Abstract

BOSA O, CARLOS FELIPE  and  COTES, ALBA MARINA. Effect of culture conditions on the entomopathogenic activity of Serratia marcescens against Tecla solanivora (Lepidoptera: Gelechiidae). Rev. Colomb. Entomol. [online]. 2004, vol.30, n.1, pp.87-92. ISSN 0120-0488.

A model was established to evalúate the effect of successive inoculations and successive growths in culture media suppiemented or not with potential virulence inductors (wheat bran and homogenised Tecla solanivora Povolny larvae) on the enzymatic and biocontrol actlvity of Serratia marcescens. The bacteria biomass obtained from these media was evaluated for biocontrol activity against insect larvae, and enzymatic extracts were prepared to determined the activity of the enzymes Macetilglucosaminidase, quimoelastase protease PR-1 and jJ-esterase. These activities were evaluated in each of five successive bacteria cultures. In general, both the type of substrate added to the media as well as successive growth affected the biocontrol and enzymatic activities, increasing in the third growth of the bacteria. The greatest biocontrol activities of S. marcescens, with or without activation in larvae, corresponding to 65 and 64% mortality, respectively, were obtained when were the bacteria were grown . in wheat bran médium, followed by 58 and 59% mortality, respectively, when grown in the larval médium, activities that were significantly different than that obtained when S. marcescens grew in médium without supplement (48,5%). In addition, a positive correlation was found between M-acetilglucosaminidase and quimoelastase protease activities and S. marcescens biocontrol activity, suggesting that the activity of these enzymes could be related with the mode of action of entomopathogenis bacteria of he genus Serratia.

Keywords : Entomopathogenic bacteria; Serratia sp; Mode of action; Enzymes.