Toxicity of conventonal insecticides to fourth instar larvae of tobaccocaterpillar, Spodoptera litura (Fab.) in different generations

Irshad Ahmad; Ishtiyaq Ahad; R K Gupta; Mohd Monobrullah; R M Bhagat; Hafeez Ahmad

Authors

Irshad Ahmad SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India
Ishtiyaq Ahad SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India
R K Gupta SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India
Mohd Monobrullah SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India
R M Bhagat SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India
Hafeez Ahmad SK-University of Agricultural Sciences and Technology Main Campus Chatha-180 009, Jammu, India

Keywords:

Spodoptera litura, Resistance factor, LC50

Abstract

Studies on development of resistance in tobacco caterpillar against some insecticides were carried out in the laboratory, Division of Entomology, Udheywalla, Jammu. The differential susceptibility level of parental and susceptible strains of tobacco caterpillar to conventional insecticides revealed that the level of susceptibility in 4th instar larvae of this insect has decreased considerably in parental strain as compared to recommended concentrations of insecticides. The highest resistance factor of 9.33 was observed with monocrotophos whereas malathion encountered lowest resistance factor of 1.50. Comparison of the LC50 values obtained in succeeding generations with the 1st generation in 4th instar larvae of S. litura revealed that the resistance developed in an increasing order in all the six generations. The resistance ratio in the 6th generation as compared to the 1st generation was 3.97- fold in endosulfan, 3.11 in malathion and 3.45 in carbaryl.