Population Genetics, Demographic History, and Potential Distributions of the New Important Pests Monolepta signata (Coleoptera: Chrysomelidae) on Corn in China

<i>Monolepta signata</i> are polyphagous pest widely distributed in China, and the damage as well as economic losses it caused were increasing in recent years. Knowledge of species diversity, population structure and habitat suitability could enhance the efforts of pest control. Here, we sampled the populations of <i>M. signata</i> in almost all of China's major corn-producing regions. A total of 568 sequences were obtained from each gene. There were 48, 29, and 30 haplotypes of <i>COI</i>, <i>ITS2</i> and <i>EF-1α</i>, respectively. The genetic distance between the HuangHuaiHai population and other populations was the largest. There were 61.90%, 71.43% and 61.90% of <i>Nm</i> values smaller than 1 in <i>COI</i>, <i>ITS2</i> and <i>EF-1α</i>, respectively, which indicated that gene flow between most populations was weak. The degree of differentiation in most populations of <i>M. signata</i> was relatively high. The population of <i>M. signata</i> has also experienced rapid expansion. Population history dynamic analysis showed that the effective population size of <i>M. signata</i> remained relatively stable before 0.075 Ma. There was a slow contraction trend from 0.075 to 0.010 Ma. It has been rapidly and continuously expanding since 0.010 Ma. Among the investigated geographical populations, the "yellow-spot type" was only present in the populations of southern and southwestern regions, while the "two-spot type" and "four-spot type" were widely distributed in all other geographical populations. Predictions of the potential distribution areas of <i>M. signata</i> indicated that the northeast and north China regions will remain being the high suitability areas of <i>M. signata</i> in the future. Our results will not only facilitate studies on the phylogeography of <i>M. signata</i> but also benefit the effective monitoring and management of this agricultural pest.