Enhanced biodegradation of nematicides after repetitive applications and its effect on root and yield parameters in commercial banana plantations

The effects of five consecutive applications, every 4 months, of Counter, Furadan, Mocap, Nemacur, Rugby, and Vydate on functional root percentage, production parameters, and on enhanced biodegradation were compared in a commercial banana plantation in Costa Rica. To quantify nematode numbers and estimate functional root percentage, root samples were taken monthly from the field experiment. The enhanced biodegradation test was carried out in the laboratory. Samples taken from the field after five consecutive applications of each nematicide were treated in the following way: (1) not sterilized and no nematicide applied; (2) not sterilized but nematicide applied; and (3) nematicide applied after sterilization. The number of Radopholus similis which had penetrated the maize plantlets was used as a parameter to determine the degradation of the applied nematicide. Degradation was measured 0, 2, 4, 6 and 8 weeks after inoculation of pregerminated maize plantlets with 500 nematodes in soil under laboratory conditions. At harvest, 20 months after starting the field experiment, the lowest percentage of functional roots ( P =0.024) and bunch weight ( P =0.0001) were found in the non-treated control, followed by the Furadan treatment. On average, nematicides increased the bunch weight by 38%. In general, higher bunch weights coincided with higher percentages of functional roots. Furadan showed a high level of enhanced biodegradation while for Counter and Rugby this phenomenon was not detected. In the case of Mocap and Nemacur, a relatively high level of enhanced biodegradation in the soil biotest coincided with a high number of nematodes per 100 g roots in the field experiment. A high correlation between mean nematode numbers per 100 g roots and mean percentage of functional roots was observed ( R ²=0.81, P =0.006) for all treatments together. Data show that a rotation of different nematicidal molecules is the best option for long-term nematode management in commercial banana plantations.     

Pathogenicity and reproductive fitness of <Emphasis Type="Italic">Pratylenchus coffeae</Emphasis> and <Emphasis Type="Italic">Radopholus arabocoffeae</Emphasis> on Arabica coffee seedlings (<Emphasis Type="Italic">Coffea arabica</Emphasis> cv. Catimor) in Vietnam

The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128, and 256 nematodes per cm³ soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage model Y = m + (1-m).z^Pi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm³ soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of nematode numbers at 30 and 60 dai.     

应用双倍PCR技术快速检测大豆胞囊线虫

描述了一种基于双倍PCR技术，用种特异性引物快速鉴定大一啼胞囊线虫方法。应用两组引物扩增胞囊线虫的rDNA。第一组引物含有2个通用引物D3A和D3B，用于扩增大亚基核糖体基因（28S rDNAgene）的D3扩展区；第二组引物包括大豆胞囊线虫特异性引物GlyF1和一个通用引物rDNA2，用于扩增ITS2区的片断和部分28S基因，用此双倍PCR扩增技术检测了来自中国、俄罗斯、美国和巴西的53个大豆胞囊线虫群体，结果表明，用两组引物进行双倍PCR扩增，所有53个大豆胞囊线虫群体都产生两个明显的片断（181bp and 345 bp），其中181bp片断是SCN特异性引物GlyF1和rDNA2扩增出大豆胞囊线虫中特异性片断，在所测试的其它胞囊线虫群体，仅仅扩增出345bp的片断，而不能扩增出大豆胞囊线虫的特异性片断，用该项技术能从大豆胞囊经一虫的胞囊或单头二龄幼虫的微量DNA中，扩增出大豆胞囊线虫的特异性片断，该技术的敏感性达到单条二龄幼虫的水平。     

A minimally invasive method for clinical trans‐diaphragmatic pressure measurement in anaesthetized dogs

ObjectiveTo measure trans-diaphragmatic pressures, as an indication of diaphragmatic contractility, in anaesthetized dogs breathing normally, or during inspiratory obstruction (Mueller’s manoeuvre) in order to assess if the method is practicable for use in clinical circumstances.Study designPilot study.AnimalsTwenty eight client-owned dogs, ASA I or II, 1–10 years old, 5–30 kg bodyweight, which required anaesthesia for surgery, and were to be positioned in lateral recumbency.MethodsFollowing a standardized regimen of premedication and anaesthetic induction, anaesthesia was stabilized and maintained with isoflurane. Two commercially available balloon catheters were introduced orally, and advanced, one into the stomach and one into the mid-third of the oesophagus. Oesophageal and gastric pressures were measured from these catheters, and trans-diaphragmatic pressure (P_di) calculated and recorded continuously. At three separate time points during anaesthesia, for one breath, inspiration was obstructed (Mueller’s manoeuvre) and P_di was measured.ResultsPlacement of the catheters in the stomach was not easy, and failed in three cases. In five dogs, their size resulted in failure of correct placement of catheters. Good traces of all three pressures reflecting respiratory cycles were obtained from 20 dogs. During normal spontaneous breathing (mean ± SD [range]) P_di was 5 ± 2.1 (3–10) mmHg. During Mueller’s manoeuvre, P_di was 14.6 ± 4.5 (9–21) mmHg. Abnormal waveforms were seen included cardiac oscillations (five dogs), inadequate intra-gastric pressure tracing (one dog), deflections with a double peak (one dog), and multiple artifacts when there was increased heart rate and tachypnoea (two dogs in response to surgery).Conclusions and clinical relevanceMeasurement of trans-diaphragmatic pressure with balloon catheters was practicable in suitably sized dogs anaesthetized for clinical purposes and might be a useful tool in the assessment of diaphragmatic function. A range of catheters are required if the technique is to work in all dogs.     

