Isolation of a Bacillus strain toxic to Spodoptera frugiperda (LEP.:NOCTUIDAE)

ÁLVAREZ, ANALÍA; PERA, LICIA MARÍA; VIRLA, EDUARDO; BAIGORI, MARIO DOMINGO

Tafi del Valle, Tucumán, Argentina

Jornada; XXII Annual Scientific Meeting; 2006

Tucumán Biology Society

ISOLATION OF A BACILLUS STRAIN TOXIC TO SPODOPTERA frugiperda (LEP.: NOCTUIDAE) Alvarez, A; Pera, L M; Virla, E and Baigorí, M D.   PROIMI Av. Belgrano y Pje. Caseros, 4000 Tucumán. Tel: 4344888, e-mail: alvarez_analia@hotmail.com     Introduction. The fall armyworm, Spodoptera frugiperda (Sf), is one of the most important corn pests in tropical and subtropical America. Some microorganisms are important candidates for its control. Bacillus thuringiensis (Bt) is an entomopathogenic spore-forming bacterium, which produces proteinaceous crystalline parasporal inclusions (Cry). Objective. Evaluation of ten “Cry” producer strains against first instar larvae of Sf . Materials and methods. Individuals comes from a laboratory colony maintained under controlled conditions (25°C, 70-75% RH and 12:12 L/D). The artificial diet was immersed in sterile water “Cry” protein suspension. Microorganisms isolated from soil and dead larvae were used. Larval mortality was determined during 7 days. Results and conclusions. One of the native strains tested, called RT3, had a strong toxicity against Sf larvae. Considering two independent assays, a mortality level from 76,6 (F=60,50; gl=1; P=0,0015) to 100% was observed after 3 and 4 days, respectively. Finally, in the first assay no larva was survived. Larval mortality using serial dilution of “Cry” suspension was also determined. According to these results, the isolated RT3 can be considered an active strain. This work were supported by grant CIUNT D308 and CONICET