Comparison of diagnostic procedures for porcine leptospirosis.

Kidneys and matched serum samples were obtained from 368 pigs slaughtered at three Victorian abattoirs, and originating from 42 farms. Macroscopic lesions (white spots) were observed on 102 of the kidneys. Serum samples were tested by the microscopic agglutination test (MAT) and by an IgM enzyme immunoassay (EIA). Kidneys were cultured for leptospires, examined histologically after Warthin-Starry silver staining and after immunogold silver staining (IGSS), and tested for leptospiral DNA by DNA hybridization. Forty-four infected pigs were identified by culture or immunogold silver staining of kidneys or by high MAT titres (greater than or equal to 1024). Infection was demonstrated in 7.5% of visibly normal kidneys, in 23.5% of kidneys with white spots, and in 48% of kidneys with large white spots, of 1 cm diameter or greater. The apparent (maximum) sensitivities of diagnostic procedures for detecting infection were as follows: MAT (at a titre of either 64 or 1024) 95%; IgM EIA 82%; culture 61%; presence of white spots 55%; IGSS 52%; presence of large white spots 30%; Warthin-Starry silver staining 20%. IGSS, Warthin-Starry staining and DNA hybridization all appeared to be highly specific. Of 22 kidney sections identified as positive by IGSS, 13 showed intact leptospires, and these kidneys were all culture-positive. Nine others showed leptospiral antigen in the kidney tubules but no intact leptospires. Only five of these kidneys were culture-positive.     

Jupiter's Radiation Belts: Can Pioneer 10 Survive?

Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft.     

Early growth and quality of radiata pine in a silvopastoral system in New Zealand

The effect of different understoreys on the early growth and quality of radiata pine (Pinus radiata) in a silvopastoral system was evaluated in Canterbury, New Zealand. Fitted models successfully represented the effect of understorey on the growth (basal area and height) and a quality of trees (diameter over stubs). Basal area, diameter, height and volume growth were affected by understorey competition. Trees growing with no-understorey had 34%and 29% higher volume than trees growing with lucerne (Medicagosativa) and cocksfoot (Dactylis glomerata)understoreys, respectively. However, the height of trees at age 10 grown without understorey competition was only 9% and 15% more than trees grown with grass and lucerne understorey, respectively. Understorey competition effects on growth became more evident during the summer and early autumn months when water deficits occurred. The quality of trees was also affected by understorey competition. While trees grown in bare ground had higher growth than trees grown with understorey competition, they had the poorest stem quality with higher diameters over stubs, branch size, sweep and proportion of stem defects. This will have an impact on the agroforestry system profitability by affecting the net harvest revenue. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enhancement of cation diffusion rates across the 410-kilometer discontinuity in Earth's mantle

Rates of cation diffusion (magnesium, iron, and nickel) have been determined in olivine and its high-pressure polymorph, wadsleyite, at 9 to 15 gigapascals and 1100 degrees to 1400 degreesC for compositions that are relevant to Earth's mantle. Diffusion in olivine becomes strongly dependent on composition at high pressure. In wadsleyite, diffusion is one to two orders of magnitude faster than in olivine, depending on temperature. Homogenization of mantle heterogeneities (chemical mixing) and mineral transformations involving a magnesium-iron exchange will therefore occur considerably faster in the transition zone than at depths of less than 410 kilometers.     

天津市种植业现代化的对策研究

经济体制改革以来,天津农业、农村经济社会有了长足发展,提前完成了党中央提出的第二步战略发展目标,基本实现小康,为农业、农村现代化建设提供了良好的经济社会环境、物质基础和物质技术条件。为落实党的十五届三中全会 决定 和江泽民同志关于 沿海发达地区要率先基本实现农业现代化"的指示精神,本文仅就天津种植业现代化的对策谈点粗浅看法。基本思路是:在加大政府组织推动和扶持力度的同时,采取 一个稳定、二个加大、三个完善、四个提高"的综合对策措施,整体推进种植业现代化进程     

Water movement and macroporosity of an Australian Alfisol under different tillage and pasture conditions

We assessed the effect of different tillage practices (i.e. conventional tillage and direct drilling) and pasture conditions on the infiltration and distribution of infiltrated rain water in an Australian Alfisol. Bromide was used as a tracer for the infiltrated rain under simulated rainfall conditions. The different infiltration patterns were then related to the macroporosity of the soils.

A 25-year-old permanent pasture was found to have the highest density (number per area) of macropores and percentages of transmitting macropores. A 9-year-old pasture phase in a pasture/crop rotation did not fully restore the macroporosity of the soil. Conventional cultivation by scarifying to 0.1 m for 4 years significantly reduced macropore density as well as continuity when compared with the pasture soil. The reduced macroporosity led to increased run-off by reducing preferential flow and altered the pathway of infiltrated water movement. As a consequence, the increase in water content below 0.1 m in the cultivated soil was predominantly from downward displacement of original soil solution, resulting in more leaching. The infiltrated rain water largely remained on the surface 0.1-m layer. In contrast, macroporosity found under direct drilling was similar to that of the pasture soil.     

