The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManA-UMC3085 realized 100% mortality at concentrations of 5.5×10 6 conidia ml −1 , 5.86×10 5 conidia ml −1 , and 4.8×10 6 conidia ml −1 , respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC 50 values were 1.43× 10 3 , 1.04×10 5 and 5.06×10 4 for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis program as 0.738±0.008, 0.635± 0.007 and 1.120±0.024, respectively.

Trichoderma is environmentally vital due to their plant growth-promoting effects (such as enhancement of nutrients supply, suppression of plant pathogens, and promotion of plant defense). Biogenic volatile organic compounds (VOCs) are diverse chemical substances emitted by Trichoderma spp. The potential role of VOCs in biological control and plant growth promotion has recently been recognized. Here, the Trichoderma-VOCs' performance for plant growth promotion and suppression of plant pathogens are evaluated. We further investigated VOC emission profiles of T. harzianum using GC–MS. The Trichoderma-VOCs exhibited significant (p < 0.05) antifungal properties against all tested pathogenic fungi. T. atroviride-VOCs showed a decisive inhibition of Alternaria panax, Botrytis cinerea, Cylindrocarpon destructans, and Sclerotinia nivalis. The germinating seeds demonstrated growth enhancement in the presence of Trichoderma-VOCs emitted by different strains. Low levels of cyclopentasiloxane, decamethyl, cyclotetrasiloxane, and octamethyl were found in T. harzianum KNU1 strain whereas cyclopentasiloxane, decamethyl, cyclotetrasiloxane, and octamethyl showed higher emission levels as Si-containing compounds. The results reveal the potentiality of VOCs as a biocontrol resource against deleterious rhizosphere microorganisms and underline the importance of Trichoderma-VOCs emissions in regulating plant growth and development.

Recently, public concerns regarding the use of agrochemicals have increased due to the environmental impacts and potential risks to human health. The application of beneficial microorganisms is a novel technology to improve plant health and productivity and has therefore been extensively studied as an alternative strategy for biocontrol. In our study, 122 microbial isolates were obtained from the rhizosphere of Panax ginseng and subsequently tested in vitro for phosphate solubilization and indole acetic acid (IAA) production. Pikovskaya's medium was used to estimate rhizomicrobial isolates to solubilize tricalcium phosphate [Ca 3 (PO 4 ) 2 ]. Among all the investigated strains, 82 % of rhizospheric fungi showed phosphate solubilization activity; however, only 57.1 % of the rhizobacteria isolates showed phosphate solubilization ability. For IAA production, 64.7 % of the tested rhizofungi isolates were able to produce the phytohormone; however, only 47.62 % of the rhizobacteria isolates exhibited IAA production. Among all investigated species, Pseudomonas fluorescence and Azotobacter chroococcum showed the highest phosphate solubility demonstrating 885.4 and 863.4 lg mL -1 , respectively. Mucor sp. produced 42.3 lg mL -1 of IAA in Czapek's tryptophan medium, and the highest fungal species to solubilize the inorganic phosphate (237.5 lg mL -1 ) was estimated by Penicillium sp. Rhizobacteria were more effective than rhizofungi in phosphate solubilization and IAA production. This study introduces some potent species in terms of phosphate solubilization and IAA production which could be likely to improve soils' quality and promote plant growth.