author(s)
Sushila N, Pavitra, Sreenivas AG, Ashoka J and Sharanagouda H

abstract
Green silica nanoparticles were synthesised from Paddy husk. They were amorphous in shape and zetasizer revealed that average particle diameter of silica nanoparticles was 26.19 nm. Green silica nanoparticles were tested at various doses from 250 to 2000ppm and compared with metal nanoparticles and an insecticide check against second and fifth instar larva of Spodoptera litura larvae. Observations were also recorded on pupal and adult deformity. The cent per cent mortality of second instar larva of Spodoptera litura larvae was observed by green and metal silica nanoparticle at 1500 ppm at five days after treatment. The dead bodies became extremely dehydrated and shrunken in comparison with the live larva. Silica nanoparticles induced dehydration was the main reason behind their nanocidal property. At five days after treatment they registered 53.33 per cent mortality of fifth instar larva. The larval deformity was highest at green and metal silica nanoparticle at 2000 ppm which registered 23.33 and 30.00 per cent. The pupal deformity was noticed highest at green and metal silica naoparticle at 250 ppm with 23.33 and 16.67 per cent. In further observation adult deformity was highest with green and metal nanoparticle at lowest dosage of 250 ppm which recorded 16.67 and 13.33 per cent respectively. This might be due to the mortality of larvae at lower concentration was less compared to the higher concentration. The lower mortality in lower dosages resulted in deformed pupa and adults. Green silica nanoparticle can be used as an alternative to chemical pesticides.