Comparative damage potential of three storage insect pests in stored wheat under laboratory conditions

Stored grain pests differ in their feeding behavior and damage potential. This study evaluated the comparative impact of three key storage pests of wheat Tribolium castaneum (Coleoptera: Tenebrionidae), Trogoderma granarium (Coleoptera: Dermestidae), and Sitophilus oryzae (Coleoptera: Curculionidae) under controlled laboratory conditions. Homogeneous-age insects were introduced separately for each species into vials containing 2 grams of whole wheat grains, with three replicates per species, as experiments were conducted independently for all three species. After 35 days, data were recorded on insect survival, number and weight of damaged grains, number and weight of undamaged grains, and percent weight loss. S. oryzae exhibited the highest mean number of live insects (16.67), followed by T. granarium (9.89) and T. castaneum (6.67). S. oryzae also caused the most grain damage (21.33 damaged grains) and the most significant weight loss (16.75 %), followed by T. castaneum (8.56 grains, 2.07 %) and T. granarium (2.56 grains, 0.74 %). Regression analysis revealed a strong relationship between insect number and weight loss for S. oryzae (R² = 0.57) and T. granarium (R² = 0.46), but a weak relationship for T. castaneum (R² = 0.0044), likely due to its lower survival and superficial feeding behavior. These findings provide comparative insights into species-specific damage patterns and may inform more targeted post-harvest pest management strategies.