Deciphering canola–aphid interaction: a review on the role of hostplant nutrients and phenolic compounds

Canola, Brassica napus L., is the top-ranked vegetable oil crop in the world, and its production is significantly hindered by aphids (mustard-oil bombs), which compromise the host plant defense. The prominent aphid species which infest the canola include Brevicoryne brassicae , Lipaphis erysimi , and Myzus persicae . They feed on tender parts of the plant and suck the cell sap that ultimately reduces the plant's vigor. Floral buds are weakened, and flowers may fall to reduce the number of potential pods, causing a significant yield loss (60%–77%). They also transmit ∼20 different plant viruses in canola. Aphids sustain their populations through a consecutive biological cycle to produce multiple generations in a single cropping season. Continuous feeding by a multitude of aphids ultimately reduces plant growth and yield attributes, i.e ., plant height, number of siliques, seeds per silique, thousand-seed weight, and plant yield, significantly. Hostplant nutrient profile comprising macro- and micronutrients, i.e ., nitrogen, phosphorous, potassium, calcium, magnesium, iron, sulfur, copper, and zinc, also alters. These nutrients have a dual role in aphid–canola interaction, i.e ., they accomplish biological needs of aphids on one side and enhance host plant defense and yield on the other side. In addition, phenolic compounds are also important, especially myricetin, quercetin, gallic, caffeic, syringic, vanillic, ferulic, chlorogenic, m -coumaric, p -coumaric, sinapic, and cinnamic acid. Their role in plant defense and aphid reduction has been discussed. Classification, biosynthetic pathways, and the role of plant phenolics in countering aphid defense have been elaborated. Conclusively, this review delivers an inclusive framework for understanding the chemical and nutritional drivers responsible for aphid resistance and yield improvement, offering significant insights for developing pest-resilient canola cultivars.