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The characterization of entomopathogenic microorganisms is important for the selection of more effective strains for use in integrated pest-control programs. Five Nomuraea rileyi strains (SA86101, GU87401, SR86151, CG128 and VA9101) were characterized using random amplified polymorphic DNA (RAPD) analysis, virulence studies and assessment of chitinolytic and proteolytic activity. RAPD analysis divided the strains into two groups with a similarity coefficient of 0,76%, group 1 consisting of strains SA86101, GU87401 and SR86151 and group 2 of strains CG128 and VA9101. The LT50 varied from 165h with strain VA9101 to 246h with strain GU87401. Chitinolytic and proteolytic activity of the fungi after 144h growth in minimal medium were tested using colloidal chitin as substrate. All strains exhibited enzyme activity, with strain VA9101 having the highest chitinase activity (0,0040 mumol/mL/min the 40ºC) and strain SA86101 the highest proteolytic activity. No relationship was found between RAPD analysis, virulence and chitinase or protease activity.
Caracterizaram-se cinco linhagens de N. rileyi por análise de RAPD, avaliação da virulência e atividade enzimática (quitinolítica e proteolítica). Pela técnica de RAPD foi possível distinguir, entre as cinco linhagens avaliadas, dois grupos com similaridade 0,76: grupo I (linhagens SA86101, GU87401, SR86151) e grupo II (linhagens VA9101 e CG128). O TL50 variou de 165 horas com a utilização da linhagem VA9101 a 246 horas com GU87401. Todas as linhagens apresentaram atividade quitinolítica e proteolítica, destacando-se quanto à produção de quitinases a linhagem VA9101 (com 0,0040 mimol/mL/min a 40ºC) e em relação à protease, a linhagem SA86101. Não foi possível evidenciar relações entre virulência, análise genética e atividade enzimática

BACKGROUND Essential oils (EOs) are volatile natural compounds produced by plant secondary metabolism, and some of them exhibit antimicrobial activity. The objective of the present study was to determine the chemical composition the EOs of Eucalyptus staigeriana and Eucalyptus globulus, and their effect in vitro and in vivo against Botrytis cinerea and Colletotrichum acutatum, the most important fungal rot diseases of grapes. Moreover, grapes collected from field experiments were used to evaluate the impact of the alternative control on the alcoholic fermentation and wine composition. RESULTS The major compound of E. staigeriana EO were citral 30.91% (19.74% geranial, 11.17% neral), 1.8‐cineole (24.59%) and limonene (19.47%), while 1.8‐cineole represented 68.26% of E. globulus EO. The two EOs showed in vitro antifungal activity against both pathogens. Eucalyptus staigeriana EO exhibited the highest activity inhibiting mycelial growth (MG) and conidial germination at 0.5 μL mL−1. Moreover, this EO was able to reduce the incidence and severity of grey rot caused by B. cinerea and the severity of ripe rot caused by C. acutatum The alternative control did not significantly influence alcoholic fermentation, the physicochemical characteristics, and the volatile composition of wines. CONCLUSION These results are promising and indicate that E. staigeriana EO might be further investigated as a natural alternative for the control of fungal rots on wine grapes. © 2019 Society of Chemical Industry

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