Effectiveness of Laurus nobilis and Mentha pullegium essential oils against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) on stored maize

Abstract: Laboratory studies were carried out to evaluate the effects of some essential oils from Laurus nobilis and Mentha pulegium against unsexed adult insects aged from 1 to 7 d of Sitophilus zeamais on stored maize. The concentrated essential oils at different volumes of 0.5 μl, 1.5 μl, 2.5 μl, 5.0 μl and 10 μl, were poured on filter papers with 2 cm Ø each. For diluted oils, the fixed volume of 15 μl of different concentrations of 1:150 v/v, 1:100 v/v, 1:75 v/v, 1:50 v/v and 1:10 v/v either in methanol or n-hexane were used to impregnate the filter papers. Treatments with the concentrated oils were more effective particularly those from M. pulegium. All the concentrations used from M. pulegium provided 100% adult mortality and no progeny production was achieved. L. nobilis has revealed 100% adult mortality at 0.796 μl/cm2. Regarding the treatments with diluted oils once again the oil from M. pulegium provided 100% adult mortality at concentrations of 1:50 v/v and 1:10 v/v. L. nobilis was not effective at any of the concentrations used. There were no significant differences between the solvents used.