Acetylcholinesterase (AChE) is the target of organophosphate and carbamate pesticides. Organophosphate resistance is worldspread in the cotton bollworm[Helicoverpa armigera (Hübner)]. With the degenerate primers we amplified a 281 bp cDNA fragment of acetylcholinesterase (AChE) gene in H. armigera by reverse transcription-polymerase chain reaction (RT-PCR) method using total RNA extracted from 4th larva as the template. The cDNA fragment was inserted into pGEMT vector and then cloned. The deduced amino acid...