Contact toxicity of different insecticides to third and fifth instar nymphs of brown plant hopper Nilaparvata lugens stal (Delphacidae : Homoptera)

Abstract

The relative efficacy of 1 2 contact insecticides to the third and fifth instar nymphs of the brown plant-hopper Nilaparvata lugens was assessed in the laboratory by assessing their LC 50 values. These chemicals were found to be equally effective against both the stages of the pest. Insecticides found most effective were carbaryl, monocrotophos, quinalphos, fenthion, phosalone, fenitrothion and dichlorvos. On relative cost basis these may be ranked ascarbaryl, monocrotophos dichlorvos, phosolone, fenthion, fenitrothion and quinalphos, against third instar nymphs and carbaryl, monocrotophos, quinalphos, fenitrothton, fenthion, phosalone and dichlorvos against fifth instar nymphs.