COMPARATIVE POPLITEAL AND MESENTERIC COMPUTED TOMOGRAPHY LYMPHANGIOGRAPHY OF THE CANINE THORACIC DUCT

Thoracic duct computed tomography (CT) lymphangiograms were performed on seven clinically normal dogs. The appearance of the thoracic duct system was compared following administration of contrast medium through a mesenteric lymphatic vessel vs. ultrasound guided percutaneous injection into a popliteal lymph node using helical and sequential CT acquisition modes. The number of visible thoracic duct branches and the largest thoracic duct branch cross‐sectional area and mean Hounsfield units (HU) were determined from thoracic vertebra 9 to lumbar vertebra 1. Procedural time and patient discomfort were also assessed. Popliteal administration produced a successful thoracic duct lymphangiogram in eight of 11 dogs (73%) after two attempts, while mesenteric administration was successful in eight of 10 dogs (80%) after a single attempt. Popliteal lymphography required 46% of the time and was associated with less patient discomfort than mesenteric lymphangiography. The number of thoracic duct branches seen was not significantly different for either administration technique (P=0.256) or CT acquisition mode (P=0.417). However, the cross‐sectional area and mean HU of the largest thoracic duct branch were greater with mesenteric administration (P<0.001), and helical image acquisition (P<0.001). The thoracic duct branch number, size, and location were highly variable between dogs. Percutaneous popliteal lymphography appears to be an acceptable alternative to mesenteric lymphangiography for the detection of thoracic duct branches in the dog when using either helical or sequential CT acquisition modes.     

The influence of light and temperature during winter on growth and death in simulated swards of Lolium perenne

Two growth experiments were carried out in January-March 1978 in which simulated swards of perennial ryegrass were (1) heated by soil warming cables to give soil surface temperatures of approx. 7·5-9·C above ambient temperature, (2) shaded with netting to reduce light levels by approx. 50%, or (3) both heated and shaded.
Heating alone increased leaf appearance, death, extension, lamina size, leaf area index (LAI), tillering (month 1)and whole plant weight (month 2) and reduced stubble water-soluble carbohydrates and specific leaf weight (SLW).
Shading alone increased leaf extension, lamina size and LAI but to a lesser extent than did heating. Shading decreased SLW, leaf death rate, tillering (month 2), stubble carbohydrates and whole plant weight, but not herbage weight.
The effects of heating plus shading were similar to those of heating alone, except that the increases in leaf size, extension and LAI were even greater, and shoot bases and roots had low or negative growth rates.
In general the heating treatments caused a rapid turnover of leaf material, but net herbage growth was relatively insensitive. It is concluded that (1) temperature rather than light was limiting whole plant growth, especially from mid-February to mid-March and (2) mild, dull weather in winter is likely to induce tiller death associated with reduced investment in carbohydrate reserves.     

Insecticide resistance in Bemisia tabaci biotype Q (Hemiptera: Aleyrodidae) from China

Dispersion of invasive biotypes of the tobacco whitefly, Bemisia tabaci, has led to protracted crop protection constraints in numerous countries over recent decades. These polyphagous, highly efficient vectors of plant viruses present an intractable problem as they frequently carry a diverse suite of insecticide resistance mechanisms. In many areas of China, native biotypes have been supplanted by the invasive and globally widespread biotype B since the 1990s. More recently, biotype Q has established, posing a new and more potent threat to agricultural production systems throughout the country. Insecticide resistance profiles for a range of Chinese B. tabaci strains covering biotypes B and Q were examined, to establish the potential for insecticides to play a pivotal role in biotype competition and ultimate displacement. Commonly used compounds including pyrethroids, neonicotinoids, abamectin and pyriproxyfen were targeted as widespread use is pre-requisite to drivers of population dynamics on a national scale.     

Incidence and characterisation of resistance to neonicotinoid insecticides and pymetrozine in the greenhouse whitefly,Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae)

BACKGROUND: Trialeurodes vaporariorum (Westwood), also known as the greenhouse whitefly, is a serious pest of protected vegetable and ornamental crops in most temperate regions of the world. Neonicotinoid insecticides are used widely to control this species, although resistance has been reported and may be becoming widespread. RESULTS: Mortality rates of UK and European strains of T. vaporariorum to a range of neonicotinoids and pymetrozine, a compound with a different mode of action, were calculated, and significant resistance was found in some of those strains. A strong association was found between neonicotinoids and pymetrozine, and reciprocal selection experiments confirmed this finding. Expression of resistance to the neonicotinoid imidacloprid and pymetrozine was age specific, and resistance in nymphs did not compromise recommended application rates. CONCLUSION: This study indicates strong parallels in the phenotypic characteristics of neonicotinoid resistance in T. vaporariorum and the tobacco whitefly Bemisia tabaci Gennadius, suggesting possible parallels in the underlying mechanisms. Copyright © 2010 Society of Chemical Industry     

