Harnessing the bio-adhesive power of natural deep eutectic solvents for trichome-inspired pest control

The carnivorous <i>Drosera</i> species employ hair-like appendages called trichomes that secrete a deadly adhesive consisting of an acidic polysaccharide, sugars, organic acids, and water to capture prey insects. Here, we develop a sustainable alternative to chemical pesticides using hyaluronic acid in a sugar-based natural deep eutectic solvent to mimic the composition and trapping mechanism of the <i>Drosera</i> mucilage. We formulate trichome biomimetic adhesives that become sprayable with added water to lower their viscosity, which can then regain the required adhesiveness as water evaporates up to the equilibrium content. Using a custom indentation setup, we measure promising adhesion energies between 9.5-14.5 µJ over one week, along with the formation of elongated fibrils (>2.3 cm) for the best-performing sample. Additionally, the material shows no phytotoxicity for over two weeks and effectively immobilizes western flower thrips through multiple contact points with the material in Petri dish bioassays, highlighting its efficacy and trapping mechanism akin to natural trichomes.