Species diversity and crop stage in relation to predatory potential of spiders on rice brown plant hopper Nilaparvata lugens (Stål)

This study investigated the spider diversity, species, and predatory efficiency of various spider species predating on the rice brown plant hopper Nilaparvata lugens (Stål). The experimental period was divided into three phenological stages viz., active tillering, panicle bearing-grain filling and grain maturity. Diversity indices such as Shannon-Wiener diversity index, Simpson diversity indices, species richness and species evenness index were calculated. Twelve predatory spider species from nine families were recorded and their population was observed to increased with growth stages. Adjusted mortality rates were calculated and predatory potential was observed to follow the order as Plexippus paykulli ˃Pardosa pseudoannulata ˃Oxyopes hindostanicus˃ Neoscona theisi ˃ Thomisius ˃Atypena formosona ˃Tetragnatha nitens ˃ Bianor angulosus ˃ Araneus sp. ˃ Clubiona sp. ˃ Theridion sp.˃ Ostearius melanopygius.