Seasonal variation in resistance of chrysanthemum cultivars to Frankliniella occidentalis (Thysanoptera: Thripidae)

Seasonal variation in the level of host plant resistance can have important consequences for the repeatability of tests to measure host plant resistance to insect pests. In the present study, the levels of resistance to Frankliniella occidentalis of a susceptible and a partially resistant cultivar of chrysanthemum, Dendranthema grandiflora, were determined throughout the year. Thrips damage, reproduction and adult female survival were determined on excised leaves in Petri dishes under uniform conditions. Strong seasonal fluctuations were observed in these three characteristics. On leaves from plants grown in winter, damage, reproduction, and survival were higher than on leaves from plants grown in summer. Clear differences in resistance were observed between the susceptible and the partially resistant cultivar on leaves from plants grown in winter, while differences disappeared in summer. Damage on both cultivars and survival on the susceptible cultivar were negatively correlated with mean daily solar radiation during plant growth, suggesting that the level of resistance depends on light intensity during plant growth. This was confirmed in an experiment carried out in summertime with shaded and unshaded plants. Leaves from control plants, grown under high light intensity had a higher level of resistance than leaves from shaded plants grown under reduced light intensity. There were clear differences in resistance between the cultivars under shaded conditions (low light intensity), but not under unshaded control conditions (high light intensity). This revised version was published online in July 2006 with corrections to the Cover Date.     

Virtual water: Virtuous impact? The unsteady state of virtual water

“Virtual water,” water needed for crop production, is now being mainstreamed in the water policy world. Relying on virtual water in the form of food imports is increasingly recommended as good policy for water-scarce areas. Virtual water globalizes discussions on water scarcity, ecological sustainability, food security and consumption. Presently the concept is creating much noise in the water and food policy world, which contributes to its politicization. We will argue that the virtual water debate is also a “real water” and food and agricultural policy debate and hence has political effects. Decisions about food strategies and resource allocation play out on the national political economy, benefiting some while harming others. Therefore, a policy choice for virtual water is not politically neutral. “Real␣water” interventions are, likewise, inspired by economic as well as political considerations like control of the countryside, geopolitical strategy, and food sovereignty (independence from international political conditionality and market uncertainties). To illustrate these ideas, we look into case studies of Egypt and the State of Punjab in India. In India, a debate on the merits and demerits of a virtual water strategy is now emerging. In Egypt, which switched to food imports in the early 1970s, a long-standing taboo on debating virtual water is now being relaxed.

Virulence genes in bla(CTX-M) Escherichia coli isolates from chickens and humans

The aim of this study was to determine the presence of virulence genes in isolates of CTX-M Escherichia coli from diseased chickens, from healthy chickens and from urinary tract infections in people. Three CTX-M E. coli strains from three different instances of disease in poultry (two of which were E. coli related) were tested for bla(CTX-M) sequence type and replicon type. Additionally, they were tested for the presence of 56 virulence genes (encoding fimbriae, adhesins, toxins, microcins and iron acquisition genes) using a micro-array. Results were compared to the virulence genes present in isolates from 26 healthy chickens and from 10 people with urinary tract infections. All genes found in isolates from diseased birds, including the astA (heat stable toxin) and tsh (temperature sensitive haemagglutinin) genes which have previously been associated with colibacillosis in chickens, were also present in isolates from healthy birds. However, 6/10 of the virulence genes found were exclusive to isolates from humans. Genes exclusive to chicken isolates included ireA (sidephore receptor), lpfA (long polar fimbriae), mchF (microcin transporter protein) and tsh whilst genes exclusive to human isolates included ctdB (cytolethal distending toxin), nfaE (non-fimbrial adhesion), senB (plasmid encoded enterotoxin) and toxB (toxin B). The results support previous findings that CTX-M E. coli strains in chickens are generally different from those causing disease in humans, but genes such as astA and tsh in isolates from diseased birds with colisepticaemia were also present in isolates from healthy birds.     

Pulsed-wave Doppler evaluation of intracardiac blood flow in 30 clinically normal Standardbred horses

Pulsed-wave Doppler echocardiography was performed on 30 clinically normal 1- to 6-year-old racing Standardbreds. There were 13 females, 13 geldings, and 4 stallions. Cardiac disease was not detected with M-mode, 2-dimensional real-time or pulsed-wave Doppler echocardiography. Normal flow velocities for right and left atrial outflow, right and left ventricular outflow, the aorta, and pulmonary artery were determined. Peak flow velocities for right and left atrial outflow occurred during the rapid filling phase and were higher toward the mitral valve (mean, 0.70 +/- 0.24 m/s) than toward the tricuspid valve (mean, 0.49 +/- 0.17 m/s). Peak flow velocities in the right and left ventricular outflow tracts were similar (means, 0.81 +/- 0.10 m/s and 0.75 +/- 0.39 m/s, respectively). Peak flow velocities in the pulmonary artery (mean, 1.09 +/- 0.42 m/s) and aorta (mean, 1.01 +/- 0.29 m/s) were similar, although flow peaked earlier in systole in the aorta than in the pulmonary artery.     

