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为研究影响玫瑰黄链霉菌Streptomyces roseoflavus Men-myco-93-63活性代谢产物roflamycoin光不稳定的因素,采用高效液相色谱仪测定了不同光照环境、光照强度、光照时间、溶剂、质量浓度等因素下roflamycoin的光分解率;检测8种光稳定剂对roflamycoin光分解的抑制作用;并通过抑菌圈法测定了光分解前后物质抑菌效果的变化。结果显示,在roflamycoin的光分解过程中,太阳光和日光灯是其敏感光源,而紫外光并不能引起光分解;光照强度越大、光照时间越长、质量浓度越低,其光分解速率越快;在甲醇、丙酮、N,N-二甲基甲酰胺、二甲基亚砜、四氢呋喃5种溶剂中的光分解速率无显著差异;roflamycoin光分解过程最终可以达到一个稳定状态,主要分解为3种物质,并与roflamycoin具有相同的五烯大环内酯骨架;8种光稳定剂均未表现出抑制光分解的作用。roflamycoin光照分解后对12种病原菌仍有抑制作用,其中对番茄灰霉病菌、玉米穗腐病菌等6种病原菌的抑制活性显著增强,抑菌圈直径增大7.64%～21.91%,对棉花黄萎病菌、苹果斑点落叶病菌等4种病原菌的抑制活性显著降低,抑菌圈直径减小10.03%～91.46%。推测roflamycoin的光分解产物仍具有抑菌活性。 相似文献
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Abstract White-tailed deer (Odocoileus virginianus) pose economic and safety problems for agricultural and transportation industries. We tested an electronic mat to determine if it would reduce deer crossing through fence openings. We measured deer intrusions and corn consumption at five sites with charged mats and five sites with non-charged mats. Weekly intrusions at treated sites decreased an average of 95% from pre-treatment. Weekly intrusions at control sites were reduced 60% during weeks 1 and 2 and increased to 10% reduction by week 6. Weekly corn consumption at treated sites decreased from pre-treatment through all treatment weeks. Weekly corn consumption at control sites decreased in weeks 1 – 4 and 6 but was not different from pre-treatment in week 5. Consumption remained higher than expected at treated sites because deer jumped over or broke through the fence that delineated sites. Based upon the conditions and results of this test, we believe that electrified mats could reduce deer passage through fence openings. 相似文献
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Nagat Aly Kawther EL-Gendy Abdel Khalek El-Sebae 《Pesticide biochemistry and physiology》2010,97(1):7-12
Pesticides may induce oxidative stress leading to generate free radicals and alternate antioxidant or oxygen free radical scavenging enzyme system. This study was conducted to investigate the acute toxicity of chlorpyrifos toward male mice and the oxidative stress of the sub-lethal dose (1/10 LD50) on the lipid peroxidation level (LPO), reduced glutathione content (GSH) and antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD), and glutathione-S-transferase (GST) activities. Also, the protective effects of vitamin C (200 mg/kg body weight, bw) 30 min before or after administration of chlorpyrifos were investigated. The results demonstrated that the LD50 value of chlorpyrifos was 134.95 mg/kg bw. The oral administration of 13.495 mg/kg chlorpyrifos significantly caused elevation in LPO level and the activities of antioxidant enzymes including CAT, SOD and GST. However, GPx activity remained unchanged, while the level of GSH and G6PD activity were decreased. Vitamin C treatment to chlorpyrifos intoxicated mice decreased LPO level and GST activity, normalized CAT, SOD and G6PD activities, while GSH content was increased. We conclude that vitamin C significantly reduces chlorpyrifos-induced oxidative stress in mice liver and the protective effect of the pre-treatment with vitamin C is better than the post-treatment. 相似文献
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The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda-cyalothrin from 68.0 ng bee?1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha?1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field. 相似文献
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The influence of different combinations of illumination and shaking on the growth dynamics, pathogenicity and toxin production of the fungus Fusarium oxysporum f. sp. orthoceras, a biocontrol agent of Orobanche cumana, was studied. The fastest biomass accumulation was obtained under shaking, with or without illumination, with the highest biomass obtained after 3–4 weeks of growth. The biological activity of chloroform extracts of the culture filtrate was characterised: it contained at least two main toxic metabolites that caused necrosis and wilting of various plants and led to mortality of germinating seeds of O. cernua, O. aegyptiaca, O. ramosa and O. cumana. The highest toxic activity of the chloroform extract was obtained under illumination without shaking after 3–4 weeks of growth. The two toxic metabolites were purified and identified as fusaric acid (FA) and 9,10‐dehydrofusaric acid (DFA). Both FA and DFA production began in the first week of growth, increasing gradually to their maxima after 4 weeks. The highest level of pathogenic activity of the fungus was obtained after three or more weeks of fungal growth. It can be concluded that in order to produce high levels of toxin and pathogenic activity, the fungus should be grown under illumination without shaking for 4 weeks. 相似文献
