Development of an ecofriendly biomimetic nano-silica acaricide featuring fusion protein-based self-encapsulation and biocontrol functions against Tetranychus urticae

The two-spotted spider mite ( Tetranychus urticae ) is a major pest that causes severe agricultural losses. Its resistance to chemical acaricides diminishes their effectiveness, exacerbating their misuse and environmental pollution, highlighting the need for alternative solutions. This study presented a biomimetic nano silica acaricide (BNSA) developed using a fusion protein, BAP-R5, which integrated the acaricidal protein BAP from Bacillus vallismortis NBIF-001 with the R5 peptide from Cylindrotheca fusiformis . Through ecofriendly biomimetic silicification, the BAP-R5 protein achieved high encapsulation efficiency (91.2%-98.0%) within nano silica matrices. The resulting BNSAs featured tunable micromorphologies from dispersed nanoparticles to dense wet gels. The formulation sustained protein release in 14 days with release rates ranging from 12.5% to 21.0%, and robust adhesion to both mite cuticles and fava bean leaves. Notably, the BNSAs exhibited 2.45-fold higher contact toxicity against T. urticae compared to free BAP-R5, confirming synergistic effects of nanoencapsulation. Under abiotic stress (pH 2-12, 60-80 °C), the BNSAs retained 67.3%-93.9% residual activity versus 38.2%-71.5% for free protein, validating their environmental resilience. These results establish a novel paradigm for precision-targeted nano pesticide design through biomimetic engineering, addressing critical challenges in sustainable agriculture.