Journal of Environmental Biology

Toxicity and bioefficacy of individual and combination of diversified insecticides against jute hairy caterpillar, Spilarctia obliqua

K. Selvaraj*, V. Ramesh Babu., B.S. Gotyal and S. Satpathy

ICAR-Central Research Institute for Jute and Allied Fibres (CRIJAF), Kolkata-700 120, India

*Corresponding Author?s E-mail : selvaentomo@gmail.com

Publication Data

Paper received:

17 April 2014

Revised received:

09 December 2014

Accepted:

20 March 2015

Abstract

Toxicity of conventional (profenofos 50 EC and λ-cyhalothrin 5 EC) and non-conventional (flubendiamide 480 SC, chlorantraniliprole 18.5 SC, emamectin benzoate 5 SG) insecticides was determined on the basis of median lethal concentration (LC₅₀) values on third instar larvae of jute hairy caterpillar, Spilarctia obliqua? under laboratory conditions. Further, the promising binary insecticides combinations with lesser LC₅₀ values and adequate synergistic activity were evaluated under field conditions. The LC₅₀ values calculated for insecticides viz., chlorantraniliprole, flubendiamide emamectin benzoate, λ-cyhalothrin and profenophos were 0.212, 0.232,? 0.511,? 0.985 and? 3.263 ppm, respectively. Likewise, the LC50 values for flubendiamide with λ-cyhalothrin in 3:1 proportion was most toxic (0.103 ppm) amongst all the other binary combinations with λ-cyhalothrin.? Chlorantraniliprole in combination with λ-cyhalothrin at 1:1 proportion (0.209 ppm) was most toxic followed by 3:1 proportion (0.345 ppm). Similarly, emamectin benzoate in combination with λ-cyhalothrin at 1:1 proportion was more toxic (0.271 ppm) than 3:1 ratio (0.333 ppm). Toxicity index of flubendiamide + λ-cyhalothrin (3:1 ratio) was highest (970.87). Bioefficacy of synergistic binary combinations along with individual insecticides established the superiority of profenophos + λ-cyhalothrin (3:1) with 89.12% reduction in infestation and recorded maximum fibre yield 38.67qha-1 under field condition. Moreover, combination of diverse insecticides group might sustain toxicity against the target insect for longer period with least probability of resistance development. ?????  

 Key words

Bio-efficacy, Insecticides, Median lethal concentration, Spilarctia obliqua,? Toxicity index 

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