加速溶剂萃取-液相色谱-串联质谱法同步检测白菜中的丁硫克百威及其代谢物残留

建立了白菜中丁硫克百威及其代谢物克百威、3-羟基克百威和3-酮基克百威的同步检测方法。白菜样品匀浆后用硅藻土混合分散,经加速溶剂萃取仪(ASE)用二氯甲烷萃取,固相萃取柱净化,在液相色谱-串联质谱(LC-MS/MS)仪上采用正电离方式以多反应监测模式(MRM)检测,内标法定量。丁硫克百威及其3种代谢物在白菜中的平均回收率在85%～122%之间,相对标准偏差为2.3%～12.5%,检出限为0.002～0.01 mg/kg,定量限为0.005～0.02 mg/kg。采用该方法测定的消解动态结果表明:丁硫克百威在白菜中的消解半衰期为0.9 d,代谢物克百威在施药当天即达到最大值,并在1 d内消解70%以上,而3-羟基克百威与3-酮基克百威的浓度则在1 d时达到最大值,然后呈现快速降低的趋势。     

气相色谱-质谱法测定烟叶和土壤中丁硫克百威及其代谢产物的残留

建立了气相色谱-质谱法同时检测烟叶和土壤中丁硫克百威及其代谢产物(克百威和3-羟基克百威)残留量的分析方法。土壤样品用丙酮-石油醚[V(丙酮)∶V(石油醚)=1∶4]混合溶液提取,无需净化;鲜烟叶样品用丙酮-乙腈[V(丙酮)∶V(乙腈)=1∶9]混合溶液提取;烤后烟叶用乙腈提取。鲜烟叶和烤后烟叶提取液经旋转蒸发浓缩后,用弗罗里硅土柱净化。结果表明:在0.05~1 mg/kg添加水平下,丁硫克百威及其代谢产物的平均回收率在74%~99%之间,相对标准偏差(RSD,n=5)在1.5%~9.2%之间。该方法的前处理相对于萃取过程较简单,其准确度、精密度和灵敏度均符合农药残留分析与检测的技术要求,适合于丁硫克百威及其代谢产物在烟叶和土壤中的残留分析与检测。     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Integrated management of Meloidogyne incognita‐Fusarium oxysporum f. sp. ciceri wilt disease complex in chickpea

A field experiment was conducted to study the management of a root‐knot nematode, Meloidogyne incognita (Kofoid and White) Chitw. (Tylenchida: Heteroderidae)‐wilt inducing fungi, Fusarium oxysporum Schlecht. emend. Snyd & Hans. f. sp. ciceri (Padwick) Snyd. & Hans. (Moniliales: Tuberculariaceae) wilt disease complex in chickpea (Cicer arietinum L.). cv. Annegiri. The results indicated that integration of soil solarization (for 6 weeks), VA mycorrhizal fungus (VAM), Glomus fasciculatum inoculation (12g/hill) and seed treatment with carbosulfan (3% w/w) was highly effective in reducing population levels of both pathogens, root‐knotdisease and wilt incidence and in increasing chickpea grain yield significantly. However, seed treatment with carbendazim (0.25% w/w) together with carbosulfan (3% w/w) was not only effective in reducing the wilt disease complex but also economic with an incremental cost: benefit ratio of 1: 2.4.     

光周期对莲草直胸跳甲生长发育和繁殖的影响

为明确莲草直胸跳甲Agasicles hygrophila Selman et Vogt的生态适应性,提高其对恶性杂草喜旱莲子草Alternanthera philoxeroides(Martius)的生物防治效率,研究了7组不同光周期对其生长发育和繁殖的影响。结果表明:不同光周期处理下,莲草直胸跳甲卵的孵化历期差异显著,在L∶D=12 h∶12 h时孵化历期最短,为4.33 d;其化蛹率无显著差异。相较于短光期,长光期条件更适合其幼虫生长发育。随着光照时数的增加,莲草直胸跳甲成虫寿命、产卵历期、雌虫产卵量呈明显单峰趋势,光周期为L∶D=12 h∶12 h时,成虫寿命和产卵历期最长,分别为41.8 d和34.0 d;光周期为L∶D=8 h∶16 h时,雌虫产卵量最高,为98.5块。不同光周期处理下其成虫后代的孵化率均高于85%,各处理间均无显著差异。在7组光周期处理下,莲草直胸跳甲均未出现生长与生殖停滞及大量死亡现象。生命表分析结果显示,光周期为L∶D=12 h∶12 h时,莲草直胸跳甲种群的净增殖率、平均世代周期及内禀增长率均最高,分别为386.88、45.36和0.13;而种群增殖时长最短,为5.27 d。表明光周期为L∶D=12 h∶12 h时最适合莲草直胸跳甲生长发育和繁殖。     

