The authors thank Yongqiang Liu, Chao Li, Xiaoyang Zhao,
Bingtang Xie and Chaoxing Hu (Institute of Plant Protection, Chinese
Academy of Agricultural Sciences) and also Kai Xiong, Yu Cui,
Congzheng Yuan and Shengyuan Zhao (College of Agronomy and
Plant Protection, Qingdao Agricultural University) for their contributions
to the field investigation. The comments and suggestions
from Dr. F. P. F. Reay-Jones and Dr. V. A. Drake and anonymous
referees helped a lot to improve the manuscript. This research was
supported by the National Natural Science Foundation of China
(grant number. 31321004).