Impact of imidacloprid sprays on the spider diversity in cotton ecosystem

The impact of a chloronicotinyl compound imidacloprid with different doses on spiders in cotton and bhendi ecosystems were assessed for two seasons in different locations. The whole plant sampling method was adopted to observe the spiders in cotton and bhendi plants. Diversity indices viz., species richness, evenness and diversity were calculated using SPDIVERS.BAS programme of Ludwig and Reynolds (1988). Nine species of spiders’ viz., Oxyopes javanus, Oxyopes rufisternum, Peucetia viridanus, Salticus sp., Clubiona sp., Phidippus sp., Thomisus sp., Araneus sp. and Argiope sp. were recorded from cotton ecosystem out of which O. javanus, O. rufisternum and Clubiona sp. were found predominant. The study further revealed that the application of imidacloprid did not have greater influence on the species richness of spiders but there was a short term reduction in the population but tends to increase later. The evenness index (E4) revealed more even distribution of spiders.