Worldwide losses of stored and post-harvested products are mainly due to insect attacks. Although conventional pesticides are widely applied to control pest invasions, there has been an increasing pressure to reduce reliance on conventional pesticides in the interests of avoiding health and environmental consequences. In this work, the effect of ingested Makisterone A, which is a phytoecdysteroid, was tested on the major insect pest of stored products, Tribolium castaneum (Herbst). Firstly, the effect of this molecule on post-embryonic development parameters (mortality, pupation and adult emergence) was tested after ingestion at 300, 600, 900 and 1200 ppm. Secondly, the effect of the Makisterone A was also tested on the biochemical parameters (proteins, alpha-amylase, detoxification enzymes). Ingestion of Makisterone A by T. castaneum larvae induced mortality and significantly reduced pupation and adult emergence rates. Our results show that the level of proteins decreases significantly (P < 0.001) in larvae treated with Makisterone A in comparison with the controls in a dose-dependent manner. Protein content was 176.94, 106.72, 93.16 and 39.32 µg/larva, respectively for 300, 600, 900 and 1200 ppm. In addition, a significant inhibition of alpha-amylase activity was also registered. Its activity achieved 131.68 ± 1.7 µg of starch consumed/larva at 1200 ppm. Results also showed that ingestion of Makisterone A decreased the esterase and P-450 monooxygenases activities when used at higher concentration. In contrast, glutathione S-transferase activity increased in a dose dependent manner. The activity reached 273.26 ± 6.4 nanomoles of substrate conjugated/min/mg of protein using Makisterone A at 1200 ppm. All the results showed the bioinsecticidal potential of phytoecdysteroids in control of insect pests of stored products.