Characterisation of Neonicotinoid and Pymetrozine Resistance in Strains of Bemisia tabaci (Hemiptera: Aleyrodidae) from China

Four strains of the Q biotype and one of the B biotype of the whitefly Bemisia tabaci collected from China were characterised for resistance to four neonicotinoid insecticides and pymetrozine. Q biotype strains showed moderate to strong resistance to imidacloprid, thiamethoxam and acetamiprid, but little or no cross-resistance to dinotefuron. Resistance to neonicotinoids was consistently associated with resistance to pymetrozine, despite the latter having a distinct (though unresolved) mode of action. The single B biotype strain proved largely susceptible to all the insecticides investigated. Resistance in the Q biotype strains was associated with over-expression of a cytochrome P450 monooxygenase gene, CYP6CM1, whose substrate specificity presumably accounts for the observed cross-resistance profiles.     

Neonicotinoid resistance in rice brown planthopper, Nilaparvata lugens

BACKGROUND: Rice brown planthopper, Nilaparvata lugens Stål, is a primary insect pest of cultivated rice, and effective control is essential for economical crop production. Resistance to neonicotinoid insecticides, in particular imidacloprid, has been reported as an increasing constraint in recent years. In order to investigate the extent of resistance, 24 samples of N. lugens were collected from China, India, Indonesia, Malaysia, Thailand and Vietnam during 2005 and 2006. Their responses to two diagnostic doses of imidacloprid (corresponding approximately to the LC₉₅ and 5 × LC₉₅ of a susceptible strain) were examined. RESULTS: Ten of the 12 samples collected during 2005 were found to be susceptible to imidacloprid, but two late‐season samples from India showed reduced mortality at both diagnostic doses. All 13 strains collected in 2006 showed reduced mortality at both doses when compared with the susceptible strain. Dose–response lines showed resistance in one of the most resistant field strains to be approximately 100‐fold compared with the susceptible standard. CONCLUSION: The data demonstrate the development and spread of neonicotinoid resistance in N. lugens in Asia and support reports of reduced field efficacy of imidacloprid. Copyright © 2008 Society of Chemical Industry     

An open prospective investigation into aetiology in a group of cats with suspected allergic skin disease

