Insecticidal toxicity of some botanicals against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) in stored sorghum grains in Nigeria
Mohammed Suleiman, Costancia P Rugumamu and Nasiru D Ibrahim
Toxicity of leaf powders and extracts of Euphorbia balsamifera, Lawsonia inermis, Mitracarpus hirtus and Senna obtusifolia against Sitophilus zeamais was evaluated. The study was conducted in Postgraduate laboratory of the Department of Biology, Umaru Musa Yar’adua University, Katsina (Nigeria). Five pairs of 7 day old S. zeamais were released in 20 g of disinfested sorghum variety, Farar Kaura (FK) treated with powders, methanolic, ethanolic and aqueous extracts of the botanicals in plastic bottles, separately, at different concentrations of 2.5, 5.0 and 10.0 x 104 ppm. Botanical powders caused 67.50 ± 2.50 to 100.00 ± 0.00% adult morality of S. zeamais within 12 days after treatment (DAT). Both methanolic and ethanolic extracts applied at the three concentrations led to total adult mortality within 5 DAT. The highest (75.00 ± 2.89%) mortality recorded in aqueous extracts treatments was at 10.0 x 104 ppm of E. balsamifera, while the least (30.00 ± 4.08%) was in 2.5 x 104 ppm of S. obtusifolia within 28 DAT. E. balsamifera was the most effective botanical with its LC50 values ranging from 0.049 ± 0.739 to 1.410 ± 0.874 x 104 ppm. The botanicals were found to be highly effective in killing adult S. zeamais and therefore could be utilized to reduce the weevils’ infestations in stored sorghum. However, further investigations on their toxicity on mammals and other insect pests are hereby recommended.
Mohammed Suleiman, Costancia P Rugumamu, Nasiru D Ibrahim. Insecticidal toxicity of some botanicals against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) in stored sorghum grains in Nigeria. J Entomol Zool Stud 2018;6(1):1280-1287.