Comparison of an infrared anaesthetic agent analyser (Datex‐Ohmeda) with refractometry for measurement of isoflurane,sevoflurane and desflurane concentrations

ObjectiveTo assess agreement between infrared (IR) analysers and a refractometer for measurements of isoflurane, sevoflurane and desflurane concentrations and to demonstrate the effect of customized calibration of IR analysers.Study designIn vitro experiment.SubjectsSix IR anaesthetic monitors (Datex-Ohmeda) and a single portable refractometer (Riken).MethodsBoth devices were calibrated following the manufacturer’s recommendations. Gas samples were collected at common gas outlets of anaesthesia machines. A range of agent concentrations was produced by stepwise changes in dial settings: isoflurane (0–5% in 0.5% increments), sevoflurane (0–8% in 1% increments), or desflurane (0–18% in 2% increments). Oxygen flow was 2 L minute^?1. The orders of testing IR analysers, agents and dial settings were randomized. Duplicate measurements were performed at each setting. The entire procedure was repeated 24 hours later. Bland–Altman analysis was performed. Measurements on day-1 were used to yield calibration equations (IR measurements as dependent and refractometry measurements as independent variables), which were used to modify the IR measurements on day-2.ResultsBias ± limits of agreement for isoflurane, sevoflurane and desflurane were 0.2 ± 0.3, 0.1 ± 0.4 and 0.7 ± 0.9 volume%, respectively. There were significant linear relationships between differences and means for all agents. The IR analysers became less accurate at higher gas concentrations. After customized calibration, the bias became almost zero and the limits of agreement became narrower.Conclusions and clinical relevanceIf similar IR analysers are used in research studies, they need to be calibrated against a reference method using the agent in question at multiple calibration points overlapping the range of interest.     

A novel flow partition device for spirometry during large animal anaesthesia

ObjectiveWe describe and test a novel device for large animal anaesthesia monitoring that uses standard human medicine spirometry sensors.Study designIn-vitro study.MethodsThe device consists of two adapters that enable the flow to be split evenly into four tubes in parallel, each tube containing a D-lite sensor. The performance of this flow partitioning device (FPD) over a range of flows from 100 to 700 L minute^?1 was determined and the pressure versus flow relation, resistance and dead space was compared with a Horse-lite (Moens 2010).ResultsEquipped with four D-lite sensors, and a flow of 700 L minute^?1 the pressure drop of the FPD was 13.5 cmH₂O, resistance 1.17 cmH₂O second L^?1 and volume (potential dead space) 182 mL, compared to 2.8 cmH₂O, 0.24 cmH₂O second L^?1 and 54 mL respectively for the Horse-lite. The predicted value of the flow partition of ¼ could be confirmed. Limits of agreement were found to be 4.2% in inspiratory direction and 7.1% in expiratory direction.Conclusions and clinical relevanceThe FPD is an affordable device that extends the specification of any commercially available human spirometry sensors to large animal applications. However, an increase in total resistance and dead space has to be taken into account. Therefore, the new device could be useful during equine anaesthesia.     

Maxillary Granulomatous Inflammation Caused by Halicephalobus gingivalis (Nematoda) in a Connemara Mare in Belgium

A 5-year-old anorexic and lethargic Connemara mare presented with severe facial swelling and dyspnea. No distinct central nervous symptoms were present. Radiographs of the skull showed diffuse radiolucency with loss of definition of the periodontal lamina dura and swelling of the decalcified nasal bones. Given the severe bone damage and its poor general condition, the pony was euthanized. Histological evaluation of the lesion revealed a granulomatous reaction with numerous sections of adult and juvenile nematodes, which were morphologically and molecularly identified as Halicephalobus gingivalis. The position of this facultative parasite within its free-living congeners is reviewed in this article, and the possible infection routes are discussed. This report presents the first record of equine halicephalobiasis in Belgium.     

RESEARCH PAPER: Comparison of two different methods for physiologic dead space measurements in ventilated dogs in a clinical setting

ObjectiveTo compare physiologic dead space (V_D) and physiologic dead space to tidal volume (V_T) ratio (V_D/V_T) obtained by an automated single breath test for carbon dioxide (CO₂) (method SBT) and a manual calculation (method MC) in ventilated healthy dogs.Study designProspective clinical study.AnimalsTwenty client‐owned dogs, ASA I and II undergoing anaesthesia for clinical purposes.MethodsFollowing pre‐medication, induction of anaesthesia, and intubation of the trachea, intermittent positive pressure ventilation was commenced. Mixed expired CO₂ partial pressure (PēCO₂) was measured by two methods: method MC by analysis, using an infrared capnograph, of the expired gas collected in a mixing box and method SBT which calculated it automatically by a device consisting of a mainstream capnograph and a pneumotachograph. At four time points arterial partial pressure of CO₂ (PaCO₂) was measured. Physiologic dead space variables (V_D and V_D/V_T) were calculated manually (method MC) or automatically (method SBT) using the Bohr–Enghoff equation.Method MC and SBT were compared using Bland–Altman plots and linear regression. Intra‐class correlation coefficient (ICC) was used to measure consistency of each method.ResultsFour measurement pairs were obtained in all 20 dogs for method SBT and MC. The bias was ?1.15 mmHg, 7.97 mL and 0.02 for PēCO₂, V_D and V_D/V_T, respectively. Linear regression analysis revealed a correlation coefficient (r²) of 0.79, 0.94, and 0.83 for PēCO₂, V_D and V_D/V_T, respectively. The ICC revealed an excellent consistency for both methods.ConclusionsThe single breath test (SBT) can be used for clinical evaluation of V_D and V_D/V_T in anaesthetized ventilated dogs.Clinical relevanceThrough measuring V_D and V_D/V_T important information about lung ventilation can be obtained and the SBT is an easy method to use for this purpose.