Abstract This prospective study evaluated the cause(s) of dermatitis in a series of cats with signs suggestive of allergic skin disease. Twenty cases completed the díagnostic evaluation, which included intradermal skin testing, a rigorous flea-control programme, and a 4-month stabilization period on a restricted protein source commercial diet, followed by rechallenge with the cat's original diet. The most common final díagnoses included flea allergic dermatitis (seven cases), and flea allergic dermatitis together with atopy (seven cases). Three additional cases which did not complete the study were also considered to be atopic. No cases were considered to be primarily associated with food hypersensitivity, an observation supporting previous data indicating this to be a rare cause of allergic skin disease in the cat. These observations emphasize the value of a rigorous flea-control programme as part of the management of many cases of feline allergic dermatitis. Résumé Une étude étiologique prospective a été réalisée dans une population de chats suspects de dermites allergiques. Des tests cutanés intradermiques ont été réalisés ainsi qu'un contrôle antipuce rigoureux et un régime d'élimination, faisant appel à une alimentation du commerce restreinte en protéines pendant 4 mois, suivi par une réintroduction de l'alimentation initiale du chat. Le díagnostic le plus fréquent est la Dermite par Allergie à la Piqûres de Puce (DAPP) (7 cas), une DAPP associée à une atopie (7 cas). Trois cas supplémentaires sont atopiques. Aucun cas n'est en rapport avec seulement une allergie alimentaire. Cette observation montre que l'allergie alimentaire est une cause rare de dermite allergique chez le chat. Ces observations confirment par ailleurs l'intérêt d'un contrôle antipuce rigoureux dans la gestion thérapeutique des dermites allergiques du chat. [O'Dair, H.A., Markwell, P.J., Maskell, I.E. An open prospective investigation into aetiology in a group of cats with suspected allergic skin disease (Etude étiologique prospective ouverte dans une population de chats suspects de dermite allergiques). Veterinary Dermatology 1996; 7 : 193–202.] Resumen Este estudio prospective evalúa la(s) causa(s) de dermatitis en un grupo de gatos con sintomas sugestivos de dermatosis alérgica. Se evaluó el díagnóstico de veinte casos, incluyendo pruebas cutáneas intradérmicas, programa riguroso de control de pulgas y un periodo de cuatro meses de estabilización con una dieta comercial con fuente de proteina restringida, seguido de una re-exposición a la dieta original del gato. El díagnóstico final más frecuente fue de dermatitis alérgica a las pulgas (siete casos) y dermatitis alérgica a las pulgas con atopia (siete casos). Tres casos más que no completaron el estudio fueron también considerados atópicos. Ninguno de los casos fue considerado estar principalmente asociado a una hipersensibilidad alimentaria, lo que apoya hallazgos previos indicativos de que este tipo de hipersensibilidad es poco frecuente en el gato. Estos hallazgos resaltan la importancia de un programa rigurosos de control de pulgas en el protocolo de manejo de muchos casos de dermatitis alérgica felina. [O'Dair, H.A., Markwell, P.J., Maskell, I.E. An open prospective investigation into aetiology in a group of cats with suspected allergic skin disease (Investigacion prospectiva abierta de la etiologia en un grupo de gatos sospechosos de dermatosis alérgica). Veterinary Dermatology 1996; 7 : 193–202.] Zusammenfassung Diese prospektive Untersuchung wertete die Fälle von Dermatitis bei einer Reihe von Katzen aus, die Symptome aufwiesen, welche auf eine allergische Hautkrankheit deuteten. Zwanzig Fälle wiesen eine vollständige díagnostische Untersuchung äuf, die intradermale Hauttests, striktes Flohbekämpfungsprogramm und eine viermonatige Stabilisierungsphase mit einer kommerziellen Diät mit begrenzten Eiweißquellen, gefolgt von einer Provokation mit dem bisher üblichen Katzenfutter, beinhaltete. Die häufigste endgültige Diagnose bestand in Flohbißdermatitis (sieben Fälle) und Flohbißdermatitis zusammen mit Atopie (sieben Fälle). Drei weitere Fälle durchliefen die Studie nicht vollständig, wurden aber als atopisch angesehen. Kein Fall wurde primär in Verbindug mit Futtermittelhypersensibilität gesehen, eine Beobachtung, die frühere Daten unterstützt, die dies als seltene Ursache bei allergischen Hautkrankheiten der Katze nennt. Diese Beobachtungen betonen die Bedeutung des genauen Flohbekämpfungsprogramms als Teil des Management vieler Fälle von allergischen Hautkrankheiten bei der Katze. [O'Dair, H.A., Markwell, P.J., Maskell, I.E. An open prospective investigation into aetiology in a group of cats with suspected allergic skin disease (Offene prospektive Untersuchung über die Ätiologie bei einer Gruppe von Katzen mit Verdacht auf allergische Hautkrankheiten). Veterinary Dermatology 1996; 7 : 193–202.]     

Incidence and inheritance of resistance to METI-acaricides in European strains of the two-spotted spider mite (Tetranychus urticae) (Acari: Tetranychidae)

A strain of Tetranychus urticae (Koch; Acari: Tetranychidae), collected from hops (Humulus humuli L; Cannabaceae) in England with a short history of tebufenpyrad use, exhibited resistance to four METI (mitochondrial electron transport inhibitor)-acaricides; tebufenpyrad, pyridaben, fenazaquin and fenpyroximate. Resistance factors for these compounds in a microimmersion assay were 46, 346, 168 and 77 respectively, and corresponded to those exhibited by a Japanese METI-acaricide-resistant reference strain. Levels of resistance remained stable without further selection, and selection with tebufenpyrad did not increase them. The UK strain was also resistant (c 6-fold) to bifenthrin. Crosses of homozygous, diploid females with hemizygous, haploid males showed that, in the UK strain, METI-acaricide resistance was paternally and maternally inherited, and was an incompletely dominant trait. Another tebufenpyrad-resistant strain from the UK, originating from a chrysanthemum nursery (Chrysanthemum foeniculaceum Giseke; Asteraceae) was collected eight months later at a site c 210 km distant from the first. These are the first published incidences of METI-acaricide resistance in Europe and implications for the future use of these compounds are discussed.     

Concurrent Cryptosporidium and parvovirus infections in a puppy

Cryptosporidium parvum, an intestinal coccidian parasite, was isolated from faeces and intestinal biopsies of a 9-week-old puppy with acute parvoviral gastroenteritis. Gene sequence analysis identified a Cryptosporidium genotype not previously recorded in Australia. The puppy recovered after treatment with crystalloid fluids, synthetic and natural colloids and jejunostomy tube feeding.