Insecticidal activity of N,N-diethyl-, N,N-dipropyl-, N,n-di-isopropyl-, and n,n-di-isobutylalkanamides against mosquito larvae

N,N-Diethyl-, N,N-dipropyl-, N,N-di-isopropyl, and N,N-di-isobutylalkanamides in which the acyl moiety ranged from C₈ to C₂₁ were synthesised, and their larvicidal activity was determined against the first-instar larvae of the southern house mosquito Culex quinquefasciatus Say. The four homologous series of amides generally showed an increase in their larvicidal activity as the carbon number in the acyl moiety of the amides increased, until the activity reached a maximum. Subsequently, an increment of carbon number resulted in declining activity in the higher homologues, until the activity disappeared. N,N-Diethyltetradecanamide, N,N-dipropylundecanamide, N,N-di-isopropylundecanamide, and N,N-di-isobutlynonanamide or -dodecanamide were the most active compounds in their respective homologous series of amides; however, they were less active than their analogous N,N-dimethylalkanamides previously studied.     

Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish.     

长武旱塬不同麦玉轮作系统产量效应模拟研究

利用EPIC模型对不同麦玉轮作系统进行模拟,通过对其输出结果的分析,综合考虑产量、经济效益、干旱胁迫和氮肥生产率等因素,对不同麦玉轮作系统进行综合评价,从而比较不同麦玉轮作系统的优劣。结果表明:(1)在模拟研究期间,8种麦玉轮作系统的产量均呈波动性下降趋势,其平均值分别为4.61、4.40、4.16、4.48、4.28、4.29、4.714、.55 t/hm2。所有的麦玉轮作系统中,麦玉轮作系统"春玉米→冬小麦"的经济效益最好。(2)在模拟研究期间,麦玉轮作系统"春玉米→冬小麦→冬小麦"的冬小麦和春玉米所遭受的年均干旱胁迫日数最少(29.51d)。在干旱年份麦玉轮作系统中的冬小麦较春玉米更容易遭受干旱威胁。综合产量、经济效益、作物所遭受的干旱胁迫天数和麦玉轮作系统的氮肥生产率等因素,在长武地区适宜采用的麦玉轮作系统为春玉米→冬小麦。     

Comparison of trifluralin,oryzalin, pronamide,propham, and colchicine treatments on microtubules

The mode of action of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), oryzalin (3,5-dinitro-N⁴,N⁴-dipropylsulfanilamide), pronamide(N-(1,1-dimethylpropynyl) 3,5-dichlorobenzamide), and propham (isopropyl carbanilate) on purified microtubules from pig brains and on the ultrastructure of wheat (Triticum aestivum L. “Mediterranean,” C. I. 5303) and corn (Zea mays L. “yellow dent, U. S. 13”) roots was compared with that known for colchicine. Colchicine disrupts the in vivo cortical and spindle microtubules of root cells. Like colchicine, the herbicides trifluralin, oryzalin, and pronamide caused the loss of both cortical and spindle microtubules of root cells. The rate of microtubule disappearance depended on the type of herbicide and length of exposure of roots to the herbicide. Unlike colchicine, cortical microtubules were present in propham-treated roots but they were disoriented within the cell.In vitro polymerization studies with pig brain microtubules (Sus scrofa) showed that the herbicides failed to inhibit the assembly of purified microtubular protein into microtubules and that radioactively labeled herbicides did not bind to the microtubular protein. Colchicine inhibited the polymerization of microtubular protein and readily bound to the microtubular subunits. These results indicate that the mode of action of the herbicides is not similar to that of colchicine and that the loss of microtubules from root tip cells treated with trifluralin, oryzalin, and pronamide may be caused by these herbicides interfering with synthesis of microtubular protein or metabolism of endoplasmic reticulum membranes involved in microtubule assembly. The mode of action of propham appears to be on the microtubular organizing centers rather than on microtubules per se.     

