Residual Efficacy of Beauveria Bassiana and Diatomaceous Earth on Wheat Grain against Red Flour Beetle, 𝑇𝑟𝑖𝑏𝑜𝑙𝑖𝑢𝑚 𝐶𝑎𝑠𝑡𝑎𝑛𝑒𝑢𝑚 (Herbst)

Laboratory bioassays were conducted to assess the efficacy of each entomopathogenic fungus, Beauveria bassiana (Bb), and diatomaceous earth (DE) and their combinations against the red flour beetle, Tribolium castaneum (Herbst) (Tenebrionidae: Coleoptera) on stored wheat (Triticum aestivum L.). The results indicated that the highest concentrations of Bb and DE in their combinations were more effective in suppression of red flour beetle. After a nine-month storage period, the Bb2+DE2 treatment achieved the highest level of adult mortality (76.61%). In contrast, the Bb1 treatment alone demonstrated the lowest mortality rate (16.33%). Minimum grain damage (23.36, 25.69, 31.57, 33.45, 41.93, 42.57, 46.73, and 47.63%) was observed on Bb2+DE2, Bb2+DE1, Bb1+DE2, Bb1+DE1, DE2, DE1, Bb2, and Bb1, respectively, with the minimum weight loss after 9 months of storage. It has been clearly observed that seed germination was not affected adversely in any treatment during 9 months of storage. Moreover, during the storage period (≈nine months), the Bb2+DE2 was the most powerful combination reduced grain damage and weight loss, resulting in germinating by more than 75% compared with untreated grains by only 24%. The study highlighted that the combination of Bb and DE has residual efficacy leading to long-term protection of wheat against red flour beetle.