• Mycobiology
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• v.47 no.1
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• pp.126-133
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• 2019

Isaria javanica pf185 is an important entomopathogenic fungus with potential for use as an agricultural biocontrol agent. However, the effect of I. javanica pf185 on plant growth is unknown. Enhanced tobacco growth was observed when tobacco roots were exposed to spores, cultures, and fungal cell-free culture supernatants of this fungus. Tobacco seedlings were also exposed to the volatiles of I. javanica pf185 in vitro using I-plates in which the plant and fungus were growing in separate compartments connected only by air space. The length and weight of seedlings, content of leaf chlorophyll, and number of root branches were significantly increased by the fungal volatiles. Heptane, 3-hexanone, 2,4-dimethylhexane, and 2-nonanone were detected, by solid-phase micro-extraction and gas chromatography-mass spectrophotometry, as the key volatile compounds produced by I. javanica pf185. These findings illustrate that I. javanica pf185 can be used to promote plant growth, and also as a biocontrol agent of insect and plant diseases. Further studies are necessary to elucidate the mechanisms by which I. javanica pf185 promotes plant growth.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.631-642
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• 2017

For effective control of insect pest which can outbreak in a field during crop cultivation, various control agents such as eco-friendly agricultural materials (EFAM) including microbial control agents and chemical pesticides have been applied at fields and these control agents may be treated simultaneous or sequential in the same field to suppress diverse pests and diseases. The agents may influence each other and control efficacy may also differ from interactions. Therefore we need to test compatibility of microbial control agents with other agricultural agents. In this study, we investigated influence of pre-treated EFAMs, which are registered for whitefly control in greenhouse, on germination, mycelial growth and control efficacy of Isaria javanica isolate against sweet potato whitefly. The results showed that a mixture of paraffin oil+cinnamon oil among 4 EFAMs highly reduced germination ($8.9{\pm}1.3%{\sim}24.5{\pm}0.9%$) and mycelial growth ($0.81{\pm}0.01cm{\sim}0cm$) of I. javanica. To investigate the effects of the treatment interval between EFAMs and I. javanica on sweet potato whitefly control, four different EFAMs were pre-treated 0, 1, 4, and 7 days before applying I. javanica. Pre-treatment of four EFAMs inhibited insecticidal activity of I. javanica against sweet potato whitefly. Therefore when EFAMs and a mycopesticide using I. javanica spray simultaneous or sequential, application of EFAMs need more than 7 days interval after treatment of mycopesticide at field.

• The Korean Journal of Mycology
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• v.46 no.4
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• pp.479-490
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• 2018

Red pepper is seriously damaged by thrips (Thrips palmi) and anthracnose caused by Colletotrichum acutatum throughout its development. Because of biotic constraints, producers often depend on chemicals that are expensive and have adverse effects on the environment, operator, and beneficial insects. In addition, resistance is developed because of the repeated use of chemicals. In recent decades, the use of microorganisms in crop protection has become a credible alternative because it is eco-friendly. In this study, we aimed to select isolates with insecticidal and fungicidal activities against the pathogens that cause anthracnose and thrips. We treated T. palmi adults and juveniles with 13 strains of entomopathogenic fungi (isolated from the soil by using the insect-bait method), and 6 strains showed excellent insecticidal activity (70-100%) 5 days after the treatment. The selected isolates were cultured with C. acutatum to screen for the strain with excellent anti-fungal activities, among which an isolate FT333 showed more than 95% control efficacy against C. acutatum in vitro. The isolate was identified as Isaria javanica through its morphological characteristics and phylogenetic analysis of the ITS and ${\beta}-tubulin$ nucleotide sequences. The Isaria javanica FT333 isolate could be used effectively for dual bio-control of thrips and anthracnose during red pepper cultivation.

• Mycobiology
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• v.46 no.4
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• pp.440-447
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• 2018

Dual biocontrol of both insects and plant pathogens has been reported for certain fungal entomopathogens, including Beauveria bassiana and Lecanicillum spp. In this study, we demonstrate, for the first time, the dual biocontrol potential of two fungal isolates identified by morphological and phylogenetic analyses as Isaria javanica. Both these isolates caused mortality in the greater wax moth, and hence can be considered entomopathogens. Spores of the isolates were also pathogenic to nymphs of the green peach aphid (Myzus persicae), with an $LC_{50}$ value of $10^7spores/mL$ 4 days after inoculation and an $LT_{50}$ of 4.2 days with a dose of $10^8spores/mL$. In vitro antifungal assays also demonstrated a strong inhibitory effect on the growth of two fungi that are pathogenic to peppers, Colletotrichum gloeosporioides and Phytophthora capsici. These results indicate that I. javanica isolates could be used as novel biocontrol agents for the simultaneous control of aphids and fungal diseases, such as anthracnose and Phytophthora blight, in an integrated pest management framework for red pepper.

• Mycobiology
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• v.42 no.4
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• pp.346-352
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• 2014

Recently, the Q biotype of tobacco whitefly has been recognized as the most hazardous strain of Bemisia tabaci worldwide, because of its increased resistance to some insecticide groups. As an alternative control agent, we selected an Isaria javanica isolate as a candidate for the development of a mycopesticide against the Q biotype of sweet potato whitefly. To select optimal mass production media for solid-state fermentation, we compared the production yield and virulence of conidia between 2 substrates (barley and brown rice), and we also compared the effects of various additives on conidia production and virulence. Barley was a better substrate for conidia production, producing $3.43{\times}10^{10}$ conidia/g, compared with $3.05{\times}10^{10}$ conidia/g for brown rice. The addition of 2% $CaCO_3+2%$ $CaSO_4$ to barley significantly increased conidia production. Addition of yeast extract, casein, or gluten also improved conidia production on barley. Gluten addition (3% and 1.32%) to brown rice improved conidia production by 14 and 6 times, respectively, relative to brown rice without additives. Conidia cultivated on barley produced a mortality rate of 62% in the sweet potato whitefly after 4-day treatment, compared with 53% for conidia cultivated on brown rice. The amendment of solid substrate cultivation with additives changed the virulence of the conidia produced; the median lethal time ($LT_{50}$) was shorter for conidia produced on barley and brown rice with added yeast extract (1.32% and 3%, respectively), $KNO_3$ (0.6% and 1%), or gluten (1.32% and 3%) compared with conidia produced on substrates without additives.

• Research in Plant Disease
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• v.27 no.3
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• pp.99-106
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• 2021

The fungal isolate Isaria javanica pf185 has potential as a mycopesticide because it demonstrates insecticidal activity against the green peach aphid and antifungal activity against Colletotrichum gloeosporioides. For commercialization of this isolate, determination of the optimal and least expensive culture conditions is required; however, these data are not currently available. This study describes the conditions for optimal development of conidia and production of metabolites for the biocontrol of the fungal pathogen. The optimal culture conditions were examined using cultures on solid agar and liquid media. High growth temperature enhanced spore formation but reduced antifungal activity in both solid and liquid media. The highest spore yield was obtained in a medium containing glucose as a carbon source and yeast extract as a nitrogen source. Soybean powder and wheat bran were effective nitrogen sources that promoted spore production and antifungal activity of the isolate. These results revealed the basic, cost-effective growth media for commercial production of a biopesticide with insecticidal and antifungal properties for use in integrated pest management.