Efficacy of Soil-Isolated Entomopathogenic Fungi From Manipur (N-E India) Against Nilaparvata lugens Stal and Their Safety Assessment on Beneficial Insects

Abstract

In recent years, there has been a shift toward natural and biological methods for controlling insect pests in agricultural crops to reduce dependence on chemical products. Entomopathogenic fungi (EPF) have gained attention as alternatives to conventional insecticides for pest management. The brown plant hopper (Nilaparvata lugens), a major threat to rice crops worldwide, has shown increasing resistance to insecticides due to overuse, creating an urgent need for non-chemical, environmentally friendly, safe and sustainable alternatives for BPH control. The biodiversity-rich North-East region of India holds untapped potential for discovering new, effective strains of EPF. This study was therefore conducted to examine the diversity of EPF in this region and assess their effectiveness against BPH for pest control. The primary objective was to evaluate the pathogenicity of indigenous EPF isolates from soil on BPH. Laboratory and polyhouse tests were conducted, beginning with eight Beauveria bassiana isolates in the laboratory, with the top three isolates moving to polyhouse trials. Preliminary findings showed that CCPR-Bb1 achieved the highest mortality rates, with 93.33% in laboratory conditions and 91.67% in polyhouse conditions against BPH. Temperature assessments indicated that 25°C was optimal for radial growth and sporulation across most isolates. Additionally, safety tests examined the effects of EPF isolates on Trichogramma chilonis, Chrysoperla zastrowi sillemi and Apis cerana indica. Results demonstrated that, at lower concentrations, these pathogens were generally safe for beneficial organisms, posing minimal risk. These EPF strains have the potential to aid farmers in reducing pesticide use, promoting environmental sustainability and serving as vital elements in integrated pest management (IPM) strategies.