Destinations of third-generation Mythimna separata (Lepidoptera: Noctuidae) moths in Jilin and its effects on population genetic diversity

Third-generation oriental armyworm larvae, Mythimna separata (Walker) (Lepidoptera: Noctuidae), have caused considerable economic losses in Jilin. Understanding the occurrence, regularity and return movement of third-generation adults is crucial for pest forecasting. The study was conducted using systemic monitoring, radar observations and molecular markers from 2015 to 2019. The main results are as follows: (1) third-generation moths were regularly captured from late August to late September. These moths have been attributed to local emergence and were identified as an “emigration population.” Wind speed and temperature were advantageous for moth migration, and advantageous northeasterly winds account for 9.6% of the total. Radar studies determined that the migrant flying height was mainly below 600 m. Moths migrated over a range of directions, including their return movements. Forward trajectories predicted that the destination regions of the Korean Peninsula, the Russian Far East, and northern China were unfavorable for survival. (2) A total of 29 haplotypes were detected. There were unique haplotypes between two sampling years. The haplotype analysis indicated similar content in the two sampling years. The haplotype diversity indices appear to have been maintained. Overall, our findings indicate that the moths did not make a successful return flight, but the genetic diversity was unaffected.