、苘麻间的选择性指数分别为13.0、2.80和1.13,高于嘧草硫醚的2.29、1.78和0.86,但其在华棉5号与反枝苋和马齿苋间的选择性指数分别为2.80和1.74,低于嘧草硫醚的4.75和3.38;两种药剂在山农棉8号棉花与杂草间的选择性指数与华棉5号的相似。     

棉蚜在棉田的空间分布型研究

棉蚜是为害棉花的重要害虫之一。近年来棉花蕾铃期的伏蚜为害加重,给棉花生产造成巨大损失。了解棉蚜在棉田的空间分布可以为防治棉蚜提供科学依据。为此本文进行了棉田棉蚜种群分布调查,并采用聚集度指标法、Iwao回归分析法、Taylor幂法测定。结果表明,棉蚜在棉田的空间分布是聚集型的。     

6种农药对瓜蚜的毒力测定及田间药效

为了筛选防治西瓜瓜蚜的有效药剂,用6种药剂进行了室内毒力测定和田间药效试验。结果表明,1.8%阿维菌素EC对瓜蚜的毒力最高,60g/L乙基多杀菌素SC毒力最低,48hLC50分别为0.38mg/L和2 225.63mg/L。6种药剂毒力大小依次为阿维菌素溴氰虫酰胺氟啶虫胺腈啶虫脒吡虫啉乙基多杀菌素。田间试验结果表明,1.8%阿维菌素EC 3 000倍、10%溴氰虫酰胺OD 2 000倍、22%氟啶虫胺腈SC 4 000倍对瓜蚜速效性及持效性均较好,3~14d防效均达到90%以上,防效差异不显著;20%啶虫脒WP 3 000倍和10%吡虫啉WP 3 000倍速效性及持效性均较差,1d防效分别为31.31%和6.66%,14d防效分别为57.39%和47.80%;60g/L乙基多杀菌素SC 1 000倍防效最差,药后14d的最高防效仅为34.70%。推荐田间轮换使用阿维菌素、溴氰虫酰胺、氟啶虫胺腈防治瓜蚜。     

5种药剂对枸杞棉蚜室内毒力及田间防效

为了明确5种药剂对枸杞棉蚜的适宜施药剂量,开展了室内毒力测定和田间药效试验.结果 表明,1％甲维盐EC对枸杞棉蚜的毒力最高,50％噻虫嗪WG毒力最低,24 h LC50分别为2.44 mg/L和1875.69 mg/L.5种药剂毒力大小依次为甲维盐＞啶虫脒＞吡蚜酮＞呋虫胺＞噻虫嗪.田间试验结果表明,随着施药时间的延长,...     

棉蚜抗药性及其化学防治

棉蚜［Aphis gossypii（Glover）］属半翅目蚜科,是一种世界性的害虫,主要通过取食植物汁液和传播病毒给农业生产造成严重损失。长期以来,棉蚜的防治一直以化学防治为主,棉蚜对有机氯、有机磷、氨基甲酸酯、拟除虫菊酯、新烟碱类等多种杀虫药剂已经产生了抗性。本文主要从棉蚜抗药性发展历史、抗药性机制以及棉蚜的化学防治等方面进行论述,期望能为农业生产上延缓棉蚜抗药性产生、有效治理棉蚜提供指导。     

保护扩增南疆棉蚜天敌源库生态防治棉蚜

新疆农业生态系统中,防护林等树木、小麦等夏熟作物、农田边缘区及绿洲内野生植物、各种果树是现今棉蚜的主要源库.建设和完善农田和绿洲防护林体系,扩种果树、农田四周种植增殖天敌的植物,可有效增强棉蚜天敌的数量.防治林木、果树、小麦等的害虫,应尽量采用保护天敌的有效措施.田外野草应注意保护,防止盲目铲除;防治棉叶螨不宜提倡田边喷药,设置所谓保护带.棉蚜的生物防治,更应注意田内、田外的协调,充分发挥生态防治棉蚜的作用.     

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 1: mortality rates and sources of variation

Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil-treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host-plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed.     

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 2: indirect effects of oil deposits

The primary mode of action of petroleum spray oils (PSOs) on pest insects is through direct contact. Indirect effects are, however, also possible, and deposits of the oils may influence pest populations by killing insects and/or by influencing their behaviour. The indirect effects of deposits of a new nC24 oil against the cotton aphid, Aphis gossypii Glover, were therefore determined. The effects of oil deposits on the acceptance of cotton as host plant by the aphids were assessed, as well as aphid mortality rates and their success in the establishment of colonies. The efficacy of deposits of a heavier oil (nC27) was also evaluated. Deposits of PSO were toxic to A. gossypii and remained effective until 8 days after spraying. Mortality decreased with time, so that, the older the deposit, the lower was the mortality. Significantly higher aphid mortalities were achieved on younger leaves than on mature ones. Thus, leaf age proved a significant factor in the efficacy of the deposits. Consecutive prophylactic applications (at 9 day intervals) did not have a cumulative effect, and their killing power proved to be independent of one another. Thus, applying the oil prior to aphid infestations would confer only minimal protection. The mortality inflicted by the deposits was not improved by increasing the molecular mass of the oil used (nC27 oil), but the toxic life of the oil deposit was increased. Oil deposits did not deter alates from landing on oil-sprayed plants. Oil deposits did, however, affect subsequent alate and nymphal survival, and thus the establishment of aphid colonies. The impact that the oils could have on the longer-term development of aphid populations in the field was thus demonstrated. First- and second-instar nymphs were the most susceptible life stages, with > 50% mortality compared with < 10% for the other stages. These nymphs did not show the typical signs of oil-induced mortality observed in aphids killed by direct oil applications, which suggests an alternative mode of action to that of the directly applied oil. Anoxia does not seem to be involved in either process, and alternative modes of action of the oil deposits are discussed. The implications of these findings for cotton aphid control are also considered, primarily in relation to the timing and frequency of oil application.     

Efficacy of dose-dependent indigenous microbial insecticides against cotton aphid,Aphis gossypii Glover (Homoptera: Aphididae) at various temperature regimes

Strain selection based on temperature may be warranted when choosing an isolate for development as a microbial control agent. To this end, the effects of three temperature regimes, namely 20, 25 and 30°C, on the virulence of four Beauveria and two Metarhizium isolates against the cotton aphid, Aphis gossypii, were investigated under controlled conditions, 65–70% relative humidity, and a photoperiod of 12:12 (light: dark) hours. The isolates did vary significantly in their activities of efficacy over a range of temperatures. The highest mortality and lowest survival times were observed at 25°C for DLCO41 and at 30°C for DLCO87; while mortality decreased and survival time increased at temperatures of 20°C. Besides the tested fungal isolate DLCO87 had the lowest LC₅₀ value (6.84 × 10⁵ conidia mL^?1) at 30°C. The promising result of this study should enable us to conduct further studies to determine the potential use of the fungus as an agent against Aphis gossypii both in greenhouse and under field conditions.