关键词: 白纹伊蚊, 双氧木脂素A, nAChR-α5, RNAi技术, 壳聚糖/dsRNA纳米颗粒

Abstract: 【Aim】To explore whether the nicotinic acetylcholine receptor α5 (nAChR-α5) subunit in Aedes albopictus is a potential target for haedoxan A (HA), so as to provide a reference for the effective control of A. albopictus. 【Methods】 The coding sequence (CDS) of nAChR-α5 gene of A. albopictus was cloned by PCR and phylogenetic tree was constructed. RT-qPCR was used to detect the expression level of nAChR-α5 in A. albopictus at different developmental stages (1st-4th instar larvae, pupa and female adult without blood feeding). The expression level of nAChR-α5 in the 2nd instar larva of A. albopictus was knocked down by chitosan/dsRNA nanoparticle-mediated RNAi technology. The susceptibility of the 3rd instar larva of A. albopictus to HA ［LC₃₀ (0.3 mg/L) and LC₅₀ (0.4 mg/L)］ after RNAi was determined by bioassay. 【Results】 The CDS of A. albopictus nAChR-α5 is 1 296 bp in length, encoding 431 amino acids with a typical cysteine loop (Cys-loop) of nAChR. Protein sequence alignment and phylogenetic tree showed that nAChR-α5 of A. albopictus had the highest homology and closest relationship with nAChR-α5 of A. aegypti. The expression level of nAChR-α5 in the 4th instar larva was the highest, followed by that in the female adults of A. albopictus. At 24 h after feeding chitosan/dsnAChR-α5 nanoparticles (the concentration of dsRNA was about 0.3% w/w), the interference efficiency of chitosan/dsnAChR-α5 nanoparticles on nAChR-α5 was the highest, reaching 70% in the 2nd instar larva of A. albopictus. The mortalities of the 3rd instar larvae of A. albopictus in nAChR-α5 knockdown group under treatment of HA at LC₃₀ and LC₅₀ were significantly reduced by 9.89%-15.45% as compared with those in the blank control fed with the diet without dsRNA and negative control fed with the diet containing chitosan/dsGFP nanoparticle, indicating that the susceptibility of A. albopictus to HA was significantly reduced by knockdown of nAChR-α5. 【Conclusion】nAChR-α5 of A. albopictus may be one of the potential targets of HA, and HA may affect nerve conduction by interfering with the function of nAChR-α5 of A. albopictus.

Key words: Aedes albopictus; haedoxan A, nAChR-α5, RNAi technology, chitosan/dsRNA nanoparticles