八种杀虫剂对棉田龟纹瓢虫,草间小黑蛛的影响

在棉田常用的８种杀虫剂中，对害虫天敌瓢虫安全的杀多灭威和哒螨灵；对草间小黑蛛安全的杀虫剂有啉虫啉、哒螨灵和灭多威。３种拟除虫菊酯类杀虫剂对两种天敌的毒性最大，有机磷类杀虫剂则低于菊酯类。     

Effects of diterpene esters of tigliane,daphnane, ingenane,and lathyrane types on pink bollworm,Pectinophora gossypiella saunders (Lepidoptera: Gelechiidae)

Twenty esters, representing the biogenetically related tigliane, daphnane, ingenane, and lathyrane series of diterpenes, were screened for growth-inhibitory and insecticidal effects on newly hatched larvae of the North American cotton pest,Pectinophora gossypiella (pink bollworm). Among the tigliane derivatives tested, only 12-O-tetradecanoylphorbol-13-acetate and 12-O-(2-methyl)butyrylphorbol-13-decanoate, of seven phorbol diesters isolated from croton oil by a new procedure involving droplet countercurrent chromatography, were active againstP.gossypiella as both growth inhibitors and insecticides. The effects of the former compound were not significantly diminished by acetylation of its C-20 primary hydroxy group. Three other croton oil phorbol diester constituents, as well as daphnetoxin and daphnetoxin-5,20-diacetate, exhibited activity as growth inhibitors, but not as insecticidal agents, at the doses used. None of the ingenane or lathyrane derivatives investigated was active in either respect. 12-0-Tetradecanoylphorbol-13-acetate was found to cause 100% mortality on second-stadium larvae ofCulex pipiens at 0.6 ppm, but exhibited less significant effects onOncopeltus fasciatus (second-stadium nymphs) andTribolium confusion (adults) when applied at higher doses.     

粉虱的发生与抗药性治理

粉虱是一种非常重要的害虫,可为害很多作物,给农业生产造成严重损失。虽然一些农业防治、物理防治和生物防治措施对预防和控制田间粉虱对作物的危害具有很好效果,但是目前粉虱的防治仍然是以化学防治为主,尤其是当粉虱暴发时,化学农药是唯一有效的手段,从而导致化学农药的大量使用所产生的粉虱抗药性问题日益突出。本文拟对粉虱的发生、新烟碱类杀虫剂抗性产生和治理情况作一简单介绍,以期为粉虱的综合治理提供科学指导。     

Analysis of pesticide residues in seaweeds using matrix solid-phase dispersion and gas chromatography–mass spectrometry detection

Products containing organophosphates, carbamates and pyrethroids pesticides, employed as chemotherapeutants in aquaculture, can remain as residues in the marine environment. Matrix solid-phase dispersion (MSPD) was developed to extract seventeen pesticides from seaweed samples using Florisil and graphitized carbon black as clean-up adsorbents prior to gas chromatography–mass spectrometry (GC–MS) determination. The extraction has been optimised by a Box–Behnken design. The optimal conditions were 1 g of seaweed sample, 4 g of anhydrous sodium sulphate as dispersant, 3.6 g of Florisil and 0.4 g of GCB and an elution volume of 14 mL of a hexane:ethyl acetate mixture containing 40% ethyl acetate. The recoveries ranged from 81.6% to 113.2% with relative standard deviations (RSDs) ranging from 1.6% to 13.2%. The limits of detection (LOD) ranged from 0.5 to 2.9 ngg⁻¹. Internal quality control was successfully carried out to verify the quality of the data obtained in the analysis of these pesticides in seaweed samples.     

Contact and fumigant toxicity and repellency of Eucalyptus citriodora Hook., Eucalyptus staigeriana F., Cymbopogon winterianus Jowitt and Foeniculum vulgare Mill. essential oils in the management of Callosobruchus maculatus (FABR.) (Coleoptera: Chrysomelidae,Bruchinae)

The weevil Callosobruchus maculatus (Fabr.) is considered the most important pest of cowpea, Vigna unguiculata (L.) Walp., stored in tropical and subtropical countries. Secondary compounds extracted from plants can be used in its control, as a potential alternative to synthetic insecticides. Therefore, the present study aimed to: (a) make the chromatographic and mass spectrometry analyses of the essential oils of Eucalyptus citriodora Hook, Eucalyptus staigeriana F., Cymbopogon winterianus Jowitt and Foeniculum vulgare Mill; (b) to evaluate the contact and fumigant toxicity; (c) test the repellent effect. The oils' main compounds were: E. citriodora (citronellal 89.59%; citronellyl acetate 3.34%; 1,8-cineole 2.87%), E. staigeriana (limonene 28.75%; geranial 15.20%; neral 12.16%), C. winterianus (geranial 21.83%; citronellal 10.94%) and F. vulgare (limonene 41.82%; (E)-anethole 17.91%; α-pinene 11.13%). The LC_50s of F. vulgare, E. citriodora, C. winterianus and E. staigeriana in contact tests were estimated at 178.13, 298.17, 328.42 and 345.57 ppm cowpea grains, respectively. According to regression analyses, the higher the oil concentration, the lower the number of laid eggs and emerged insects. In fumigation tests with adults, LC_50s ranged from 2.58 to 7.85 μL/L of air, while the toxicity ratios ranged from 1.25 to 3.04. In all concentrations tested, the E. citriodora and C. winterianus oils were repellent to adult C. maculatus; F. vulgare was classified as neutral, while E. staigeriana was neutral at lower than 558 ppm concentrations and repellent at higher concentrations. Regarding the essential oils tested, the percentage of oviposition reduction varied from 6.3 to 100%, while emergence percentages varied from 0.9 to 100%.     

