Performance of basil powder as insecticide against maize weevil, Sitopillus zeamais (Coleoptera: Curculionidae).

Abstract

Sitophilus zeamais Motschulsky continue to cause considerable damage to maize grain in most stores in Africa. A study was carried out to determine effectiveness of Ocimum basilicum plant part powders of leaf, bark and combined effect of the two (1:1). The results indicated that basil leaf powder repelled S. zeamais the furthest distance (6.6cm) in comparison of bark (4.2cm) and admix of the two (5.5cm) within the first 2-hour exposure period. Prolonging exposure duration to 96 hoursr led to reduction of repelence distance to 3.2cm for basil leaf and 2.0 and 2.6cm for leaf and the admix (1:1) of the two respectively. Basil plant effective powder lethal dose (LD99) for leaf, bark and the admix (1:1) was achieved in 1.84, 1.83 and 2.25g powder amounts respectively. Plant powder shelf-life was determined to be a maximum of 2-weeks causing 40≥80% mortality of S. zeamais. These findings show that basil powders are only for a short duration as protectants against S. zeamais.