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Topical application of the synergists piperonyl butoxide (PB) and S,S,S-tributyl phosphorotrithioate (DEF) to second-instar larvae of a standard laboratory strain (FS) and an unselected Malaysian field strain (CH) of the diamondback moth Plutella xylostella had no significant effect on the toxicity of the acylurea insecticides, chlorfluazuron and teflubenzuron, in a subsequent leafdip bioassay. In contrast, pre-treatment with PB or DEF in acylurea-selected subpopulations of the CH strain with varying levels of cross-resistance to chlorfluazuron and teflubenzuron significantly increased (up to 34-fold and 28-fold, respectively) the toxicity of both compounds, suggesting that microsomal monooxygenases and esterases may be involved in resistance. The addition of a mineral oil, ‘Sunspray 6E’, to topically-applied chlorfluazuron consistently reduced its LD50 value, and the effect of the oil appeared to be greatest on the most resistant population of P. xylostella. However, the effects of the oil were not significant (P > 0·05) and further studies are necessary to determine whether a penetration factor is present in the CH strain. 相似文献
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Hector Masuh Andrea Fontn María I. Picollo Susana A. de Licastro Eduardo Zerba 《Pest management science》1996,47(2):181-184
The butyl ester of buthionine sulfoximine (BBSO) applied topically to the nymph V stage of Triatoma infestans (Klug) caused glutathione depletion which was maintained for four days after treatment. Topical pre-treatment of nymph V with BBSO significantly synergised the toxicity of DDT and fenitrothion to T. infestans. 相似文献
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脱镁叶绿酸钠是叶绿素代谢中间产物脱镁叶绿酸a的水溶性钠盐,具有良好的光敏抑菌活性。为探索光照条件对其抑菌活性的影响,采用菌丝生长速率法,研究在不同光照度、光波长及光照时间条件下,脱镁叶绿酸钠对忽视拟盘多毛孢Pestalotiopsis neglecta的抑制作用。结果表明:20 mg/mL的脱镁叶绿酸钠在照度为2 000 lx的白光照射下对菌丝生长的抑制率为83.7%,在黑暗条件下抑制率为77.0%,表明光照对脱镁叶绿酸钠抑菌活性有显著影响 (P < 0.05);此外,白光的效果好于单色光;光照度及光照时间对抑菌活性也有显著影响,其中当照度为16 000 lx且光照时间为24 h时抑菌作用最强。 相似文献
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苏云金杆菌与高效氯氰菊酯对美国白蛾的协同作用 总被引：2，自引：0，他引：2
为了明确苏云金杆菌 Bacillus thuringiensis (Bt)和高效氯氰菊酯的协同作用,采用Bt预处理及直接混用2种方式施药,室内饲毒法测定了2种药剂对美国白蛾 Hyphantria cunea (Drury) 2龄幼虫的活性,同时研究了高效氯氰菊酯对Bt生长曲线的影响。结果表明:试虫先用每mL含1×106个孢子的Bt S19菌悬液预处理,1 d后再用系列浓度的高效氯氰菊酯处理,其48 h的LC50值为0.76 mg/L,而未经预处理,仅用高效氯氰菊酯处理48 h的LC50值为1.28 mg/L;2种处理在高效氯氰菊酯质量浓度为2.25 mg/L时对试虫的半致死时间(LT50值)分别为9.2 h和34.7 h,两者间增效作用明显。对于直接混用,采用1×106个/mL的Bt S19与6 mg /L的高效氯氰菊酯混剂处理,增效作用明显,72 h的共毒系数为122.5,此后再增加高效氯氰菊酯的浓度则表现出轻微的拮抗作用。高效氯氰菊酯处理可使Bt生长对数期延迟,且浓度越高影响越大,说明高效氯氰菊酯可影响Bt芽孢萌发,使菌体增殖延迟。研究表明,先用Bt预处理后再使用高效氯氰菊酯对美国白蛾的作用效果优于二者直接混用。 相似文献
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Metabolism of the plant-derived phototoxic insecticide, α-terthienyl (α-T), was examined in larvae of the mosquito Culex tarsalis Coquillett (Diptera: Culicidae). Results indicated that metabolism of [3H]α-T occurred and that the resulting hydrophilic metabolites were the principal products excreted from 1-hr post-treatment onward. Pretreatment of larvae with piperonyl butoxide increased susceptibility to α-T phototoxicity and decreased the extent of [3H]α-T elimination as compared to controls. Pretreatment with β-naphthoflavone reduced α-T toxicity without affecting its elimination. Phenobarbital pretreatment affected neither toxicity nor elimination of the phototoxin. A model for interaction of Phase I and Phase II systems in metabolism of α-T by C. tarsalis larvae is proposed. 相似文献
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Malcolm M. Campbell 《Pest management science》1983,14(2):199-212
A system for testing the effect of a repellent against nonbiting flies attracted to man was developed for Musca domestica L. and Musca vetustissima Walk., and was used to compare the repellency of a range of chemicals against the former. Both arms of one person were simultaneously exposed to large numbers of the test insect in a cage, with repellent applied to a 45 cm2 area on one arm, and the solvent to an identical area on the other arm. By varying the dose of repellent, a dose-to-repellency relationship was established and evaluated using probit analysis to determine 50% (RD50) and 90% (RD90) repellency. Both values were required to characterise a repellent. Greatest uniformity of results was obtained with even illumination of the cages from above and exclusion of side lighting. RD50 and RD90 values were not affected by prior exposure of the flies in a cage and did not change with time. Of the repellents tested, dipropyl isocinchomeronate was the most effective against M. domestica. The repellent effect of mixtures of the compounds was tested against M. domestica and was less than expected by summation of the components acting alone, suggesting that to minimise the total dose of chemical applied to skin, single compounds are preferable to mixtures. 相似文献
