The cowpea beetle Callosobruchus maculates (Fabr.) is a serious pest that infests pulse seeds in storage. The current study aimed to assess the sublethal effects of two insecticides deltamethrin, thiamethoxam and a botanical power of fennel (Foeniculum vulgare Mill) on C. maculatus development and its essential enzymes. Thiamethoxam, deltamethrin insecticides and fennel plant powder activities against the cowpea beetle, C. maculatus, were assessed throughout direct contact application. Thiamethoxam showed the LC₅₀ value of 21.05 ppm followed by deltamethrin (LC₅₀= 85.1 ppm) while, the least effect was recorded with fennel seeds powder with LC₅₀ value 36325.8 ppm. Concerning sublethal effects, sublethal concentrations of thiamethoxam (LC₁₀, LC₂₅, LC₅₀ and LC₇₅) significantly reduced egg-laying. While LC₇₅ of deltamethrin significantly decreased egg-laying related to control. In contrast, fennel seeds powder failed to turn down the number of eggs laid by C. maculatus females compared with the control. Complete protection to deltamethrin against C. maculatus adults was maintained after 24 h till 7 months and to thiamethoxam from 24 h till 4 months. Biochemical studies showed that the activity of acetylcholine esterase (AChE), α, ß esterase and glutathione-S-transferase (GST) showed a significant decrease in sublethal concentrations of thiamethoxam and deltamethrin related to the control. Regarding the effect on germination, no adverse effect was noticed due to the chemical and botanical seed protectants application.