RELATIVE EFFICACY OF SOME BIORATIONAL AND MICROBIAL INSECTICIDES AGAINST YELLOW STEM BORER AND WHORL MAGGOT OF BORO PADDY

Abstract

A field trial was conducted at Rice Research Station, Hooghly of West Bengal during boro season to evaluate the effect of some biorational and microbial insecticides against rice insect-pests. Insecticides of different origins such as, Beauveria bassiana Balsamo-Crivelli, Bacillus thuringiensis Berliner, Metarhizium anisopliae Metchnikoff, spinosad, azadirechtin, and cartap hydrochloride as check, have been tested in different combinations against yellow stem borer (Scirpophaga incertulas Walker) and whorl maggot (Hydrellia spp. Robineau-Desvoidy). The lowest whorl maggot infestation was recorded in spinosad treated plots (1.84%) followed by B. thuringiensis var. kurstaki (2.58%) and azadirachtin treatment (2.59%). The lowest yellow stem borer infestation as dead heart was recorded in plots treated with spinosad (2.92%) followed by M. anisopliae (3.32%) followed by azadirachtin (3.44%). The white ear head damage was recorded lowest in spinosad (8.04%) followed by B. bassiana + B. thuringiensis var. kurstaki (9.25%) and M. anisopliae treatment (9.48%). The highest grain yield and straw yield of boro rice were obtained from the plots treated with spinosad (57.72 q ha-1 grain yield and 6958 kg ha-1 straw yield) followed by B. bassiana + B. thuringiensis var. kurstaki (54.31 q ha-1 grain yield and 6681 kg ha-1 straw yield) followed by B. bassiana + M. anisopliae (53.47 q ha-1 grain yield and 64.58 q ha-1 straw yield). The overall results revealed spinosad as the most effective insecticide against both the insect species whorl maggot and yellow stem borer, showing minimum white ear head and dead heart with higher grain and straw yield.