Some unorthodox views on the classification and evolution of the migratory locusts in China prompted by molecular population genetic study
ZHANG De Xing ** YAN Lu Na KANG Le JI Ya Jie (State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China)
The migratory locusts have perhaps been the most important agricultural pest in China since the earliest historical time. Traditionally, locust populations in China have been classified into three subspecies based mostly on morphological differences, viz: the oriental migratory locust (Locusta migratoria manilensis), the Asiatic migratory locust (Locusta migratoria migratoria) and the Tibetan migratory locust (Locusta migratoria tibetensis) . Morphological characters (as well as other characters such as generation number) are, however, not always reliable particularly for widely distributed organisms such as Locusta, since they can be much affected by regional climatic and ecological variation in addition to genetic difference. Significant overlaps, for example, of morphometric values between locusts from different groups have well been observed. Also, the central area of the Huabei plain has been considered to be the ancestral area of the migratory locusts in China, in connection with the dynamics of river development and the formation of delta and alluvial fans. However, the impact of some major historical climatic events such as the last glaciation has not been considered in such analyses. Therefore, the validity of the aforementioned conclusions and opinions on the classification and population evolution of the migratory locusts in China are questionable and deserves further examination. Here we give our unorthodox views on these issues prompted by data from molecular population genetic study, and suggest some major revisions. This also implies that the migratory locusts have a great potential to colonize further north in North China following the global warming crisis, for it appears that the only limiting factor for their northward dispersal up to the latitude 46°N is winter temperature and not photoperiod or genetic background .