Insecticidal activities of <i>Azadirachta indica</i> (A. Juss) leaf and seed powder against larval and adult stages of <i>Sitophilus zeamais</i> (Motschulsky)

The global impact of the post-harvest losses due to insect pests, including Sitophilus zeamais (maize weevil), requires effective and sustainable pest management. To address this need, the present work investigated the efficacy of Azadirachta indica (neem) leaf and seed powders at larval and adult stages of S. zeamais. The study was undertaken at the Department of Crop and Environmental Protection, University of Abuja, using a randomized complete block design. The neem seeds were collected from mature trees that have reached 10 years old, which makes them fully productive. The treatments consist of concentrations of neem leaf and seed powders (5, 10 and 15%) and control group applied on maize grains infested with S. zeamais, respectively. A sample size of 300 maize weevils was used for the study. Both the treatment and control groups were divided equally among the samples. Mortality rate, oviposition inhibition and damage were monitored for 14 days. Data collected were analysed using ANOVA. Detection of mortality occurred at a 15% concentration of neem seed powder. Adult mortality, oviposition inhibition and damage to grain after 14 days, respectively, were greatest at 15% concentration of neem seed powder. Neem leaf powder also demonstrated insecticidal efficacy but was less than neem seed powder. Both treatments inhibited oviposition and damage to the grain. Results. showed that A. indica is an alternative biologically active pesticide. Future studies will examine ways to include A. indica in different biopesticide formulations to boost efficacy and scalability.