Survey of storage insect pests and management of rice weevil, Sitophilus oryzae, using botanicals on sorghum (Sorghum bicolor L.) at Jawi District, Northwestern Ethiopia

Storage pests are the main cause of crop losses. This study was carried out to assess the status of storage insect pest infestation and evaluate the efficacy of botanicals for the management of rice weevil at Jawi District, Ethiopia. A cross-sectional study was conducted to assess storage insect pest infestation. Botanical insecticides were evaluated against Sitophilus oryzae. The treatments were arranged using completely randomized design and replicated three times. Data were collected through questionnaire and experiment and analysed using SAS version 9.0. The result of the study showed that the most important insect pests of stored sorghum were S. oryzae (57%), maize weevil 17% and other pests were 26% and 100% store infestation were recorded. The species of storage insect pests identified were rice weevil, maize weevil, angoumois grain moth, flour beetle, flat grain beetles and saw-toothed grain beetle. The average grain weight loss was 13.63%, physical grain damage 7.22%, germination speed index of 46.36% and germination percentage of 68.75% were recorded. Experimental results revealed that all treatments were exhibited significant differences in mortality rate against S. oryzae. Efficacy of botanical revealed that neem seed powder (50.70%) and garlic (53.33%) were significantly superior in efficacy against S. oryzae after 28th days of exposure. Neem leaf powder, Mexican tea, orange peel and ginger gave moderate mortality rate of 48.55, 26.11, 36.87 and 41.65, respectively, compared with the control. All botanicals have the potential F-1 S. oryzae reduction effect. The highest F-1 reduction was recorded in neem seed powder (73.14%), neem leaf powder (72.54%) and garlic (66.94%). The highest mean germination of 70, 63.33 and 61.33% were recorded from neem seed powder, garlic and neem leaf powder exposed seeds, respectively. Neem seed powder, garlic and neem leaf powder can be suggested as management options of S. oryzae in storage condition.