A nonlinear model for temperature‐dependent development of Erysiphe necator chasmothecia on grapevine leaves

Production and development of the chasmothecia of Erysiphe necator on Vitis vinifera leaves were studied using potted plants in controlled and outdoor environments and grapevines in a vineyard. The optimum temperature for ascocarp production was 20°C; fewer chasmothecia were produced at 15°C and even fewer at 25°C; at 10 and 30°C, no or very few chasmothecia were observed, and none reached maturity. Nonlinear equations describing ascocarp development as a function of time and temperature were developed, parameterized with data from experiments at constant temperatures, and evaluated under fluctuating temperatures. Goodness‐of‐fit showed high agreement between observed and predicted data: the model efficacy ranged from 0·74 to 0·97 (1·0 indicates a perfect fit), and the root mean square error ranged from 0·001 to 0·01 (zero indicates a perfect fit). The high proportion of the observed variability accounted for by these equations (R² = 0·83–0·98) supported the hypothesis that temperature has a predominant role in ascocarp development under natural conditions, when all environmental factors interact. The equations tended to overestimate the production of mature chasmothecia (the coefficient of residual mass was ?0·23), but this inconsistency mainly occurred when rainfall apparently washed the mature chasmothecia from leaves during the logarithmic phase of the ascocarp developmental curve. Results from this work will be useful for predicting the development of chasmothecia in a vineyard and for timing the use of natural products, fungicides or biocontrol agents for reducing the population of chasmothecia, which are all more effective when they are applied to immature chasmothecia.     

Influence of maternal habitat choice,environment and spatial distribution of juveniles on their propensity for anadromy in a partially anadromous population of rainbow trout (Oncorhynchus mykiss)

This study evaluated the importance of the environment and spatial distribution of juvenile fish for the adoption of alternative migratory tactics in a partially anadromous population of rainbow trout (Oncorhynchus mykiss) from the Santa Cruz River. We captured young‐of‐the‐year fish along the river during autumn 2009, 2010 and spring 2010 and determined their maternal origin (anadromous vs. resident) using strontium to calcium ratios in the otolith core. Relative proportion of anadromous offspring, modelled with logistic regression, increased towards headwaters and in areas with deeper channels and larger substrate composition. Body length, modelled with linear multiple regression, varied positively with site depth, water velocity, substrate size and anadromous maternal origin. Based on evidence for limited juvenile movements (<25 km), the spatial extent of this study (240 Rkm) and the identification of large, contrasting reaches along the river, it is likely that the observed spatial distribution of juveniles and their association to sites with coarse substrate composition reflects maternal spawning activity. Results further indicate that anadromous females breed predominantly in middle and upper river sections in areas with coarse substrate. Given that body size in this system has been positively related to propensity for anadromy, we propose that female spawning choice affects their offspring's spatial distribution, providing the adequate physical template for anadromous offspring to reach or maintain larger body sizes and display anadromy themselves. Relevance of this study is also discussed in the context of alterations in response to future dam construction in one of the latest free‐flowing rivers sustaining anadromous O. mykiss.     

A radiological study of the incidence of unilateral canine hip dysplasia

The authors reviewed pelvic radiographs of 891 dogs in a retrospective study, to determine the incidence of Unilateral Canine Hip Dysplasia (UCHD). Results show that 149 (16.7%) dogs had UCHD. Comparing dogs affected uni- and bilaterally, results show a maximum of 37.6% with UCHD in dogs less than 12 month old, 22.8% in dogs between 12-24 months of age, 25.5% in dogs between 25-72 months and 14.1% in dogs older than 73 months.     

Computed tomography-guided fine-needle aspiration and tissue-core biopsy of bone lesions in small animals

In humans, free-hand computed tomography (CT)-guided biopsy is an accurate method to obtain a tissue sample. There are only a few reports of this technique in veterinary medicine. In the present study, 21 dogs and two cats underwent a free-hand CT-guided tissue-core biopsy (17 animals) or fine-needle aspiration (six animals) of a bone lesion. Two out of 17 tissue-core samples were also cultured. All 17 tissue-core biopsy samples were diagnostic (accuracy of 100%). Five out of six aspirates were diagnostic (accuracy of 83.3%). The overall accuracy was 95.7%. In one aspirate, cytologic quality was insufficient containing only blood. No major complications were encountered. Fourteen neoplastic, two infectious and six benign lesions were diagnosed. CT examination after intravenous contrast medium added useful information to avoid large vessels and to biopsy-viable tissue. Free-hand CT-guided tissue-core biopsy and aspiration appears to be a safe and very accurate procedure for use in the diagnosis of bone-associated diseases in small animals.     

