Determination of LD50 and LT50 of Bacillus native strains toxic to Spodoptera frugiperda (Lep.: Noctuidae).

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

Tafí del Valle, Tucumán, Argentina

Jornada; XXIII Annual Scientific Meeting; 2007

Tucumán Biology Society

Introduction: Spodoptera frugiperda (Sf) is one of the most important corn pests in tropical and subtropical America. Bacillus thuringiensis (Bt) is an entomopathogenic spore-forming bacterium that produces parasporal crystalline proteinaceous inclusions (Cry). Objective: The aim of this work was to determine the lethal dose (DL50) and the lethal time (TL50) of native crystalliferous Bacillus strains against first instar larvae of Sf. Materials and methods: Insects comes from a laboratory colony. The artificial diet was immersed in serial dilutions of Cry protein suspension. DL50 and TL50 were calculated by Probit analysis. Results and conclusions: The DL50 (UFC) calculated for B. sp RT, B. sp LSM, B. sp L Q and Bt kurstaki (HD1) were 8.99 X 106, 5.60 x 107, 2.70 X 107 and 1.04 X 107, respectively. Under our assays conditions, B. sp RT shows the lower TL50 for doses of about 6 x 107 cfu. These results show that Bacillus sp RT is an interesting strain for further development for Sf control programmes. Acknowledgments: PICTO-UNT 761, CIUNT D308 and PIP 6062