K. NAGARAJUPRAVEEN RANADEV2023-05-312023-05-312023-05-31Th-13662https://krishikosh.egranth.ac.in/handle/1/5810197487The bioefficacy of entomopathogenic fungi against major insect pests of gerbera was studied under polyhouse conditions. Out of the 81 fungal isolates isolated from two agro-climatic zones of Karnataka, India, 16 isolates showed insecticidal activity and were identified as Metarhizium spp. Beauveria spp. Aspergillus spp. Lecanicillium spp. Isaria spp. and Hirsutella spp. Additionally, the 16 isolates were examined for cuticle degrading enzyme activity, namely chitinase, protease and lipase. The enzymes activity of Beauveria sp. and Lecanicillium sp. ranged between 0.87-1.21 U/ml, 0.1-0.32 U/mL, and 0.28-0.43 U/mL, respectively. The leaf discs treated with Lecanicillium sp. (ENPF-24 & ENPF-41), Beauveria (ENPF-60) and Hirsutella sp. (ENPF-58) showed significantly higher mortality rate in test insects (aphids, thrips, mites and whitefly). The LC50 and LT50 were determined by probit analysis and the lowest LC50 (9.4×104, 1.5×105 and 1.5×105 conidia/mL) and LT50 (5.7, 5.89, and 5.51 days) were recorded from Lecanicillium sp. (ENPF-41). Sabouraud’s dextrose was found to be the best medium to produce entomopathogenic isolates. Further, Among the agro-wastes, the isolates produced significantly higher conidial in sorghum grains fortified with 10% molasses, followed by the treatment, 25% paddy husk + 25% Bagasse + 25% PMS + 25% Crushed Sorghum grains + 10% molasses. Subsequently, six virulent strains of entomopathogenic fungi were molecularly identified as Beauveria bassiana, Lecanicillium lecanii, Isaria fumosorosea and Hirsutella thompsonii. Under polyhouse conditions, the application of biocontrol agents reduced the gerbera pest population by 35-50%. Native entomopathogenic fungal isolates performed better than reference strains.EnglishThesis