Neuropeptides are the key molecules in a multiplicity of physiological processes and their use in pest control has recently been suggested. Most neuropeptides are produced in the form of a precursor that is cleaved by proteolysis to yield various biologically active peptides. To mimic this structure, a method has been developed for synthesizing genes that code for putative polyneuropeptide precursors. As a model neuropeptide, the 5-amino-acid proctolin, one of the best studied invertebrate neuropeptides, functioning both as a visceral and a skeletal neuromuscular transmitter, was chosen. The synthetic gene was introduced into bacteria and tobacco plants, where it was efficiently transcribed. We present our results as a possible approach for the expression, in a variety of organisms, of synthetic genes coding for a wide repertoire of insect neuropeptides.