Assessment of bioactivity of selected botanicals against the maize weevil, sitophilus zeamals motsch. (Coleopter: curculionidae) in stored sorghum, sorghum bicolor (L.) Moench in northern Nigeria
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Date
2018
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University of Dar es salaam
Abstract
Laboratory and field studies were conducted with the aim of investigating the efficacy of some botanicals in the management of sitophilus zeamals Motsch infesting stored sorghum. The selected plant species were Euphorbia balsamifera Aiton, Lawsonia inermis L. Mitracarpus hirtus L. and Senna obtusifolia L. Leaf powders, methanolic and ethanolic extracts of the botanicals applied at 2.5, 5.0 and 10.0 x104 ppm were tested for their repellency, toxicity, suppression of development and protectant ability against S. zeamais in the laboratory at 30 ± 2oc and 70 ± 5% R.H. The leaf powders were also applied to four sorghum varieties namely “Farar Kaura” (KF), “Year Gidan Daudu” (YGD) and ICSV 400 at the dose of 5.0% (W/W) and stored in “rhumbus” and store rooms at Dallaje and Pauwa villages, northern Nigeria. In the laboratory, all the botanicals significantly (p<0.05) repelled the weevils with percentage repellency ranging from 40.49 ± 1.44 to 100.00 ± 0.00% in 24 hours after exposure (HAE). The botanicals also resulted in high adult mortality, reduced body protein and inhibited the activity of acetylcholinesterase (AChE) in S. zeamais. Significant percentage oviposition deterrence (POD) ranging from 56.25 ± 2.44 to 94.68 ± 2.68% and complete inhibition rate in adult emergence of the weevils by the botanicals was recorded. The botanicals reduced grain damages, preserved nutrient composition and did not have any adverse effect on germination of the treated sorghum. In storage structures, the insect species found infesting sorghum were Sitophilus zeamais Motsch, Rhyzopertha dominica (F.), Sitotroga cerealella (Olivier), Tribolium casta neum (Herbst), Cryptolestes ferrugineus (Stephens) and Oryzaephilus surinamensis (L.). The plant powders reduced infestation levels of the insect species in different sorghum varieties. The weight losses in the treated varieties varied between 0.50 ± 0.10 and 6.60 ± 0.48% with the highest in FK with S. obtusifolia and the least in ICSV 400 with E. balsamifera. The botanical powders have shown evidence of protecting the sorghum varieties against damages caused by multiple infestations in “rhumbus” and store rooms. It is concluded that all the botanicals tested could serve as eco-friendly alternatives to chemical insecticides in the management of insect pests of sorghum in the storage.
Description
Available in print form, East Africana collection, Dr. Wilbert Chagula Library, class mark (THS EAF QL596.C94)
Keywords
Sitophilus, Curculionidae, Sorghum, Nigeria, North
Citation
Suleiman, Mohammed (2018) Assessment of bioactivity of selected botanicals against the maize weevil, sitophilus zeamals motsch. (Coleopter: curculionidae) in stored sorghum, sorghum bicolor (L.) Moench in northern Nigeria, Doctoral dissertation , University of Dar es salaam