BIOEFFICACY OF NEWER INSECTICIDES AGAINST LEPIDOPTERAN PESTS AND THEIR RESIDUE DYNAMICS ON CABBAGE
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Date
2019-06-18
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CSK HPKV, Palampur
Abstract
Field experiment was conducted at Experimental Research Farm of
Department of Entomology, CSKHPKV, Palampur during the rabi season 2018-19 to
determine the bioefficacy of insecticides against Plutella xylostella and their residue
dynamics on cabbage, variety Pusa Cabbage-1. The bioefficacy of insecticides
comprising chlorantraniliprole, cypermethrin, diafenthiuron, emamectin benzoate,
indoxacarb, novaluron, azadirachtin, spinosad and Bacillus thuringiensis was
determined. After two sprays, chlorantraniliprole @ 10g a.i./ha recorded minimum
larval population with 1.21 larvae/plant followed by spinosad @ 15 g a.i./ha (1.43)
and indoxacarb @ 40 g a.i./ha (1.6). The treatments with high larval population were
azadirachtin (5.56 larvae/plant) followed by Bt (5.47). The per cent reduction of larval
population over untreated check was highest in chlorantraniliprole (81.02%), followed
by spinosad (78.13%) and indoxacarb (78.02%). The lowest per cent reduction was
found in the plots treated with Bt (45.14%) and azadirachtin (45.52%). Incremental
cost benefit ratio was maximum (1:18.44) in chlorantraniliprole followed by spinosad
(1:16.33) and diafenthiuron (1:13.96). The lowest incremental cost benefit ratio was
found with novaluron (1:2.48). The initial deposits of diafenthiuron, indoxacarb and
novaluron on cabbage heads were found to be 0.604, 0.309 and 0.218 mg/kg,
respectively which were below the quantification limits on 7th day after spray. The
half-life values were calculated to be 1.05, 1.73 and 1.14 days, the safety intervals
were found to be 0.77, 0.13 and 1.91 days, for diafenthiuron, indoxacarb and
novaluron, respectively.
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