Dual-functional nanopesticide based on polydopamine-modified metal-organic framework for enhancing the control of Asian Citrus psyllid and inhibiting of Candidatus Liberibacter asiaticus.

Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus (CLas) and transmitted by Asian citrus psyllid (ACP), Diaphorina citri, poses a severe threat to global citrus production. In this study, a dual-functional nanopesticide, THX@ZIF-8/PDA, by encapsulating thiamethoxam (THX) within zeolitic imidazolate framework-8 (ZIF-8) followed by polydopamine (PDA) coating was developed, and THX loading capacity was 17.25%. THX@ZIF-8/PDA exhibited pH-responsive release, with cumulative release rates of 99.54%, 65.53%, and 59.14% at pH 5.0, 7.0, and 9.0 after 168 h, respectively. PDA modification reduced surface tension and contact angle on citrus leaves, enhancing foliar adhesion and wash-off resistance. Foliar application of THX@ZIF-8/PDA demonstrated superior toxicity against ACP and extended protection duration compared to commercial THX suspension. Comparative analysis with ZIF-8 controls confirmed that the PDA coating was the primary contributor to ROS scavenging and CLas suppression, while Zn2+ released from ZIF-8 degradation provided additional antimicrobial activity. Confocal microscopy confirmed root-to-leaf translocation of ZIF-8/PDA via the vascular system, and root-applied THX@ZIF-8/PDA enhanced antioxidant enzyme activities while reducing H₂O₂ levels. Transcriptomic analysis revealed significant enrichment in ABC transporter and circadian rhythm pathways. These results demonstrate that THX@ZIF-8/PDA offers a promising integrated strategy for simultaneously suppressing ACP and CLas, advancing sustainable HLB management.