EFFICACY OF PROTECTANTS AGAINST CALLOSOBRUCHUS-PHASEOLI (GYLL) AND C-MACULATUS (F) (COLEOPTERA, BRUCHIDAE) IN MUNGBEANS

The organophosphorus (OP) compounds chlorpyrifos-methyl, fenitrothion, methacrifos and pirimiphos-methyl, synthetic pyrethroids (SP) deltame thrin and permethrin, and the insect growth regulator (IGR) fenoxycarb were evaluated as protectants against Callosobruchus phaseoli (Gyll.) and C. maculatus (F.) in mungbeans (Vigna radiata (L.) Wilczek). Trea ted mungbeans were sampled for efficacy testing using C. phaseoli afte r various periods of storage in hot and humid conditions (30-degrees-C , 70% r.h.). Minimum effective application rates were determined for d ifferent periods of protection. During storage the OP compounds (chlor pyrifos-methyl, fenitrothion, methacrifos and pirimiphos-methyl) lost activity against C. phaseoli much faster than the SPs (deltamethrin an d permethrin) and the IGR (fenoxycarb). Tests were carried out on mung beans which were infested with C. phaseoli before treatment with pirim iphos-methyl, fenoxycarb or deltamethrin. These tests showed that imma ture insects in the treated beans were protected from insecticides. Fi nally, freshly-treated mungbeans were exposed to C. maculatus for comp arison with the results for C. phaseoli. The four OP compounds, two SP s and the IGR tended to have similar potency against C. maculatus and C. phaseoli.