Studies on the taxonomy and bionomics of some predscious spiders on insect pests of Rice Agroecosystem in Kuttanad, Kerala

Abstract

A study on the diversity of spider fauna in Kuttanad rice agroecosystems of Kerala was conducted during 2001-2004. Standard sweeping and hand picking methods were used for spider sampling from 8 sclected study sites. A total of 99 species of spiders belonging to 66 genera of 20 families were collected during the study. Spider population in the monsoon (Rabi) and winter (Kharif) seasons had a slight different species composition. There was significant difference in Shannon, Richness and Evenness indices between the two seasons. The collected spiders were classified into 7 feeding guilds and 5 vertical strata. Biological studies revealed that the number of instars and longevity period varied among the species and sexes of the same species. Laboratory experiments on feeding potential of the dominant spiders on major insect pests revealed that Pardosu pseudoannulata was the most efficient predator. Toxicological studies suggested the usefulness of Monocrotophos as a component of integrated pest management strategy for sustainable paddy cultivation. Of the three dominant species tested, P. pseudoannulatu was the least susceptible to the application of insecticides both by topical application and the dipping methods under laboratory conditions.