Efficacy of Bone Charcoal Dust of Six Mammalian Species in the Post Harvest Control of Sitophilus zeamais Motschulsky (Cleoptera: Curculionidae)

Abstract

The study evaluated the efficacy of bone charcoal dusts of six species of mammals as eco-friendly alternative to conventional synthetic insecticides in the management of Sitophilus zeamais infestation in stored, resistant and susceptible maize under laboratory conditions. Dry femur and ribs of the African humped cow (Bos indicus), rabbit (Lepus spp), goat (Capra hircus), sheep (Ovis aries), dog (Canis domesticus) and pig (Suis scrota) were burnt with fire wood flame. The resulting charcoal was ground aseptically using mortar and pestle and sieved to produce the fine inert dust for the assay. Charcoal dusts of the animals and permethrin powder were comparatively tested at the rates of 0.25, 0.50 and 1.00 % w/w against stored resistant and susceptible maize infested with S. zeamais. Although the charcoal dusts of cow and sheep were best at controlling S. zeamais infestation after matching with the efficacy of permethrin, the potentials of all the charcoal dusts of the mammals should be exploited in the management of weevil infestation in both stored resistant and susceptible maize. Complete suppression of S. zeamais progeny emergence and total grain protection from pest-feeding were achieved with ~0.25 % (w/w) of each of the animal charcoal dusts in resistant maize stored for 54 days. In the susceptible variety however, higher dust concentration of z 0.50 % (w/w) was needed to achieve same result. High mortality and protection achieved by the charcoal dusts may be attributable to weevil cuticular abrasion, active components of the bones and combustion-related factors. Type of maize variety stored and protected with the animal bone charcoal dusts had no obvious impact on weevil mortality at short storage duration of < 5 days. However, at prolonged storage duration of 54 days, varietal effect became conspicuous in terms of adult emergence and grain damage