Efficacy of Cow Bone Charcoal Dust in the Management ofthe Maize Weevil, Sitophilus zeamais Motsch. [Coleoptera: Curculionidae], and the Lesser Grain Borer, Rhyzopertha dominica Fab. [Coleoptera:
Bostrichidae)), Infesting Stored Maize (Zea mays L.)Grains.

NWAUBANI, S. I. AND FASORANTI, J. O.

ABSTRACT: Dry bones (femur and ribs) of the African humped cow, Bos indicus (L.), were burnt with wood fire and the resulting charcoal was manually ground and sieved to produce the fine inert cow bone charcoal dust (CBCD) that was admixed-with maize (Zea mays L.) grains at the rates of 0.1 ,0.25,0.5, 1.0,2.0,4.0, and 8.0 g /100 g of grain. Adults of Sitophilus zeamais Motsch. and Rhyzopertha dominica Fab. were exposed to the treated grain and mortality was recorded at 2, 4, 6, and 8 days post-infestation. The study was conducted under ambient conditions (28.5-32.5°C and 50-62 % RH) in the laboratory. For both species, mortality increased significantly (P<0.05) with application rate and exposure interval. CBCD significantly (P<O.01) suppressed F, progeny production and repelled adults from treated grain. Complete inhibition of S. zeamais progeny emergence was achieved with ~ 0.25 g CBCD /100g of grain from the 4th through to the 12th month of storage at ambient laboratory conditions of 23.5- 33°C and 63.5-87.5 % RH. Test with R. dominica gave similar results when 100 g grains were treated with ~ 0.5 g CBCD. The regression of mortality (probit) on rate of application (log) indicated that R. dominica was less susceptible to CBCD than S. zeamais. CBCD appears
to have a potential in the management of insect pests of stored grains.

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