An analysis of the contrasting fates of locust swarms on the plains of North America and East Asia

[摘要] Prior to ~1880 AD locust swarms periodically raged acrossboth the North American Plains (NAP) and East Asian Plains (EAP). After thisdate, locust outbreaks almost never recurred on the NAP but have continuedto cause problems on the EAP. The large quantities of pesticides used in themajor agriculture regions of the NAP in the late 1870s have been suggested asa possible reason for the disappearance of locust outbreaks in this area.Extensive applications of modern, i.e. more effective, chemical pesticideswere also used in the granary regions of the EAP in the 1950s in an effortto reduce pest outbreaks. However, locust swarms returned again in manyareas of China in the 1960s. Therefore, locust extinction on the NAP stillremains a puzzle. Frequent locust outbreaks on the EAP over the past 130 yrmay offer clues to the key factors that control the disappearance oflocust outbreaks on the NAP.

This study analysed the climate extremes and monthlytemperature–precipitation combinations for the NAP and EAP, and found thatdifferences in the frequencies of these climate combinations resulted in thecontrasting locust fates in the two regions: restricting locust outbreaks inthe NAP but inducing such events in the EAP. Validation shows that severeEAP locust outbreak years were coincidental with extreme climate-combinationyears. Therefore, we suggest that changes in frequency, extremes and trendsin climate can explain why the fate of locust outbreaks in the EAP wasdifferent from that in the NAP. The results also suggest that, with presentglobal warming trends, precautionary measures should be taken to make sureother similar pest infestations do not occur in either region.

[学科分类] 地球化学与岩石