<p>The indiscriminate use of fertilizers by farmers in developing countries has increased crop susceptibility to pest attacks. Insecticides pose several implications for the environment and human health. A two-year nutrient deterrence experiment (using 25 and 50&#xa0;kg ha^− 1 of Silicon-Si and ammonium sulfate-AS) was conducted and compared to an insecticide (Carbosulfan) for managing brassica aphids (<i>Brevicoryne brassicae</i> L.) on canola (<i>Brassica napus</i> L.). The Si 50&#xa0;kg ha^− 1 treatment reduced aphid populations by 23.2%, followed by the Si 25&#xa0;kg ha^− 1 treatment (17.3%). Similarly, the AS 25&#xa0;kg ha^− 1 treatment also reduced the aphid population, but to a lesser extent than the Si 25&#xa0;kg ha^− 1 treatment. Conversely, the AS 50&#xa0;kg ha^− 1 showed no significant effect on aphid abundance. The number of siliques, seeds per silique, thousand-seed weight, yield per m², and oil content were significantly increased. Seed yield was improved by 37.8% in the AS 50&#xa0;kg ha^− 1 treatment and by 29.8% in the Si 50&#xa0;kg treatment, compared to the insecticide treatment. Oil yield was highest in the AS 25&#xa0;kg ha^− 1 treatment, followed by the AS 50 and Si 50&#xa0;kg ha^− 1 treatments. <i>Reverse-Phase</i> High Performance Liquid Chromatography (<i>RP</i>-HPLC) revealed the elicitation of phenolic defense compounds in canola. Myricetin, gallic acid, chlorogenic, <i>m</i>-coumaric, <i>p</i>-coumaric, and sinapic acid levels were highest in the Si 50&#xa0;kg ha^− 1 treatment, while quercetin, syringic acid, and sinapic acid levels were highest in the AS 50&#xa0;kg ha^− 1 treatment. Our results suggest that the judicious use of nutrients can contribute to pest management without the additional cost of insecticides. Moreover, manipulating phenolic content could aid in breeding aphid-resistant varieties of canola. However, further research is needed to explore the potential of nutrient management for controlling other insect pests on different crops.</p>