Abstract

SANTOS DIAZ, Adriana Marcela; DE BRITO BRANDAO, Pedro Filipe  and  VILLAMIZAR RIVERO, Laura Fernanda. Effect of thermal stress and ultraviolet radiation during massive production of Nomuraea rileyi. Rev. colomb. biotecnol [online]. 2017, vol.19, n.1, pp.82-91. ISSN 0123-3475.  https://doi.org/10.15446/rev.colomb.biote.v19n1.55943.

The entomopathogenic fungus Nomuraea rileyi (isolate Nm006) is a possible microbial control agent against "fall armyworm" Spodoptera frugiperda. However, this fungus is affected by abiotic stress conditions that cause a slow development of the biopesticide. The objective of this study was to assess the individual effect of abiotic stress (temperature and UV light) during solid fermentation of Nomuraea rileyi Nm006. Conidia were produced under different stress conditions and then characterized microbiologically (yield and germination), enzymatically (β-esterese, N-acetylglucosaminidase and subtilin-like protease Pr1) and biologically against Spodoptera frugiperda. All the treatments were compare with conidia produced without stress. Yield and N-acetylglucosaminidase activity did not improve in conidia produced under temperature stress. Germination, efficacy and β-esterase activity were significantly higher in conidia exposed to thermal shock compared to unexposed conidia. UV light shocks did not improve any characteristics of Nm006. Thermal stress at 5 °C and 45 °C were select for fungus fermentation because conidia had higher enzymatic activity (β-esterase y N-acetilglucosaminidase) and any characteristic was negatively affect. This thermal stress could be a strategy to improve the insecticidal activity against S. frugiperda.

Keywords : Entomopathogen fungi; virulence; abiotic stress; biopesticide; tolerance.

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