Insecticidal and Repellent Effects of Botanical Extracts against Tribolium castaneum Under Laboratory Conditions

Stored grain losses caused by insect infestation pose a serious threat to food security, particularly in developing countries. The red flour beetle, Tribolium castaneum, is a major pest responsible for significant quantitative and qualitative damage to stored products. The present study evaluated the insecticidal and repellent effects of aqueous extracts of neem (Azadirachta indica), black pepper (Piper nigrum), garlic (Allium sativum), and clove (Syzygium aromaticum) under laboratory conditions using a completely randomized design with three replications. The efficacy of the botanical extracts was assessed based on mortality, repellency, oviposition deterrence, and grain weight loss. Mortality increased with exposure time, with neem showing the highest mortality (28%) after 72 hours, followed by black pepper (20%), garlic (14%), and clove (11%). Repellency peaked at 48 hours, where neem exhibited maximum repellency (73%), followed by black pepper (60%), garlic (50%), and clove (30%). Oviposition was significantly affected by treatments, with neem showing the lowest oviposition (32.33%), followed by black pepper (45%), garlic (55%), and clove (60%), compared to the control (92.33%). Similarly, grain weight loss was minimized in neem-treated samples (2.13 g) compared to the control (8.53 g). Overall, the results demonstrate that botanical extracts, particularly neem, significantly reduce insect survival, reproduction, and grain damage, highlighting their potential as environmentally safe alternatives for the management of stored grain pests.