Action of some herbicides on growth,respiration, plasmalemma integrity,and proton extrusion of Acer pseudoplatanus cells: II. Amides,diphenyl ethers,nitriles, phenols,triazines, and uracils

The activity of 15 herbicides from different families was assayed on nonphotosynthetic Acer pseudoplatanus cells, in batch suspension culture. They inhibited growth, stimulated the oxygen consumption by cells, and changed the pH evolution of the culture medium. Amides did not seem to disturb the membrane properties. Some diphenyl ethers and phenols directly modified the proton compartmentation of cells whereas some other diphenyl ethers, nitriles, triazines, and uracils altered permeabilities to potassium and leucine. Changes in membrane permeabilities to protons and medium constituents were discussed.     

Modeling the Risk of Entry, Establishment, Spread, Containment, and Economic Impact of Tilletia indica, the Cause of Karnal Bunt of Wheat, Using an Australian Context

ABSTRACT Modeling techniques were developed to quantify the probability of Tilletia indica entering and establishing in Western Australia (WA), and to simulate spread, containment, and the economic impact of the pathogen. Entry of T. indica is most likely to occur through imports of bulk grain or fertilizer (0.023 +/- 0.017 entries per year and approximately 0.009 +/- 0.009 establishments per year). Entry may also occur through straw goods, new or second-hand agricultural machinery, and on personal effects of travelers who have visited regions with infected plants. The combined probability of entry and establishment of T. indica, for all pathways of entry, is about one entry every 25 years and one establishment every 67 years. Alternatively, sensitivity analysis does show that increases in quarantine funding can reduce the probability of entry to about one entry every 50 years and less than one establishment every 100 years. T. indica is spread efficiently through contaminated farm machinery, seed and soil, rain, air currents, and animals. Depending on the rate of spread of the pathogen and the amount of resources allocated for detection, the time until first detection could range from 4 to 11 years and the economic impact could range from 8 to 24% of the total value of wheat production in WA.     

Establishment of, and preliminary impact studies on, the rust, Maravalia cryptostegiae, of the invasive alien weed, Cryptostegia grandiflora in Queensland, Australia

The rust fungus Maravalia cryptostegiae , from south-west Madagascar, was introduced into Australia in 1995 as a classical biological control agent against the highly invasive rubber-vine weed Cryptostegia grandiflora , a woody climber endemic to Madagascar. The rust was released at 69 sites between 1995 and 1997 and is now established throughout the plant's exotic range in Queensland, estimated at over 40 000 km². Dispersal was low in the first 3–4 months but was virtually linear thereafter, and the rust spread over 100 km within the first year; after 3 years it was recorded 550 km away from the nearest release site. Spraying both dry and aqueous inoculum of uredinioid teliospores from the ground using mist-blowers, as well as from the air by atomizing spore suspensions, resulted in rust-induced defoliation, producing an overall reduction in fecundity and biomass of the weed. In sites with low water tables, weed growth decreased markedly, with a reduction in plant volume from 9 m⁻³ to 1 m⁻³ over a 4-year period. Both rust- and drought-induced stress combined to cause up to 75% plant mortality at some sites, and at all monitored sites, seedling recruitment was virtually nil. Improved growth of indigenous grasses amongst rubber-vine thickets has increased fuel loads and created opportunities to use fire as a component of an integrated approach to the management of this economically and ecologically damaging weed.     