MAGNETIC RESONANCE IMAGING OF ARTICULAR PROCESS JOINT GEOMETRY AND INTERVERTEBRAL DISK DEGENERATION IN THE CAUDAL LUMBAR SPINE (L5–S1) OF DOGS WITH CLINICAL SIGNS OF CAUDA EQUINA COMPRESSION

The geometry of the lumbosacral region has been suspected to play a role in the development of degenerative lumbosacral stenosis in the dog. In this study, 50 dogs (21 German Shepherd dogs and 29 dogs of other breeds) with clinical signs of cauda equina compression were studied by magnetic resonance (MR) imaging. The orientation of the articular process joints in the L5-S1 region and the angle difference between two adjacent motion segments were calculated. Intervertebral disc degeneration of the same region was identified and classified in four stages. A positive association between MR-imaging stage and articular process joint angle difference in the transverse plane was found in the two groups of animals. German Shepherd dogs and dogs of other breeds had different geometry of the lumbosacral region with different articular process joint angles in the transverse plane and statistically different stages of disc degeneration.     

Possible phytoplasma transovarial transmission in the psyllids Cacopsylla melanoneura and Cacopsylla pruni

The possible transovarial transmission of two phytoplasmas, ' Candidatus Phytoplasma mali' and ' Candidatus Phytoplasma prunorum', through their respective psyllid vectors Cacopsylla melanoneura and Cacopsylla pruni , was investigated. Different life stages of the progeny of infected female psyllids were analysed by PCR detection of phytoplasma DNA. While ' Ca. Phytoplasma mali' could not be detected in any of the C. melanoneura life stages tested, ' Ca. Phytoplasma prunorum' could be detected in eggs, nymphs and newly emerged adults of C. pruni . Infectivity tests using both nymphs and newly emerged adults of C. pruni showed that ' Ca. Phytoplasma prunorum' inherited from infected females can be transmitted to healthy plum plants. Although further validations are required, these findings open up new perspectives on the study of the epidemiology of diseases associated with European stone fruit yellows.     

Dermatophilosis of Alpine Chamois (Rupicapra rupicapra) in Italy

A proliferative dermatitis similar to the condition generally referred to as strawberry footrot was observed in two Alpine chamois (Rupicapra rupicapra) from Eastern Alps, Italy. Branching septated filaments and packets of PAS-positive coccoid organisms were observed in histological sections of the affected skin. The actinomycete, Dermatophilus congolensis, was isolated from crusted lesions in one chamois. As wild ruminants are presumed to be a reservoir of infection in the Alpine area, the authors discuss the potential role of chamois in the epidemiology of dermatophilosis.     

Full season efficacy of moxidectin microsphere sustained release formulation for the prevention of heartworm (Dirofilaria immitis) infection in dogs

The authors report the efficacy of an injectable, moxidectin sustained release (SR) formulation for the prevention of canine heartworm infection in endemic areas in northern and central Italy. Three field trials were carried out on a total of 324 dogs. Two hundred forty-three dogs were treated with moxidectin SR 6 months apart and 81 dogs (positive controls) with moxidectin tablets given monthly for 5 consecutive months during the risk season each year throughout the study. Results of testing for microfilariae and circulating adult female antigens were negative for all the experimentally treated dogs at the 6, 7, 11 and 19 months after the last injection. No adverse reactions to moxidectin SR were observed but a moderate pain at palpation and swelling (5-6 cm) at the injection site after the first treatment. In the study areas, prevalence of Dirofilaria immitis infection calculated by testing dogs which had no preventive treatment in the previous transmission season ranged from 33 to 63%. This study confirms the efficacy and safety of injectable, moxidectin SR formulation in the prevention of heartworm infection in dogs and demonstrates that the prophylactic efficacy lasts for the full season and strongly suggests that the product gives 1-year protection.     

Genetic, phenotypic and pathogenic diversity of Xanthomonas arboricola pv. corylina strains question the representative nature of the type strain

A collection of 31 Xanthomonas arboricola pv. corylina strains isolated from Corylus maxima and C. avellana of different countries were assessed by means of repetitive PCR using ERIC, BOX and REP primer sets and analysis of whole-cell protein extracts; pathogenicity tests to three hazelnut ( C. avellana ) cultivars; and some key biochemical tests. From these studies, the X. arboricola pv. corylina strains were clustered into five and three groups by repetitive PCR and protein analysis, respectively, and by using UPGMA cluster analysis, with two strains forming an outlier group to these. The groups showed a high degree of similarity. Strain membership between the groups designed by the two methods exhibited a high degree of congruence, and diversity between the groups was low. Surprisingly, the two strains originating from C. maxima , that include the type strain NCPPB 935, formed the most distinctive group. No relationship to geographic origin of the strains was evident. All strains proved pathogenic towards three different hazelnut cultivars, although the strains obtained from C. maxima did not incite any significant symptoms on buds and twigs. No other relationships between rep-PCR and whole-cell protein groups and pathogenicity were evident. The distinctiveness of the C. maxima strains was supported further by atypical negative gelatin liquefaction test and reduced quinate metabolism results.