Lethal action of a refined mineral oil on adult Sitophilus granarius (L.)

Abstract

Refined soybean and crude castor oils were evaluated for the control of infestations of Callosobruchus maculatus (F.) and Callosobruchus phaseoli (Gyllenhal) in stored chick-pea (Cicer arietinum L.). Both oils were used at 0,5 and 10 ml/kg of seeds. Oviposition, adult emergence and development from egg to adult emergence were evaluated after storing the treated seeds for up to 5 months. At the end of the storage period the effect of the treatments on flavour, consumer acceptability and seed germination were evaluated. Both oils inhibited population growth of the two insect species as compared to untreated seeds. Castor oil was more effective than soybean oil. Castor oil at 5 and 10 ml/kg protected stored chick-peas from infestation by C. maculatus for 60 and 150 d, and from infestation by C. phaseoli for 60 and 90 d, respectively. Soybean oil was not an effective protectant, but did reduce the C. maculatus and C. phaseoli population development for approximately 60 d at 5 ml/kg and for 90 d at 10 ml/kg. No harmful effect was observed on the germination of oil-treated seeds. The oil treatments conferred off-flavours to the chick-peas, and product acceptability was compromised by treatment with castor oil and soybean oil at 10 ml/kg.