Campylobacter monitoring in German broiler flocks: an explorative time series analysis

Campylobacter, a major zoonotic pathogen, displays seasonality in poultry and in humans. In order to identify temporal patterns in the prevalence of thermophilic Campylobacter spp. in a voluntary monitoring programme in broiler flocks in Germany and in the reported human incidence, time series methods were used. The data originated between May 2004 and June 2007. By the use of seasonal decomposition, autocorrelation and cross-correlation functions, it could be shown that an annual seasonality is present. However, the peak month differs between sample submission, prevalence in broilers and human incidence. Strikingly, the peak in human campylobacterioses preceded the peak in broiler prevalence in Lower Saxony rather than occurring after it. Significant cross-correlations between monthly temperature and prevalence in broilers as well as between human incidence, monthly temperature, rainfall and wind-force were identified. The results highlight the necessity to quantify the transmission of Campylobacter from broiler to humans and to include climatic factors in order to gain further insight into the epidemiology of this zoonotic disease.     

Rhabdovirus-like particles in the sporocyst of the trematode Brachylaimus fuscatus from terrestrial mollusc Ponsadenia duplocincta

Rhabdovirus-like particles containing nucleoprotein in a helix with eight turns was demonstrated by transmission electron microscopy in subtegumental cells and syncytial layer of tegument in Brachylaimus fuscatus sporocyst. This is the first case of virus infection in trematodes. The possibility of transfer of the virus to intra-molluscan parasitic generations of the trematode is discussed with respect to the peculiarities of the life cycles of the family Brachylaimidae.     

Inheritance of virulence in Fusarium circinatum,the cause of pitch canker in pines

Wildtype strains of Fusarium circinatum, the causal agent of pitch canker, were crossed to obtain an F₁ generation. Progeny of this cross were tested for virulence by inoculating Pinus radiata seedlings, and were found to induce a wide range of lesion lengths. Two strains from the F₁ generation that induced long lesions (= high virulence) were used as parents to produce an F₂ generation, followed by a second round of selection for high virulence to obtain an F₃ generation. Mean lesion lengths were not significantly different between the three generations (P ≥ 0.196). A parallel set of crosses was performed to select for low virulence by using progeny in the F₁ and F₂ generations that induced short lesions as parents for F₂ and F₃ generations, respectively. In this case, both rounds of selection resulted in a significant reduction in mean lesion length, from 33.8 ± 0.8 mm in the F₁ generation, to 19.7 ± 0.7 and 12.9 ± 0.7 mm in the F₂ and F₃ generations, respectively. Thus it is apparent that F. circinatum retains the genetic capacity for avirulence to pines, which could reflect a lack of strong selection for virulence in nature. Progeny of a cross between high and low virulence parents manifested nearly continuous variation in lesion lengths, consistent with virulence being a quantitatively inherited trait. Based on this cross, broad‐sense heritability (H²) was determined to be 0.74, which suggests that virulence is under strong genetic control.     

Influence of anions on dispersion and physical properties of the A horizon of a Red-brown earth

Three groups of anions were distinguished in order of effectiveness with respect to the dispersion and flocculation of soil samples treated with Fe(III) polycations: phosphate and fulvate citrate, oxalate, silicate and tartrate and salicylate, catechol, aspartate, lactate and acetate. This was also the order of the amount of anion adsorbed by the soil. The addition of phosphate and fulvate to soil samples with a net charge of zero lowered the zero point of charge producing particles with a net negative charge. This increased the amount of dispersible clay present from 0 to 9% by weight of soil. The sorption of phosphate and fulvate by soil samples with a net positive charge reduced the zero point of charge and caused flocculation of dispersed clay. Electrophoretic and electron microscopic studies confirmed the dispersion-flocculation phenomena.Treatments which produced dispersed clay led to increased bulk densities, plastic limits and moduli of rupture but lower porosities, water holding capacities and hydraulic conductivities. The sorption of anions on soil samples with a net charge of zero reduced friability.     

Urethral conformation and position in relation to urinary incontinence in the bitch.

The conformation of the urethra, the position of the bladder neck and the distance between the external urethral orifice and the cranial pubic brim were compared in 30 continent and 30 incontinent bitches with incompetence of the urethral sphincter mechanism, using the measurements made from vagino-urethrograms. The bladder neck was significantly (P less than 0.001) further caudal in incontinent dogs than in continent dogs. Its position was not affected by neutering and could not be explained by the degree of urethral curvature. The distance from the external urethral orifice to the cranial pubic brim was correlated (P less than 0.001) with bodyweight but was not significantly different in the continent and incontinent bitches. In neutered animals, the distance between the cranial pubic brim and the external urethral orifice was significantly (P less than 0.05) shorter than in entire animals.     

Attempted transmission of Ehrlichia risticii by field-captured Dermacentor variabilis (Acari: Ixodidae)

The capability of field-collected American dog ticks, Dermacentor variabilis, to infect horses with Ehrlichia risticii, causative agent of Potomac horse fever (PHF), was examined by allowing adult ticks collected from horse farms with a history of PHF to feed on susceptible horses. More than 500 male and female ticks attached and fed on 3 test horses; however, no clinical or serologic evidence of PHF was observed in treated or control horses. All horses were challenge exposed with E risticii-infective blood by inoculation at 60 to 65 days after ticks fed, and all developed clinical PHF with subsequent seroconversion. The data, therefore, indicated that adult D variabilis, a common parasite of horses on Maryland premises where PHF is enzootic, may not serve as a vector of E risticii.     

