EVALUATION OF PROTECTANTS FOR CONTROL OF ACANTHOSCELIDES-OBTECTUS (SAY) (COLEOPTERA, BRUCHIDAE) IN NAVYBEANS (PHASEOLUS-VULGARIS (L))

Five organophosphorus compounds (OPs), one carbamate, five synthetic pyrethroids (SPs) and three insect growth regulators (IGRs) were tested against the bruchid Acanthoscelides obtectus (Say) in navybeans (Phaseolus vulgaris L.) stored in the laboratory. Activities of the insecticides varied greatly in short-term assays with the IGRs having low potency. Four OPs (fenitrothion, chlorpyrifos-methyl, pirimiphos-methyl and methacrifos) and two SPs (permethrin and deltamethrin) were assessed further during 36 weeks storage at 30-degrees-C, 70% r.h. The OPs lost activity rapidly during storage compared to the SPs. Pirimiphos-methyl, permethrin and deltamethrin gave the best results. Estimated rates of application to give 36 weeks protection are 10-25 mg kg-1 of pirimiphos-methyl, 0.2-0.5 mg kg-1 of deltamethrin, or 1-1.5 mg kg-1 of permethrin.