Are outbreaks of Nilaparvata lugens (Stål) associated with global warming?

Outbreaks of the Nilaparvata lugens (Stål), have occurred frequently in China during the past few years, resulting in a broad and significant reduction in rice yield. N. lugens immigrate into China each spring from Southeast Asia, and the Guangxi Zhuang Autonomous Region is the first area affected. Light trap catches for the early season period (March-June) in Guangxi for the past 30 yr have been analyzed, and the catch sequences for five observation stations (Longzhou, Hepu, Yongning Yongfu, and Quanzhou) were studied in detail. It was found that during the past 10 yr the first appearance of N. lugens at light traps occurs earlier, there is a higher frequency of days with large light-trap catches, and catches in southern Guangxi are larger. Recently light-trap catches have also increased in northern Guangxi. It is concluded that the increasing number of immigrants from overseas is one of the primary reasons for the increase in N. lugens outbreaks in the past 10 yr. Global warming, and specifically winter temperature increases, appears to be for a factor accelerating outbreaks of N. lugens in Asia.