Population Genetic Structure of Chlorops oryzae (Diptera, Chloropidae) in China

Simple Summary Recently, Chlorops oryzae has become one of the major pests of rice in some regions, which has caused serious economic losses. To understand the genetic mechanisms of frequent local outbreaks and population expansion of C. oryzae, we analyzed the population genetic structure using two molecular markers, COI and ITS1 sequences. The results indicated that the C. oryzae populations experienced rapid expansion after a "Bottleneck effect" and the local outbreaks were probably caused by frequent gene flow among populations. Frequent outbreaks have made Chlorops oryzae one of the major pests of rice in some regions. In order to understand the ecological adaptation of C. oryzae at the molecular level, and provide a scientific basis for formulating management strategies, we used two molecular markers, COI and ITS1 sequences, to systematically analyze the genetic structure of 31 populations. The higher haplotype diversity and lower nucleotide diversity indicated that the C. oryzae populations experienced rapid expansion after a "Bottleneck effect". The results of the mismatch distribution, neutrality test (Fu's Fs < 0, p < 0.001), and haplotype network analysis suggested that the population has recently undergone an expansion. Although genetic differentiation among C. oryzae populations was found to have existed at low/medium levels (Fst: 0.183 for COI, 0.065 for ITS1), the frequent gene flow presented as well (Nm: 2.23 for COI, 3.60 for ITS1) was supposed to be responsible for frequent local outbreaks.