2.1 Insects collection
The C. japonica were fed on walnut tree growing naturally. We collected the pupae from walnut trees on mountain from Longnan, Gansu province, China in July 2019. Then pupae were placed in Key Laboratory of Green Pesticide and Agricultural Bioengineering of Ministry of Education, Guizhou University, under 27±2℃, relative humidity of 75±5%, and photoperiod 14 L: 10D for 40 days. After emerging, 1 male was collected and stored at -80℃ for sequencing.