ABSTRACT

Laboratory experiments were conducted to evaluate the effects of deltamethrin dust as a protectant of maize against Sitophilus zeamais under ambient laboratory conditions of 27 ± 3°C and 70 ± 5% relative humidity. Four sets of fifty grams of disinfested maize grains were measured into jars in four replicates. Each replicate was infested with ten 0-7days old adult S.zeamais. Each set of three replicates were treated separately with 0.25g, 0.187g and 0.125g of deltamethrin while the fourth set which served as the control was not treated with the insecticide. The following parameters were taken; percentage mortality, number of adult emergence, and percentage weight loss. Analysis Of Variance and Probit analysis were determined. The results showed significant difference p>0.05 in mortality between the treatments and control. The 0.187g treatment corresponding to 75% of the recommended dosage had the highest mortality of 90% while the 0.125g treatment corresponding to 50% of the recommended dosage had the lowest mortality of 77.5%. There was no difference between the 0.125g treatment and the control in the adult emergence in the first generation. However, the adult emergence in the 0.125g treatments and the control were significantly higher than the 0.187g and 0.125g treatments. There was a significant difference between the control and all other treatments p<0.05 with no adult emerging in the grain treated with the recommended dose of 0.25/50g of grains. Deltamethrin, at a lower dose than the recommended dose gave a good protection on maize against Sitophilus zeamais infestations. It is therefore recommended that further evaluation of the chemical be carried out to avoid using a higher dose than required.