Silica nanoparticle-enhanced citronella nanoemulsion for sustainable control of stored-product insect pests

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This study evaluated the insecticidal efficacy of citronella nanoemulsion (CNE) enhanced with silica nanoparticles (SNPs) and formulation adjuvants against the stored-product pests Sitophilus oryzae and Tribolium castaneum. Contact toxicity and grain treatment bioassays demonstrated that SNP-based formulations significantly improved insecticidal performance compared with citronella nanoemulsion alone. Among the tested formulations, SNP–CNE combined with Provecta® and PEG 600 dioleate demonstrated the highest efficacy, achieving 91.3–100% mortality at 2.0 g/kg after one and two weeks of exposure. LC₅₀ values decreased markedly with the addition of adjuvants, indicating enhanced toxicity and formulation efficiency. Complete suppression of progeny emergence was observed at higher application rates (1.5–2.0 g/kg), whereas nanoemulsion alone demonstrated lower persistence and partial adult emergence. The enhanced efficacy is attributed to improved dispersion, increased adhesion to insect cuticle and grain surfaces, controlled release of active compounds, and the combined chemical and physical modes of action provided by silica nanoparticles. The findings demonstrate that SNP-enhanced citronella nanoemulsions represent a promising, eco-friendly alternative to conventional insecticides for sustainable stored-product pest management.