Development of Formulations of a Native Entomopathogenic Fungus, Lecanicillium lecanii and Testing Virulence Against Mealybug, Paracoccus marginatus Infesting Cotton

Lecanicillium lecanii is an entomopathogenic fungus with high potential in the biological control of pests. Bioassays were conducted to evaluate the activity of formulations of a native entomopathogenic fungus, L.lecanii stored at room temperature against Cotton mealy bug, Paracoccus marginatus infesting cotton in India. Time Mortality responses (LT₅₀) for different formulations were calculated using Probit analysis. The results revealed that the LT₅₀ was found to be increased with increase in duration of storage. At the end of six months of storage, oil and talc based formulations recorded LT₅₀ values of 10.21 (9.21 – 11.33) and 10.31 (9.43 – 11.29), respectively. No significant difference in the virulence of spores formulated in talc and oil was noticed as there was overlapping in fiducial limit was observed. But when tested under pot culture condition, oil based formulation recorded significantly higher mortality of P. marginatus. Spraying of oil based formulation of L. lecanii twice at 15 days interval recorded a maximum of 75.00 per cent mortality. The results indicate that a comprehensive evaluation of entomopathogenic fungus in agriculture using oil based formulation is advisable particularly in organic cultivation.