The synergistic effect of spinosad with three botanical (Aframomum melegueta, Eugenia aromatica and Piper guineense) powders as biorational insecticides against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) infesting melon (Citrullus lanatus) seeds was investigated. Treatments included sole application of each botanical powder (50 g/kg of melon seed), sole application of spinosad (SASp) (1.0 g/kg), mixture of spinosad (0.5 g/kg) + botanical powders (25 g/kg) and an untreated control. Data were collected on tenebronid mortality rate (%) (PM) and melon seed weight loss rate in % (PWL). Phytochemical analysis of the botanicals was also carried out. At 3‒14 days after treatment (DAT), PM observed in melon seeds treated with SASp (90.00‒100.00%) was not significantly (p>0.05) different from PM observed in melon seeds treated with spinosad + E. aromatica powder (86.67‒100.00%)andspinosad + P. guineense powder (85.00‒100.00%). PWL observed in melon seeds treated with spinosad + botanical powders (1.17‒1.40%) was not significantly different from PWL observed in seeds treated with SASp (0.42%), but it was significantly lower than PWL (3.28%) observed in melon seeds treated with sole application of A. melegueta powder. P. guineense powder had the highest contents of alkaloids (868.33 mg/100 g), tannins (550.00 mg/100 g), phenolics (53.57 GAE/g), and steroids (740.00 mg/100 g). E. aromatica powderhad the highest contents of flavonoids (1466.67 mg/100 g), terpenoids (1276.00 mg/100 g) and cardiac glycosides (7.33 mg/100 g), while A. melegueta powder had the highest content of saponins (376.67 mg/100 g). The combination of spinosad with P. guineense powderor E. aromatica powder performed better than the combination with A. melegueta powder and is therefore recommended as a biorational approach for thecontrol of T. castaneum.