The Provision and Subsequent Management of Plant Material for Herbicide Pot Experiments

Abstract

The marked resistance of Spodoptera spp. to endotoxins of Bacillus thuringiensis including the well recognized standards HD‐1–1971 and HD‐1‐S‐1980 has necessitated the search for a new active strain that can be used as a standard reference in the bioassays of these lepidopterous insects. The high activity of B. thuringiensis var. entomocidus HD‐635 vs. Spodoptera littoralis and S. exigua was found to fulfill these requirements. The sporeendotoxin complex of this strain, designated as HD‐635‐S‐1987, is proposed as a reference standard for bioassays against Spodoptera spp. and is assigned arbitrarily the value of 10,000 iu/mg. Potencies of an active strain, i.e. B. thuringiensis var. aizawai HD‐133 and of a low‐active preparation, i.e. HD‐1‐S‐1980 were carried out in reference to the newly proposed standard. Comparative studies revealed the possible reduction of bioassay period to 4 days as time saving and for a priori judgement on the activity of certain bioinsecticide preparations derived from B. thuringiensis.     

Side-effects of botanical insecticides derived from Meliaceae on coccinellid predators of the date palm scale

Bioassays were conducted in Mauritania to determine the toxicity of botanical insecticides from the tree Melia volkensii Gürke (Meliaceae) to ladybird predators (Coleoptera: Coccinellidae) of the date palm scale, Parlatoria planchardi Targ. (Homoptera: Diaspididae). M. volkensii seed extract was formulated in neem oil or a mixture of neem and maize oil. Three preparations were tested on Chilocorus bipustulatus L. var. iranensis, an introduced species, and one on the indigenous Pharoscymnus anchorago F., a species already used in previous bioassays. Fourth instar larvae were exposed for 2 days to treated scale-infested date palm leaves. The botanical insecticides were toxic to C. bipustulatus. Median lethal application rates (LR₅₀s) were close to the recommended application rate of 1 l/ha. In contrast, P. anchorago showed no increased mortality at this rate. Hazard quotients (application rate divided by the LR₅₀) were generally less than 2, suggesting a low risk for both species. However, risk mitigation measures are recommended when using oil formulations because the threshold value for C. bipustulatus, the more susceptible of the two ladybird species, would be exceeded at higher dose rates or when conducting multiple applications. Sublethal effects included an extension of the larval stage and morphogenetic defects. These effects were again more pronounced in C. bipustulatus than in P. anchorago.     

云南烟蚜的抗药性差异研究初报

 用“浸渍法”检测了云南省7个烟区11个地方的烟蚜种群对有机磷类（50%甲胺磷乳油）、氨基甲酸酯类（90%万灵可湿性粉剂）及拟除虫菊酯类（2.5%功夫乳油）的抗性现状。结果表明,不同烟区的烟蚜对3种农药的抗性差异较大,丽江石古、丽江斜阳及丽江中果的烟蚜种群对3种农药的抗性最低,而大理巍山及楚雄菊花村等地的烟蚜种群对3种农药的抗性较其它地方高。不同地方的烟蚜种群对有机磷、氨基甲酸酯、拟除虫菊酯3大类农药均产生了不同程度的抗性。     

蝗虫对光谱光照特性趋光反应的对比及数学分析

为给蝗虫灾害光电诱导机械化捕集技术中诱导光源光照参数的选取及设计提供技术支持,该文利用LED光源和自制的行为反应试验装置采用对比试验法,进行了蝗虫趋光选择最佳的光谱优选,并测试了蝗虫趋光行为反应的光照阈值,探讨了不同光谱和光照度对蝗虫趋光行为影响的机理。结果显示：相同光照度条件下,蝗虫对紫光（405?nm）的内在趋光反应率最高,对紫绿蓝（520+465+405?nm）组合光的反应次之;蝗虫对紫（405?nm）、绿（520?nm）、蓝（465?nm）及组合光的趋光反应率数学模型求解表明,蝗虫对不同光谱的趋光反应存在最高趋光光照度值和最低灵敏光照度值,其中紫光对二者的光照度最低;蝗虫的趋光响应受光谱和光照度的影响,在绿、紫、蓝光谱组合的光照度值内提高光照强度可达到蝗虫对紫光反应的逼近效果。     

