The ladybird beetles have been used as biological control agents against several pest species. The aim of this study is to evaluate the compatibility between ladybird beetles and an entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin AAD16. The virulence of AAD16 strain was compared with that of commercial GHA strain on three developmental stages of two coccinellids; Harmonia axyridis Pallas and Chilocorus stigma Say. The topical application method was used for both adult and larval stage while dipping method was used for egg stage. The LT50 and mycosis rate for all life stages of two ladybird beetles tested were not significant between AAD16 and GHA strain. In larval stage, the mycosis rates of H. axyridis and C. stigma were 36 and 40% and 63 and 60% in AAD16 and GHA strain. In adult stage, the mycosis rates of H. axyridis (male and female) and C. stigma (unsexed) were 20, 23, and 23% and 26, 30, and 30% in AAD16 and GHA strain, respectively. Therefore, the two predatory coccinellids could be compatible with these two fungus strains due to their relatively lower mycosis rate.

It is well known that the root-knot nematodes, Meloidogyne spp., incite and aggravate the diseases caused by fungal and bacterial pathogens. The synergistic effects of the inoculation of Meloidogyne incognita combined with Fusarium oxysporum f. sp. lycopersici showed the greatly increased wilt symptoms developed on tomato plants compared to the inoculation of either of the two pests alone. For the biological control of the complex disease, a variety of bacterial isolates were tested for antagonistic effects to select ones that had both nematicidal and antifungal activities. Among forty plant growth-promoting rhizobacteria (PGPR) tested, Paenibacillus polymyxa G508 and G462 and P. lentimorbus G158 showed strong antifungal and nematicidal activities against F. oxysporum f. sp. lycopersici and second-stage juveniles (J2) of M. incognita, respectively, and also inhibited egg hatch of the nematode. The addition of Paenibacillus strains into potted soil suppressed the Fusarium-wilt severity and root galling on tomato and increased plant growths. P. lentimorbus G158 were abundantly proliferated on tomato seeds and hypocotyls more than P. polymyxa G 462 and had no phytotoxic effect on tomato plant. Under the greenhouse conditions, seed treatment of P. lentimorbus G158 reduced wilt severity caused by Fusarium wilt-root knot disease complex and root gall formation and increased tomato growth compared to the untreated control. Root-galls caused by both pathogens treated with bacterial culture had fewer and smaller giant-cells than untreated control, and scanning electron microscopy revealed alteration and distortion of hyphal cell wall of F. oxysporum and lysis of M. incognita egg shell by the bacterial treatment. All of these results suggest the Paenibacillus strains, especially G158 may have a high potential developed as biological control agents for the complex disease.

Background : Plants cultivation is hindered by root rot, a major disease caused by the soil-born fungi. The ginseng-cultivated soil is one of the nutritious habitats for soil-borne microorganisms. Bacteria from ginseng-cultivated soil can increase plant growth by supplying nutrients and hormones as well as protecting against pathogenic fungal infections and induced systematic resistance. Methods and Results : The novel species DCY115T was isolated from ginseng-cultivated soil in Gochang province, Republic of Korea. The isolate was assigned to the genus Paraburkholderia due to its 16S rRNA gene sequence closely proximity to P. xenovorans LB400T (98.8%). Strain DCY115T is gram-negative, facultative aerobic, rod-shaped, non-flagellated, oxidase and catalase positive. The predominant isoprenoid quinone is ubiquinone Q-8. The genomic DNA G + C content is 61.3 mol%. Phenotypic tests and chemotaxonomic analysis place strain DCY115T in the genus Paraburkholderia. DNA-DNA hybridization values between strain DCY115T and closely related reference strains were lower than 51%. The DNA relatedness data in combination with phylogenetic and biochemical tests showed that strain DCY115T could not be assigned to any recognized species. Finally, strain DCY115T showed the plant growth promoting activities of siderophores production, phosphate solubilization, and antagonistic activity against root rot fungal pathogen Fusarium solani (KACC 44891T) and Cylindrocarpon destructans (KACC 44660T). Conclusion : The results support the novel strain DCY115T as a potential biocontrol agent against root rot fungal pathogen within the genus Paraburkholderia for which the name Paraburkholderia panacihumi is proposed. The type strain is DCY115T (= KCTC52952T = JCM32099T).

This study was conducted to isolate and identify the fungal pathogen causing seedling rot of Lithospermum erythrorhizon Siebold & Zuccarini, and to know the optimum growing temperature for decreasing seedling rot of Lithospermum erythrorhizon. On the basis of morphological characteristics, EF-1a sequence analysis, and pathogenecity to host plant, the fungi isolated from seedling rot and seeds of Lithospermum erythrorhizon were identified as Fusarium fujikuroi, indicating that disease causing fungus is seed-borne pathogen. Optimum temperature for germination of seeds of Lithospermum erythrorhizon was 15~20℃, but pathogenicity of Fusarium fujikuroi was shown more readily at 25~30℃. These results suggested that seedling culture of Lithospermum erythrorhizon between 15℃ and 20℃ might reduce seedling rot of Lithospermum erythrorhizon caused by seed-borne pathogen Fusarium fujikuroi.