Effects of organic‐farming‐compatible insecticides on four aphid natural enemy species

BACKGROUND: The toxicities of pyrethrins + rapeseed oil, pyrethrins + piperonyl butoxide (PBO), potassium salts of fatty acids and linseed oil were assessed in the laboratory on the parasitic wasp Aphidius rhopalosiphi (Destefani‐Perez), the ladybird Adalia bipunctata (L.), the rove beetle Aleochara bilineata (Gyll.) and the carabid beetle Bembidion lampros (Herbst.). The methods selected were residual contact toxicity tests on inert and natural substrates. RESULTS: Both the pyrethrin products led to 100% mortality in the adult parasitic wasps and ladybird larvae on glass plates and plants. The pyrethrins + PBO formulation was toxic for B. lampros on sand and natural soil, but the pyrethrins + rapeseed oil formulation was harmless for this species. Insecticidal soaps were harmless for all these beneficial species. None of the tested products significantly affected the parasitism of the onion fly pupae by A. bilineata. CONCLUSION: The results indicated the potentially high toxicity of natural pyrethrins for beneficial arthropods. Although this toxicity needs to be confirmed in field conditions, the toxicity levels obtained in the laboratory were similar to or higher than those of several synthetic insecticides known to be toxic in the field. Insecticidal soaps could be considered as an alternative for aphid control in organic farming in terms of selectivity. Copyright © 2010 Society of Chemical Industry     

包气带土壤pH对灌溉施肥响应的变异过程

为了分析灌溉施肥活动引起的包气带土壤pH值变异特征及其对地球化学条件的响应,通过历时3 a的野外原位灌溉施肥试验,应用不同季节灌前、灌后6 m土层中不同深度的测定资料,系统分析了土壤pH对灌溉、施肥的响应过程,结果表明：各深度pH值呈弱变异性（CV=1.01%~2.28%）,与灌溉前相比,灌后土壤pH值的均值和变异系数均呈现明显的变化;灌前包气带各层pH具有强烈的空间自相关性,灌后受水分、基质等相互作用影响,pH的空间自相关性有所减弱,C₀/(C₀+C)和变程a分别由7.23 m和3.54 m(灌前0 d)减少到3.26 m和2.76 m(灌后第10天)。土壤基质是决定土壤酸碱性的主要因素,在灌溉施肥活动对pH的响应过程中,地球化学条件（土壤含水量、土壤温度、土壤有机质(SOM)、氧化还原电位（RP）等)、土壤基质组成和氮底物浓度（NH⁺₄-N）等的交互作用影响pH的动态。土壤含水量和温度单独对pH影响不显著,两者交互作用对pH有显著影响。引起土壤pH变化的主要变异源为Cl^-、土壤有机质(SOM)、NO^-₃-N、NH⁺₄-N等营养物质和不同空间深度土壤基质的差异,表明灌溉施肥改变了包气带pH地球化学动力场、营养物质和土壤基质的交互作用,引起各深度的生物地球化学反应,控制pH值的空间变异特性。当包气带介质土壤水分变化时,首先营养物氨态氮以分子态或水合态形式被介质吸附,H⁺得到释放,使得灌后第4天pH值下降。随着氨氧化过程中H⁺的释放,pH在灌前和灌后第10天和第30天有显著差异。氨的氧化引起硝酸盐含量不断增加,使得硝酸盐对pH值的影响在灌后不断增强,相关系数由0.24(0 d,P<0.05)增加到0.41(30 d,P<0.01),而氨态氮对pH值的影响逐步降低,相关系数由0.43(0 d,P<0.01)降低为0.19(30 d,P>0.05)。     

Improved chemical control ofCapnodis tenebrionis andC. carbonaria in stone-fruit plantations in Israel

Nine compounds and three modes of applications were tested to improve the control of twoCapnodis spp.,C. tenebrionis L. and C.carbonaria Klug (Coleoptera: Buprestidae), in local stone-fruit plantations. The best result was obtained by azinphos-methyl applied as a foliar spray. Suitable chemicals for dusting were methiocarb, azinphos-methyl and carbosulfan applied to the stem in late spring or prior to fruit harvest. Soil application of imidacloprid as a systemic insecticide is successful for protection of young plantations and nurseries. C.tenebrionis was less susceptible thanC. carbonaria to the tested insecticides.     

