TOXICITY OF PLANT-EXTRACTS TO 3 STORAGE BEETLES (COLEOPTERA)

Eleven indigenous Ghanaian plant species were tested for their toxicity to 3 storage pest species: Acanthoscelides obtectus, Prostephanus truncatus and Sitophilus oryzae under laboratory conditions. P. truncatus was reared on loose maize grains, S. oryzae on wheat grains and A. obtectus on cowpeas. All rearings were done in an incubator at 25-26-degrees-C and 65-75% R.H. The plant extracts evaluated were obtained from the neem Azadirachta indica leaf and seed, Chromolaena odorata leaf, Cissampelos owariensis leaf and root, Datura metel seed, Datura stramonium seed, Erythrophleum suaveolens leaf, Grewia carpinifolia leaf, Ricinus communis seed, Sida acuta leaf, Solanum nigrum leaf, and Strophanthus hispidus leaf. Crude ethanol extracts at concentrations of 10% (wt/vol) were used as topical applications. The effect of the plant extracts was compared with that of the neem. R. communis and S. nigrum were the crude materials most toxic to the three pest species. Extracts of C. owariensis and E. suaveolens were also very effective, and more promising than the neem extracts. Least effective were S. acuta, C. odorata, G. carpinifolia and S. hispidus. A. obtectus was usually most and P. truncatus least sensitive to the plant extracts.