Plant oils as common bean (Phaseolus vulgaris L.) seed protectants against infestations by the mexican bean weevil Zabrotes subfasciatus (Boh.)

Abstract

Five plant oils from sesame (Sesamum indicum), oil-palm (Elaeis guineensis), cotton (Gossypium hirsutum), castor (Ricinus commu-nis) and maize (Zea mays) at a dosage of 5 ml/kg of common bean seeds and a control of malathion dust 2% active substance (a.s.) at a dose 0.5 g/kg of seeds were evaluated for their ability to suppress the populations of Z. subfasciatus. Castor and palm oils resulted in effective protection comparable to that of malathion. There were a significant low percentage seed damage and weight loss in seeds treated with malathion, castor and palm oils. Total number of weevils in these treatments were least, compared to other plant oils studied. All treatments did not show adverse effect on germination capability of the seeds. This study showed that it is possible to use castor or palm oils to protect common bean seeds against Z. subfasciatus infestations. These products can be obtained locally at a reasonable cost.