Tick Bite Prophylaxis: Results From a 2012 Survey of Healthcare Providers

In a recent national survey, over 30% of healthcare providers (HCPs) reported prescribing tick bite prophylaxis in the previous year. To clarify provider practices, we surveyed HCPs to determine how frequently and for what reasons they prescribed tick bite prophylaxis. We included four questions regarding tick bite prophylaxis in the DocStyles 2012 survey, a computer‐administered questionnaire of 2205 US primary care physicians, paediatricians and nurse practitioners. Responses in 14 states with high Lyme disease incidence (high LDI) were compared with responses from other states (low LDI). Overall, 56.4% of 1485 providers reported prescribing tick bite prophylaxis at least once in the previous year, including 73.9% of HCPs in high LDI and 48.2% in low LDI states. The reasons given were ‘to prevent Lyme disease’ (76.9%), ‘patients request it’ (40.4%) and ‘to prevent other tickborne diseases’ (29.4%). Among HCPs who provided prophylaxis, 45.2% did so despite feeling that it was not indicated. Given a hypothetical scenario involving a patient with an attached tick, 38.1% of HCPs from high LDI states and 15.1% from low LDI states would prescribe a single dose of doxycycline; 19.0% from high LDI states and 27.5% from low LDI states would prescribe a full course of doxycycline. HCPs prescribe tick bite prophylaxis frequently in areas where Lyme disease is rare and for tickborne diseases for which it has not been shown effective. HCPs may be unaware of current tick bite prophylaxis guidelines or find them difficult to implement. More information is needed regarding the efficacy of tick bite prophylaxis for diseases other than Lyme disease.     

Assessment of the Risk of White Sturgeon to become Infected and Potential Carriers of Infectious Pancreatic Necrosis Virus

Abstract

Little scientific information is available to assess whether White Sturgeon Acipenser transmontanus can become infected and potential carriers of infectious pancreatic necrosis virus (IPNV). To assess this risk, monitoring results of adult and progeny White Sturgeon were examined from waters historically stocked with salmonid fish known to be IPNV carriers. From 1999 through 2004 White Sturgeon from a total of 30 separate families whose parentage came from waters historically stocked with IPNV carrier fish were tested. Duplicate groups of 25 juvenile Snake River White Sturgeon were waterborne exposed to 1.0×10⁴ 50% tissue culture infective dose (TCID50)/mL of water for 1 h and an additional group was injected intraperitoneally with 1.0×10⁵ TCID50/fish. A negative control group was handled similarly but was not exposed to the virus. No morbidity was detected in any of the treatment groups or the negative control. At 34, 40, 47, and 54 d postexposure to IPNV, virus reisolation was attempted on five fish from each group, and an additional five fish from each group were examined for histological changes consistent with an IPNV infection. At 34 and 40 d postinjection with IPNV, 20% (one of five) of the fish tested positive for the virus per sample interval; however, fish from groups that were waterborne-exposed to IPNV were all negative. At 47 and 54 d after exposure or injection with IPNV an additional five fish from each group were tested at each sample interval and all results were negative. Histological analysis of target tissue obtained from five fish per group at 34 and 54 d postinfection also failed to detect any consistent change associated with an IPNV infection. These results suggest that the risk of White Sturgeon to become infected and develop into potential carriers of IPNV is negligible.

Received May 21, 2013; accepted July 8, 2013     

Quantifying inherent predictability and spatial synchrony in the aphid vector Myzus persicae: field-scale patterns of abundance and regional forecasting error in the UK

Background

Sugar beet is threatened by virus yellows, a disease complex vectored by aphids that reduces sugar content. We present an analysis of Myzus persicae population dynamics with and without neonicotinoid seed treatment. We use 6 years' yellow water trap and field-collected aphid data and two decades of 12.2 m suction-trap aphid migration data. We investigate both spatial synchrony and forecasting error to understand the structure and spatial scale of field counts and why forecasting aphid migrants lacks accuracy. Our aim is to derive statistical parameters to inform regionwide pest management strategies.

Results

Spatial synchrony, indicating the coincident change in counts across the region over time, is rarely present and is best described as stochastic. Uniquely, early season field populations in 2019 did show spatial synchrony to 90 km compared to the overall average weekly correlation length of 23 km. However, 70% of the time series were spatially heterogenous, indicating patchy between-field dynamics. Field counts lacked the same seasonal trend and did not peak in the same week. Forecasts tended to under-predict mid-season log₁₀ counts. A strongly negative correlation between forecasting error and the proportion of zeros was shown.

Conclusion

Field populations are unpredictable and stochastic, regardless of neonicotinoid seed treatment. This outcome presents a problem for decision-support that cannot usefully provide a single regionwide solution. Weighted permutation entropy inferred that M. persicae 12.2 m suction-trap time series had moderate to low intrinsic predictability. Early warning using a migration model tended to predict counts at lower levels than observed. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.