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

Abstract

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, 2x10 6 , 4x10 6 , 6x10 6 , 8x10 6 and 1x10 7 conidia ml -1 were 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 10 7 conidia ml -1 in direct application. Mortality of the larvae varied according to the concentration of conidia, method of application and fungi. The lowest LC 50 (1.89 x 10 6 conidia ml -1 ) and LT 50 (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.