园林树木种类及树冠大小对自流式注干药剂吸收及传导的影响

为探明园林树木种类、树冠大小及药剂种类对自流式注干药剂吸收及传导的影响,将甲氨基阿维菌素苯甲酸盐（简称甲维盐）分别与丁硫克百威、吡虫啉及阿维菌素组合,配制成2.8%甲维盐＋0.3%丁硫克百威（简称3.1% EB）、6%甲维盐＋4%吡虫啉（10%EB）与2%甲维盐＋0.5%阿维菌素（2.5% EB）3种乳油（EC）注干液剂,通过自流式树干注药方式,将3.1% EB和10% EB分别导入香抛树、柳树与栾树体内,研究了不同树种及不同药剂下药液吸收与传导的差异;采用2.5% EB,研究了香抛树树冠直径对药液吸收及传导的影响,同时通过HPLC-UVD检测方法,考察了药剂的残效期。结果表明:树木种类会显著影响注干药剂的吸收,且吸收速率依次为柳树>香抛树>栾树,开始注药5 d后,柳树上的药剂已被全部吸收,而栾树上3.1% EB和10% EB 的剩余量分别为66.6% 和48.6%;开始注药5 d后,10% EB在香抛树上的吸收率显著高于3.1% EB,两者剩余量分别为12.6%和29.3%,而其他处理则显示药剂种类对其吸收率影响不大;香抛树树冠直径大小对2.5% EB的吸收具有显著影响,冠径越大越利于药剂的吸收;开始注药起第113天,在香抛树枝叶中仍能检测到阿维菌素和甲维盐残留。研究表明,柳树对3.1% EB和10% EB的吸收性能均最佳,且供试药剂种类对其吸收性能影响不大;香抛树冠径大小与其对2.5% EB的吸收呈正相关性,且药剂残效期高达90~120 d。     

超高效液相色谱-串联质谱法检测水稻及稻田环境中速灭威的残留

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)检测稻田土壤、田水、水稻植株、谷壳和糙米样品中速灭威残留的分析方法。样品经乙腈提取及盐析处理后,用乙二胺-N-丙基(PSA)和白炭黑(SiO2·nH2O)净化,UPLC-MS/MS 多离子反应监测模式下测定。结果表明,在0.005~1 mg/L 范围内,速灭威的仪器响应值与进样质量浓度间呈良好线性关系,相关系数(r)大于0.98。当添加水平为0.01~5 mg/kg(田水样品中为0.005~1 mg/L)时,速灭威在不同样品基质中的平均回收率为76.7% ~107.8%,相对标准偏差(RSD)为1.7% ~8.5%,最小检出量(LOD)均为2.0×10-13g,最低检测浓度(LOQ) 除在田水样品中为0.005 mg/L外,其余均为0.01 mg/kg。当按推荐剂量的1.5倍(有效成分45 g/hm2)分别施药2次和3次后,采用所建方法测得距最后一次施药10、14和21 d采收的糙米样品中速灭威的最终残留量均为未检出(低于0.01 mg/kg)。     

Relative resistance or susceptibility of maple (Acer) species,hybrids and cultivars to six arthropod pests of production nurseries

BACKGROUND: Maples (Acer spp.) in production nurseries are vulnerable to numerous arthropod pests that can stunt or even kill the young trees. Seventeen cultivars representing various Acer species and hybrids were evaluated for extent of infestation or injury by shoot and trunk borers (Proteoteras aesculana, Chrysobothris femorata), potato leafhopper (Empoasca fabae), Japanese beetle (Popillia japonica), maple spider mite (Oligonychus aceris) and calico scale (Eulecanium cerasorum). Evaluations were done in replicated field plots in central and western Kentucky. RESULTS: All of the maples were susceptible, to varying degrees, to one or more key pest(s). Red maples (A. rubrum) were relatively vulnerable to potato leafhopper injury and borers but nearly free of Japanese beetle feeding and spider mites. Sugar maples sustained conspicuous Japanese beetle damage but had very low mite populations, whereas the opposite was true for Freeman maples (A. × freemanii). A. campestre was heavily infested by calico scale. Within each species or hybrid there were cultivar differences in degree of infestation or damage by particular pests. CONCLUSION: The results should help growers to focus pest management efforts on those plantings at greatest risk from particular pests, and to choose cultivars requiring fewer insecticide inputs to produce a quality tree. Copyright © 2012 Society of Chemical Industry     

