Effect of talc-formulated entomopathogenic fungus Beauveria against leaffolder (Cnaphalocrosis medinalis) in rice

Abstract

Thirteen Beauveria strains were isolated from the soil and infected insects. Among the various isolates, B2 isolate (Arachalore) showed a higher percentage of mortality against C. medinalis (73.3%) under in vitro conditions. Conidial concentration of 1 × 108 of the B2 strain registered maximum mortality of 76.7%. The least LT50 value of 4.4 days was registered in B2 isolate with the spore concentration of 1 × 108 and the LC50 value was 3.4 × 104. Beauveria strains altered the feeding behavior of C. medinalis, reduced the pupal weight, prolonged the pupation period, malformed the pupa and adult under in vitro. The efficacy of the talc-based bioformulation of Beauveria (B2) strain was tested as seed treatment + seedling dip + soil application + foliar spray against rice leaffolder under in vitro and greenhouse conditions. The percentage damage was significantly less (5.5) in B2 as compared to untreated healthy control (25.8). In addition, the same treatment increased the activities of defense-related enzymes, namely peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase, chitinase, and phenolics in rice. © 2007 Springer Science+Business Media B.V.