Ultrasonographic evaluation of fetlock annular ligament constriction in the horse

The diagnosis of restriction of free movement of the flexor tendons through the fetlock canal usually rests on the characteristic clinical appearance of this condition, or airtendography. In a series of seven normal Warmblood horses and 16 diseased horses of various breeds, the efficacy of ultrasonography in the diagnosis of this condition was determined. In normal limbs, the annular ligament is a very thin structure usually not visible on sonograms. In diseased limbs, ultrasonography outlined flexor tendon injury, distension and thickening of the digital sheath, peritendovaginal tissue proliferation and thickening of the annular ligament. Four different types of constriction syndrome were noticed. The first type (nine cases), was characterised by thickening of the annular ligament and distension of the digital sheath; the second type (three cases) was dominated by distension of the digital sheath; the third type (three cases) was characterised by superficial digital flexor tendon injury and thickening of the annular ligament and in the fourth type (one case), the constriction resulted from distension of the digital sheath and extensive peritendovaginal tissue proliferation.     

Prevalence of antimicrobial resistance among bacterial pathogens isolated from cattle in different European countries: 2002–2004

Background

The project "Antibiotic resistance in bacteria of animal origin – II" (ARBAO-II) was funded by the European Union (FAIR5-QLK2-2002-01146) for the period 2003–2005, with the aim to establish a continuous monitoring of antimicrobial susceptibility among veterinary laboratories in European countries based on validated and harmonised methodologies. Available summary data of the susceptibility testing of the bacterial pathogens from the different laboratories were collected.

Method

Antimicrobial susceptibility data for several bovine pathogens were obtained over a three year period (2002–2004). Each year the participating laboratories were requested to fill in excel-file templates with national summary data on the occurrence of antimicrobial resistance from different bacterial species.A proficiency test (EQAS – external quality assurance system) for antimicrobial susceptibility testing was conducted each year to test the accuracy of antimicrobial susceptibility testing in the participating laboratories. The data from this testing demonstrated that for the species included in the EQAS the results are comparable between countries.

Results

Data from 25,241 isolates were collected from 13 European countries. For Staphylococcus aureus from bovine mastitis major differences were apparent in the occurrence of resistance between countries and between the different antimicrobial agents tested. The highest frequency of resistance was observed for penicillin. For Mannheimia haemolytica resistance to ampicillin, tetracycline and trimethoprim/sulphonamide were observed in France, the Netherlands and Portugal. All isolates of Pasteurella multocida isolated in Finland and most of those from Denmark, England (and Wales), Italy and Sweden were susceptible to the majority of the antimicrobials. Streptococcus dysgalactiae and Streptococcus uberis isolates from Sweden were fully susceptible. For the other countries some resistance was observed to tetracycline, gentamicin and erythromycin. More resistance and variation of the resistance levels between countries were observed for Escherichia coli compared to the other bacterial species investigated.

Conclusion

In general, isolates from Denmark, England (and Wales), the Netherlands, Norway, Sweden and Switzerland showed low frequencies of resistance, whereas many isolates from Belgium, France, Italy, Latvia and Spain were resistant to most antimicrobials tested. In the future, data on the prevalence of resistance should be used to develop guidelines for appropriate antimicrobial use in veterinary medicine.     

Occurrence of antimicrobial resistance among bacterial pathogens and indicator bacteria in pigs in different European countries from year 2002 – 2004: the ARBAO-II study

Background

The project "Antibiotic resistance in bacteria of animal origin – II" (ARBAO-II) was funded by the European Union (FAIR5-QLK2-2002-01146) for the period 2003–05. The aim of this project was to establish a program for the continuous monitoring of antimicrobial susceptibility of pathogenic and indicator bacteria from food animals using validated and harmonised methodologies. In this report the first data on the occurrence of antimicrobial resistance among bacteria causing infections in pigs are reported.

Methods

Susceptibility data from 17,642 isolates of pathogens and indicator bacteria including Actinobacillus pleuropneumoniae, Streptococcus suis and Escherichia coli isolated from pigs were collected from fifteen European countries in 2002–2004.

Results

Data for A. pleuropneumoniae from infected pigs were submitted from five countries. Most of the isolates from Denmark were susceptible to all drugs tested with the exceptions of a low frequency of resistance to tetracycline and trimethoprim – sulphonamide.Data for S. suis were obtained from six countries. In general, a high level of resistance to tetracycline (48.0 – 92.0%) and erythromycin (29.1 – 75.0%) was observed in all countries whereas the level of resistance to ciprofloxacin and penicillin differed between the reporting countries. Isolates from England (and Wales), France and The Netherlands were all susceptible to penicillin. In contrast the proportion of strains resistant to ciprofloxacin ranged from 12.6 to 79.0% (2004) and to penicillin from 8.1 – 13.0% (2004) in Poland and Portugal.Data for E. coli from infected and healthy pigs were obtained from eleven countries. The data reveal a high level of resistance to tetracyclines, streptomycin and ampicillin among infected pigs whereas in healthy pigs the frequency of resistance was lower.

Conclusion

Bacterial resistance to some antimicrobials was frequent with different levels of resistance being observed to several antimicrobial agents in different countries. The occurrence of resistance varied distinctly between isolates from healthy and diseased pigs, with the isolates from healthy pigs generally showing a lower level of resistance than those from diseased pigs.The study suggests that the choice of antimicrobials used for the treatment of diseased animals should preferably be based on knowledge of the local pattern of resistance.