Plant Disease Control

Abstract

Experiments have been carried out in the Ivory Coast to assess the performance of a prototype rapid release system to apply larvicides for the control of S. damnosum, the vector of onchocerciasis. The equipment was fitted to a Pilatus Porter aircraft and was used to apply Abate larvicide to a large river during conditions of low water level. It was shown that the equipment could accurately deliver volumes of larvicide between one and 50 l and that these quantities could be placed exactly along chosen points in the river, provided the aircraft was flown along the direction of the watercourse. Satisfactory control of S. damnosum larvae was achieved at three sites using a dosage rate of 0.05 ppm/10 min of waterflow. However, it was recommended that a dosage of 0.1 ppm/10 min be adopted in future work because some of the more extensive sites treated were underdosed. It was not possible to assess the biological effectiveness of the equipment for treating small rivers, but physical tests were carried out which suggest that the system should be suitable for applying larvicide to rivers as narrow as five metres width. Recommendations were made to improve the reliability of the equipment for use in an operational onchocerciasis programme.     

Efficacy of bacteriophage therapy on horizontal transmission of Salmonella gallinarum on commercial layer chickens

A Salmonella Gallinarum (SG)-specific bacteriophage isolated from sewage effluent was used to prevent horizontal transmission of SG in commercial layer chickens. Six-week-old chickens, each challenged with 5 x 10(8) colony-forming units of SG, cohabited with contact chickens treated with 10(6) plaque-forming units/kg of bacteriophage, prepared in feed additives, for 7 days before, and 21 days after challenge with SG. Mortality was observed for 3 wk after challenge and SG was periodically reisolated from the liver, spleen, and cecum of chickens. SG re-isolation from organs was decreased and a significant (P < 0.05) reduction in mortality was observed in contact chickens treated with the bacteriophage, as compared to untreated contact chickens, indicating that bacteriophage administration in feed additives significantly prevented the horizontal transmission of SG. These results provide important insights into prevention and control strategies against SG infection and suggest that the use of bacteriophages may be a novel, safe, and effectively plausible alternative to antibiotics for the prevention of SG infection in poultry.     

Expression of esterase gene in yeast for organophosphates biodegradation

Organophosphates are esters of phosphoric acid and can be hydrolyzed and detoxified by carboxylesterase and phosphotriesterase. In this work esterase enzyme (Est5S) was expressed in yeast to demonstrate the organophosphorus hydrolytic activity from a metagenomic library of cow rumen bacteria. The esterase gene (est5S) is 1098 bp in length, encoding a protein of 366 amino acid residues with a molecular weight of 40 kDa. Est5S enzyme was successfully produced by Pichia pastoris at a high expression level of approximately 4.0 g L⁻¹. With p-nitrophenol butyrate as the substrate, the optimal temperature and pH for enzyme activity were determined to be 40 °C and pH 7.0, respectively. The esterase enzyme was tested for degradation of chlorpyrifos (CP). TLC results obtained inferred that CP could be degraded by esterase enzyme (Est5S) and HPLC results revealed that CP could be efficiently degraded up to 100 ppm. Cadusafos (CS), coumaphos (CM), diazinon (DZ) dyfonate (DF), ethoprophos (EP), fenamiphos (FM), methylparathion (MPT), and parathion (PT) were also degraded up to 68, 60, 80, 40, 45, 60, 95, and 100%, respectively, when used as a substrate with Est5S protein. The results highlight the potential use of this enzyme in the cleanup of contaminated insecticides.     