金秋梨无公害化生产关键技术

金秋梨无公害化生产过程中,合理使用无公害肥料、无公害农药,以及无公害化采收、包装与贮运技术都十分重要。从实践中研究总结了金秋梨无公害肥料的使用原则、方法及用量,无公害农药的使用标准,金秋梨果品无公害化采收、包装与运输的技术。     

丁草胺对三种拟除虫菊酯杀虫剂光降解的猝灭效应研究

本文以高压汞灯为光源,研究了丁草胺对氯氰菊酯、溴氰菊酯和氰戊菊酯在玻片表面光降解的影响。结果表明:等剂量丁草胺与三种拟除虫菊酯混合照光48小时,对氯氰菊酯、溴氰菊酯、氰戊菊酯光降解的猝灭效应分别为20.7、14.5、7.6%;猝灭效率与其剂量呈显著相关;丁草胺的光猝灭效应受光敏剂农药哒嗪硫磷或多菌灵的影响而显著减弱,而丁草胺也使哒嗪硫磷或多菌灵对三种拟菊酯光解的敏化效率显著降低,说明它们之间存在交互拮抗作用。     

Status and outlook for acaricide and insecticide discovery

To guarantee sustainability and progress, the agrochemical industry is faced with several major challenges. Currently, loss of active ingredients due to consumer perception, changing grower needs and ever‐changing regulatory requirements is far higher than the number being introduced into the market. Therefore, there is a need to develop new products that can provide improved efficacy, selectivity and favorable environmental profiles. Strategies to achieve these goals are the search for acaricides and insecticides with new modes of action, or the discovery of novel molecules with activity on the most attractive target sites having resistance breaking properties against pest species. In this context, the introduction of halogen atoms or asymmetric centers into an active ingredient remains an important tool to modulate their properties, but so too is the pro‐pesticide concept. This review gives an overview of agrochemicals launched over the past 8 years, reflects new insights into known mechanisms of action, and describes the status and outlook for acaricide and insecticide discovery.     

棉蚜对新烟碱类杀虫剂的抗性现状及其治理策略

棉蚜Aphis gossypii Glover是棉花生产中最严重的害虫之一。长期以来防治棉蚜主要依赖于化学杀虫剂,其中新烟碱类杀虫剂扮演着十分重要的角色,但由于其长期、大量的使用,棉蚜已对该类杀虫剂产生了较高水平的抗性,严重影响了对棉蚜的防治效果。抗性机制研究表明,棉蚜对新烟碱类杀虫剂产生抗性的机制主要涉及解毒代谢能力增强和靶标敏感性下降。细胞色素P450、羧酸酯酶、谷胱甘肽S-转移酶、UDP-葡糖基转移酶等解毒酶基因过量表达介导的解毒代谢增强和烟碱型乙酰胆碱受体β1亚基突变引起的靶标敏感性下降是棉蚜对新烟碱类杀虫剂产生抗性的关键。针对我国棉蚜对新烟碱类杀虫剂抗性问题突出的现状,为更好地利用该类药剂防治棉蚜,亟需根据棉蚜抗性机制制定合理的抗性治理策略。本文将从棉蚜对新烟碱类杀虫剂的抗性现状、抗性机制以及抗性治理策略等方面进行综述,以期为抗性棉蚜的科学治理提供参考。     

吡虫啉和噻虫嗪对苜蓿盲蝽的防治效果及其在苜蓿中的残留

为了评价新烟碱类杀虫剂吡虫啉和噻虫嗪对苜蓿盲蝽的防治效果及安全性,采用田间喷雾法测定了20%吡虫啉可溶液剂(SL)和30%噻虫嗪悬浮剂(SC)对苜蓿盲蝽的防治效果,使用超高效液相色谱-串联质谱法(UPLC-MS/MS)测定了施药1、2、3次后(间隔7 d),药剂在苜蓿中的残留情况。结果表明,当吡虫啉和噻虫嗪在施药剂量分别为25.02 g/hm²和18.00 g/hm²时,药后3～7 d对苜蓿盲蝽的防治效果分别为80.01%～82.01%和77.54%～83.29%。吡虫啉和噻虫嗪连续施药3次后,在苜蓿中的最终残留量分别为1.90 mg/kg和0.08 mg/kg,吡虫啉已超过我国食品安全国家标准GB 2763-2021规定的果蔬中的最大残留限量(0.5 mg/kg)。因此建议每茬苜蓿生长期,可选用吡虫啉和噻虫嗪防治苜蓿盲蝽,吡虫啉和噻虫嗪喷施次数分别不宜超过2次和3次。