Abstract

HERNANDEZ DIAZ-ORDAZ, Noé; PEREZ, Nelson  and  TOLEDO, Jorge. Pathogenecity of three strains of entomopathogenic fungus on Anastrepha obliqua adults (Macquart) (Diptera: Tephritidae) under laboratory conditions. Acta Zool. Mex [online]. 2010, vol.26, n.3, pp.481-494. ISSN 2448-8445.

In order to develop biorrational fruit fly control methods, the activity of two strains of Beauveria bassiana (Bb₂6 and Bb_JLSV) and a strain of Metarhizium anisopliae (Ma_CENGICAÑA) against adults of Anastrepha obliqua was evaluated in the laboratory. The Bb₂₆ strain caused the highest infection rate (99.8%), followed by the Bb_JLSV strain (93.5%), and the Ma_CENGICAÑA strain which caused the lowest infection (89.8%). Both males and females were susceptible to the strains tested, with a similar mortality in both sexes. The median lethal time (LT₅₀) was 3.9, 5.3 and 6.4 days for Ma_CENGICAÑA, Bb₂₆ and Bb_JLSV, respectively, with an average median lethal time for the three strains of 5.2 days. Results indicate that the most pathogenic strain against adults of A. obliqua was Bb₂₆, with a median lethal concentration (LC₅₀) equivalent to 3.8 x 10⁶ conidia ml-¹, followed by the Ma_CENGICAÑAstrain equivalent to 4.8 x 10⁶ conidia ml-¹ and the Bb_JLSV strain with an equivalent to 8.8 x 10⁶ conidia ml-¹. The Bb₂₆ strain produced the highest sporulation, with a concentration of 1.52 x 10⁸ conidia ml-¹, and a sporulation of 77.9% of infected adults; followed by the Ma_CENGICAÑA strain (1.50 x10⁸ conidia ml-¹) and Bb_JLSV (1.76 x10⁸ conidia ml-¹) with 73.8 and 72.6% of sporulation, respectively. Sporulation of infected cadavers and inoculum concentration showed a positive correlation between the applied concentration and the production of conidia by flies (R² = 0.91, Y = 1.63 + 0.14x), which suggested that when increasing the concentration of inoculum, the production of conidia tended to increase.

Keywords : Microbial control; entomopathogen; Anastrepha obliqua; fruit flies.

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