东北日光温室葡萄园水热通量特征及其对气象因子的响应

运用温室葡萄水热平衡观测资料，分析了东北日光温室葡萄的能量平衡和能量分量日变化、生育期变化以及分配规律，同时也分析了潜热通量（λET）对环境因子的响应。结果表明：水热通量各分量在整个生育期日变化总体上呈现为单峰趋势，净辐射（R_n）的峰值最大为618.75 W·m^-2，λET峰值最大为242.73 W·m^-2，感热通量（H）峰值最大为327.93 W·m^-2；在新梢生长期，白天λET较小，为34.55 W·m^-2,随着生育期推进，λET逐渐增大，在果实着色成熟期达到最大值（78.49 W·m^-2）之后减小；H在各生育期能量中均占了绝大部分；白天潜热通量占净辐射的比例（λET/R_n）在新梢生长期最小，为25.28%，在果实着色成熟期最大，为44.17%；感热通量占净辐射比例（H/R_n）整个生育期几乎都达50%以上，土壤热通量占净辐射比例（G/R_n）相对较小，变化范围为4.46~12.32 W·m^-2；在整个生育期能量比率大小依次为H/R_n>λET/R_n>G/R_n。在不同生育阶段瞬时尺度上，R_n是影响潜热变化最主要的气象因子，R²高达0.88。在日尺度上，各气象因子对潜热通量的影响在逐渐变弱，相对湿度（RH）与λET相关系数仅为0.28。但无论从瞬时尺度还是日尺度，R_n都是影响潜热通量最主要的气象因子。各气象因子对潜热通量的影响大小依次为：R_n>VPD>T_a>RH。     

施肥对小麦、玉米和大豆连作土壤微生物群落功能多样性的影响

为了明确长期施肥和不施肥条件下作物连作对土壤微生物群落功能多样性的影响,以典型黑土为研究对象,选取长期定位实验站长期施肥和不施肥条件下的小麦、玉米和大豆连作处理,通过稀释平板法和Biolog Eco微平板法,测定土壤细菌、真菌、放线菌数量、碳源代谢活性等指标,为建立合理的农田管理措施提供数据支撑和理论依据。结果表明:长期施肥条件下大豆、小麦和玉米连作土壤细菌、真菌和放线菌数量均高于不施肥处理,且均以大豆连作处理细菌和真菌数量最高。不施肥条件下小麦和玉米连作土壤细菌总数较大豆连作处理分别下降了24.8%和31.0%,真菌总数分别下降了64.0%和51.2%;施肥条件下小麦和玉米连作土壤细菌总数则较大豆连作处理分别下降了29.0%和45.5%,真菌总数分别下降了26.7%和31.5%。Biolog结果表明,不施肥条件下小麦连作处理的平均颜色变化率(AWCD)高于玉米和大豆连作处理,施肥条件下则是大豆连作处理的AWCD值高于小麦和玉米连作处理。不施肥条件下大豆、玉米和小麦连作处理利用最多的碳源是碳水化合物类,施肥后不同连作处理利用最多的是碳水化合物类和多聚物类。大豆和小麦连作不施肥条件下土壤微生物利用率最高的碳源均是α-D-乳糖,施肥条件下利用率最高的碳源均是D,L-α-甘油,而不论施肥与否,玉米连作条件下土壤微生物利用率最高的碳源均是D-半乳糖醛酸;葡萄糖-1-磷酸盐和γ-羟基丁酸是农田黑土微生物群落特异利用的关键碳源。主成分分析得出,施肥对土壤微生物碳源代谢能力的影响大于作物的影响。     

Metabolic aspects of the toxicology of diazinon. I. Hepatic metabolism in the sheep,cow, pig,guinea-pig,rat, turkey,chicken and duck

The phosphorothionate insecticide diazinon was incubated with liver microsomes from the sheep, cow, pig, guinea-pig, rat, turkey, chicken and duck. Metabolism by liver slices of most of these species was also examined. Hydroxydiazinon, isohydroxydiazinon, dehydrodiazinon, their oxons and diazoxon were identified and determined quantitatively or semi-quantitatively. An eighth metabolite was tentatively identified as the 6-aldehyde analogue of diazinon. Yields and rates of production of these metabolites varied greatly between species. Production of oxons was not generally correlated with susceptibility to diazinon poisoning, although it was lowest in the least susceptible animal, the sheep. The degradation of oxons by liver slices was too slow to explain the low toxicity of diazinon to the mammals. The relative importance of hepatic and extrahepatic metabolism in determining toxicity to vertebrates is discussed.     

