To discover non-food renewable forest bioactive products as new potential pesticidal alternatives for crop protection, a series of C15-imines alkaloids were obtained by structural modification of matrine and oxymatrine. Compounds Id, Ih, Ii and IIg (>2–3 folds of their precursors) showed the most potent antifeedant activity against armyworm. Against red spider mite, compounds Ie, Il, IIb, IIc and IIg displayed 1.8–3.1 folds acaricidal activity of their precursors. Notably, compound IIg exhibiting the most pronounced pesticidal activities, can be used as a promising bio-sourced agrochemical agent. The study of stress responses showed that the nAChR subunit α5 and VGSC might be the targets of action of matrine, oxymatrine and IIg against red spider mite. © 2021 Elsevier Ltd