Effect of crop establishment methods on the abundance and the diversity of natural enemy populations in rice agro-ecosystem.

摘要

The four methods of rice crop establishment viz., conventional transplanting, bed transplanting, furrow transplanting and puddled direct seeding were evaluated during two wet seasons to determine their effect on the abundance and the diversity of natural enemy populations in rice agro-ecosystem. Population counts of natural enemy fauna (insect predators/parasitoids and spiders) were recorded from randomly selected two quadrates of 1 m2 per replication at 10 days intervals starting from 40 days up to 110 days after crop establishment. Over the years in all the crop establishment methods insect predator/parasitoid population of (Braconidae, Ichneumonidae, Coenagrionidae, Coccinellidae and Carabidae) were significantly more in puddled direct seeding followed by transplanted crop than other methods. Spider predator population (Tetragnathidae, Araneidae, Oxyopidae, Salticidae, Lycosidae, Metidae and Tomisidae) were significantly more in bed transplanting than in other crop establishment methods. Overall natural enemy fauna (insect predators/parasitoids and spider predators) were significantly more in bed transplanting and puddled direct seeding. The diversity index across years and observation days was high in case of bed transplanting, which was due to high evenness index in the crop establishment method.