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F. P. Olivieri M. C. Lobato E. González Altamiranda G. R. Daleo M. Huarte M. G. Guevara A. B. Andreu 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(1):47-56
Since most plants possess resistance mechanisms which can be induced upon pre-treatment with a variety of chemical compounds,
the use of β-aminobutyric acid (BABA) as a defence inducer without reported toxic effect on the environment was studied. The
aim of this work was to analyse the effectiveness of BABA to induce resistance against Phytophthora infestans and Fusarium solani in potato cultivars differing in their level of resistance to late blight. The behaviour of some components of biochemical
mechanisms by which BABA increases resistance against P. infestans, as well as the effect of BABA on the activity of a potential pathogenic factor of F. solani, were studied. Plants with four applications of BABA throughout the crop cycle produced tubers more resistant to P. infestans and F. solani than non-treated plants. In addition, tuber slices from treated plants, inoculated with P. infestans, showed an increase in phenol and phytoalexin content. The aspartyl protease StAP1 accumulation was also higher in tubers obtained from treated plants and inoculated with P. infestans. This result was observed only in the more resistant potato cv. Pampeana, early after infection. In the potato–F. solani interaction, infected tubers coming from BABA-treated plants showed minor fungal proteolytic activity than infected, non-treated
ones. For potato cvs Pampeana and Bintje, the BABA treatment improved the yield of harvested tubers. The number of tubers
per plant and total weight of harvested tubers was greater for those obtained from treated plants with two early or four applications
of BABA. The results show that the BABA treatment increases the resistance of potatoes but the degree of increase depends
on the original level of resistance present in each cultivar. 相似文献
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Ju Ding Kai Shi Yan Hong Zhou Jing Quan Yu 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):141-150
Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (FO), is one of the major diseases in cucumber (Cucumis sativus) production. Root and foliar applications of 24-epibrassinolide (EBL), an immobile phytohormone with antistress activity,
were evaluated for their effects on the incidence of Fusarium wilt and changes in the microbial population and community in
roots of cucumber plants. EBL pre-treatment to either roots or shoots significantly reduced disease severity followed by an
improved plant growth regardless of the treatment methods applied. EBL applications decreased the Fusarium population on root surfaces and in nutrient solution, but increased the population of fungi and actinobacteria on root surfaces. PCR-DGGE analysis showed that FO-inoculation had significant effects on the bacterial community on root
surfaces as expressed by a decreased diversity index and evenness index, but EBL applications alleviated these changes. Moreover,
several kinds of decomposing bacteria and growth-promoting bacteria were identified from root surfaces of FO-inoculated plants
and EBL-pre-treated plants, respectively. Overall, these results show that the microbial community on root surfaces was affected
by a complex interaction between phytohormone-induced resistance and plant pathogens. 相似文献
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Ten insect growth regulators (IGRs): four juvenile hormone analogs (JHAs) — fenoxycarb, MV-678, R-20458 and dofenapyn, and
six molt inhibitors (MIs) — triflumuron, chlorfluazuron, hexaflumuron, teflubenzuron, Dowco 439 and flufenoxuron; and the
organophosphate malathion, were evaluated for residual activity in stored grain for 2 years against the rice weevil,Sitophilus oryzae (L.). Triflumuron, flufenoxuron, teflubenzuron, chlorfluazuron, hexaflumuron and fenoxycarb, each at a concentration as low
as 1 ppm a.i., were superior to 10 ppm malathion throughout the experiment. The six MIs, each tested at 50 and 100 ppm a.i.,
gave complete control for 2 years. Moreover, a concentration as low as 1 ppm a.i. of triflumuron, teflubenzuron, flufenoxuron
and chlorfluazuron had good residual activity for 1 year post-treatment and provided almost complete grain protection during
this period. Among the JHAs, fenoxycarb had the best residual activity. It gave almost complete control (96.6%) ofS. oryzae at 10 ppm for 18 months post-treatment. The other JHAs at the four test concentrations failed to produce this level of control.