Metabolism of carbosulfan [2,3-dihydro-2,2-dimethylbenzofuran-7-yl (di-n-butylaminothio)methylcarbamate] in the rat and house fly

The metabolism of carbosulfan, 2,3-dihydro-2,2-dimethylbenzofuran-7-yl (di-n-butylaminothio)-methylcarbamate, was studied in the rat and house fly. Carbosulfan was metabolized via at least two major pathways in the rat, by initial oxidation of the sulfur atom and by NS bond cleavage. The principal rat metabolites were the conjugated keto-phenol from the ring-labeled carbo-sulfan, carbon dioxide from the carbonyl-labeled carbosulfan, and dibutylamine from the dibutylamino-labeled carbosulfan. In house flies, carbosulfan was converted primarily into carbofuran and related oxidation products. The lower mammalian toxicity of carbosulfan compared to its insecticidal activity is explained on the basis of differences in routes and rates of metabolism of carbosulfan in mammals and insects.     

Mutagenic, genotoxic and enzyme inhibitory effects of carbosulfan in rainbow trout Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss; 116.88 ± 21.69 g) were exposed to sublethal concentrations (25 μg/L) of carbosulfan for 60 days to test if the long term exposure of fish to carbosulfan affects red blood cells acetylcholinesterase (AChE), δ-aminolevulinic acid dehydratase (ALA-D) and paraoxonase (PON) enzyme activity and induces genotoxic and/or mutagenic effects. The exposure resulted in inhibition of AChE and ALA-D activity of rainbow trout when compared to control fish. The activity of PON was not affected by carbosulfan. Interestingly, carbosulfan was found to induce DNA damage in red blood cells (comet assay) and proved to be mutagenic as revealed by the Ames test. Results indicate that blood AChE and ALA-D of rainbow trout may be a sensitive biomarker for assessment of carbosulfan contaminated water bodies. Furthermore, because the Ames test and comet assay were proven successful to detect the genotoxicity of carbosulfan, we proposed that nonlethal techniques such as blood collection from caudal vein of fish should be used to determine potential toxic effects of other pesticides to surrounding environment.     

Pathogens of bark beetles (Coleoptera: Curculionidae) in Bulgarian forests

The occurrence and prevalence of bark beetle pathogens in forest stands in Bulgaria were investigated in 944 specimens belonging to 21 bark beetle species. Protozoa, microsporidia, fungi and nematodes occurred in 19 of all investigated species. The infections were found in the gut (nematodes, gregarines, microsporidia), gonads (microsporidia) and hemolymph (nematodes) of the infected insects. Protozoan species (Gregarina typographi, Gregarina spp.) were detected in eight bark beetle species. Morphometric data about G. typographi and Gregarina spp. are presented. The prevalence of the gregarines varied between 1.4% and 64.2%. Microsporidia of the genera Nosema and Chytridiopsis were revealed in three bark beetle species. The prevalence of microsporidia ranged between 1.5% and 11.8%. This is the first report of a microsporidium in Taphrorychus villifrons and of gregarines in T. villifrons, Pityogenes bistridentatus, P. conjunctus, and Orthotomicus erosus. The fungus Beauveria bassiana was found in 3.4% of Hylurgops palliatus specimens. Nematodes (in gut and haemolymph) were revealed in 19 bark beetle species and their prevalence varied between 10% and 98.5%.     

