Stimulatory effects (hormesis) of acetamiprid on demographical traits and vitellogenin gene expression of melon aphid, Aphis gossypii Glover, were examined. The longevity and fecundity of the parental aphids (F-0) were both reduced by a low lethal concentration of acetamiprid (LC15), while no effect was observed when exposed to a sublethal concentrations (LC5). However, acetamiprid-induced hormetic effects were observed in the (F)1 generation. The pre-adult developmental period and fertility of progeny aphids were increased by both concentrations (LC5 and LC15). Subsequently, key demographic parameters such as intrinsic rate of increase (r) and finite rate of increase (lambda) were increased by the LC5, and the mean generation time (T) and net reproductive rate (R-0) were enhanced by both concentrations of acetamiprid. Furthermore, both acetamiprid concentrations induced the expression level of Vg gene in the progeny generation. The higher mRNA transcript level of Vg might be translated into an increased reproduction of F-1 generation in A. gossypii. Based on the results, acetamiprid at low or sublethal concentrations may induce stimulatory effects on the subsequent generations of A. gossypii along with the increased transcription of Vg gene. These findings may help understanding the hormetic effects of acetamiprid in insects and could help optimizing the use of this insecticide against A. gossypii.