Generation and Evaluation of Nanoparticles of Supernatant of Photorhabdus luminescens (Thomas and Poinar) against Mite and Aphid Pests of Cotton for Enhanced Efficacy

Cell-free supernatant of Photorhabdus luminiscens was converted to nanoparticles (NPs) using a spray dryer fitted with ultrasonic nozzle. NPs were characterized by both scanning electron microscopy and zeta size analyser, and found to have average particle diameter of 89 nm. While converting to NPs, gum arabica @ 3% was used to eliminate hygroscopic property. Nanoparticulated supernatant exhibited superior pesticidal property against serious sucking pests of cotton, viz. Tetranychus macfarlanei and Aphis gossypii. On mites, NPs of P. luminiscens recorded lower median lethal concentration (LC₅₀ : 0.0001 ppm) compared to normal form (8.36 x 10² ppm) within 12 h of exposure. Similarly, on aphids, lower LC₅₀ (LC₅₀ : 0.0027 ppm) was recorded by NPs compared to normal form (LC₅₀ : 2.12 x 10³ ppm). High mortality coupled with quick action emphasizes the potential of nanotechnology in enhancing the pathogenicity of a microbial pesticide.