Companion planting of flowering annuals enhances the colonization of natural enemies in white cabbage fields

White cabbage, Brassica oleracea var. capitata L., is a popular cultivar of the Brassicaceae plant family and is mainly used as a leafy green vegetable. Most farmers rely on the use of chemical insecticides to safeguard their crops ignoring their non-target effect on ecosystem. We investigated how ecological engineering of white cabbage fields with eight distinct flowering annuals impacted both insect pests affecting white cabbage and the populations of their natural enemies during the winter seasons of 2020–21 and 2021–22. White cabbage intercropped with chenopodium, Chenopodium album displayed the lowest aphid (563.7 and 61.00 aphids/plant) and diamondback moth (1.8 and 8.0 larvae/plant) infestations. White mustard, Sinapis alba intercropping resulted in the least white cabbage butterfly infestation (2.7 and 11.00 larvae/plant). White cabbage plots with C. album had the highest number of coccinellid predators (5.6 and 11.9/plant), while sweet alyssum, Lobularia maritima attracted most syrphids (5.1 and 4.0/plant). Intercropping with calendula, Calendula officinalis attracted the highest number of aphid parasitoid, Diaeretiella rapae (69.1 and 55.5/plant). Study of different biodiversity indices using three distinct sampling techniques revealed that C. album intercropping system recorded high Shannon index (H) and comparable evenness index (Ei). The enhanced colonization of natural enemies in engineered plots is attributed to the sugars and protein content in the flowers, boosting fecundity and survival during food scarcity. Notably, a higher mean head weight of white cabbage, i.e., 2027.78 g was recorded when intercropping with C. album compared to 1050 g in sole white cabbage crops. Benefit–Cost Ratio (BCR) analysis indicated that C. officinalis intercropping yielded the highest return of USD 12.00, followed by Cineraria sp intercropping at USD 11.35.