Rapeseed- mustard (gobhi sarson; Brassica naphus L.) crop is a vital source of edible oil and is vulnerable to more than three dozen insect pests in India. Among them, the mustard aphid Lipaphis erysimi (Kalt.) is a major pest on rapeseed mustard. In the current investigations, the plant derivative extract (Brahmastra – (BA)) was characterized, the composition of active ingredients from individual components was identified, and their role is correlated with field efficacy. The BA was employed at 7.5, 10.0 and 12.5 L ha−1 against L. erysimi on gobhi sarson under organic farming conditions. All treatments were applied two times. We found that active ingredients such as phytols act as antifeedants and metabolite inhibitors, while Nimbin, a triterpenoid, might provide fungicidal activity. Other components include ryenosin, copaene, caryophyllene, and naphthalene, which are attractive and antibacterial. BA employed at 12.5 L ha−1 was found to be most effective against mustard aphids, offering the highest per cent reduction over control (PROC), i.e., 38.1—67.2 and 38.4—58.9% during 2020–21 and 2021–22, respectively, with the non-significant coccinellid population in all treatments. BA employed at 12.5 L ha−1 registered the highest seed yield (20.5 and 17.3 q ha−1) as against control (16.8 and 15.4 qha−1) for two consecutive years. The economic returns were more elevated in brahmastra at 12.5 L (235 USD ha−1) over the other treatments in gobhi sarson. The possible active ingredients identified using GC–MS and FTIR studies are attributed to control the mustard aphids. The plant derivative extract brahmastra emerged as an innovative pest management system, and its effects on non-target organisms or natural enemies are minimal.
