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The mycelial growth inhibition (MGI) of Curvularia eragrostidis by Swietenia humilis seeds extracts (hexane, ethyl acetate, dichloromethane and methanol) at four concentrations (250, 500, 1000 and 2000 ppm) was evaluated. The daily mycelial growth (DMGR), MGI and median effective concentration (EC50) were determined. The DMGR and MGI were significantly affected (p < 0.05) by crude extracts concentrations. The ethyl acetate precipitate (EtOAcp) at the highest concentration (500 ppm) achieved the lowest DMGR (2.54 mm/day, p < 0.05) against the control (9.96 mm/day). Moreover, EtOAcp (500 ppm) significantly increased the MGI% of C. eragrostidis (p < 0.05) by 68.2%, resulting to be the most inhibitory extract by its low EC50 (729 ppm). The medium polarity extracts of S. humilis (EtOAcp) could be considered for future studies on antifungal activity against phytopathogens. [ABSTRACT FROM AUTHOR]

The aims of this work were to evaluate the phosphate-solubilization and hydrogen peroxide (HO) production by the soil-borne micromycetes, Aspergillus japonicus, Penicillium italicum and Penicillium dipodomyicola, isolated from Phragmites australis rhizosphere and to study the effect of several concentrations of Cadmium (Cd) on both variables. Our results showed that P. italicum achieved a higher P-solubilization and HO production than A. japonicus and P. dipodomyicola, as only P. italicum showed a positive correlation (R = 0.71) between P-solubilization and HO production. In dose-response assays, P. italicum was also more tolerant to Cd (0.31 mM) in comparison to A. japonicus (0.26 mM). Analysis of the 2 factorial experimental design showed that P-solubilization by P. italicum was negatively affected by increases in Cd ( p = 0.04) and yeast extract ( p = 0.02) in the culture medium. The production of HO was positively affected only by glucose ( p = 0.002). Fungal biomass production was reduced significantly ( p = 0.0009) by Cd and increased ( p = 0.0003) by high glucose concentration in the culture medium. The tolerance and correlation between P-solubilization and HO production in the presence of Cd was strain and species dependent. The effects of Cd, glucose, ammonium sulfate and yeast extract on those variables were evaluated through a two-level factorial design. P. italicum is promising for P-solubilization in soils contaminated with Cd and may be an alternative for manufacture of biofertilizers to replace chemical fertilizers. [ABSTRACT FROM AUTHOR]

Background: The two-spotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae), is one of the most damaging mites in agriculture. Due to the concern for the intensive use of synthetic acaricides, entomopathogenic fungi represents a feasible alternative to T. urticae management. In the present study, 7 isolates of Metarhizium were characterized physiological and molecularly (based on the ITS1-5.8s-ITS2 rDNA) and evaluated for their acaricidal activity [mortality, mean and 90 lethal concentration (LC50: LC90) and mean and 90 lethal time (LT50: LT90)] against T. urticae under laboratory conditions. Results: Sequencing of the ITS1-5.8s-ITS2 rDNA region indicated that the 7 isolates belong to M. anisopliae. The isolates Ma114 (3.7 ± 0.006 mm day−1), Ma109 (3.5 ± 0.009 mm day−1) and Ma106 (3.5 ± 0.006 mm day−1) had the highest radial growth rate and Ma114 (92.2 ± 0.86%) and Ma108 (94.4 ± 1.07%) had the highest germination percentage. All isolates were pathogenic to T. urticae, causing mortality that ranged from 45.3 to 85.3%. The LC50 and LC90 were 1.2 and 2.8, 1.1 and 2.5, and 1.2 and 2.8 × 108 conidia mL−1 for isolates Ma110, Ma109 and Ma106, respectively, while the LT50 and LT90 were 7.7 and 16.5, and 7.2 and 16.1 days for isolates M110 and Ma109, respectively. Conclusion: The isolates Ma110 and Ma109 of M. anisopliae were moderately pathogenic and virulent against T. urticae. [ABSTRACT FROM AUTHOR]