Abstract

CASTELLANOS-MOGUEL, Judith et al. Relationship between protease and chitinase activity and the virulence of Paecilomyces fumosoroseus in Trialeurodes vaporariorum (Hemiptera: Aleyrodidae). Rev. Mex. Mic [online]. 2008, vol.28, n.spe, pp.71-80. ISSN 0187-3180.

The production of protease and chitinase activities of isolates of Paecilomyces fumosoroseus and their virulence in whitefly nymphs were evaluated. Enzyme production was tested in 18 fungal isolates, on synthetic liquid medium with colloidal shrimp cuticle and remazol bright blue stained colloidal chitin as substrates for protease and chitinase activity, respectively. The virulence bioassay was carried out in second stage whitefly (Trialeurodes vaporariorum) nymphs in 9 monospore cultures of selected isolates. The virulence was determined by the median lethal concentration (LC₅₀) in whiteflies. Isolates EH-506/3 and EH-511/3 with the highest virulence (LC₅₀ of 1.1 x 10³ and 6.9 x 10³, respectively) also showed the highest protease activity (PU/mL of 39.8 and 14.9, respectively) at 120 h. Chitinases reached maximum activities at the end (264 and 312 h) of thein vitro enzymatic assay. This is the first time that an ample intraspecific variability in protease and chitinase activities as well as in virulence has been reported in a representative sample of P. fumosoroseus strains from Mexico, which suggest that protease activities could be used in the selection of candidates for whiteflies biological control.

Keywords : biological control; virulence factors; entomopathogenic fungus.

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