Laboratory Evaluation of Four Fungal Pathogens against the Teak Defoliator, Hyblaea puera (Cramer) (Lepidoptera: Hyblaeidae)

Effect of four entomopathogenic fungi, Beauveria bassiana, B. brongniartii, Paecilomyces fumosoroseus and Metarhizium anisopliae, isolated from different host insects, was tested in the laboratory against the teak defoliator, Hyblaea puera (Cramer) (Lepidoptera: Hyblaeidae) to assess their virulence and efficiency. Five different concentrations, 2x10⁶, 4x10⁶, 6x10⁶, 8x10⁶ and 1x10⁷ conidia ml^-1were directly and indirectly applied onto third instar larvae of H. puera. All the four fungi tested under both application methods were pathogenic to H. puera with higher efficiency in direct application than indirect application. At 9 days after exposure, the mean per cent mortality obtained was 100, 93.02, 93.02 and 66.74%, respectively, for B. bassiana, B. brongniartii, P. fumosoroseus and M. anisopliae at the highest concentration of 1 x 10⁷ conidia ml^-1 in direct application. Mortality of the larvae varied according to the concentration of conidia, method of application and fungi. The lowest LC₅₀ (1.89 x 10⁶ conidia ml^-1) and LT₅₀ (91.18 hr) values obtained for B. bassiana in direct application showed that B. bassiana was more pathogenic to H. puera than the other three fungi.