The insecticidal activity and efficacy of some insecticides against Helopeltis theobromae Miller on cocoa

S. Jamaludin

Abstract

The efficacy of chlorpyrifos/cypermethrin mixture, cypermethrin, chlorpyrifos and gamma-HCH was investigated in the field against the mirid, Helopeltis theobromae Mill. The residual activity of these insecticides at 10,500 and 1000 ppm on pod surface was found to vary depending on the concentration used. Generally, the chlorpyrifos/cypermethrin mixture was more effective against H. tleobromae than cypermethrin, chlorpyrifos and gamrna-HCH. The residual activity of chlorpyrifos/cypermethrin ar 1000 ppm remained effective up to the 10th day after application giving about 72% motality.In field spraying, chlorpyrifos/cypermethrin at 0.05, 0.11 and 0.16% a.i. gave higher mirid mortality than cypermethrin, chlorpyrifos and gamma-HCH at 0.2% a.i. There was no significant difference between chlorpyrifos/cypermethrin mixture and cypermethrin, but there was significant difference between chlorpyrifos/cypermethrin mixture and chlorpyrifos, and gamma-HCH. Based on efficacy and cost effectiveness, chlorpyrifos/cypermethrin mixture could be a suitable alternative insecticide for controlling infestation of H. theobromae.

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