Biocontrol Science and Technology (2003) 13, 323-340

E . Quesada-Moraga and A. Vey (2003)
Intra-specific variation in virulence and in vitro production of macromolecular toxins active against locust among Beauveria bassiana strains and effects of in vivo and in vitro passage on these factors
Biocontrol Science and Technology 13 (3), 323-340
Abstract: Strains of Beauveria bassiana isolated from locust or from the soil varied considerably in their virulence and their ability to produce in vitro toxic metabolites against Locusta migratoria. Among the pathogenic isolates, only culture filtrates of 90/2-Dm, 92/11-Dm and 0023-Su were toxic by injection, a result which demonstrates that isolates of B. bassiana can be pathogenic for L. migratoria whether they secrete toxic metabolites in vitro or not. Toxic metabolites secreted by strains 90/2-Dm and 92/11-Dm were macromoleculer as they were retained by dialysis (cut-off of 6-8 kDa for globular proteins), whereas those secreted by 0023-Su were not. The effect of in vitro passage on virulence and on toxicogenic activity of isolate 90/2-Dm was dependent on the mycological media the inoculum was produced on. The virulence of isolate 90/2-Dm was significantly reduced after two passages through Sabouraud Dextrose Agar (SDA) whereas two passages through Malt Agar (MA) increased its virulence and its toxicogenic activity. Nevertheless, the most aggressive conidia and the most toxic macromolecules were obtained after two passages of the isolate 90/2-Dm through the host. The bioactive macromolecules present in the crude filtrate of isolate 90/2-Dm were precipitated by 90% saturation of ammonium sulphate, and the insecticidal activity was exclusively detected in high molecular mass fraction after gel filtration on Sephadex G-25. In addition, the insecticidal effect of the Sephadex G-25 fraction was significantly reduced after exposure for 2 h at 60°C and 20 min at 120°C, suggesting that the insecticidal metabolites in the culture filtrates of isolate 90/2-Dm were proteinaceous.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Enrique Quesada-Moraga, Alain Vey

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
rearing/culturing/mass production

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Locusta migratoria
Beauveria bassiana (entomopathogen)	Locusta migratoria