Abstract

The objective of the study was to evaluate the effects of different concentrations of four spices on the adult mortality and emergence of Sitophilus zeamais Motsch. in maize. The study was carried out in 2017 at the Department of Crop Protection Laboratory, University of Ilorin, Nigeria at prevailing temperature of 28±3°C, relative humidity of 68±3% and photoperiod of L12: D12. The maize variety (SAMMAZ 52) was obtained from Institute for Agricultural Research, Zaria, Nigeria. The seeds were cleaned, stored in air-tight polyethylene bag, kept in domestic deep freezer and later thawed. The experiment consisted of 50 g of seeds weighed into each jar and then treated with African nutmeg Monodora myristica (Gaertn) Dunal, garlic, Allium sativum (L.), cloves Syzygium aromaticum (L.) Merr. and ginger, Zingiber officinale Roscoe powders at the concentrations of 0.00, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25 and 2.50 g and permethrin at 0.12 g against S. zeamais. Five newly emerged adults (2 males: 3 females) of 1–2 day old were used to infest the treated seeds and the untreated control. The experiment was a completely randomized design with four replications. S. zeamais mortality data were taken at 1, 3 and 5 days post-infestation (DPI), anti-oviposition activity was estimated at 6 DPI and adult emergence of S. zeamais was determined at 31, 33 and 35 DPI. Results showed that percentage mortality was significantly (P<0.05) increased compared with the untreated control. At 5 DPI, total mortality (100.0%) of S. zeamais in garlic and clove powders was recorded at highest concentration, suggested their performance in matching the efficacy of permethrin. No adults emerged from the African nutmeg from1.25 to 2.50 g per 50 g seeds at 31 and 33 DPI compared with the control with cumulative mean adult emergence that ranged from 1.25 to 2.25. It could be concluded that the spices had great insecticidal potentials against S. zeamais under small-scale storage. The spices are, therefore, recommended for incorporation in the management of S. zeamais.