The viability of the wheat grain was not affected by any of the insecticidal treatments, with 90% germination recorded in
treated and control, grains at all intervals tested. 相似文献
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Iason Kostaropoulos Dr Athanasios I Papadopoulos Athanasios Metaxakis Evridiki Boukouvala Euphemia Papadopoulou-Mourkidou 《Pest management science》2001,57(6):501-508
The correlation between the natural levels of glutathione S-transferase (GST) and the tolerance to the organophosphorus insecticides parathion-methyl and paraoxon-methyl, as well as the interaction of affinity-purified enzyme and the insecticides were investigated in order to collect further information on the role of the glutathione S-transferase system as a mechanism of defence against insecticides in insects. The studies were carried out on the larvae and pupae of the coleopteran Tenebrio molitor L, which exhibit varying natural levels of GST activity. Stage-dependent susceptibility of the insect against insecticides was observed during the first 24 h. However, 48 h after treatment, the KD50 value increased significantly due to the recovery of some individuals. Simultaneous injection of insecticide with compounds which inhibit GST activity in vitro caused an alteration in susceptibility of insects 24 or 48 h post-treatment, depending on stage and insecticide used. Inhibition studies combined with competitive fluorescence spectroscopy revealed that the insecticides probably bind to the active site of the enzyme, thus inhibiting its activity towards 1-chloro-2,4-dinitrobenzene in a competitive manner. High-performance liquid chromatography and gas chromatography revealed that T molitor GST catalyses the conjugation of the insecticides studied to a reduced form of glutathione (GSH). From the above experimental results, it is considered that GST offers a protection against the organophosphorus insecticides studied by active site binding and subsequent conjugation with GSH. © 2001 Society of Chemical Industry 相似文献
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Experiments were conducted in a controlled environment growth room to compare the phytotoxicity of five formulations of clopyralid and to determine the effect of post-treatment simulated rainfall applications on the efficacy of these formulations. Clopyralid, formulated as the acid, monoethanolamine salt, potassium salt, 2-ethylhexyl ester or 1-decyl ester was applied to Cirsium arvense or Polygonum convolvulus at the 8–10 and 4–6 leaf stage of development, respectively. Based on the shoot and root dry weight data from both species, the 2-ethylhexyl ester was consistently less phytotoxic than the other four formulations. With respect to Cirsium arvense shoot and root dry weight, there was no difference in efficacy between the acid, monoethanolamine salt, potassium salt and 1-decyl ester. Root dry weight changes of Polygonum convolvulus did not correlate well with an increase in dose of the five formulations. Maximum increase in stem diameter of Polygonum convolvulus occurred after application of 100 g a.e. ha?1 of the acid, monoethanolamine salt, potassium salt and 1-decyl ester whereas with the 2-ethylhexyl ester, the maximum increase occurred after application of 200 g a.e. ha?1. Simulated rainfall was applied 3, 6, 9 or 12 h after application of 200 g a.e. ha?1 of the five clopyralid formulations to both species. Rainfall reduced the efficacy of clopyralid, regardless of the formulation or species. The 2-ethylhexyl ester was less efficacious than the other four formulations, irrespective of the timing of simulated rainfall. 相似文献
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为探索新型生防菌剂解淀粉芽胞杆菌对小麦黄花叶病的防治作用,通过盆栽和田间药效试验研究了解淀粉芽胞杆菌对小麦黄花叶病的防治效果和对小麦幼苗的促生长作用。结果表明,解淀粉芽胞杆菌对小麦黄花叶病有较好的预防效果和一定的治疗效果,浓度为500~2 000 mg/L时,预防效果为24.86%~84.55%,治疗效果为13.61%~62.58%,预防效果明显优于治疗效果。其中灌根处理的防治效果显著高于喷雾、拌种处理,且随着施用浓度的增大,防治效果提高;当灌根处理浓度为2 000 mg/L时效果最好,预防和治疗效果分别达到84.55%和62.58%。另外解淀粉芽胞杆菌对小麦有一定的促生作用,并可提高麦苗的地上部鲜重,浓度为1 200 mg/L时,地上部鲜重增重最大,较对照提高52.76%。表明解淀粉芽胞杆菌可作为生防菌剂防治小麦黄花叶病。 相似文献
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