新型二氯丙烯类杀虫剂的合成及杀虫活性

在研究以往二氯丙烯类杀虫剂的基础上，保留化合物的活性部分，改变其它可变基团，研究开发出九种新结构的化合物，结构经^1HNMR确认。杀虫活性测试结果表明，新化合物与先导化合物S-1812相比，具有相同或更高的杀虫效果，而且部分化合物的杀虫谱更宽，活性更高。     

Degradation of neonicotinoid insecticides by different advanced oxidation processes and studying the effect of ozone on TiO2 photocatalysis

Although some studies concerning the effect of pH and ozone dosage on TiO₂ photocatalysis (O₂/TiO₂/UV) have already been published, no complete investigation and explanation of the effects of both parameters on photocatalytic ozonation (O₃/TiO₂/UV) have been carried out. Aqueous solutions of neonicotinoid insecticides (thiacloprid and imidacloprid) were chosen as a degradation medium, since they exhibit a high threat for aquatic systems and it is of great importance to find an effective method for their elimination from the environment. In preliminary stability tests, thiacloprid showed higher photo- and chemical stability compared to imidacloprid, therefore its degradation was studied in detail. To assess the suitability of various treatments for degradation and mineralization of thiacloprid in water at different pH values and ozone dosages, we applied ozonation (O₃) and three different photochemical advanced oxidation processes, namely ozonation, coupled with UV radiation (O₃/UV), O₃/TiO₂/UV and O₂/TiO₂/UV. Light source emitting mainly in UVA range was applied in all three processes. The photocatalytic ozonation (O₃/TiO₂/UV) was found to be the most efficient process irrespective of pH. The synergistic effect of ozone and TiO₂ photocatalysis was noticed at acidic and neutral pH, but the synergism was lost at basic pH, probably due to faster self-decompositon of ozone under alkaline conditions. At acidic pH, also the oxidation of chloride anions to chlorate(V) was noticed in O₃/TiO₂/UV and in O₃/UV processes. By plotting the disappearance rate constants of thiacloprid degradation in O₃/TiO₂/UV and O₃/UV systems as a function of the flow rate of ozone, the synergistic effect of ozone was undoubtedly proven. The slope of the linear fit in case of O₃/TiO₂/UV process was considerably steeper than in case of O₃/UV, which would not happen in absence of synergistic effect. The linearity in O₃/TiO₂/UV system was lost only at very high flow rates of ozone.     

新烟碱类杀虫剂的发展及趋向

阐述了新烟碱杀虫剂的发展及趋向。     

VNX-000440系列均三嗪类杀虫活性物质的发现和活性

ω-hexatoxin-Hv1a是蜘蛛体内存在的多肽毒素,是昆虫电压门控离子通道拮抗剂。建立了此物质的3D药效团模型,用计算机从已知的商品化物质数据库中筛选出了与药效团模型相匹配的物质,并进一步用Accelrys软件进行筛选。对选出的物质进行活性测定,均三嗪类物质VNX-000440是得到的一个活性物质。经结构修饰得到了对埃及伊蚊和甜菜夜蛾活性高的物质VNX-000443。经对蜚蠊DUM神经元离子通道的影响测定试验,发现此类物质对昆虫电压门控离子通道有抑制作用。     

五种杀虫剂对甜菜夜蛾的田间防效评价

甜菜夜蛾是危害蔬菜的重要害虫。用10%溴虫腈SC 750mL/hm2、3%甲氨基阿维菌素苯甲酸盐WG 125g/hm2、20%氯虫苯甲酰胺SC 150mL/hm2、48%毒死蜱EC 900mL/hm2、18g/L阿维菌素450 mL/hm2防治甜菜夜蛾,结果表明,10%溴虫腈SC速效性和持效性均最好,药后1d和7d的防效分别高达96.76%和97.93%;18g/L阿维菌素EC速效性较差,持效性较好,药后1d、7d防效分别为27.18%和87.02%。其余3种药剂均具有较好的速效性和持效性,药后1d防效均在60%以上,药后7d防效均在85%以上。