高效液相色谱法检测苦参碱在小白菜及土壤中的残留与消解动态

通过一年两季(春季和冬季)的田间试验,采用C18固相萃取-高效液相色谱分析方法,研究了苦参碱在小白菜及土壤中的残留和消解动态。方法验证试验表明:在0.02~0.5mg/kg添加水平下,苦参碱在小白菜和土壤中的平均回收率为71%~87%,相对标准偏差为5.7%~14%,在小白菜与土壤中的定量限(LOQ)均为0.02mg/kg。消解动态试验结果表明:苦参碱在小白菜及土壤中的消解过程均符合一级动力学方程,消解半衰期分别为1.0d(春季,小白菜)、1.5d(冬季,小白菜)、1.4d(春季,土壤)和1.6d(冬季,土壤)。最终残留结果显示:距最后一次施药7d后,高浓度(有效成分6.71g/hm2)和低浓度(有效成分4.47g/hm2)苦参碱在春季和冬季小白菜中的最终残留量在0.061~0.074mg/kg之间;在土壤中的最终残留量在未检出~0.075mg/kg之间。可见,苦参碱在小白菜及土壤中易消解,为保障小白菜食用安全,建议可将0.1mg/kg作为其最大残留限量,安全间隔期不小于3d。     

High‐level of resistance to spinosad,emamectin benzoate and carbosulfan in populations of Thrips tabaci collected in Israel

BACKGROUND: The onion thrips, Thrips tabaci Lindeman, is a major pest of several crop plants in the genus Allium, such as onions, garlic and chives. In Israel, these crops are grown in open fields and in protected housing. This thrips is usually controlled by the application of chemical insecticides. In recent years, spinosad, emamectin benzoate and carbosulfan have been the major insecticides used for the control of the onion thrips. In the last 4 years, growers of chives and green onion from several regions of Israel have reported a significant decrease in the efficacy of insecticides used to control the onion thrips. RESULTS: The susceptibility of 14 populations of the onion thrips, collected mainly from chives between the years 2007 and 2011, to spinosad, emamectin benzoate and carbosulfan was tested using a laboratory bioassay. The majority of the populations showed significant levels of resistance to at least one of the insecticides. LC₅₀ values calculated for two of the studied populations showed that the resistance factor for spinosad compared with the susceptible population is 21 393, for carbosulfan 54 and for emamectin benzoate 36. Only two populations, collected from organic farms, were susceptible to the insecticides tested. CONCLUSION: This is the first report of a high resistance level to spinosad, the major insecticide used to control the onion thrips. Resistance cases to spinosad were associated with failures to control the pest. Populations resistant to spinosad also had partial or complete resistance to other insecticides used for controlling the onion thrips. Copyright © 2012 Society of Chemical Industry     

基于室内高光谱数据的多种类型土壤有机质估算模型比较

基于高光谱数据的土壤有机质反演是土壤遥感及精准农业的重要研究内容,然而不同的光谱处理及建模方法使得模型的估算能力及精度差异明显,限制了模型之间的通用性。为了构建陕西省土壤有机质含量估算的最优模型,以陕西省9种主要土壤类型的216个土样的光谱反射曲线和土壤有机质含量为数据基础,将光谱反射曲线进行一阶微分d(R)、倒数对数log(1/R)、倒数对数一阶微分d[log(1/R)]和包络线去除N(R)4种变换,结合一元线性回归(SLR)、偏最小二乘回归(PLSR)和支持向量机回归(SVR)3种建模方法构建了不同的土壤有机质含量估算模型。结果显示:不同类型土壤的反射光谱曲线总体态势基本一致,吸收特征位置基本相同,且土壤有机质含量与光谱反射率呈负相关态势;基于d [log(1/R)]光谱变换构建的SVR估算模型精度最高,建模集和验证集的判断系数(R~2)分别为0.9210、0.8874,验证均方根误差(RMSE)为2.18,相对分析误差(RPD)达到2.8751,是估算陕西省土壤有机质含量的最优模型,PLSR次之,SLR最差。     