Metabolism of the methoxychlor isostere,dianisylneopentane, in mouse,insects, and a model ecosystem

Dianisylneopentane or 1,1-bis(p-methoxyphenyl)-2,2-dimethylpropane was metabolized largely by O-demethylation to form mono- and diphenol derivatives. Only a small percentage was degraded by α-hydroxylation and rearrangement. In the model ecosystem, dianisylneopentane reacted very similarly to methoxychlor, accumulating in fish to about the same extent and yielding a slightly higher ratio of polar to nonpolar metabolites. The neopentyl group proved to be approximately as stable in biological systems as the isosterically equivalent trichloromethyl group.     

Effects of pymetrozine, an antifeedant of Hemiptera, on Asian citrus psyllid, Diaphorina citri, feeding behavior, survival and transmission of Candidatus Liberibacter asiaticus

BACKGROUND: Vector‐borne plant disease management can be enhanced by deployment of antifeedants in addition to the use of broad‐spectrum neurotoxic insecticides. The effects of pymetrozine on Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, feeding behaviour, survival and transmission of Candidatus Liberibacter asiaticus (Las), the presumed causal pathogen of huanglongbing, were investigated. RESULTS: Pymetrozine applied at 52 and 104 µg mL^?1 to citrus plants [Swingle citrumelo (X Citroncirus webberi Ingram and Moore)] modified the feeding behavior of ACP and increased the amount of time spent performing non‐penetration behaviors while decreasing the time spent performing ingestion behaviors compared with the controls 1 day after treatment. However, the antifeedant effect of pymetrozine subsided 5 days after application. Pymetrozine reduced the survival of both adults and nymphs on treated plants compared with the control. However, it had a greater impact on survival of nymphs than on survival of adults. Pymetrozine applied at 52 and 104 µg mL^?1 on Las‐infected ‘Valencia’ sweet orange plants [Citrus sinensis L. (Osbeck)] reduced acquisition (12 and 21% respectively) and transmission (11 and 18% respectively) of Las by feeding ACP adults compared with the controls; however, these reductions were not statistically significant. CONCLUSIONS: Pymetrozine exhibited moderate antifeedant effects by modifying the feeding behavior of ACP adults with short residual activity. The impact of pymetrozine on survival of nymphs was greater than on adults at the higher concentrations tested. Pymetrozine also reduced the acquisition and transmission of Las by feeding ACP adults up to 21 and 18%, respectively, compared with untreated controls. Copyright © 2010 Society of Chemical Industry     

Response of black, cranberry, kidney, and white bean to linuron

Dry bean producers in Ontario, Canada, have few herbicide options available for annual broad-leaved weed management and there is little information on the tolerance of dry bean to linuron. The tolerance of black, cranberry, kidney, and white bean to the pre-emergence (PRE) application of linuron at the rates of 0, 500, 1000, 1500, 2000, and 2500 g ai ha⁻¹ was evaluated in field studies conducted in 2005 and 2006 at Exeter and in 2006 at Ridgetown, Ontario. The four market classes differed in their response to linuron. Cranberry and kidney bean were more tolerant to the PRE application of linuron than black and white bean. Linuron applied PRE caused as much as 12% injury in cranberry and kidney bean, 47% injury in black bean, and 56% injury in white bean. Linuron applied PRE at 500–2500 g ai ha⁻¹ had no effect on the height of cranberry and kidney bean but decreased the height by 7, 8, and 15% in black bean and by 10, 13, and 23% in white bean at 1500, 2000, and 2500 g ai ha⁻¹, respectively. Linuron applied PRE at the rates evaluated did not cause any adverse affect on the yield of cranberry, kidney, and white bean but black bean yield was reduced by 16% at 2500 g ai ha⁻¹. Based on these results, there is not an adequate margin of crop safety for the PRE application of linuron in black and white bean at rates >1000 g ai ha⁻¹. However, there is a potential for the use of linuron PRE for weed management in cranberry and kidney bean at the rates evaluated.     

