Relative Efficacy and Persistence of Toxicity of Some Insecticides against Grown-Up Larvae of Bihar Hairy Caterpillar, Diacrisia Obliqua Walker.

A set of fifteen different insecticides viz, dichlorovos, carbaryl. monocrotophos, quinalphos, fenthion, feaitrothion. malathion, ambithion, chloropyriphos, leptophos, chlorofenvinphos, dichrotophos, phosalone, formothion and endosulfan were tested for their relative efficacy and persistence of toxicity against the gown up caterpillars of Diacrisia obliqua Walk. Chlorofenvinphos (0.05%), endosulfan (0.07%) and fenitrothion (0.05%) proved to be the most effective when the initial larval mortality was taken into consideration. On the basis of the PT values, the relative persistence of toxicity was calculated. As a result of this, it was found that the endosulfan (0 07%) followed by chlorofenvinphos (0.05%) persisted for a relatively longer duration when compared with the rest of the insecticides.