Automated identification of sugar beet diseases using smartphones

Cercospora leaf spot (CLS) poses a high economic risk to sugar beet production due to its potential to greatly reduce yield and quality. For successful integrated management of CLS, rapid and accurate identification of the disease is essential. Diagnosis on the basis of typical visual symptoms is often compromised by the inability to differentiate CLS symptoms from similar symptoms caused by other foliar pathogens of varying significance, or from abiotic stress. An automated detection and classification of CLS and other leaf diseases, enabling a reliable basis for decisions in disease control, would be an alternative to visual as well as molecular and serological methods. This paper presents an algorithm based on a RGB‐image database captured with smartphone cameras for the identification of sugar beet leaf diseases. This tool combines image acquisition and segmentation on the smartphone and advanced image data processing on a server, based on texture features using colour, intensity and gradient values. The diseases are classified using a support vector machine with radial basis function kernel. The algorithm is suitable for binary‐class and multi‐class classification approaches, i.e. the separation between diseased and non‐diseased, and the differentiation among leaf diseases and non‐infected tissue. The classification accuracy for the differentiation of CLS, ramularia leaf spot, phoma leaf spot, beet rust and bacterial blight was 82%, better than that of sugar beet experts classifying diseases from images. However, the technology has not been tested by practitioners. This tool can be adapted to other crops and their diseases and may contribute to improved decision‐making in integrated disease control.     

Identification of Mulberry Dwarf Phytoplasmas in the Genital Organs and Eggs of Leafhopper Hishimonoides sellatiformis

ABSTRACT The presence of mulberry dwarf (MD) phytoplasmas in organs of the inoculative vector insects Hishimonoides sellatiformis and Hishimonus sellatus was determined by means of electron microscopy (EM) and polymerase chain reaction (PCR) assays. Many MD phytoplasmas were detected in genital organs as well as in the intestines, salivary glands, brains, fat bodies, and thoracic ganglia of Hishimonoides sellatiformis, but only in the intestine and salivary glands of Hishimonus sellatus. Many phytoplasmas with characteristic morphology were observed via EM in ovaries, seminal receptacles, and testes, and they were further identified by PCR assays with group I-specific primers. In addition, the organisms were detected by direct or nested PCR assays in eggs (head pigmentation stage of embryos) laid on mulberry shoots by inoculative leafhoppers and in the newly hatched nymphs from these eggs. These findings indicate that transovarial transmission of MD phytoplasmas occurs in Hishimonoides sellatiformis.     

几种工程措施对黄土区陡峭边坡植被盖度的影响及其机理

陡削以兰州新区的一段陡峭边坡作为试验地点,通过分析在植被重建初期经人工整地后形成的4种微地形(大圆形坑、小圆形坑、条形坑和原状坡面)的植被盖度特征及环境因子(土壤硬度和水分、地表和空气温度、坡位、无纺布)对植被盖度的影响,探寻能有效提高植被盖度的几种工程改造措施。研究表明:①铺设了无纺布坡面的植被盖度显著大于对照坡面;陡峭边坡不同坡位的植被盖度:下坡位>中坡位>上坡位(P<0.05),这与自然坡面植被盖度分布规律一致。②3种微地形的植被盖度均显著大于陡峭坡面,其中条形坑的土壤水分和植被盖度最大,最大盖度维持的时间最长。③微地形和坡面的植被盖度均与土壤水分呈显著正相关,与空气温度、地表温度均呈显著负相关;微地形的土壤硬度(3kg·cm^-2)适宜植物生长,大于该值会对植被生长产生抑制作用;铺设无纺布有利于促进上坡位的植被生长,使坡面植被分布更均匀。研究结果表明,在陡峭边坡坡度、坡位和温度等无法改变的情况下,选择对压实的坡面进行整地翻耕处理,增加长条坑的数量并铺设无纺布等有效的工程改造措施,能显著增加植被盖度,促进植被恢复。     

Effects of latent infection, temperature, precipitation, and irrigation on panicle and shoot blight of pistachio in california

ABSTRACT Panicle and shoot blight, caused by a Fusicoccum sp., is an economically important disease of pistachio in California. Between 1999 and 2001, the disease severity was monitored throughout the growing season in 10 pistachio orchards, irrigated with drip, microsprinklers, low-angled (12 degrees ) sprinklers, or flood. The effect of temperature, precipitation pattern, irrigation system, and incidence of Fusicoccum sp. latent infection on panicle and shoot blight severity was quantified with a generalized linear model for repeated measures. The number of continuous rainy days in April and May and the cumulative daily mean temperatures from June to early September had a significant positive effect on panicle and shoot blight of pistachio leaves and fruit. Drip irrigation significantly decreased disease risk. Other factors, such as the number of discontinuous rainy days in April and May, the cumulative deviation from the 30-year average temperature during the dry days of April and May, the incidence of latent infection (only on leaves), and irrigation with microsprinklers or lowangled (12 degrees ) sprinklers were weak explanatory variables of panicle and shoot blight severity. Knowledge of panicle and shoot blight risk may contribute significantly to decisions regarding the appropriate application of fungicides, especially in years or fields of low risk.