Cloning of an acetylcholinesterase gene in Locusta migratoria manilensis related to organophosphate insecticide resistance

An acetylcholinesterase (AChE, EC 3.1.1.7) cDNA was cloned and characterized from oriental migratory locust (Locusta migratoria manilensis). The complete cDNA contains a 1638-bp GC-rich (GC% = 66%) open reading frame encoding 546 amino acid residues. The key amino acid residues, including the three residues Ser151 (200 in Torpedo), Glu277 (327) and His391 (440) forming a catalytic triad, five out of six cysteines putatively forming intra-chain disulfide bonds, and 10 out of the 14 aromatic residues lining the active site of the Torpedo AChE, are conserved. Bioinformatics analysis shows that the cloned gene belongs to a member of ace1. RNA interfering (RNAi) with a specific double strand RNA (dsRNA) led to a significant decrease in AChE1 mRNA, enzyme synthesis and activity. Bioassay showed that the RNA interfered locust was more susceptible to malathion than the control. The results are discussed in the light of the hypothesis that the cloned AChE1 gene is related to the organophosphate insecticide resistance of L. migratoria manilensis.