Optimisation of Lecanicillium saksenae: Propagation on various agro-waste media for future bioinsecticide development

Lecanicillium saksenae is an entomopathogenic fungus with high potential as a biological control agent against plant pests. However, information regarding the optimal growth medium for its mass propagation is still limited. This study aimed to determine the most effective medium for maximising L. saksenae propagation and enhancing cultivation efficiency. The treatments included solid media (PDA, rice, broken corn, and tofu waste) and liquid media (PDB, rice washing water, coconut water, and liquid tofu waste). L. saksenae fungus was obtained from diseased brown planthoppers in Pasir Kulon Village, Karanglewas District, Banyumas Regency, Central Java Province, Indonesia. The experimental design used a randomised complete block design with five replications. Observed variables included incubation time, growth percentage, conidial density, and mortality of Brown Planthopper (BPH). Data were analysed using ANOVA followed by DMRT at a 5% significance level. The results showed that coconut water is the best medium for cultivating L. saksenae because, in addition to containing complete and balanced nutrients (sugar, amino acids, vitamins, minerals, and cytokinins) that support vegetative growth and fungal sporulation, it can also increase the production of conidia with high viability and produce wine-red secondary metabolites suspected to be oosporein. In testing the efficacy of secondary metabolites against BPH, the highest mortality rate of BPH pests was observed in coconut water compared to other media. Thus, using coconut water as a natural culture medium has great potential in the mass production of L. saksenae to develop effective and sustainable bioinsecticides.