Ferulago campestris Essential Oil as Active Ingredient in Chitosan Seed-Coating: Chemical Analyses, Allelopathic Effects, and Protective Activity against the Common Bean Pest Acanthoscelides obtectus

Ferulago campestris is an aromatic plant, distributed in Mediterranean Europe, and a source of essential oils (EOs) regarded as promising alternatives to synthetic herbicides and pesticides. F. campestris EO, hydrodistilled and analyzed, was tested for its antigerminative activity and for its effect on radicle elongation, hydrogen peroxide concentration, and lipid peroxidation on four infesting weed species (Papaver rhoeas, Taraxacum campylodes, Poa annua, and Setaria verticillata) and on Phaseolus vulgaris. Its repellent ability was also tested against Acanthoscelides obtectus, a pest commonly affecting P. vulgaris during storage. Moreover, a chitosan coating layer was developed with the addition of F. campestris EO and tested for its toxic and oviposition-deterring effects against A. obtectus. Myrcene, -pinene, and -terpinene were detected as the main compounds in F. campestris EO. The EO demonstrated a selective in vitro antigerminative activity towards the weed species, without affecting the bean seeds. Moreover, the chitosan coating layer exerted a dose-dependent repellent effect against A. obtectus adults, thus effectively protecting the bean seeds, while preserving their germinative ability. To the best of our knowledge, this is the first report on a chitosan–EO coating proposed with the aim of protecting bean seeds for sowing from insect attack.