Distribution and Diversity of Spiders in a Paddy field and in adjacent barren land in response to application of Insecticides

Abstract :

The effect of insecticide application in paddy crop (Oryza sativa) on spider population was evaluated by monitoring their abundance and density in a paddy field and its adjacent barren land, in Nallathukudi village located in Nagapattinam District, Tamil Nadu, from May 2014 to September 2014. Overall, 26 species of spiders belonging to nine families were recorded from both the habitats. The paddy field harbored lower number of species (n = 17) than nearby barren field (25 species). After the application of insecticide viz., Profenofos (organophosphate insecticide EC. 40%) the spider density in the paddy field declined significantly while the barren field experienced significantly higher density. However, a few days after the application of insecticide, the spider density increased gradually in paddy field, indicating the in and out-word movements of spiders from crop field to barren land and back to avoid the effect of insecticide. Thus, the unmanaged barren lands in agro-ecosystem have a significant role of acting as temporary refuge for the spiders.