Evaluation of insecticides against blister beetle (Mylabris pustulata Thunb.) on pigeonpea, Cajanus cajan

Abstract

Blister beetle, Mylabris pustulata (Family: Meloidae: Coleoptera) an important pest of pigeonpea, Cajanus cajan when fed on its different floral parts including petals, anthers, stigma and ovary. Stigma and ovary were damaged and there was no pod formation. In view of its significant damage potential, a few number of insecticides were evaluated against the beetles in the laboratory: thiodicarb (0.09%), chlorpyriphos (0.10%), quinalphos (0.10%), cypermethrin (0.007%), deltamethrin (0.012%) and novaluron (0.10%). Fresh pigeonpea twigs bearing flowers were dipped for 5 seconds in requisite concentrations of different insecticides and allowed to air dry at room temperature (28oC). For each treatment, three replicates were taken and dead beetle were counted 24 and 48 hours after release. Observations after 24 hours of application indicated that thiodicarb (84.23 %), chlorpyriphos (57.50 %), quinalphos (37.31 %) and cypermethrin (29.77 %) significantly reduced blister beetle population compared with the control (without insecticidal treatment). After 48 hours, all insecticidal treatments were significantly superior over control. Maximum cumulative mortality (100%) was observed in thiodicarb followed by quinalphos (95.7%), cypermethrin (95.7%) and chlorpyriphos (91.6%), while minimum in novaluron and deltamethrin. It was concluded from the studies that among the different insecticidal treatments thiodicarb (0.09%) proved most effective which brought 99.75 % mortality even 24 hours after the treatment.