Coupled mesoporous silica nanoparticles and limonene–chitosan Pickering emulsions: enhanced insecticidal delivery and selectivity

Abstract Background Nanodelivery represents a promising strategy to enhance pesticide efficacy while reducing associated environmental risks. Mesoporous silica nanospheres (MSNs) can serve as effective nanocarriers but improvements are essential in terms of targeting and efficiency. A promising approach involves combining nanocarriers-mediated pesticide delivery system with bioactive compounds, in which the compounds act as synergist that can disrupt insect defence mechanisms. Pickering emulsions (PEs) offer significant advantages in improving the bioavailability of active ingredients from compounds, which would enhance the synergistic effect to insecticides. Beyond encapsulating bioactive compounds, PEs serve as efficient pesticide delivery vehicles, enhancing leaf wettability and foliar deposition, making them effective adjuvants. This study aimed to construct a hybrid platform that integrates pesticides-loaded MSNs with synergistic PE as adjuvants, developing porous nanocarrier-based nanoemulsions to fight against insecticide-resistant pests. Results The nanosystem (IMI@MSNs@lim@chs) that integrates imidacloprid (IMI)-loaded MSNs with limonene–chitosan (lim@chs) Pickering emulsions as adjuvants was developed and successfully control the resistance agroforestry pests, Myzus persicae (Sulzer). The IMI@MSNs complex showed increased toxicity than IMI, which account for the pesticide absorption and delivery capacity of MSNs. While incorporation IMI@MSNs with lim@chs, the IMI@MSNs@lim@chs nanosystem achieved the highest efficacy, indicating the remarkable synergistic effect of the lim@chs adjuvant. Mechanistic analyses have demonstrated that the lim@chs enhanced IMI activity was attributed to remarkable antibacterial effects, hydrophobicity, and lipophilicity, which suppress P450-mediated detoxification by inducing gut microbiota deficiency and facilitating epidermal penetration via cuticle disruption. In parallel, the porous MSNs promote nanosystem adhesion, preventing run-off and improving the IMI recovery rate after leaching. The lipophilic lim@chs enhances leaf wettability via supramolecular interactions, benefiting droplet rebound and promoting foliar deposition. Importantly, IMI@MSNs@lim@chs exhibits reduced toxicity and minimal impact on the predation capacity of Coccinella septempunctat, demonstrating the lower environmental risks. Conclusions The findings of this study demonstrate an effective synergistic coupling of porous nanocarriers with Pickering emulsions as adjuvants to enhance pesticide delivery and selectivity, offering a promising platform for sustainable pest management. Graphical abstract