Damage potential of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) on wheat grains stored in hermetic and non-hermetic storage bags

Abstract

Post-harvest storage of wheat in grain storage bags is commonly adopted practice in many developing countries, which offers a viable chemical-free approach to control storage insects. The damage potential of Tribolium castaneum in wheat grains stored in different storage bags at various storage periods was studied. A highly significant effect (P < 0.01) of the storage bags and storage periods was observed in variables measured (insect growth rate, damaged grains, grain weight loss and weight of insect feeding residues). The maximum mean insect growth rate (85.20 ± 2.80), percent damaged wheat grains (73.24 ± 0.17%), percent grain weight loss (21.14 ± 0.21%) and weight of insect feeding residues (2.15 ± 0.01 g) were recorded in wheat grains stored in cotton cloth bag at 150 d, whereas minimum mean insect growth rate (30.00 ± 0.00), percent damaged wheat grains (10.44 ± 0.16%), percent grain weight loss (0.82 ± 0.06%) and weight of insect feeding residues (0.22 ± 0.02 g) were recorded on wheat grains stored in hermetic bag due to 100% mortality of T. castaneum in hermetic bag at 30 d. A significant and positive correlation between storage periods, insect growth rate, damaged wheat grains, grain weight loss and weight of insect feeding residues was observed, except for the storage bags which were significantly and negatively correlated with other factors. In addition, the simple and linear regressions analysis were significant (P < 0.01), and all the equations for these analyses were fitted for the regression models and perfectly described the association between the dependent and independent variables. Hermetic bag proved resistance to external environment fluctuations in abiotic factors such as temperature and relative humidity. While grain moisture in all other bags fluctuated with external environment. The results showed that quantitative and qualitative losses of stored wheat grains depends not only the type of storage bags, but also on the storage periods. T. castaneum can have a negative impact on wheat grains stored in all storage bags except hermetic bag. So, it is recommended that hermetic bag be used at farmers’ level to achieve greater benefits by reducing T. castaneum infestation.