Outcomes of 35 dogs with craniomaxillofacial osteosarcoma treated with stereotactic body radiation therapy

Canine craniomaxillofacial osteosarcoma (OSA) is most commonly treated surgically; however, in cases where surgery is not feasible or non-invasive treatment is desired, stereotactic body radiation therapy (SBRT) may be elected for local tumour control. In this study, we evaluated 35 dogs treated with SBRT. Nine dogs (26%) had calvarial, seven (20%) had mandibular and 19 (54%) had maxillary OSA. Median time to first event (TFE) was 171 days, and overall median survival time (MST) was 232 days. Site-specific MSTs were 144 days for mandible, 236 days for calvarium and 232 days for maxilla (p = .49). Pulmonary metastatic disease was observed in 12/35 (34%) patients and was detected pre-SBRT in six dogs (17%) and post-SBRT in the remaining six dogs (17%). Eighteen adverse events post-SBRT were documented. Per veterinary radiation therapy oncology group criteria, five were acute (14%) and three were late (9%) grade 3 events. Neurological signs in two dogs were suspected to be early-delayed effects. Cause of death was local progression for 22/35 (63%) patients, metastasis for 9/35 (26%) patients and unknown for four. On univariate analysis, administration of chemotherapy was associated with a longer TFE (p = .0163), whereas volume of gross tumour volume was associated with a shorter TFE (p = .023). Administration of chemotherapy and five fractions versus single fraction of SBRT was associated with increased survival time (p = .0021 and .049). Based on these findings, a treatment protocol incorporating chemotherapy and five fractions of SBRT could be considered for dogs with craniomaxillofacial OSA electing SBRT with careful consideration of normal tissues in the field.     

Comparing aboveground carbon sequestration between moso bamboo (Phyllostachys heterocycla) and China fir (Cunninghamia lanceolata) forests based on the allometric model

The purpose of this study was to compare carbon sequestration between moso bamboo (Phyllostachys heterocycla) and China fir (Cunninghamia lanceolata) forests. The study site was located in the lower mountain area of central Taiwan, where both moso bamboo and China fir were rich. In addition, moso bamboo and China fir forests were surveyed on 12 and 19 plantations, respectively. We predicted carbon sequestration based on the allometric model for moso bamboo and China fir forests and compared the relationships between characteristics of bamboo forests and elevation. The results showed that mean diameter at breast height (DBH), culms per hectare and aboveground biomass were not clearly affected by elevation, whereas a negative correlation (R = −0.600, p = 0.039) between mean DBH and stand density was found for moso bamboo forests. Moreover, the aboveground carbon storage was higher for China fir forests than for moso bamboo (99.5 vs. 40.6 Mg ha⁻¹). However, moso bamboo is an uneven-aged stand which is only composed of 1-5-year-old culms, while China fir is an even-aged stand and the age range is from 15 to 54 years, such that, per year, the mean aboveground carbon sequestration is 8.13 ± 2.15 and 3.35 ± 2.02 Mg ha⁻¹ for moso bamboo and China fir, respectively. On the other hand, the mean carbon sequestration of China fir decreases with increasing the age class. Furthermore, the ratio of moso bamboo to China fir is 2.39 and a T-test showed that the aboveground carbon levels were significantly different between these two species; thus, moso bamboo is a species with high potential for carbon sequestration.     

Rat lens aldose reductase inhibitory activities of Coptis japonica root-derived isoquinoline alkaloids

The inhibitory activity of Coptis japonica root-derived materials was evaluated against lens aldose reductase isolated from male Sprague-Dawley rats and compared to that of three commercially available isoquinoline alkaloids (berberine sulfate, berberine iodide, and palmatine chloride), as well as quercitrin as aldose reductase inhibitor. The biologically active constituents of C. japonica extract were characterized as the isoquinoline alkaloids, berberine chloride and palmatine iodide, by spectral analysis. The inhibitory effects varied with both chemical and concentration used. The IC(50) values of berberine chloride and palmatine iodide are 13.98 and 13.45 nM, respectively. Among three berberines and two palmatines, the inhibitory activity was much greater for the choridated and sulfated analogues than for those with iodide. Quercitrin was a much more potent inhibitor than berberines and palmatines. Nonetheless, berberines and palmatines may be useful as lead compounds and new agents for aldose reductase inhibition.     

Rapid detection of plum pox virus by reverse transcription recombinase polymerase amplification

Journal of Plant Diseases and Protection - Plum pox virus (PPV) is one of the most destructive viral pathogens infecting stone fruit trees worldwide. As PPV causes a viral disease that requires...