Entomopathogenic Fungi as Dual Control Agents against Both the Pest Myzus persicae and Phytopathogen Botrytis cinerea

The green peach aphid (Myzus persicae), a plant pest, and gray mold disease, caused by Botrytis cinerea, affect vegetables and fruit crops all over the world. To control this aphid and mold, farmers typically rely on the use of chemical insecticides or fungicides. However, intensive use of these chemicals over many years has led to the development of resistance. To overcome this problem, there is a need to develop alternative control methods to suppress populations of this plant pest and pathogen. Recently, potential roles have been demonstrated for entomopathogenic fungi in endophytism, phytopathogen antagonism, plant growth promotion, and rhizosphere colonization. Here, the antifungal activities of selected fungi with high virulence against green peach aphids were tested to explore their potential for the dual control of B. cinerea and M. persicae. Antifungal activities against B. cinerea were evaluated by dual culture assays using both aerial conidia and cultural filtrates of entomopathogenic fungi. Two fungal isolates, Beauveria bassiana SD15 and Metarhizium anisopliae SD3, were identified as having both virulence against aphids and antifungal activity. The virulence of these isolates against aphids was further tested using cultural filtrates, blastospores, and aerial conidia. The most virulence was observed in the simultaneous treatment with blastospores and cultural filtrate. These results suggest that the two fungal isolates selected in this study could be used effectively for the dual control of green peach aphids and gray mold for crop protection.

The Usefulness of Pressure-regulated Volume Control(PRVC) Mode in Mechanically Ventilated Patients with Unstable Respiratory Mechanics / 결핵

BACKGROUND: Since the late 1960s, mechanical ventilation has been accomplished primarily using volume controlled ventilation(VCV). While VCV allows a set tidal volume to be guaranteed, VCV could bring about excessive airway pressures that may be lead to barotrauma in the patients with acute lung injury. With the increment of knowledge related to ventilator-induced lung injury, pressure controlled ventilation(PCV) has been frequenfly applied to these patients. But, PCV has a disadvantage of variable tidal volume delivery as pulinonary impedance changes. Since the concept of combining the positive attributes of VCV and PCV(dual control ventilation, DCV) was described firstly in 1992, a few DCV modes were introduced. Pressure-regulated volume control(PRVC) mode, a kind of DCV, is pressure-limited, time-cycled ventilation that uses tidal volume as a feedback control for continuously adjusting the pressure limit. However, no clinical studies were published on the efficacy of PRVC until now. This investigation studied the efficacy of PRVC in the patients with unstable respiratory mechanics. METHODS: The subjects were 8 mechanically ventilated patients(M: F= 6 : 2, 56+/-26 years) who showed unstable respiratory mechanics, which was defined by the coefficients of variation of peak inspiratory pressure for 15 minutes greater than 10% under VCV, or the coefficients of variation of tidal volume greater than 10% under PCV. The study was consisited of 3 modes application with VCV, PCV and PRVC for 15 minutes by random order. To obtain same tidal volume, inspiratory pressure setting was adjusted in PCV. Respiratory parameters were measured by pulmonary monitor(CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). RESULTS: 1) Mean tidal volumes(VT) in each mode were not different(VCV, 431+/-102ml ; PCV, 417+/-99ml; PRVC, 414+/-97ml) 2) The coefficient of variation(CV) of VT were 5.2+/-3.9% in VCV, 15.2+/-7.5% in PCV and 19.3+/-10.0% in PRVC. The CV of VT in PCV and PRVC were significantly greater than that in VCV(p<0.01). 3) Mean peak inspiratory pressure(PIP) in VCV(31.0+/-6.9cm HD) was higher than PIP in PCV(26.0+/-6.5cm H20) or PRVC(27.0+/-6.4cm HD)(p<0.05). 4) The CV of PIP were 13.9+/-3.7% in VCV, 4.9+/-2.6% in PVC and 12.2+/-7.0% in PRVC. The CV of PIP in VCV and PRVC were greater than that in PCV(p<0.01). CONCLUSIONS: Because of wide fluctuations of VT and PIP, PRVC mode did not seem to have advantages compared to VCV or PCV in the patients with unstable respiratory mechanics.