Genotypic, phenotypic, biochemical, physiological and pathogenicity-based categorisation of Acanthamoeba strains

The genus Acanthamoeba includes more than 20 morphological species, but classification is problematical. Recently, the discovery of substantial interstrain differences in ribosomal DNA (rDNA) sequences has prompted questions about the relatedness of strains of the same species. In this study, therefore, we have investigated relationships between two isolates of A. polyphaga, CCAP 1501/3c and ATCC 30871, using morphological, biochemical, physiological, molecular and cytotoxicity assays. We observed that A. polyphaga ATCC 30871 exhibited up to six arms in endocyst while A. polyphaga CCAP 1501/3c exhibited a maximum of 5 arms thus indicating their position in group 2 and 3, respectively. Acanthamoeba polyphaga ATCC 30871 exhibited growth at 37 degrees C and growth on 1M mannitol plates while A. polyphaga CCAP 1501/3c did not. In addition, both isolates exhibited differences in isoenzyme banding patterns and rDNA restriction fragment polymorphisms. More importantly, A. polyphaga ATCC 30871 produced cytotoxicity on corneal epithelial cells while A. polyphaga CCAP 1501/3c had no effects, suggesting differences in pathogenicity. Thus, all the results provide evidence for significant differences between the strains and further provided the basis for reclassification of the isolates. Implications of these results in the clinical diagnosis of pathogenic Acanthamoeba are discussed.     

Tolerance of black, cranberry, kidney, and white bean to cloransulam-methyl

The level of tolerance of various market classes of dry bean to cloransulam-methyl is not known. Three field studies were conducted in Ontario, Canada during 2007 and 2008 to determine the level of tolerance of black, cranberry, kidney, and white bean to the pre-emergence (PRE) and postemergence (POST) application of cloransulam-methyl at 17.5, 35, and 70 g ai ha⁻¹. Cloransulam-methyl applied at 17.5, 35, and 70 g ha⁻¹ caused between 13 and 23% injury in black, cranberry, kidney, and white bean, respectively. Cloransulam-methyl applied at 17.5, 35, and 70 g ha⁻¹ reduced the shoot dry weight by between 16 and 28% compared to the untreated control. Cloransulam-methyl applied PRE reduced the height of black bean by 27% and the height of cranberry bean by 25% at 70 g ha⁻¹ and reduced the height of white bean by 19% at 35 g ha⁻¹ and by 37% at 70 g ha⁻¹. Cloransulam-methyl applied PRE reduced the yield of black bean by 29% at 35 g ha⁻¹ and by 43% at 70 g ha⁻¹, reduced the yield of cranberry bean by 43% at 70 g ha⁻¹, and reduced the yield of white bean by 36% at 35 g ha⁻¹ and by 54% at 70 g ha⁻¹. Based on these results, there is not an adequate margin of crop safety for the PRE and POST application of cloransulam-methyl in black, cranberry, kidney, and white bean at the rates evaluated.     

Intestinal uptake,metabolism, and transport of naphthol: In vitro capacity,requirements, and inhibition

