A biomimetic biofilm-inspired hydrogel for enhanced ultraviolet- shielding and anti-scouring ability of microbial pesticides

Bacillus thuringiensis is a widely used microbial pesticide but suffers from rapid degradation under ultraviolet radiation and wash-off due to rainwater, limiting its field persistence. Bacterial biofilms are formed by communities that are embedded in a self-produced matrix exhibit a set of “emergent properties” such as ultraviolet- resistance and viscosity. While conventional hydrogels primarily function as passive carriers, this study develops a novel supramolecular hydrogel formulation combining B. thuringiensis spores and crystals simulating a biofilm to enhance environmental resilience. The B. thuringiensis hydrogel exhibits a three-dimensional porous network structure, significant shear-thinning behavior, and rapid self-healing properties, facilitating spray application and adhesion. Compared to conventional B. thuringiensis wettable powder, the hydrogel demonstrates superior anti-scouring ability, increasing 47%–55% insecticidal protein deposition on the surface due to inhibited droplet bouncing and increase in adhesion force by about 85% to tomato leaves. It also enhances ultraviolet resistance, retaining 64–73% more insecticidal proteins after ultraviolet exposure indoors and outdoors, thus, inducing more damage on the gut of target insect larvae. Consequently, the field control efficiency of the hydrogel reached 73% against tomato leafminer after 14 days, 27% higher than the wettable powder. This hydrogel offers a promising approach to prolong microbial pesticide persistence in sustainable agriculture.