The ability of powders and slurries from ten plant species to protect stored grain from attack by Prostephanus truncatus horn (Coleoptera: Bostrichidae) and Sitophilus oryzae L. (Coleoptera: Curculionidae)

Abstract

Powders and slurries prepared from parts of 10 different plant species indigenous to Ghana were tested under laboratory conditions for their ability to protect stored grain from damage by Sitophilus oryzae L. and Prostephanus truncatus Horn on wheat and maize, respectively. Two concentration levels 10% and 1% (wt/wt) were used. Powders and slurries of all plant species of 10% (wt/wt) significantly ( P < 0.001) reduced insect damage by the grains and caused mortality of both insect species. Powders of four species; Cissampelos owariensis, Azadirachta indica, Ricinus communis and Solanum nigrum, gave a significant ( P < 0.001) reduction in grain damage by the insect species as well as high mortality, even at the lower concentration level of 1% (wt/wt). The slurry preparations were generally better protectants than the powders especially against S. oryzae where complete control was achieved except with Chromolaena odorata and Sida acuta, which permitted some survival. The pattern of action of the slurries against P. truncatus was similar to that of S. oryzae, except that P. truncatus was relatively more tolerant.