Role of Exogenous Elicitors in Canola Plant Defense against Cabbage Aphid by Regulating Physiological Balance and Secondary Metabolite Biosynthesis

Induced resistance in plants can be manipulated using the application of elicitors. In this study, the effects of Salicylic Acid (SA), chitosan, γ-Aminobutyric Acid (GABA), Serenad Aso (Bacillus subtilis QST713), and combined application of these elicitors were studied on the resistance of canola to cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae). The number of B. brassicae attracted to canola plants treated with different inducers was significantly lower compared to the control in the field experiments. The lowest population density of aphid was observed on plants treated with SA+GABA and SA+chitosan. Moreover, the highest amounts of glucosinolates in canola leaves were recorded in SA+GABA treatment. The contents of sugar, lipid, and glycogen of B. brassicae were lowest when fed on the plants treated with SA integrated with GABA or chitosan. Furthermore, the activity of catalase, esterase, peroxidase and glutathione S-transferase enzymes was the lowest in SA+GABA and SA+chitosan. These findings suggest that exogenous application of SA integrated with GABA or chitosan on canola plants are successful in suppressing the B. brassicae population and can be considered in integrated management programs against this and other aphids.