The metabolism and transport of [¹⁴C]-naphthol were investigated in sacs of rat small intestine to better understand metabolism of the pesticide carbaryl (which contains naphthol) in the intestine. The capacity to synthesize polar ¹⁴C-labeled metabolites was approximately saturated at 50 μM naphthol. The metabolic capacity of the cranial small intestine was about two times the capacity of the caudal. Anaerobic incubation severely suppressed naphthol metabolism. Sodiumfree medium suppressed metabolism only slightly but altered transport of water and of the polar ¹⁴C-labeled metabolites to serosal and mucosal fluids; the effect on metabolite transport cannot be explained by the effects of sodium on water movements, however. Calcium-free medium did not affect metabolism or metabolite transport; 2,4-dinitrophenol, and possibly phlorizin, but not ouabain, suppressed naphthol metabolism in specific regions of the intestine. Each of the three inhibitors altered metabolite transport. It is concluded that the capacity to conjugate naphthol in the small intestine is greater in the cranial than caudal regions; the quantity of naphthol taken up from the medium is proportional to the rate of formation of the polar metabolite, naphthyl glucuronide; addition of 2,4-dinitrophenol, phlorizin, or ouabain, or deletion of sodium, perturbed the transport of the polar metabolite, but the perturbance could not be explained by the effect on rate or direction of fluid transfer and indicated an effect on cellular permeability or on transport mechanisms; the effect of the three inhibitors and possibly of elevated naphthol concentrations (to 520 μM) in the medium on metabolite transport may be by a sodium interaction; the latter suggests that naphthol may be toxic to the intestine at concentrations approaching 100 to 1000 μM.     

Organochlorine residues in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Organochlorine residues of TDE, DDE, and PCBs as high as 1.96, 2.79, and 28.74 microgram/kg, respectively, have been found in sediments of American Falls Reservoir, Idaho. Residues of TDE, DDE, and dieldrin in the flesh of sport fish were as high as 52.3, 67.2, and 160.4 microgram/kg, respectively. Maximum organochlorine residue levels found in sucker taken in the commercial fishery were 1.1 mg PCBs/kg, 781.7 microgram TDE/kg, and 82.1 microgram DDE/kg.     

Pb、Cd胁迫对紫茎泽兰N、P、K吸收的影响

采用模拟Pb、Cd污染土壤培养法研究了紫茎泽兰在重金属Pb、Cd胁迫下植株不同部位对3种营养元素(N、P、K)吸收的影响。结果表明,紫茎泽兰各组织在Pb胁迫下对N、P的吸收总体上均保持一定的促进作用,对K则表现出一定的抑制效应;Cd胁迫下对N、P有良好的吸收,低浓度Cd促进K的吸收,高浓度则表现出抑制作用。Pb-Cd复合污染胁迫下根茎叶均对N的吸收有一定的促进作用,而对K的吸收有较强的抑制效应。这表明,紫茎泽兰在重金属Pb、Cd胁迫下可通过大量吸收N、P等元素来有效缓解重金属的毒害作用,这可能也是紫茎泽兰能适应高Pb、Cd胁迫的一种耐性机制。     

Effects of inoculum density, leaf age, moisture, temperature, and wetness duration on black streak of edible burdock

Inoculum density, temperature, leaf age, and wetness duration were evaluated for their effects on the development of black streak (Itersonilia perplexans) on edible burdock (Arctium lappa L.) in a controlled environment. The effect of relative humidity (RH) on ballistospores production by I. perplexans was also evaluated. Symptoms of black streak on leaves increased in a linear fashion as the inoculum density of I. perplexans increased from 10² to 10⁶ ballistospores/ml. Rugose symptoms on young leaves were observed at densities of ≥10⁴ ballistospores/ml. Disease severity of I. perplexans in relation to leaf age followed a degradation curve when the leaves were inoculated with ballistospores. Disease severity was high in newly emerged leaves up to 5 days old, declined as leaf age increased to 29 days, and was zero when leaf age increased from 30 to 33 days. Disease development of edible burdock plants exposed to ballistospores of I. perplexans was evaluated at various combinations of temperature (10°, 15°, 20°, 25°C) and duration of leaf wetness (12, 24, 36, 48, and 72 h). Disease was most severe when plants were in contact with the ballistospore sources at 15° or 20°C. The least amount of disease occurred at 25°C regardless of wetness duration. Ballistospores required 24–36 h of continuous leaf wetness to cause visible symptoms by infection on edible burdock. Ballistospores production in infected lesions required at least 95.5% RH.