AbstractPlant varieties expressing theBt(Bacillus thuringiensis) insecticidal proteins Cry1Ah and Cry2Ab have potential commercialization prospects in China. However, their potential effects on non-target arthropods (NTAs) remain uncharacterized. The cotton aphidAphis gossypiiis a worldwide pest that damages various important crops. The ladybeetlePropylea japonicais a common and abundant natural enemy in many cropping systems in East Asia. In the present study, the effects of Cry1Ah and Cry2Ab proteins onA. gossypiiandP. japonicawere assessed from three aspects. First, neither of the Cry proteins affected the growth or developmental characteristics of the two test insects. Second, the expression levels of the detoxification-related genes of the two test insects did not change significantly in either Cry protein treatment. Third, neither of the Cry proteins had a favourable effect on the expression of genes associated with the amino acid metabolism ofA. gossypiiand the nutrition utilization ofP. japonica. In conclusion, the Cry1Ah and Cry2Ab proteins do not appear to affect the cotton aphidA. gossypiior the ladybeetleP. japonica.