STUDY ON THE RELATIVE ABUNDANCE OF INSECT PESTS AND THEIR NATURAL ENEMIES ASSOCIATED IN RICE

Abstract

The field experiment was conducted at Bangladesh Agricultural University (BAU) farm in Mynmensingh during Boro season. Thirteen different rice pests viz. Short-homed grasshopper, yellow stem borer, dark- headed striped borer, pink borer, white-backed plant hopper, green leafhopper, brown Plant hopper, zigzag leafhopper, whorl maggot, long homed grasshopper, rice leaf roller, green semi looper and rice bug were recorded during the present study. Among the stem borers, yellow stem borer (Scripophaga incertulasy was most dominant throughout the crop season followed by the dark-headed striped.borer (Chilo polychrysa and pink borer (Sesamia inferens). Green leafhopper lNephotettix virescens) was the dominant species among the plant-sucking insects. The population of leaf feeding insects was quite high and their densities varied in relation to plant age and season. Local improved Pajam had lower infestation than high yielding variety BR2. Twelve natural enemies (predator/parasitiod) were recorded from the crop field. They were carabid beetle (Ophionea nigrofaciatai, damselfly (Agriocnemis famina famina), ladybird beetle (Micraspis discolor, M. crucea, Menochilous sexmaculatus), spider (Tetragnathus sp. Oxyopes sp. and Lycosa pseudoanmulata), mirid bug (Cyrtorhinus lividipennisi, Tetrastichus schoenobii and Telenomus rowani. The ladybird beetle Micraspis discolor was abundant from early to late stage of rice crops.