Supramolecular α-cyclodextrin-mediated fully bio-based Pickering emulsions as plant-derived biopesticide erucamide delivery systems enabling sustainable crop protection.

Abstract

The novel plant-derived biopesticide erucamide (Eru) holds promise for controlling plant bacterial diseases, yet its poor water solubility and formulation instability limit practical application. Here, supramolecular aggregate particles in aqueous solution via host-guest recognition between α-cyclodextrin (α-CD) and Eru were constructed. These particles serve as the sole stabilizer to emulsify a carvacrol (Car) oil phase pre-loaded with additional Eru, yielding a surfactant-free, all-natural Pickering emulsion (PE). Compared with a conventional suspension concentrate (SC), the PE exhibits superior wettability and adhesion on superhydrophobic rice leaves, improving pesticide utilization efficiency. In addition, the PE exhibited potent inhibitory activity against the mycelial growth of nine fungal pathogens, with EC50 values ranging from 8.2 to 37.2 μg/mL. This antifungal activity is closely associated with the incorporated Car, as the SC formulation without Car showed no inhibition against these strains under the same conditions. Moreover, in a 14-day greenhouse trial on rice seedlings, the PE treatment resulted in a 17.2% increase in root length, 5.6% increase in shoot length, and 17.8% increase in aboveground fresh weight relative to the untreated control. This study provides a distinctive paradigm for developing eco-friendly multifunctional agrochemical formulations, particularly for hydrophobic, long-alkyl-chain active ingredients, to overcome solubility and utilization challenges.