不同剂型吡虫啉在烟叶和土壤中的残留及消解动态

采用高效液相色谱检测技术,于2010—2011年开展了吡虫啉可溶液剂、可湿性粉剂、微乳剂和颗粒剂4种常见剂型的不同施药剂量、不同施药次数和采收间隔期的田间试验,研究了不同剂型吡虫啉在烟叶和土壤中的残留降解规律与最终残留量。结果表明,在3个添加水平（0.01~5 mg/kg）、5次重复下,鲜烟叶、干烟叶和土壤中吡虫啉的平均回收率和相对标准偏差（RSD）分别为85.6% ~89.3%,5.0% ~5.7%;85.0% ~88.3%,3.5% ~5.0%;84.1% ~91.5%,3.4% ~8.0%;符合农药残留检测要求。吡虫啉最小检出量（LOD）为0.3 ng（S/N=3）,最低检测浓度（LOQ）分别为:鲜烟叶0.01 mg/kg,干烟叶0.03 mg/kg,土壤0.01 mg/kg。由于推荐剂量不同,不同剂型农药在烟叶上的原始沉积量有较大差别,可溶液剂、可湿性粉剂、微乳剂和颗粒剂4种剂型的吡虫啉降解速率均较快,半衰期分别为5.7~6.6、3.1~3.7、5.0~5.1和10.5~11.4 d。在不同处理的干烟叶中,吡虫啉残留量有明显差异,根据国际烟草科学合作研究中心（CORESTA）的指导性残留限量为5 mg/kg,建议大田喷雾施药的3种剂型（可溶液剂、可湿性粉剂和微乳剂）安全间隔期为14 d,移栽期穴施的颗粒剂安全间隔期为70 d。     

威百亩熏蒸对土壤反硝化作用及nirS型反硝化细菌群落结构的影响

为探究威百亩对土壤反硝化作用的影响及作用机制,采用理化分析和变性梯度凝胶电泳方法分析浓度20、100和500 mg/kg威百亩熏蒸对土壤反硝化作用及nirS型反硝化细菌群落结构的影响。结果显示,威百亩熏蒸处理0、14 d后,500 mg/kg浓度处理的土壤反硝化率为84.64%、90.52%,分别显著低于对照的86.72%和91.87%,100、20 mg/kg浓度处理的土壤反硝化率与对照均无显著差异;熏蒸处理28、56和84 d后,4个处理的土壤反硝化率均无显著差异。与对照相比,3个浓度威百亩熏蒸处理0、14、28、56和84 d后的土壤nirS型反硝化细菌群落的多样性指数和均匀度指数均差异不显著。除56 d外,20 mg/kg浓度熏蒸处理0、14、28和84 d的土壤细菌群落丰富度指数分别为8.77、14.77、9.77和8.75,均显著低于对照;100 mg/kg浓度熏蒸处理0、14和28 d后的土壤细菌群落丰富度指数分别为10.76、6.77和10.78,显著低于对照,而处理56、84 d后,土壤细菌群落丰富度指数与对照无显著差异。500 mg/kg浓度威百亩熏蒸处理后,土壤反硝化作用在熏蒸后0~14 d受到抑制,28 d后土壤反硝化作用自然恢复;土壤细菌群落丰富度指数无论熏蒸初期或后期与均对照差异不显著。威百亩对土壤反硝化强度的影响与nirS型硝化细菌群落结构变化无关,说明nirS型反硝化细菌在土壤反硝化作用中不起主要作用。     

Laboratory assays of select candidate insecticides for control of Dendroctonus ponderosae

BACKGROUND: The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae), is the most destructive bark beetle in western North America. Dendroctonus ponderosae can be prevented from successfully colonizing and killing individual trees by ground‐based sprays of insecticides applied directly to the tree bole. However, the future availability of several active ingredients, including carbaryl which is most commonly used in the western United States, is uncertain. Two novel insecticides, cyantraniliprole [Cyazypyr^?‐OD (oil dispersion) and Cyazypyr^?‐SC (suspension concentrate)] and chlorantraniliprole (Rynaxypyr^®), and carbaryl were assayed in both filter paper and topical assays. RESULTS: Compared with 20 000 mg L^?1 carbaryl (i.e. the maximum label rate for solutions applied to conifers for protection from bark beetle attack in the western United States), cyantraniliprole OD caused similar rates of mortality in D. ponderosae adults at 400‐fold weaker concentrations in both bioassays, while cyantraniliprole SC caused similar rates of mortality at 40‐fold weaker concentrations. Probit analyses confirmed that D. ponderosae is most sensitive to cyantraniliprole OD, while chlorantraniliprole was effective at concentrations similar to carbaryl. CONCLUSIONS: These results suggest that lower concentrations of carbaryl have merit for field testing than have been previously considered. While cyantraniliprole and chlorantraniliprole have similar modes of action, cyantraniliprole OD appears to have greater promise for protecting individual trees from mortality attributed to D. ponderosae attack and should be evaluated in field studies. Published 2011 by John Wiley & Sons, Ltd.